JP7230673B2 - pneumatic tire - Google Patents

Description

The present invention relates to pneumatic tires.

In a pneumatic tire, a plurality of grooves are formed on the surface of the tread portion for the purpose of discharging water between the tread surface and the road surface when driving on a wet road surface. It has a tread pattern. In conventional pneumatic tires, various performances are ensured by devising tread patterns.

For example, in the tire disclosed in Patent Document 1, the center main groove is composed of a plurality of outer groove portions extending in the tire circumferential direction, a plurality of inner groove portions extending axially inward of the outer groove portions in the tire circumferential direction, and an outer groove portion. The on-snow performance is improved by forming a zigzag shape including a plurality of slanted portions that join with the inner groove portion and are slanted with respect to the tire circumferential direction. Further, in the tire described in Patent Document 2, the central block row is divided into adjacent block rows adjacent in the tire width direction by dividing grooves extending in the tire circumferential direction, and each adjacent block row is sequentially adjacent in the tire circumferential direction. arranging a plurality of blocks on both sides of the dividing groove in the tire width direction, displacing the plurality of blocks in the tire circumferential direction with respect to each other, and arranging in each block four sipes whose both ends are closed in each block. As a result, both wear resistance and uneven wear resistance are achieved while ensuring ice and snow performance. Further, in the pneumatic tire described in Patent Document 3, the crown main groove provided between the shoulder main groove and the tire equator is arranged along the tire circumferential direction between the inclined portions inclined in opposite directions. It has an extending flute.

JP 2017-121919 A Japanese Patent No. 6426051 JP 2019-18753 A

Here, among pneumatic tires, there are so-called studless tires that have improved running performance on ice and snow. Studless tires are required to have snow traction on snow-covered road surfaces. One means of improving snow traction is to make the main groove extending in the tire circumferential direction zigzag. In this technique, the main groove is extended in the tire circumferential direction and vibrated in the tire width direction, thereby forming a protrusion projecting in the tire width direction in a block defined by the main groove. For example, as in Patent Documents 1 and 3, by forming a convex portion projecting in the tire width direction in a block partitioned by a main groove, edge components can be increased and snow traction can be improved. can.

However, if the block is formed with a protrusion that protrudes in the tire width direction, there is a risk that the drainage performance will be reduced and the wet grip performance, which is the grip performance on a wet road surface, will be reduced. For this reason, it has been very difficult to ensure snow traction while suppressing deterioration in wet grip.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire that achieves both snow traction and wet grip.

In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention provides a plurality of circumferential main grooves extending in the tire circumferential direction, the tire equator in the tire width direction across the tire equatorial plane. Two inner circumferential main grooves, which are the circumferential main grooves disposed on both sides of the surface, and the circumferential main grooves disposed outside the two inner circumferential main grooves in the tire width direction. an outer circumferential main groove which is a groove; a plurality of center lug grooves disposed between the two inner circumferential main grooves and extending in the tire width direction; a plurality of middle lug grooves disposed between the directional main grooves and extending in the tire width direction; a center block partitioned by the two inner circumferential direction main grooves and the center lug groove; a middle block defined by the directional main groove, the outer circumferential main groove, and the middle lug groove, wherein the center block and the middle block are defined by the inner circumferential main groove; a second circumferential direction portion extending in the tire circumferential direction; and the inner circumferential main groove extending in the tire circumferential direction at a position different from the second circumferential direction portion in the tire circumferential direction and with respect to the second circumferential direction portion. and a first circumferential portion that is offset to the side of the center block. and a projection defined by the first circumferential portion and an imaginary line extending the second circumferential portion toward the first circumferential portion in the middle block. The area Sm is characterized by having a relationship of Sc>Sm.

Further, in the above pneumatic tire, it is preferable that the center block is divided in the tire width direction by a center narrow groove.

Further, in the pneumatic tire described above, it is preferable that the center narrow groove extends linearly in the tire circumferential direction and has a groove width of 1 mm or more and 5 mm or less.

In the above pneumatic tire, the center block has a length Lc1 in the tire circumferential direction of the first circumferential portion, and a length Lc1 in the tire circumferential direction of the center small blocks arranged on both sides of the center narrow groove in the tire width direction. The relationship with the maximum length Lc is within the range of 0.2≦(Lc1/Lc)≦0.4, and the middle block has a length Lm1 in the tire circumferential direction of the first circumferential portion, It is preferable that the relationship between the middle block and the maximum length Lm in the tire circumferential direction is within the range of 0.15≦(Lm1/Lm)≦0.35.

Further, in the above pneumatic tire, the center block is arranged on both sides of the center narrow groove in the tire width direction by an offset amount Dc between the first circumferential portion and the second circumferential portion in the tire width direction. The relationship between the center small block and the maximum width Wc in the tire width direction is within the range of 0.05≦(Dc/Wc)≦0.15, and the middle block is composed of the first circumferential portion and the second circumferential portion. The relationship between the offset amount Dm in the tire width direction from the circumferential portion and the maximum width Wm of the middle block in the tire width direction is within the range of 0.05≦(Dm/Wm)≦0.15. preferable.

Moreover, in the pneumatic tire described above, it is preferable that the center lug groove has two or more bent portions.

Further, in the above pneumatic tire, the center block and the middle block have an offset amount Dc in the tire width direction between the first circumferential portion and the second circumferential portion of the center block, and A relationship between an offset amount Dm in the tire width direction between the first circumferential portion and the second circumferential portion is within a range of 0.95≦(Dc/Dm)≦1.05, and A relationship between length Lc1 of the first circumferential portion in the tire circumferential direction and length Lm1 of the middle block in the tire circumferential direction is preferably Lc1>Lm1.

Further, in the above pneumatic tire, the center block may have a relationship between a length Lc1 of the first circumferential portion in the tire circumferential direction and a length Lc2 of the second circumferential portion in the tire circumferential direction of 0.5. 6≦(Lc1/Lc2)≦0.8, and the middle block has a length Lm1 in the tire circumferential direction of the first circumferential portion and a length Lm1 in the tire circumferential direction of the second circumferential portion. It is preferable that the relationship with the height Lm2 is within the range of 0.5≦(Lm1/Lm2)≦0.7.

Further, in the above pneumatic tire, the center block has a width direction extending portion extending in the tire width direction at an intersection with the first circumferential portion in an edge portion partitioned by the center lug groove. the middle block has an inclined portion inclined with respect to the tire width direction and the tire circumferential direction at an intersection with the first circumferential direction portion in the edge portion partitioned by the middle lug groove, The center block and the middle block have an angle θc between the first circumferential portion of the center block and the widthwise extending portion, and an angle between the first circumferential portion of the middle block and the inclined portion. θm preferably satisfies the relationship θc<θm.

Further, in the above pneumatic tire, the relationship between the groove width Lwc of the center lug groove and the pitch Pc in the tire circumferential direction between the center blocks adjacent to each other in the tire circumferential direction via the center lug groove is 0.05. It is preferably within the range of ≦(Lwc/Pc)≦0.35.

In the above pneumatic tire, the shoulder land portion is positioned outside the outer circumferential main groove in the tire width direction and defined by the outer circumferential main groove, and the maximum width of the center block in the tire width direction is provided. The relationship between Wcw, the maximum width Wm of the middle block in the tire width direction, and the maximum width Wsw of the shoulder land portion in the tire width direction is within the range of 0.4≦(Wm/Wcw)≦0.6. and preferably within the range of 0.8≦(Wsw/Wcw)≦1.0.

In the above pneumatic tire, the center block is divided in the tire width direction by a center narrow groove extending in the tire circumferential direction, thereby having center small blocks arranged on both sides of the center narrow groove in the tire width direction. The shoulder land portion is divided in the tire width direction by shoulder narrow grooves extending in the tire circumferential direction, thereby having shoulder small blocks arranged on both sides of the shoulder narrow grooves in the tire width direction. It is preferable that the same number of sipes be arranged in the block and the shoulder small block.

In the above pneumatic tire, the center block is divided in the tire width direction by a center narrow groove extending in the tire circumferential direction, thereby having center small blocks arranged on both sides of the center narrow groove in the tire width direction. Two open sipes are arranged in each of the center small block and the middle block, and one closed sipe is arranged in the center small block between the open sipe and the center lug groove. It is preferable that one closed sipe is arranged between the open sipe and the middle lug groove in the middle block.

ADVANTAGE OF THE INVENTION The pneumatic tire which concerns on this invention is effective in the snow traction property and wet grip property being compatible.

1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. FIG. FIG. 2 is a detailed view of the center block shown in FIG. FIG. 3 is a detailed view of part A in FIG. FIG. 4 is a detailed view of the B portion in FIG. FIG. 5 is a detailed view of part A in FIG. 1, and is an explanatory view of the dimensions of the projections of the center small block and the middle block. FIG. 6 is a detailed view of part A in FIG. 1, and is an explanatory view of the dimensions of the lug grooves of the center small block and the middle block. FIG. 7 is an explanatory diagram of the width of the land portion shown in FIG. FIG. 8 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the center fine groove oscillates. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the center narrow groove is curved. FIG. 10 is a modification of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the center narrow groove is formed in a crank shape. FIG. 11 is a modification of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the center fine groove is repeatedly bent. FIG. 12A is a chart showing the results of a performance evaluation test of pneumatic tires. FIG. 12B is a chart showing the results of a performance evaluation test of pneumatic tires. FIG. 12C is a chart showing the results of a performance evaluation test of pneumatic tires.

