JP6973042B2 - tire - Google Patents

Description

The present invention relates to a tire whose mounting direction on a vehicle is specified.

For example, Patent Document 1 below proposes a tire in which a main groove continuously extending in the tire circumferential direction is provided in a tread portion in which a vehicle mounting direction is specified.

Japanese Unexamined Patent Publication No. 2017-81540

In the above tire, the air column resonance sound due to the main groove was loud, and there was room for improvement in noise performance. As a result of various experiments, the inventors have found that the air column resonance sound of the main groove can be reduced by improving the land area adjacent to the main groove.

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire capable of exhibiting excellent noise performance.

The present invention is a tire having a tread portion whose mounting direction on a vehicle is specified, and the tread portion has an outer tread end located on the outside of the vehicle when mounted on the vehicle and an inner side located on the inside of the vehicle when mounted on the vehicle. The tread end includes a plurality of main grooves extending continuously in the tire circumferential direction and having a groove width of 2% or more of the tread width, and a plurality of land portions divided by the main groove, and the main groove comprises. The outermost shoulder main groove is included on the outermost tread end side, the outer shoulder main groove has the smallest groove width among the plurality of main grooves, and the land portion is the outer shoulder main groove. The outer middle land portion including the outer middle land portion adjacent to the inner tread end side extends continuously in the tire circumferential direction on the inner tread end side from the center position of the outer middle land portion in the tire axial direction. The middle longitudinal groove includes an inner portion divided into the inner tread end side of the middle longitudinal groove, and the middle longitudinal groove is less than 2% of the tread width and the outer middle land portion. The inner portion has a groove width of 3% to 10% of the width in the tire axial direction, and the inner portion is a plain rib without grooves and sipes.

In the tire of the present invention, it is desirable that the groove width of the outer shoulder main groove is 0.50 to 0.65 times the maximum groove width of the plurality of main grooves.

In the tire of the present invention, it is desirable that the depth of the middle vertical narrow groove is 0.30 to 0.45 times the depth of the outer shoulder main groove.

In the tire of the present invention, it is desirable that the width of the inner portion in the tire axial direction is 0.20 to 0.40 times the width of the outer middle land portion in the tire axial direction.

In the tire of the present invention, the land portion includes a crown land portion adjacent to the inner tread end side of the outer middle land portion, and the crown land portion includes the inner tread end from the edge on the outer tread end side. It is desirable to have an outer recess that is recessed on the side.

In the tire of the present invention, it is desirable that the maximum depth of the outer recess is 0.25 to 0.47 times the maximum depth of the main groove.

In the tire of the present invention, it is desirable that the width of the outer concave portion in the tire axial direction is smaller than the width of the inner portion in the tire axial direction.

In the tire of the present invention, the outer recess includes a first edge and a second edge that are inclined in opposite directions on the tread of the land portion, and the second edge is relative to the tire axial direction with respect to the first edge. It is desirable to incline at a small angle.

The main groove provided in the tread portion of the tire of the present invention includes the outer shoulder main groove arranged on the outermost tread end side. The outer shoulder main groove has the smallest groove width among the plurality of main grooves. In the outer shoulder main groove arranged on the outermost tread end side, the air column resonance sound easily reverberates to the outside of the vehicle, which has a great influence on the noise performance. In the tire of the present invention, the groove width of the outer shoulder main groove is relatively small, so that the air column resonance sound of the main groove is reduced, and the noise performance is improved.

The land portion includes the outer middle land portion adjacent to the inner tread end side of the outer shoulder main groove. The outer middle land portion is divided into a middle vertical groove extending continuously in the tire circumferential direction on the inner tread end side of the center position in the tire axial direction of the outer middle land portion and an inner tread end side of the middle vertical groove. Including the inner part of the tire.

Conventionally, the groove wall is deformed before and after the main groove touches the ground. Due to the vibration of the groove wall and the pressure change in the main groove at this time, the air column resonance sound of the main groove tends to be loud. On the other hand, in the tire of the present invention, when the contact pressure acts on the outer middle land portion and the main groove adjacent to the inner tread end side thereof, the middle vertical narrow groove is deformed in place of the main groove. It is possible to prevent the groove wall of the main groove from being deformed, and thus to reduce the air column resonance sound of the main groove.