EMBODIMENT OF THE INVENTION Below, embodiment of the pneumatic tire which concerns on this invention is described in detail based on drawing. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced and easily conceived by those skilled in the art, or those that are substantially the same.

[Embodiment]
In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, the tire radial direction inner side refers to the side facing the rotation axis in the tire radial direction, and the tire radial direction outer side. means the side away from the rotation axis in the tire radial direction. Moreover, the tire circumferential direction refers to the circumferential direction with the rotation axis as the central axis. In addition, the tire width direction refers to a direction parallel to the rotation axis, the tire width direction inner side refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction, and the tire width direction outer side refers to the direction in the tire width direction. The side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane perpendicular to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL is the center of the pneumatic tire 1 in the tire width direction. The tire width direction centerline, which is the position, coincides with the position in the tire width direction. The tire width is the width in the tire width direction between the outermost portions in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. A tire equator line is a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1 .

FIG. 1 is a plan view showing a tread surface 3 of a pneumatic tire 1 according to an embodiment. The pneumatic tire 1 shown in FIG. 1 has a tread portion 2 disposed on the outermost portion in the tire radial direction. ) is formed as a tread surface 3 that comes into contact with the road surface during running. A plurality of circumferential main grooves 30 extending in the tire circumferential direction and a plurality of lug grooves 40 extending in the tire width direction are formed in the tread surface 3 . A plurality of land portions 10 are defined on the tread surface 3 by the plurality of circumferential main grooves 30 and lug grooves 40 .

Specifically, four circumferential main grooves 30 are formed side by side in the tire width direction, and two inner grooves are arranged on both sides of the tire equatorial plane CL in the tire width direction across the tire equatorial plane CL. Circumferential direction main grooves 31 and two outer circumferential direction main grooves 32 arranged one by one on the outside of each of the two inner circumferential direction main grooves 31 in the tire width direction are provided. Of these, the outer circumferential main groove 32 is the outermost circumferential main groove 30 among the plurality of circumferential main grooves 30 in the tire width direction. The lug grooves 40 include a center lug groove 41 disposed between the two inner circumferential main grooves 31 and extending in the tire width direction, and the inner circumferential main grooves 31 and the outer circumferential main grooves 31 adjacent in the tire width direction. A middle lug groove 42 disposed between the main groove 32 and extending in the tire width direction, and a shoulder lug groove 43 disposed outside the outer circumferential main groove 32 in the tire width direction and extending in the tire width direction are provided. It is

The circumferential main groove 30 here means a longitudinal groove at least partially extending in the tire circumferential direction. In general, the circumferential main groove 30 has a groove width of 4 mm or more, a groove depth of 10 mm or more, and a tread wear indicator (slip sign) indicating the end of wear. In the present embodiment, the circumferential main groove 30 has a groove width of 5 mm or more, a groove depth of 15 mm or more, and a tire equator line (center line). Further, of the circumferential main grooves 30, the inner circumferential main grooves 31 are formed by repeatedly bending in the tire width direction while extending in the tire circumferential direction. The outer circumferential main groove 32 may extend linearly in the tire circumferential direction, or may be formed in a wavy or zigzag shape. In the present embodiment, the outer circumferential main groove 32 is also formed by repeatedly bending in the tire width direction while extending in the tire circumferential direction, similarly to the inner circumferential main groove 31 .

The lug groove 40 has a groove width of 4 mm or more and 10 mm or less, and a groove depth of 7 mm or more and 15 mm or less. In the present embodiment, the lug grooves 40 are inclined in the tire circumferential direction with respect to the tire width direction while extending in the tire width direction.

Further, the tread surface 3 is formed with circumferential narrow grooves 50 extending in the tire circumferential direction with a groove width narrower than the groove width of the circumferential main grooves 30 and the groove width of the lug grooves 40 . Specifically, the circumferential narrow groove 50 is arranged outside the center narrow groove 51 arranged between the two inner circumferential main grooves 31 and the outer circumferential main groove 32 in the tire width direction. A shoulder narrow groove 52 is provided. The circumferential narrow groove 50 here has a groove width in the range of 1 mm or more and 5 mm or less, and a groove depth in the range of 7 mm or more and 20 mm or less.

Among the circumferential narrow grooves 50 formed as described above, the center narrow groove 51 is disposed between the two inner circumferential main grooves 31 and near the center in the tire width direction, and is located at the tire equator. It is positioned on the plane CL or in the vicinity of the tire equatorial plane CL. The center narrow groove 51 formed in this manner extends linearly in the tire circumferential direction, and both ends in the tire circumferential direction are open to the center lug grooves 41 . That is, the center narrow groove 51 is formed to extend in the tire circumferential direction between the center lug grooves 41 adjacent to each other in the tire circumferential direction, and both ends thereof are open to the center lug grooves 41 respectively.

Note that the center narrow groove 51 may not strictly extend in the tire circumferential direction, and may be slightly inclined with respect to the tire circumferential direction. The center narrow groove 51 is preferably formed within ±2° with respect to the tire circumferential direction.

In addition, the shoulder narrow groove 52 is arranged near the center in the tire width direction between the outer circumferential main groove 32 and the design end E, which is the outer end of the tread surface 3 in the tire width direction. The design end E here refers to the outermost end of the tread portion 2 in the tire width direction, and is the outermost end of the tread portion 2 in the tire width direction where grooves are formed. The shoulder thin grooves 52 formed in this way are repeatedly bent in the tire width direction while extending in the tire circumferential direction. That is, the shoulder narrow groove 52 extends in the tire circumferential direction in a zigzag shape that repeatedly bends in the tire width direction while extending in the tire circumferential direction.

A plurality of shoulder lug grooves 43 are arranged on both sides of the shoulder thin grooves 52 in the tire width direction. Of the shoulder lug grooves 43 arranged on both sides of the shoulder narrow groove 52 in the tire width direction, the shoulder lug groove 43 arranged on the inner side in the tire width direction of the shoulder narrow groove 52 has an inner end in the tire width direction on the outside. It opens into the circumferential main groove 32 and opens into the shoulder narrow groove 52 at the outer end in the tire width direction. Further, of the shoulder lug grooves 43 arranged on both sides of the shoulder narrow groove 52 in the tire width direction, the shoulder lug groove 43 arranged on the outer side in the tire width direction of the shoulder narrow groove 52 has an inner end portion in the tire width direction. is opened to the shoulder narrow groove 52, and the end portion on the outside in the tire width direction is opened at the design end E. That is, one end of each of the shoulder lug grooves 43 arranged on both sides of the shoulder narrow groove 52 in the tire width direction opens into the shoulder narrow groove 52 , and the end portion of the shoulder lug groove 43 on the side that opens into the shoulder narrow groove 52 . are opened at different positions between the shoulder lug grooves 43 arranged on both sides of the shoulder narrow groove 52 in the tire width direction. In this way, different shoulder lug grooves 43 are arranged on the inner side and the outer side of the shoulder narrow groove 52 in the tire width direction.

A plurality of land portions 10 are formed on the tread surface 3 by a plurality of circumferential main grooves 30, lug grooves 40, and circumferential narrow grooves 50. The land portions 10 are composed of a center block 11 and a middle block 12. and a shoulder land portion 13 . Of these, the center block 11 is positioned between the two inner circumferential main grooves 31 and serves as the land portion 10 defined by the two inner circumferential main grooves 31 and the center lug groove 41 . In addition, the middle block 12 is positioned between the inner circumferential main groove 31 and the outer circumferential main groove 32 that are adjacent in the tire width direction, and the inner circumferential main groove 31, the outer circumferential main groove 32, and the middle lugs that are adjacent to each other. The land portion 10 is divided by the groove 42 . Further, the shoulder land portion 13 is positioned outside the outer circumferential main groove 32 in the tire width direction and serves as the land portion 10 defined by the outer circumferential main groove 32 and the shoulder lug grooves 43 . In this embodiment, the center lug groove 41, the middle lug groove 42, and the shoulder lug groove 43 that partition the land portion 10 as described above are all inclined in the tire circumferential direction with respect to the tire width direction.

Among the plurality of land portions 10 formed on the tread surface 3, the center block 11 is divided in the tire width direction by the center narrow groove 51, and two center blocks 11 are arranged on both sides of the center narrow groove 51 in the tire width direction. Each has a small block 11a. Specifically, each center small block 11a is defined by center lug grooves 41 on both sides in the tire circumferential direction, defined by inner circumferential main grooves 31 on the outer side in the tire width direction, and center narrow grooves 51 on the inner side in the tire width direction. are divided by The center block 11 has a center small block row 21 in which a plurality of center small blocks 11a partitioned by the center lug groove 41, the inner circumferential main groove 31, and the center narrow groove 51 are aligned in the tire circumferential direction. 51 on both sides in the tire width direction.

In other words, a plurality of center small blocks 11a are arranged on both sides of the center narrow groove 51 in the tire width direction, and the center blocks 11 are arranged on both sides of the center narrow groove 51 in the tire width direction. By arranging them side by side in the circumferential direction, they have center small block rows 21 on both sides of the center narrow groove 51 in the tire width direction. At this time, since the center lug grooves 41 that partition the center small blocks 11a are open at both ends to the inner circumferential main grooves 31, the center lug grooves 41 are located on both sides of the center narrow grooves 51 in the tire width direction. A single center lug groove 41 defines the end of the center small block 11 a in the block row 21 in the tire circumferential direction. In other words, the center lug grooves 41 that divide the ends on the same side in the tire circumferential direction of the two center small blocks 11a that are located on both sides of the center narrow groove 51 in the tire width direction at the same position in the tire circumferential direction are: It is formed continuously from one center small block 11a side to the other center small block 11a side.

A plurality of middle blocks 12 are arranged between the center block 11 and the shoulder land portion 13. Both sides in the tire circumferential direction are partitioned by the middle lug grooves 42, and the inner side in the tire width direction is the inner circumferential main portion. It is defined by grooves 31 , and the outer side in the tire width direction is defined by outer circumferential main grooves 32 . A plurality of middle blocks 12 formed in this way are arranged in the tire circumferential direction, and a middle block row 22 is formed by the plurality of middle blocks 12 arranged in the tire circumferential direction between the center block 11 and the shoulder land portion 13 . is formed.

The shoulder land portion 13 is divided in the tire width direction by shoulder narrow grooves 52 , and on both sides of the shoulder narrow grooves 52 in the tire width direction are shoulder small grooves whose both sides in the tire circumferential direction are partitioned by shoulder lug grooves 43 . Each has a plurality of blocks 13a. Of these, the shoulder small block 13a positioned on the inner side in the tire width direction of the shoulder narrow groove 52 is defined on both sides in the tire circumferential direction by the shoulder lug grooves 43, and defined on the inner side in the tire width direction by the outer circumferential main groove 32. , and the outer side in the tire width direction are defined by shoulder narrow grooves 52 . The shoulder small blocks 13a located on the outer side in the tire width direction of the shoulder narrow grooves 52 are defined on both sides in the tire circumferential direction by the shoulder lug grooves 43 and on the inner side in the tire width direction by the shoulder narrow grooves 52. The outer side in the direction is defined by the design end E. The shoulder land portion 13 has shoulder small block rows 23 in which a plurality of shoulder small blocks 13a partitioned in this manner are arranged in the tire circumferential direction on both sides of the shoulder narrow groove 52 in the tire width direction.

In other words, a plurality of shoulder small blocks 13a are arranged on both sides of the shoulder narrow groove 52 in the tire width direction, and a plurality of shoulder small blocks 13a are arranged on both sides of the shoulder narrow groove 52 in the tire width direction. By arranging them side by side in the tire circumferential direction, shoulder small block rows 23 are provided on both sides of the shoulder narrow groove 52 in the tire width direction. In this case, the shoulder lug grooves 43 that partition the shoulder small blocks 13a are provided with different shoulder lug grooves 43 on both sides of the shoulder narrow groove 52 in the tire width direction. Therefore, the shoulder lug grooves 43 divide the tire circumferential end portions of the shoulder small blocks 13 a in the shoulder small block rows 23 on both sides of the shoulder thin groove 52 in the tire width direction with different shoulder lug grooves 43 .

A plurality of sipes 70 are formed in each land portion 10 formed on the tread surface 3 . That is, a plurality of sipes 70 are formed in each of the center small block 11a, the middle block 12 and the shoulder small blocks 13a.

The sipe 70 referred to here is formed in the shape of a narrow groove on the tread surface 3, and when the pneumatic tire 1 is mounted on a regular rim and the internal pressure is normal, the sipe 70 forms a fine groove when no load is applied. Although the wall surfaces do not contact each other, when the thin groove is located on the ground contact surface formed on the flat plate when the load is applied in the vertical direction, or when the land portion where the thin groove is formed collapses, The wall surfaces forming the narrow groove, or at least a part of the portions provided on the wall surfaces, are in contact with each other due to the deformation of the land portion 10 . A regular rim is a "standard rim" defined by JATMA, a "design rim" defined by TRA, or a "measuring rim" defined by ETRTO. The normal internal pressure is the maximum air pressure specified by JATMA, the maximum value specified by TRA "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or the "INFLATION PRESSURES" specified by ETRTO. In this embodiment, the sipe 70 has a width of less than 1 mm and a depth of 7 mm or more and 12 mm or less.

When comparing the number of sipes 70 per block, the center small block 11a, the middle block 12, and the shoulder small block 13a have the same number of sipes 70, respectively. are placed. The sipes 70 include an open sipe 71 whose end in the tire width direction opens into the circumferential main groove 30 or the circumferential narrow groove 50 , and a closed sipe 72 whose end in the tire width direction terminates within the land portion 10 . have. These sipes 70 are formed by repeatedly bending in the tire circumferential direction while extending in the tire width direction substantially parallel to the extending direction of the lug grooves 40 that define the land portions 10 in which the sipes 70 are formed. ing.

Specifically, two open sipes 71 are arranged in each of the center small block 11a and the middle block 12 . One closed sipe 72 is arranged between the open sipe 71 and the center lug groove 41 in the center small block 11a, and the closed sipe 72 is arranged between the open sipe 71 and the middle lug groove 42 in the middle block 12. is arranged. That is, two open sipes 71 are arranged in the tire circumferential direction in the center small block 11a, and one closed sipe 72 is arranged between each open sipe 71 and the center lug groove 41. . Similarly, the middle block 12 has two open sipes 71 arranged in the tire circumferential direction, and one closed sipe 72 is arranged between each open sipe 71 and the middle lug groove 42 .

On the other hand, four closed sipes 72 are arranged side by side in the tire circumferential direction in each of the shoulder small blocks 13a located on both sides of the shoulder narrow groove 52 in the tire width direction. . In this way, four closed sipes 72 are arranged in the shoulder small block 13a, and two open sipes 71 and two closed sipes 72 are arranged in the center small block 11a and the middle block 12, respectively. A book sipe 70 is arranged. Therefore, the same number of sipes 70 are arranged in each of the center small block 11a, the middle block 12, and the shoulder small blocks 13a.

FIG. 2 is a detailed view of the center block 11 shown in FIG. 2 to 11, the illustration of the sipe 70 is omitted for convenience in order to explain the shape of the land portion 10. As shown in FIG. The center lug groove 41 disposed between the two inner circumferential main grooves 31 opens to the inner circumferential main grooves 31 having different ends in the tire width direction. The center lug groove 41 extends in the tire width direction and is bent at a plurality of points in the tire circumferential direction. It has two or more bent portions 45 that are changing portions.

In this embodiment, two bent portions 45 are formed in one center lug groove 41 . The two bent portions 45 bend in opposite directions when moving from one inner circumferential main groove 31 side toward the other inner circumferential main groove 31 side along the center lug groove 41 . Thus, the center lug groove 41 is formed in a crank-like shape. In addition, the center lug groove 41 formed in a crank-like shape is inclined with respect to the tire width direction at each of the portions extending from the two bent portions 45 toward the inner circumferential main groove 31. The direction and angle of inclination are the same at two portions extending from the bent portion 45 toward the inner circumferential main groove 31 . All of the plurality of center lug grooves 41 arranged between the two inner circumferential main grooves 31 are formed in the same shape.

The center narrow groove 51 , whose end in the tire circumferential direction opens to the center lug groove 41 , opens to the bent portion 45 of the center lug groove 41 . The center lug groove 41 has two bent portions 45, and since the center narrow groove 51 is open to the bent portion 45 of the center lug groove 41, it is positioned on both sides of the center narrow groove 51 in the tire width direction. The center small blocks 11a are offset from each other in the tire circumferential direction. That is, since the center lug groove 41 that partitions the center small block 11a is formed in a crank-like shape, the positions in the tire circumferential direction are different on both sides of the bent portion 45 of the center lug groove 41 in the tire width direction. . Since the center narrow groove 51 is open to the bent portion 45 of the center lug groove 41 formed in such a crank-like shape, the center lug groove 41 is positioned on both sides of the bent portion 45 in the tire width direction. Along with the different circumferential positions, the center small blocks 11a located on both sides of the center narrow groove 51 in the tire width direction also have different positions in the tire circumferential direction, similarly to the center lug grooves 41 . As a result, the center small blocks 11a located on both sides of the center narrow groove 51 in the tire width direction are shifted from each other in the tire circumferential direction.

FIG. 3 is a detailed view of part A in FIG. The center block 11 and the middle block 12, which are adjacent to each other with the inner circumferential main groove 31 interposed therebetween, have different positions in the tire circumferential direction. That is, the position where the center lug groove 41 that defines the center block 11 opens into the inner circumferential main groove 31 and the position that the middle lug groove 42 that defines the middle block 12 opens into the inner circumferential main groove 31 are different from each other. The position in the direction is different. For this reason, for example, the center lug groove 41 is formed with respect to the inner circumferential main groove 31 at a position between the positions where two middle lug grooves 42 adjacent in the tire circumferential direction open to the inner circumferential main groove 31 . It is open. Similarly, the middle lug groove 42 opens to the inner circumferential main groove 31 at a position between the positions where two center lug grooves 41 adjacent in the tire circumferential direction open to the inner circumferential main groove 31 . ing.

Further, the center block 11 and the middle block 12 have edge portions 60 defined by the inner circumferential main grooves 31 because the inner circumferential main grooves 31 extend in the tire circumferential direction and repeatedly bend in the tire width direction. are formed in a step shape. Specifically, the center block 11 and the middle block 12 have an edge portion 60 defined by the inner circumferential main groove 31 and each having a first circumferential portion 61 and a second circumferential portion 62 extending in the tire circumferential direction. are doing. That is, both the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 and the middle block 12 are formed substantially parallel to the tire equatorial plane CL.

The first circumferential portion 61 and the second circumferential portion 62 may not strictly extend in the tire circumferential direction, and may be slightly inclined with respect to the tire circumferential direction. The first circumferential portion 61 and the second circumferential portion 62 are preferably formed within ±2° with respect to the tire circumferential direction.