Since the middle vertical groove has a groove width of less than 2% of the tread width and 3% to 10% of the width of the outer middle land portion in the tire axial direction, almost no air column resonance sound is generated. Further, the middle vertical narrow groove having the groove width is more easily deformed than the main groove, and the deformation of the groove wall of the adjacent main groove can be further suppressed by the above action. In addition, since the inner part is a plain rib without grooves and sipes, deformation of the groove wall and pressure change in the groove are further suppressed in the main groove adjacent to the inner tread end side of the outer middle land part. The air column resonance is significantly suppressed.

It is a development view of the tread part of the tire of one Embodiment of this invention. It is an enlarged view of the outer middle land part of FIG. (A) is a sectional view taken along line AA of FIG. 2, and FIG. 2B is a sectional view taken along line BB of FIG. It is an enlarged view of the outer shoulder land part of FIG. (A) is a sectional view taken along line CC of FIG. 4, and (b) is a sectional view taken along line DD of FIG. It is an enlarged view of the crown land part of FIG. FIG. 6 is a cross-sectional view taken along the line EE of FIG. It is an enlarged view of the inner middle land part and the inner shoulder land part of FIG. (A) is a sectional view taken along line FF of FIG. 8, (b) is a sectional view taken along line GG of FIG. 8, and (c) is a sectional view taken along line HF of FIG. .. It is an enlarged view of the outer middle land part of the tire of the comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment is suitably used as, for example, a pneumatic tire for a passenger car. However, the present invention is not limited to such an aspect, and is used for various tires such as pneumatic tires for heavy loads and non-pneumatic tires in which pressurized air is not filled inside the tires. Can be done.

As shown in FIG. 1, the tire 1 has a tread portion 2 in which the direction of attachment to the vehicle is specified. The tread portion 2 of the present embodiment includes, for example, a tread pattern that is asymmetric with respect to the tire equator C. The tread portion 2 has an outer tread end To located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and an inner tread end Ti located on the inner side of the vehicle when the tire 1 is mounted on the vehicle. The direction of mounting on the vehicle is indicated by characters or symbols on the sidewall portion (not shown), for example.

In the case of a pneumatic tire, each tread end To and Ti are the most outer contact positions in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire 1 touches a flat surface at a camber angle of 0 °. The normal state is a state in which the tire is rim-assembled on the normal rim, the normal internal pressure is filled, and there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in a normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATTA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. "Maximum load capacity" for JATTA and "TIRE LOAD LIMITS" for TRA. The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 includes a plurality of main grooves 3 continuously extending in the tire circumferential direction, and a plurality of land portions 4 divided by the main groove 3. Each main groove 3 has a groove width of 2% or more of the tread width TW. The tread width TW is the distance in the tire axial direction from the outer tread end To to the inner tread end Ti in the normal state. The tread portion 2 of the present embodiment has, for example, five land portions 4 divided by four main grooves 3. However, the present invention is not limited to such an aspect.

The main groove 3 includes, for example, an outer shoulder main groove 5, an inner shoulder main groove 6, an outer crown main groove 7, and an inner crown main groove 8. The outer shoulder main groove 5 is provided on the outermost tread end To side of the plurality of main grooves 3. The inner shoulder main groove 6 is provided on the innermost tread end Ti side of the plurality of main grooves 3. The outer crown main groove 7 is provided, for example, between the outer shoulder main groove 5 and the tire equator C. The inner crown main groove 8 is provided, for example, between the inner shoulder main groove 6 and the tire equator C.

For the outer shoulder main groove 5 and the inner shoulder main groove 6, for example, it is desirable that the distance L1 from the tire equator C to the groove center line is 0.25 to 0.35 times the tread width TW. For the outer crown main groove 7 and the inner crown main groove 8, for example, it is desirable that the distance L2 from the tire equator C to the groove center line is 0.05 to 0.15 times the tread width TW.

The outer shoulder main groove 5 has the smallest groove width W1 among the plurality of main grooves. In the outer shoulder main groove 5 arranged on the outermost tread end To side, the air column resonance sound easily reverberates to the outside of the vehicle, which has a great influence on the noise performance. In the tire of the present invention, the groove width of the outer shoulder main groove 5 is made relatively small, so that the air column resonance sound of the main groove is reduced, and the noise performance is improved.