Of the first circumferential portion 61 and the second circumferential portion 62, the first circumferential portion 61 extends in the tire circumferential direction at a position different from that of the second circumferential portion 62 in the tire circumferential direction. It is offset toward the inner circumferential main groove 31 with respect to the second circumferential portion 62 . That is, the first circumferential portion 61 is closer to the center of the groove width of the inner circumferential main groove 31 than the second circumferential portion 62 is, or is closer to the first circumferential portion 61 or the second circumferential portion 61 in the inner circumferential main groove 31 than the second circumferential portion 62 is. It is located on the groove wall side facing the groove wall on the side where the circumferential portion 62 is located. Alternatively, the first circumferential portion 61 is located on the opposite side of the second circumferential portion 62 to the center of the block having the first circumferential portion 61 in the tire width direction. As a result, the edge portions 60 of the center block 11 and the middle block 12 having the first circumferential portion 61 and the second circumferential portion 62 both extend in the tire circumferential direction, and their positions in the tire width direction change stepwise. formed in shape.

Since the edge portion 60 defined by the inner circumferential main groove 31 is thus formed in a stepped shape, the center block 11 has a portion defined by the inner circumferential main groove 31 extending outward in the tire width direction. A projecting convex portion 14 is formed. That is, the center block 11 protrudes outward in the tire width direction by offsetting the first circumferential portion 61 of the edge portion 60 defined by the inner circumferential main groove 31 with respect to the second circumferential portion 62 . A convex portion 14 is formed, and the first circumferential portion 61 constitutes an edge portion 60 of the convex portion 14 . Similarly, the middle block 12 protrudes inward in the tire width direction to the portion defined by the inner circumferential main groove 31 by forming the edge portion 60 defined by the inner circumferential main groove 31 in a stepped shape. A convex portion 15 is formed. That is, the middle block 12 protrudes inward in the tire width direction by offsetting the first circumferential portion 61 of the edge portion 60 defined by the inner circumferential main groove 31 with respect to the second circumferential portion 62 . A convex portion 15 is formed, and the first circumferential portion 61 constitutes an edge portion 60 of the convex portion 15 .

A first circumferential portion 61 of the edge portion 60 defined by the inner circumferential main groove 31 in the center block 11 and a first circumferential portion 61 of the edge portion 60 defined by the inner circumferential main groove 31 in the middle block 12 The direction portion 61 is arranged on the same side in the tire circumferential direction with respect to the second circumferential direction portion 62 of the edge portion 60 of each block. Furthermore, the center lug groove 41 and the middle lug groove 42 open at different positions in the tire circumferential direction with respect to the inner circumferential main groove 31 . Therefore, the positions of the first circumferential portion 61 of the edge portion 60 of the center block 11 and the first circumferential portion 61 of the edge portion 60 of the middle block 12 are different in the tire circumferential direction. As a result, the first circumferential portion 61 of the edge portion 60 of the center block 11 generally faces the second circumferential portion 62 of the edge portion 60 of the middle block 12 , and the first circumferential portion 61 of the edge portion 60 of the middle block 12 faces the second circumferential portion 62 of the edge portion 60 of the middle block 12 . The circumferential portion 61 generally faces the second circumferential portion 62 of the edge portion 60 of the center block 11 . That is, the convex portion 14 of the center block 11 generally faces the second circumferential portion 62 of the edge portion 60 of the middle block 12 , and the convex portion 15 of the middle block 12 generally faces the edge portion 60 of the center block 11 . It faces the second circumferential portion 62 .

FIG. 4 is a detailed view of the B portion in FIG. A convex portion 14 is formed on the center block 11 and a convex portion 15 is formed on the middle block 12. The convex portion area Sc, which is the area of the convex portion 14 of the center block 11, and the convex portion of the middle block 12 The convex area Sm, which is the area of the portion 15, has a relationship of Sc>Sm. In this case, the convex area Sc of the center block 11 is calculated by dividing the first circumferential portion 61 with the imaginary line Vc extending the second circumferential portion 62 toward the first circumferential portion 61 in the tire circumferential direction. It is an area divided by That is, the convex portion area Sc of the center block 11 is an area defined by the convex portion 14 and the imaginary line Vc extending the second circumferential portion 62 toward the convex portion 14 side. In addition, the convex area Sm of the middle block 12 is determined by the imaginary line Vm extending the second circumferential portion 62 toward the first circumferential portion 61 in the tire circumferential direction and the first circumferential portion 61 of the middle block 12. It is a divided area. That is, the convex portion area Sm of the middle block 12 is an area defined by the convex portion 15 and the imaginary line Vm extending the second circumferential portion 62 toward the convex portion 15 .

The relationship between the convex area Sc of the center block 11 and the convex area Sm of the middle block 12 is preferably within the range of 1.05≦(Sc/Sm)≦1.15.

FIG. 5 is a detailed view of part A in FIG. 1, and is an explanatory view of the dimensions of the projections 14 and 15 of the center small block 11a and the middle block 12. As shown in FIG. The center block 11 and the middle block 12 have an offset amount Dc in the tire width direction between the first circumferential portion 61 and the second circumferential portion 62 of the edge portion 60 of the center block 11 , and the edge portion 60 of the middle block 12 . The relationship between the offset amount Dm in the tire width direction between the first circumferential portion 61 and the second circumferential portion 62 of is within the range of 0.95≦(Dc/Dm)≦1.05. That is, the offset amount Dc between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 and the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 are , are of similar size. In other words, the projection amount of the projection 14 of the center small block 11a and the projection amount of the projection 15 of the middle block 12 are approximately the same.

Also, the length Lc1 in the tire circumferential direction of the first circumferential portion 61 of the edge portion 60 of the center block 11 and the length Lm1 in the tire circumferential direction of the first circumferential portion 61 of the edge portion 60 of the middle block 12 is Lc1>Lm1. The relationship between the length Lc1 of the first circumferential portion 61 of the center block 11 in the tire circumferential direction and the length Lm1 of the first circumferential portion 61 of the middle block 12 in the tire circumferential direction is 1.1≦( Lc1/Lm1) is preferably within the range of 1.4. Also, since the first circumferential portions 61 of the center block 11 and the middle blocks 12 are offset with respect to the second circumferential portions 62 of the center block 11 and the middle blocks 12, the first circumferential portions 61 of the respective blocks are offset. Between the 61 and the second circumferential portion 62, there is a portion that is inclined with respect to the tire circumferential direction and connects the first circumferential portion 61 and the second circumferential portion 62, but the center block The length Lc1 of the first circumferential portion 61 of 11 and the length Lm1 of the first circumferential portion 61 of the middle block 12 are the portions connecting the first circumferential portion 61 and the second circumferential portion 62 in this manner. The length does not include

Further, in the center block 11, the relationship between the length Lc1 of the first circumferential portion 61 in the tire circumferential direction and the length Lc2 of the second circumferential portion 62 in the tire circumferential direction is 0.6≦(Lc1/Lc2 )≦0.8. In the middle block 12, the relationship between the length Lm1 of the first circumferential portion 61 in the tire circumferential direction and the length Lm2 of the second circumferential portion 62 in the tire circumferential direction is 0.5≦(Lm1/Lm2). )≦0.7.

The relationship between the length Lc1 of the first circumferential portion 61 and the length Lc2 of the second circumferential portion 62 of the center block 11 is within the range of 0.65≦(Lc1/Lc2)≦0.75. The relationship between the length Lm1 of the first circumferential portion 61 and the length Lm2 of the second circumferential portion 62 of the middle block 12 is within the range of 0.55≦(Lm1/Lm2)≦0.65. is preferred. In this case, the length Lc2 of the second circumferential portion 62 of the center block 11 and the length Lm2 of the second circumferential portion 62 of the middle block 12 are equal to the length Lc1 of the first circumferential portion 61 of the center block 11 . and the length Lm1 of the first circumferential portion 61 of the middle block 12, the length does not include the portion connecting the first circumferential portion 61 and the second circumferential portion 62. As shown in FIG.

In the center block 11, the relationship between the length Lc1 of the first circumferential portion 61 in the tire circumferential direction and the maximum length Lc of the center small block 11a of the center block 11 in the tire circumferential direction is 0.2≦0.2. It is within the range of (Lc1/Lc)≦0.4. Further, in the middle block 12, the relationship between the length Lm1 of the first circumferential portion 61 in the tire circumferential direction and the maximum length Lm of the middle block 12 in the tire circumferential direction is 0.15≦(Lm1/Lm)≦ It is within the range of 0.35.

The relationship between the length Lc1 of the first circumferential portion 61 of the center block 11 and the maximum length Lc of the center small block 11a is within the range of 0.25≦(Lc1/Lc)≦0.35. is preferable, and the relationship between the length Lm1 of the first circumferential portion 61 of the middle block 12 and the maximum length Lm of the middle block 12 is within the range of 0.2≦(Lm1/Lm)≦0.3. is preferred.

Further, the center block 11 has a relationship between the offset amount Dc in the tire width direction between the first circumferential portion 61 and the second circumferential portion 62 and the maximum width Wc of the center small block 11a in the tire width direction, which is 0.00. 05≦(Dc/Wc)≦0.15. Further, in the middle block 12, the relationship between the offset amount Dm in the tire width direction between the first circumferential portion 61 and the second circumferential portion 62 and the maximum width Wm of the middle block 12 in the tire width direction is 0.05. ≦(Dm/Wm)≦0.15.

The relationship between the offset amount Dc between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 and the maximum width Wc of the center small block 11a is 0.08≦(Dc/Wc)≦0. .12, and the relationship between the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 and the maximum width Wm of the middle block 12 is 0. It is preferably in the range of 0.08≦(Dm/Wm)≦0.12.

FIG. 6 is a detailed view of part A in FIG. 1, and is an explanatory view of the dimensions of the lug grooves 40 of the center small block 11a and the middle block 12. As shown in FIG. The center block 11 has a widthwise extending portion 66 extending in the tire width direction at an edge portion 60 defined by the center lug groove 41 and intersecting with the first circumferential portion 61 . That is, since the center lug groove 41 is formed to be inclined with respect to the tire width direction, the center lug groove 41 extends in the tire width direction even at the edge portion 60 defined by the center lug groove 41 in the center block 11 . On the other hand, the inclined portion is inclined in the tire circumferential direction with respect to the tire width direction. The direction of inclination of the center lug groove 41 is defined by the edge portion 60 on the side connected to the first circumferential portion 61 among the edge portions 60 on both sides in the groove width direction of the center lug groove 41 and the first circumferential portion 61 is tilted in the direction of an acute angle relative to Of the edge portion 60 defined by the center lug groove 41 of the center block 11 formed in this way, the portion near the first circumferential portion 61 is a width direction extending portion formed extending in the tire width direction. 66 , and the edge portion 60 defined by the center lug groove 41 in the center block 11 is connected to the first circumferential portion 61 at the widthwise extending portion 66 . The edge portion 60 defined by the center lug groove 41 in the center block 11 thus has a width direction extension portion 66 extending in the tire width direction at the intersection with the first circumferential portion 61 .

In addition, the middle block 12 has an inclined portion 67 inclined with respect to the tire width direction and the tire circumferential direction at the intersection of the edge portion 60 defined by the middle lug groove 42 and the first circumferential portion 61 . there is Specifically, the middle lug groove 42 extends in the tire width direction and is inclined in the tire circumferential direction with respect to the tire width direction. , the relative angle between the edge portion 60 on the side connected to the first circumferential portion 61 and the first circumferential portion 61 is inclined so as to form an acute angle. In this way, the edge portion 60 of the middle lug groove 42 on the side connected to the first circumferential portion 61 is bent at a portion closer to the first circumferential portion 61, and the bent portion and the first circumferential portion 61 are bent. A portion between and is an inclined portion 67 that is inclined with respect to the tire width direction and the tire circumferential direction. The inclination direction of the inclined portion 67 in the tire circumferential direction with respect to the tire width direction is the same as that of the portion other than the inclined portion 67 of the edge portion 60 of the middle lug groove 42 on the side connected to the first circumferential direction portion 61 with respect to the tire width direction. It is in the opposite direction to the direction of inclination in the circumferential direction. Therefore, the relative angle between the first circumferential portion 61 of the middle block 12 and the inclined portion 67 is an obtuse angle. The edge portion 60 defined by the middle lug groove 42 in the middle block 12 is inclined with respect to the tire width direction and the tire circumferential direction at the intersection with the first circumferential direction portion 61 as described above. It has an inclined portion 67 with an obtuse angle relative to 61 .

The center block 11 having the widthwise extending portion 66 and the middle block 12 having the inclined portion 67 have an angle θc between the first circumferential portion 61 of the center block 11 and the widthwise extending portion 66, The angle .theta.m between the first circumferential portion 61 and the inclined portion 67 has a relationship of .theta.c<.theta.m. Note that the relationship between the angle θc between the first circumferential portion 61 of the center block 11 and the widthwise extending portion 66 and the angle θm between the first circumferential portion 61 of the middle block 12 and the inclined portion 67 is 0.0. It is preferably in the range of 5≦(θc/θm)≦0.8. Also, the angle θc between the first circumferential portion 61 and the widthwise extending portion 66 of the center block 11 is preferably in the range of 85° or more and 95° or less.

The center lug groove 41 that partitions the center block 11 and the center block 11 are defined by the groove width Lwc of the center lug groove 41 and the tire circumference of the center blocks 11 that are adjacent to each other in the tire circumferential direction via the center lug groove 41 . The relationship with the pitch Pc in the direction is within the range of 0.05≦(Lwc/Pc)≦0.35. In this case, the groove width Lwc of the center lug groove 41 is the maximum width between opposing groove walls of the center lug groove 41 in the portion other than the widthwise extending portion 66 of the center lug groove 41 . In addition, the pitch Pc in the tire circumferential direction between the center blocks 11 adjacent in the tire circumferential direction via the center lug groove 41 is, in other words, the pitch Pc between the center small blocks 11a adjacent in the tire circumferential direction via the center lug groove 41. The pitch is Pc in the tire circumferential direction. Moreover, it is preferable that the relationship between the groove width Lwc of the center lug groove 41 and the pitch Pc of the center block 11 in the tire circumferential direction is within the range of 0.15≦(Lwc/Pc)≦0.25.

FIG. 7 is an explanatory diagram of the width of the land portion 10 shown in FIG. Between the center block 11 and the middle block 12, the relationship between the maximum width Wcw of the center block 11 in the tire width direction and the maximum width Wm of the middle block 12 in the tire width direction is 0.4≦(Wm/Wcw)≦0. .6. Further, between the center block 11 and the shoulder land portion 13, the relationship between the maximum width Wcw of the center block 11 in the tire width direction and the maximum width Wsw of the shoulder land portion 13 in the tire width direction is 0.8≦(Wsw/ Wcw)≦1.0.

The middle block 12 and the shoulder land portion 13 are edge portions defined by the outer circumferential main groove 32 because the outer circumferential main groove 32 extends in the tire circumferential direction and repeatedly bends in the tire width direction. 60 are each formed in a stepped shape. For this reason, the middle block 12 has a convex portion 16 projecting outward in the tire width direction in a portion defined by the outer circumferential main groove 32, and the shoulder land portion 13 has an outer circumferential main groove. A convex portion 17 that protrudes inward in the tire width direction is formed in a portion partitioned by 32 .

The pneumatic tire 1 according to this embodiment is used as a heavy-duty pneumatic tire. When this pneumatic tire 1 is mounted on a vehicle, it is mounted on the vehicle in a state in which it is assembled with a rim wheel and inflated. A pneumatic tire 1 mounted on a rim wheel is used by being mounted on a large vehicle such as a truck or a bus.

When a vehicle equipped with the pneumatic tire 1 runs, the pneumatic tire 1 rotates while the lower tread tread surface 3 of the tread tread surface 3 is in contact with the road surface. When a vehicle equipped with the pneumatic tire 1 runs on a dry road surface, mainly due to the frictional force between the tread surface 3 and the road surface, driving force and braking force are transmitted to the road surface and turning force is generated. It runs by letting it run. Also, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters the circumferential main groove 30, the lug grooves 40, etc., and these grooves allow the water between the tread surface 3 and the road surface to flow. Drain while driving. As a result, the tread surface 3 can easily contact the road surface, and the vehicle can run due to the frictional force between the tread surface 3 and the road surface.

When traveling on a snowy road surface, the pneumatic tire 1 compacts the snow on the road surface with the tread surface 3, and the snow on the road surface enters the circumferential main grooves 30 and the lug grooves 40, thereby removing the snow. is also pressed and hardened in the groove. In this state, driving force or braking force acts on the pneumatic tire 1, or force acts in the width direction of the tire due to turning of the vehicle. , a so-called snow shear force is generated between the pneumatic tire 1 and the snow. When driving on a snowy road surface, the shear force of the snow column generates resistance between the pneumatic tire 1 and the road surface. Since it can be secured, the vehicle can run on the snow-covered road surface.

Moreover, since the circumferential main groove 30 extends in the tire circumferential direction and repeatedly bends in the tire width direction, a portion of each land portion 10 defined by the circumferential main groove 30 has a protrusion projecting in the tire width direction. Portions 14, 15, 16 and 17 are formed. Thereby, each land part 10 can increase the edge component, and can further improve the snow traction. For example, the edge portions 60 defined by the inner circumferential main grooves 31 of the center block 11 and the middle block 12 are each formed in a stepped shape, whereby the inner circumferential main grooves of the center block 11 and the middle block 12 are formed. Protrusions 14 and 15 are formed in the portions partitioned by 31, respectively. As a result, the center block 11 and the middle block 12 can increase edge components and improve snow traction.

On the other hand, when the land portion 10 is formed with a protrusion projecting in the tire width direction, the flow of water flowing through the circumferential main groove 30 is hindered when the water is drained in the circumferential main groove 30, and the drainage performance is improved. is likely to decrease. In contrast, in the pneumatic tire 1 according to the present embodiment, the convex area Sc of the convex portion 14 of the center block 11 and the convex portion area Sm of the convex portion 15 of the middle block 12 have a relationship of Sc>Sm. It's becoming As a result, the inner circumferential main groove 31 improves the snow traction property with the protrusions 14 of the center block 11 having a large protrusion area Sc, while the protrusions 15 of the middle block 12 have a small protrusion area Sm. A decrease in drainage performance in the inner circumferential main groove 31 can be suppressed. Therefore, since it is possible to ensure the drainage performance when traveling on a wet road surface, it is possible to ensure the grounding performance of the tread surface 3 when traveling on a wet road surface. Grip performance can be secured. As a result, both snow traction and wet grip can be achieved.

In addition, since the center block 11 is divided in the tire width direction by the center narrow groove 51, the center narrow groove 51 can ensure drainage. As a result, the center narrow groove 51 can ensure drainage when the edge portion 60 defined by the inner circumferential main groove 31 is formed in a step shape to ensure snow traction. As a result, it is possible to more reliably achieve both snow traction and wet grip.