In order to improve noise performance and steering stability in a well-balanced manner, the groove width W1 of the outer shoulder main groove 5 is, for example, 0.50 to 0.65 times the maximum groove width among the plurality of main grooves. desirable. The groove width W2 of the inner shoulder main groove 6, the groove width W3 of the outer crown main groove 7, and the groove width W4 of the inner crown main groove 8 are, for example, 5.5% to 7.5% of the tread width TW. desirable. It is desirable that each of the main grooves 5 to 8 has a groove depth of, for example, 5.0 to 12.0 mm. In a more preferred embodiment, the outer shoulder main groove 5 has the smallest groove depth of the plurality of main grooves.

The land portion 4 includes an outer shoulder land portion 11, an outer middle land portion 12, an inner shoulder land portion 13, and an inner middle land portion 14. Further, the land portion 4 of the present embodiment includes the crown land portion 15. The outer shoulder land portion 11 is arranged on the outermost tread end To side of the plurality of land portions 4. The inner shoulder land portion 13 is arranged on the innermost tread end Ti side of the plurality of land portions 4. The outer middle land portion 12 is adjacent to the inner tread end Ti side of the outer shoulder land portion 11. The inner middle land portion 14 is adjacent to the outer tread end To side of the inner shoulder land portion 13. The crown land portion 15 is arranged between the outer middle land portion 12 and the inner middle land portion 14.

Each of the outer shoulder land portion 11, the inner shoulder land portion 13, and the inner middle land portion 14 is provided with a plurality of lateral grooves 20 extending in the tire axial direction. The lateral groove 20 has, for example, a groove width W5 of 1.0% to 2.0% of the tread width TW. The lateral groove 20 has a groove depth of, for example, 3.0 to 8.0 mm. The lateral groove 20 is provided, for example, at an angle θ1 of 0 to 15 ° with respect to the tire axial direction. A more detailed configuration of the lateral groove 20 provided in each land portion will be described later.

FIG. 2 shows an enlarged view of the outer middle land portion 12. As shown in FIG. 2, the outer middle land portion 12 includes a middle vertical groove 30 extending continuously in the tire circumferential direction on the inner tread end Ti side of the center position of the outer middle land portion 12 in the tire axial direction. It includes an outer portion 32 divided on the outer tread end To side of the middle vertical fine groove 30, and an inner portion 31 divided on the inner tread end Ti side of the middle vertical fine groove 30.

Conventionally, the groove wall is deformed before and after the main groove touches the ground. Due to the vibration of the groove wall and the pressure change in the main groove at this time, the air column resonance sound of the main groove tends to be loud. On the other hand, in the tire of the present invention, when the contact pressure acts on the outer middle land portion 12 and the outer crown main groove 7 adjacent to the inner tread end Ti side thereof, the middle vertical narrow groove 30 replaces the main groove. By deforming the tire tread, it is possible to prevent the groove wall of the main groove from being deformed, and thus to reduce the air column resonance sound of the main groove.

The middle vertical groove 30 of the present invention has a groove width W7 that is less than 2% of the tread width TW and 3% to 10% of the tire axial width W8 of the outer middle land portion. Therefore, the middle vertical groove 30 hardly generates the air column resonance sound. Further, the middle vertical narrow groove 30 having the groove width is more easily deformed than the main groove, and the deformation of the groove walls of the adjacent main grooves can be further suppressed by the above action.

Further, the inner portion 31 of the tire of the present invention is configured as a plain rib without grooves or sipes. Therefore, in the outer crown main groove 7 adjacent to the inner tread end Ti side of the outer middle land portion 12, the deformation of the groove wall and the pressure change in the groove are further suppressed, and the air column resonance sound is remarkably suppressed. ..

In order to improve steering stability and noise performance in a well-balanced manner, the tire axial width W9 of the inner portion 31 is, for example, 0.20 to 0.40 of the tire axial width W8 of the outer middle land portion 12. Is desirable.

The middle vertical groove 30 extends linearly along the tire circumferential direction, for example. The groove width W7 of the middle vertical narrow groove 30 is preferably 0.8 to 2.0 mm, for example.

FIG. 3A shows a cross-sectional view taken along the line AA of the middle vertical groove 30 of FIG. As shown in FIG. 3A, it is desirable that the depth d4 of the middle vertical groove 30 is, for example, 0.30 to 0.45 times the depth d1 of the outer shoulder main groove 5. Such a middle vertical groove 30 can exert the above-mentioned action while maintaining steering stability.

As shown in FIG. 2, the outer portion 32 of the outer middle land portion 12 of the present embodiment is provided with, for example, a plurality of outer middle lateral grooves 23. Each outer middle lateral groove 23 extends from the edge 12a on the outer tread end To side of the outer middle land portion 12 to the inner tread end Ti side, and is interrupted in the outer middle land portion 12. In the present embodiment, each outer middle horizontal groove 23 communicates with the middle vertical narrow groove 30.