In addition, since the center narrow groove 51 extends linearly in the tire circumferential direction and has a groove width in the range of 1 mm or more and 5 mm or less, water can flow inside the center narrow groove 51 while suppressing a decrease in rigidity of the center block 11. It can flow easily. As a result, the drainage performance of the center thin groove 51 can be ensured more reliably. As a result, wet grip properties can be improved more reliably.

Further, the relationship between the length Lc1 of the first circumferential portion 61 of the center block 11 and the maximum length Lc of the center small block 11a is within the range of 0.2≦(Lc1/Lc)≦0.4. Also, the relationship between the length Lm1 of the first circumferential portion 61 of the middle block 12 and the maximum length Lm of the middle block 12 is within the range of 0.15≦(Lm1/Lm)≦0.35. Therefore, it is possible to more reliably achieve both snow traction and wet grip. That is, when (Lc1/Lc)<0.2 or (Lm1/Lm)<0.15, the length Lc1 of the first circumferential portion 61 of the center block 11 and the length of the middle block 12 There is a possibility that the length Lm1 of the first circumferential portion 61 is too short. In this case, the volume of the convex portion 14 of the center block 11 and the convex portion 15 of the middle block 12 becomes small, and it becomes difficult to secure the rigidity of the convex portions 14 and 15. There is a risk that the properties of the product may easily deteriorate. Further, when (Lc1/Lc)>0.4 or (Lm1/Lm)>0.35, the length Lc1 of the first circumferential portion 61 of the center block 11 and the length of the middle block 12 There is a possibility that the length Lm1 of the first circumferential portion 61 is too long. In this case, it may become difficult to secure the volume of the inner circumferential main groove 31, and the amount of snow and water that can enter the inner circumferential main groove 31 is reduced, resulting in snow traction and wet grip. There is a possibility that it may become difficult to effectively secure the

On the other hand, within the range of 0.2≦(Lc1/Lc)≦0.4 and within the range of 0.15≦(Lm1/Lm)≦0.35, the convex portion 14 of the center block 11 The volume of the inner circumferential main groove 31 can be ensured while suppressing the volume of the protrusion 15 of the middle block 12 from becoming too small. This allows more snow and water to enter the inner circumferential main groove 31 while ensuring the rigidity of the projections 14 and 15 more reliably. As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, the relationship between the offset amount Dc between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 and the maximum width Wc of the center small block 11a is 0.05≦(Dc/Wc)≦0. .15, and the relationship between the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 and the maximum width Wm of the middle block 12 is 0.05≦(Dm /Wm)≦0.15, it is possible to more reliably achieve both snow traction and wet grip. That is, when (Dc/Wc)<0.05 or (Dm/Wm)<0.05, the difference between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 is Since the offset amount Dc and the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 are too small, even if the convex portions 14 and 15 are formed in the center block 11 and the middle block 12, , it may become difficult to effectively ensure snow traction. Further, when (Dc/Wc)>0.15 or (Dm/Wm)>0.15, the distance between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 is Since the offset amount Dc and the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 are too large, it may be difficult to secure the volume of the inner circumferential main groove 31 . In this case, the amount of snow and the amount of water that can enter the inner circumferential main groove 31 is reduced, so there is a risk that it will be difficult to effectively ensure snow traction and wet grip.

On the other hand, in the range of 0.05≤(Dc/Wc)≤0.15 and in the range of 0.05≤(Dm/Wm)≤0.15, the first While suppressing the offset amount Dc between the circumferential portion 61 and the second circumferential portion 62 and the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 from becoming too small, The volume of the inner circumferential main groove 31 can be ensured. As a result, more snow and water can enter the inner circumferential main groove 31 while the snow traction is effectively ensured by the protrusions 14 and 15 . As a result, it is possible to more reliably achieve both snow traction and wet grip.

In addition, since the center lug groove 41 has two or more bent portions 45, the center small block 11a and the center lug groove 41 can secure the snow column shear force in a plurality of directions. As a result, snow traction can be improved more reliably.

Also, the offset amount Dc between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 and the offset amount Dm between the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 Since the relationship is within the range of 0.95≦(Dc/Dm)≦1.05, it is possible to more reliably achieve both snow traction and wet grip. That is, when (Dc/Dm)<0.95 or (Dc/Dm)>1.05, the difference between the offset amount Dc of the center block 11 and the offset amount Dm of the middle block 12 is It is likely to grow too large. In this case, on the side where the offset amount between the first circumferential portion 61 and the second circumferential portion 62 is large, the flow of water flowing in the inner circumferential main groove 31 is obstructed, and there is a risk that the drainage performance will deteriorate. Further, on the side where the amount of offset between the first circumferential portion 61 and the second circumferential portion 62 is small, even if the first circumferential portion 61 and the second circumferential portion 62 are offset, the snow traction is effectively improved. There is a risk that it will be difficult to secure

On the other hand, when the relationship between the offset amount Dc of the center block 11 and the offset amount Dm of the middle block 12 is within the range of 0.95≦(Dc/Dm)≦1.05, the offset of the center block 11 Since the amount Dc and the offset amount Dm of the middle block 12 can be approximately the same, it is possible to effectively ensure snow traction while ensuring ease of water flow in the inner circumferential main groove 31. can be done. As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, since the relationship between the length Lc1 of the first circumferential portion 61 of the center block 11 and the length Lm1 of the first circumferential portion 61 of the middle block 12 is Lc1>Lm1, the offset amount of the center block 11 is The convex area Sc of the convex portion 14 of the center block 11 can be made larger than the convex portion area Sm of the convex portion 15 of the middle block 12 without making Dc too large. As a result, the protrusion area Sc of the protrusion 14 of the center block 11 is increased while suppressing the deterioration of the drainage performance of the inner circumferential main groove 31 when the protrusion area Sc of the protrusion 14 of the center block 11 is increased. Thus, snow traction can be improved. As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, the relationship between the length Lc1 of the first circumferential portion 61 and the length Lc2 of the second circumferential portion 62 of the center block 11 is within the range of 0.6≦(Lc1/Lc2)≦0.8. , because the relationship between the length Lm1 of the first circumferential portion 61 and the length Lm2 of the second circumferential portion 62 of the middle block 12 is within the range of 0.5≦(Lm1/Lm2)≦0.7. , it is possible to more reliably achieve both snow traction and wet grip. That is, when (Lc1/Lc2)<0.6 or (Lm1/Lm2)<0.5, the length Lc1 of the first circumferential portion 61 of the center block 11 and the length of the middle block 12 There is a possibility that the length Lm1 of the first circumferential portion 61 is too short. In this case, the volume of the convex portion 14 of the center block 11 and the convex portion 15 of the middle block 12 becomes small, and it becomes difficult to secure the rigidity of the convex portions 14 and 15. Therefore, the grip when the center block 11 and the middle block 12 touch the ground becomes difficult. There is a risk that the properties of the product may be easily deteriorated. Further, when (Lc1/Lc2)>0.8 or (Lm1/Lm2)>0.7, the length Lc1 of the first circumferential portion 61 of the center block 11 and the length of the middle block 12 There is a possibility that the length Lm1 of the first circumferential portion 61 is too long. In this case, it may become difficult to secure the volume of the inner circumferential main groove 31, and the amount of snow and water that can enter the inner circumferential main groove 31 is reduced, resulting in snow traction and wet grip. There is a possibility that it may become difficult to effectively secure the

On the other hand, within the range of 0.6≦(Lc1/Lc2)≦0.8 and within the range of 0.5≦(Lm1/Lm2)≦0.7, the convex portion 14 of the center block 11 The volume of the inner circumferential main groove 31 can be ensured while suppressing the volume of the protrusion 15 of the middle block 12 from becoming too small. This allows more snow and water to enter the inner circumferential main groove 31 while ensuring the rigidity of the projections 14 and 15 more reliably. As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, the angle θc between the first circumferential portion 61 of the center block 11 and the widthwise extending portion 66 and the angle θm between the first circumferential portion 61 of the middle block 12 and the inclined portion 67 satisfy θc<θm. Because of this relationship, the convex area Sc of the convex part 14 of the center block 11 can be made larger than the convex part area Sm of the convex part 15 of the middle block 12 more reliably. As a result, it is possible to more reliably improve the snow traction performance by the convex portion 14 of the center block 11 and suppress the deterioration of the drainage performance at the position of the inner circumferential main groove 31 on the middle block 12 side. As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, since the relationship between the groove width Lwc of the center lug groove 41 and the pitch Pc between the center blocks 11 in the tire circumferential direction is within the range of 0.05≦(Lwc/Pc)≦0.35, it is more reliable. It is possible to achieve both snow traction and wet grip. That is, if the relationship between the groove width Lwc of the center lug groove 41 and the pitch Pc of the center block 11 satisfies (Lwc/Pc)<0.05, the groove width Lwc of the center lug groove 41 may be too narrow. , it may become difficult to secure the volume of the center lug groove 41 . In this case, the amount of snow and water that can enter the center lug grooves 41 is reduced, and it may become difficult to effectively ensure snow traction and wet grip. If the relationship between the groove width Lwc of the center lug groove 41 and the pitch Pc of the center block 11 satisfies (Lwc/Pc)>0.35, the groove width Lwc of the center lug groove 41 may be too wide. . In this case, since it becomes difficult to ensure the rigidity of the center block 11, there is a possibility that the grip performance of the center block 11 at the time of contacting the ground is likely to deteriorate.

On the other hand, when the relationship between the groove width Lwc of the center lug groove 41 and the pitch Pc of the center block 11 is within the range of 0.05≦(Lwc/Pc)≦0.35, the rigidity of the center block 11 is It is possible to secure the volume of the center lug groove 41 while suppressing the excessive decrease of the center lug groove 41, and to allow more snow and water to enter the center lug groove 41. - 特許庁As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, the relationship between the maximum width Wcw of the center block 11 in the tire width direction and the maximum width Wm of the middle block 12 in the tire width direction is within the range of 0.4≦(Wm/Wcw)≦0.6. , it is possible to more reliably achieve both snow traction and wet grip. In other words, when the relationship between the maximum width Wcw of the center block 11 and the maximum width Wm of the middle block 12 is (Wm/Wcw)<0.4, the width of the middle block 12 with respect to the maximum width Wcw of the center block 11 is Since the maximum width Wm is too small, the overall length of the middle lug groove 42 may become too short. In this case, it may become difficult to secure the shearing force of the snow column and the drainage performance in the middle lug grooves 42 . Further, when the relationship between the maximum width Wcw of the center block 11 and the maximum width Wm of the middle block 12 satisfies (Wm/Wcw)>0.6, the width of the center block 11 relative to the maximum width Wm of the middle block 12 is Since the maximum width Wcw is too small, the total length of the center lug groove 41 may become too short. In this case, it may become difficult to secure the shearing force of the snow column and the drainage performance in the center lug groove 41 .

On the other hand, when the relationship between the maximum width Wcw of the center block 11 and the maximum width Wm of the middle block 12 is within the range of 0.4≤(Wm/Wcw)≤0.6, the maximum width of the center block 11 is Both the width Wcw and the maximum width Wm of the middle block 12 can be set to appropriate widths. As a result, both the center lug grooves 41 and the middle lug grooves 42 can secure appropriate overall lengths, and both the lug grooves 40 can appropriately secure snow shear force and drainage performance. As a result, it is possible to more reliably achieve both snow traction and wet grip.

Further, the relationship between the maximum width Wcw of the center block 11 in the tire width direction and the maximum width Wsw of the shoulder land portion 13 in the tire width direction is within the range of 0.8≦(Wsw/Wcw)≦1.0. In this case, it is possible to more reliably achieve both snow traction and wet grip. That is, when the relationship between the maximum width Wcw of the center block 11 and the maximum width Wsw of the shoulder land portion 13 is (Wsw/Wcw)<0.8, the maximum width Wcw of the center block 11 and the shoulder land portion Since the maximum width Wsw of 13 is too small, the length of the shoulder lug groove 43 may become too short. In this case, it may become difficult to secure the shearing force of the snow column and the drainage performance in the shoulder lug grooves 43 . Further, when the relationship between the maximum width Wcw of the center block 11 and the maximum width Wsw of the shoulder land portion 13 satisfies (Wsw/Wcw)>1.0, the center block width relative to the maximum width Wsw of the shoulder land portion 13 is Since the maximum width Wcw of 11 is too small, the overall length of the center lug groove 41 may be too short. In this case, it may become difficult to secure the shearing force of the snow column and the drainage performance in the center lug groove 41 .

On the other hand, when the relationship between the maximum width Wcw of the center block 11 and the maximum width Wsw of the shoulder land portion 13 is within the range of 0.8≦(Wsw/Wcw)≦1.0, the center block 11 Both the maximum width Wcw and the maximum width Wsw of the shoulder land portion 13 can be set to appropriate widths. As a result, both the center lug grooves 41 and the shoulder lug grooves 43 can have appropriate lengths, and both the lug grooves 40 can properly secure the snow shear force and drainage performance. can. As a result, it is possible to more reliably achieve both snow traction and wet grip.

In addition, since sipes 70 are formed in the center small block 11a, the shoulder small blocks 13a, and the middle block 12, respectively, the edge component can be increased, and the edge effect ensures more reliable snow traction and wet grip. can be improved. Furthermore, since the same number of sipes 70 are arranged in the center small block 11a, the shoulder small block 13a and the middle block 12, the edge effect can be uniformly obtained over the entire tire width direction. It is possible to further improve traction and wet grip. As a result, snow traction and wet grip can be improved more reliably.

Two open sipes 71 are arranged in each of the center small block 11a and the middle block 12, and one closed sipe 72 is arranged between the open sipe 71 and the lug groove 40, respectively. Snow traction and wet grip can be more reliably improved while suppressing uneven wear of the small block 11a and the middle block 12 . In other words, when the sipes 70 are arranged in the center small block 11a or the middle block 12, by arranging the closed sipes 72 at positions near the lug grooves 40, the rigidity at positions near the lug grooves 40, where the rigidity tends to decrease, is reduced. can be suppressed as much as possible, and the edge effect can be improved. As a result, it is possible to suppress uneven wear of the center small block 11a and the middle block 12 and more reliably improve snow traction and wet grip. As a result, snow traction and wet grip can be improved more reliably while ensuring uneven wear resistance.

[Modification]
In the embodiment described above, the center narrow groove 51 is formed in a linear shape extending in the tire circumferential direction, but the center narrow groove 51 may be formed in a shape other than a linear shape. FIG. 8 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram when the center narrow groove 51 oscillates. FIG. 9 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the center narrow groove 51 is curved. FIG. 10 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the center narrow groove 51 is formed in a crank shape. FIG. 11 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the center narrow groove 51 is repeatedly bent. For example, as shown in FIG. 8, the center narrow groove 51 may extend in the tire circumferential direction and oscillate in the tire width direction. That is, the center narrow groove 51 may be formed in a zigzag shape while extending in the tire circumferential direction. Alternatively, for example, as shown in FIG. 9, the center narrow groove 51 may extend in the tire circumferential direction and oscillate in the tire width direction by repeatedly curving. In other words, the center narrow groove 51 may be formed in a wavy shape while extending in the tire circumferential direction.

Alternatively, for example, as shown in FIG. 10, the center narrow groove 51 extends in the tire width direction and is bent at two points, thereby forming a crank-like shape between the center lug grooves 41 adjacent in the tire circumferential direction. may be formed of Alternatively, for example, as shown in FIG. 11, the center narrow groove 51 is formed between both center lug grooves 41 while repeating bending between the center lug grooves 41 adjacent in the tire circumferential direction. may The center narrow groove 51 is formed in a shape that can divide the center block 11 in the tire width direction by being formed between the center lug grooves 41 that partition both sides of the center block 11 in the tire circumferential direction. If it is, its shape does not matter.

Moreover, although four circumferential main grooves 30 are formed in the above-described embodiment, the number of circumferential main grooves 30 may be other than four. Regardless of the number of circumferential main grooves 30, the inner circumferential main grooves 31 and the outer circumferential main grooves 32 disposed on the outer side of the inner circumferential main grooves 31 in the tire width direction allow the center block 11 and the middle block 12 to be separated from each other. The number of circumferential main grooves 30 does not matter as long as they are separated from each other.

Two open sipes 71 and two closed sipes 72 are arranged in the center small block 11a and the middle block 12, and four closed sipes 72 are arranged in the shoulder small block 13a. , the sipes 70 formed in each land portion 10 may have other numbers and configurations. The sipe 70 arranged on the land portion 10 is preferably set as appropriate according to the position, size, etc. of the land portion 10 on which the sipe 70 is arranged.

[Example]
12A to 12C are charts showing the results of performance evaluation tests for pneumatic tires. Performance evaluation tests performed on the pneumatic tire 1 according to the present invention and the pneumatic tire of the comparative example will be described below. In the performance evaluation test, snow traction performance, which is traction performance on a snowy road surface, and wet braking performance, which is braking performance on a wet road surface, were tested.

In the performance evaluation test, a pneumatic tire 1 with a tire nominal size specified by JATMA of 275/80R22.5 was mounted on a rim wheel with a specified rim specified by JATMA, and the air pressure was set to the maximum air pressure specified by JATMA. 2-D4 (1 front axle with 2 wheels, rear 2 axles, front axle with 4 wheels and drive axle, rear axle with 4 wheels and free axle) mounted on a test vehicle (truck) and test run. It was done by

The evaluation method for each test item is based on ECE R117-02 (ECE Regulation No. 117 Revision 2) for snow traction. was measured to calculate the acceleration, and the calculated acceleration was evaluated by expressing it as an index with Comparative Example 1 as 100, which will be described later. The higher the value, the better the acceleration performance on snowy roads and the higher the snow traction.

In addition, wet braking performance was performed in accordance with ECE R117-02. It was evaluated by expressing it as an index. The higher the number, the better the braking performance on wet roads, and the higher the wet braking performance.

The performance evaluation test includes Examples 2 to 19, which are examples of the pneumatic tire 1 according to the present invention, Comparative Examples 1 and 2, which are examples of the pneumatic tire to be compared with the pneumatic tire 1 according to the present invention, and Reference Twenty-one types of pneumatic tires in Example 1 were tested. Of these, in the pneumatic tire of Comparative Example 1, the edge portion 60 defined by the circumferential main groove 30 does not have a stepped shape. Further, in the pneumatic tire of Comparative Example 2, although the edge portion 60 defined by the circumferential main groove 30 has a stepped shape, the convex portion area Sc of the convex portion 14 of the center block 11 and the middle block 12 and the convex portion area Sm of the convex portion 15 do not satisfy the relationship of Sc>Sm.

On the other hand, in Examples 2 to 19, which are examples of the pneumatic tire 1 according to the present invention, the edge portion 60 defined by the circumferential main groove 30 has a step shape, and the convex portion of the center block 11 The convex area Sc of 14 and the convex area Sm of the convex part 15 of the middle block 12 all satisfy the relationship of Sc>Sm. Furthermore, in the pneumatic tire 1 according to Examples 2 to 19 and Reference Example 1 , whether or not the center block 11 is divided, whether or not the center block 11 is divided by the linearly extending center narrow groove 51, and whether or not the center block 11 is divided The number of bent portions 45 of the lug groove 41, the offset amount Dc in the tire width direction between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11, and the first circumferential portion 61 and the second circumferential portion 62 of the middle block 12 The ratio of the offset amount Dm to the circumferential portion 62 (Dc/Dm), the ratio of the length Lc1 of the first circumferential portion 61 of the center block 11 to the length Lc2 of the second circumferential portion 62 (Lc1/Lc2 ), the ratio of the length Lm1 of the first circumferential portion 61 of the middle block 12 to the length Lm2 of the second circumferential portion 62 (Lm1/Lm2), the length Lc1 of the first circumferential portion 61 of the center block 11 and the maximum length Lc of the center small block 11a (Lc1/Lc), the ratio of the length Lm1 of the first circumferential portion 61 of the middle block 12 to the maximum length Lm of the middle block 12 (Lm1/Lm) , the ratio (Dc/Wc) of the offset amount Dc between the first circumferential portion 61 and the second circumferential portion 62 of the center block 11 and the maximum width Wc of the center small block 11a, the first circumferential portion of the middle block 12 ratio (Dm/Wm) between the offset amount Dm between 61 and the second circumferential portion 62 and the maximum width Wm of the middle block 12, the angle between the first circumferential portion 61 of the center block 11 and the widthwise extending portion 66 The relationship between θc and the angle θm between the first circumferential portion 61 of the middle block 12 and the inclined portion 67, the ratio of the groove width Lwc of the center lug groove 41 to the pitch Pc of the center block 11 in the tire circumferential direction (Lwc/Pc ), the ratio of the maximum width Wcw of the center block 11 to the maximum width Wm of the middle block 12 (Wm/Wcw), and the ratio of the maximum width Wcw of the center block 11 to the maximum width Wsw of the shoulder land portion 13 (Wsw/Wcw). , the number of sipes 70 in the center small block 11a and the shoulder small block 13a, and whether or not the center small block 11a and the middle block 12 have two open sipes 71 and two closed sipes 72. different.

As a result of performing a performance evaluation test using these pneumatic tires 1 , as shown in FIGS. It has been found that at least one of the traction performance and the wet braking performance can be improved without deteriorating either performance. That is, the pneumatic tires 1 according to Examples 2 to 19 can achieve both snow traction and wet grip.

1 pneumatic tire 2 tread portion 3 tread tread surface 10 land portion 11 center block 11a center small block 12 middle block 13 shoulder land portion 13a shoulder small block 14, 15, 16, 17 convex portion 21 center small block row 22 middle block row 23 Shoulder small block row 30 Circumferential main groove 31 Inner circumferential main groove 32 Outer circumferential main groove 40 Lug groove 41 Center lug groove 42 Middle lug groove 43 Shoulder lug groove 45 Bending portion 50 Circumferential narrow groove 51 Center narrow groove 52 Shoulder narrow Groove 60 edge portion 61 first circumferential portion 62 second circumferential portion 66 widthwise extending portion 67 inclined portion 70 sipe 71 open sipe 72 closed sipe

Claims (12)

Of the plurality of circumferential main grooves extending in the tire circumferential direction, two inner circumferential main grooves that are the circumferential main grooves disposed on both sides of the tire equatorial plane in the tire width direction across the tire equatorial plane. and,
an outer circumferential main groove, which is the circumferential main groove disposed on the outer side in the tire width direction of each of the two inner circumferential main grooves;
a plurality of center lug grooves disposed between the two inner circumferential main grooves and extending in the tire width direction;
a plurality of middle lug grooves disposed between the adjacent inner circumferential main groove and outer circumferential main groove and extending in the tire width direction;
a center block partitioned by the two inner circumferential main grooves and the center lug groove;
a middle block partitioned by the inner circumferential main groove, the outer circumferential main groove, and the middle lug groove, which are adjacent to each other;
with
The center block and the middle block are composed of one second circumferential portion in which the edge portion defined by the inner circumferential main groove extends in the tire circumferential direction, and a portion of the edge portion extending in the tire circumferential direction extends in the tire circumferential direction. a first circumferential portion extending in the tire circumferential direction at a position different from the second circumferential portion in the circumferential direction and offset toward the inner circumferential main groove side with respect to the second circumferential portion; each formed in a step shape consisting of
a convex area Sc defined by the first circumferential portion and an imaginary line extending the second circumferential portion toward the first circumferential portion of the center block;
In the middle block, a convex area Sm defined by a virtual line extending the second circumferential portion toward the first circumferential portion and the first circumferential portion is
It is a relationship of Sc>Sm,
A pneumatic tire , wherein the center block is divided in the tire width direction by a center narrow groove . The pneumatic tire according to claim 1 , wherein the center narrow groove extends linearly in the tire circumferential direction and has a groove width in the range of 1 mm or more and 5 mm or less. The center block has a relationship between a length Lc1 in the tire circumferential direction of the first circumferential portion and a maximum length Lc in the tire circumferential direction of the center small blocks arranged on both sides of the center narrow groove in the tire width direction. , within the range of 0.2 ≤ (Lc1/Lc) ≤ 0.4,
In the middle block, the relationship between the length Lm1 of the first circumferential portion in the tire circumferential direction and the maximum length Lm of the middle block in the tire circumferential direction is 0.15≤(Lm1/Lm)≤0.15. 3. A pneumatic tire according to claim 1 or 2 in the range of 35. The center block has an offset amount Dc in the tire width direction between the first circumferential portion and the second circumferential portion, and an offset amount Dc in the tire width direction of the center small blocks arranged on both sides of the center narrow groove in the tire width direction. The relationship with the maximum width Wc is within the range of 0.05≦(Dc/Wc)≦0.15,
In the middle block, the relationship between the offset amount Dm in the tire width direction between the first circumferential portion and the second circumferential portion and the maximum width Wm of the middle block in the tire width direction is 0.05≦( Dm/Wm)≤0.15, the pneumatic tire according to any one of claims 1 to 3 . The pneumatic tire according to any one of claims 1 to 4 , wherein the center lug groove has two or more bent portions. The center block and the middle block are
an offset amount Dc in the tire width direction between the first circumferential portion and the second circumferential portion of the center block;
a relationship between the first circumferential portion and the second circumferential portion of the middle block and an offset amount Dm in the tire width direction is within a range of 0.95≦(Dc/Dm)≦1.05;
a length Lc1 in the tire circumferential direction of the first circumferential portion of the center block;
The pneumatic tire according to any one of claims 1 to 5 , wherein the relation between the first circumferential portion of the middle block and the length Lm1 in the tire circumferential direction is Lc1>Lm1. In the center block, the relation between the length Lc1 of the first circumferential portion in the tire circumferential direction and the length Lc2 of the second circumferential portion in the tire circumferential direction is 0.6≦(Lc1/Lc2)≦ is in the range of 0.8;
In the middle block, the relationship between the length Lm1 of the first circumferential portion in the tire circumferential direction and the length Lm2 of the second circumferential portion in the tire circumferential direction is 0.5≦(Lm1/Lm2)≦ The pneumatic tire according to any one of claims 1 to 6 , which is within the range of 0.7. The center block has a width direction extension portion extending in the tire width direction at an intersection portion with the first circumferential portion in an edge portion partitioned by the center lug groove,
The middle block has an inclined portion inclined with respect to the tire width direction and the tire circumferential direction at an intersection with the first circumferential direction portion in the edge portion partitioned by the middle lug groove,
The center block and the middle block have an angle θc between the first circumferential portion of the center block and the widthwise extending portion, and an angle between the first circumferential portion of the middle block and the inclined portion. 8. The pneumatic tire according to any one of claims 1 to 7 , wherein θm has a relationship of θc<θm. The relationship between the groove width Lwc of the center lug groove and the pitch Pc in the tire circumferential direction between the center blocks adjacent to each other in the tire circumferential direction via the center lug groove is 0.05≦(Lwc/Pc)≦0. 9. A pneumatic tire according to any one of claims 1 to 8 in the range of 0.35. Having a shoulder land portion located outside the outer circumferential main groove in the tire width direction and defined by the outer circumferential main groove,
The relationship between the maximum width Wcw of the center block in the tire width direction, the maximum width Wm of the middle block in the tire width direction, and the maximum width Wsw of the shoulder land portion in the tire width direction is 0.4≦(Wm/ Wcw)≦0.6 and 0.8≦(Wsw/Wcw)≦ 1.0 . The center block has center small blocks arranged on both sides of the center narrow groove in the tire width direction by being divided in the tire width direction by a center narrow groove extending in the tire circumferential direction,
The shoulder land portion has shoulder small blocks arranged on both sides of the shoulder narrow groove in the tire width direction by being divided in the tire width direction by the shoulder narrow groove extending in the tire circumferential direction,
The pneumatic tire according to claim 10 , wherein the same number of sipes are arranged in the center small block and the shoulder small block. The center block has center small blocks arranged on both sides of the center narrow groove in the tire width direction by being divided in the tire width direction by a center narrow groove extending in the tire circumferential direction,
Two open sipes are arranged in each of the center small block and the middle block,
One closed sipe is arranged between the open sipe and the center lug groove in the center small block,
The pneumatic tire according to any one of claims 1 to 11 , wherein the middle block has one closed sipe arranged between the open sipe and the middle lug groove.

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