It is desirable that each outer middle lateral groove 23 is inclined with respect to the tire axial direction at an angle θ2 larger than that of the lateral groove 20 provided in the other land portion, for example. In other words, each outer middle lateral groove 23 of the present invention is inclined with respect to the tire circumferential direction at an angle smaller than that of the lateral groove 20 provided in the other land portion. In a preferred embodiment, in any portion of the outer middle lateral groove 23, the angle with respect to the tire axial direction is larger than the maximum angle with respect to the tire axial direction of the lateral groove 20 provided in the other land portion. In a more desirable embodiment, the angle of the straight line connecting both ends of the groove center of the outer middle lateral groove 23 with respect to the tire axial direction is larger than the maximum angle of the lateral groove 20 with respect to the tire axial direction.

Such an arrangement of the outer middle lateral grooves 23 moderately relaxes the rigidity of the land portion in the vicinity, so that it becomes easier to follow the road surface when the land portion touches the ground, and the initial responsiveness is enhanced.

The angle θ2 of the outer middle lateral groove 23 is preferably 45 to 60 °, for example. Further, the outer middle lateral groove 23 of the present embodiment is slightly curved so that the angle θ2 gradually decreases toward the inner tread end Ti side.

It is desirable that the length L5 of the outer middle lateral groove 23 in the tire axial direction is, for example, 0.50 to 0.80 times the width W8 of the outer middle land portion 12 in the tire axial direction. As a result, it is possible to alleviate the hitting sound when the land portion near the outer middle lateral groove 23 touches the ground while maintaining the steering stability.

It is desirable that the outer middle lateral groove 23 has, for example, a groove width W6 of 0.8% to 1.6% of the tread width TW. Such an outer middle lateral groove 23 is useful for improving steering stability and noise performance in a well-balanced manner.

FIG. 3B shows a sectional view taken along line BB of the outer middle lateral groove 23. As shown in FIG. 3B, the outer middle lateral groove 23 includes, for example, a first groove portion 23a and a second groove portion 23b. The first groove portion 23a communicates with, for example, the outer shoulder main groove 5 and extends at a constant depth. The second groove portion 23b communicates with the inner tread end Ti side of the first groove portion 23a, and the depth gradually decreases toward the inner tread end Ti side. As a result, the central portion of the outer portion 32 in the tire axial direction is easily deformed appropriately to improve the initial response, and uneven wear of the land portion near the outer shoulder main groove 5 and the middle vertical fine groove 30 is suppressed. Will be done.

It is desirable that the depth d2 of the first groove portion 23a is, for example, 0.45 to 0.55 times the groove depth d1 of the outer shoulder main groove 5. The first groove portion 23a can prevent the outer middle lateral groove 23 from being excessively opened when the outer middle lateral groove 23 is in contact with the ground, and thus can reduce the pumping noise of the outer middle lateral groove 23.

The second groove portion 23b includes, for example, a portion having a greater depth than the first groove portion 23a. The maximum depth d3 of the second groove portion 23b is, for example, 1.40 to 1.60 times the depth d2 of the first groove portion 23a. In the present embodiment, the second groove portion 23b is configured by gradually reducing the depth from the deepest portion of the outer middle lateral groove 23 toward the inner tread end Ti side.

FIG. 4 shows an enlarged view of the outer shoulder land portion 11. As shown in FIG. 4, the outer shoulder land portion 11 is provided with a plurality of outer shoulder lateral grooves 38 extending in the tire axial direction and an outer shoulder lateral narrow groove 39 having a groove width smaller than that of the outer shoulder lateral groove 38. There is. In a preferred embodiment, the outer shoulder lateral grooves 38 and the outer shoulder lateral fine grooves 39 are provided alternately in the tire circumferential direction.

The outer shoulder lateral groove 38 completely crosses, for example, the outer shoulder land portion 11. The outer shoulder lateral groove 38 is inclined in the same direction as the outer middle lateral groove 23 with respect to the tire axial direction, for example. The angle θ4 of the outer shoulder lateral groove 38 with respect to the tire axial direction is preferably, for example, 5 to 15 °.

It is desirable that the groove width W10 of the outer shoulder lateral groove 38 is larger than, for example, the groove width W6 (shown in FIG. 2) of the outer middle lateral groove 23. It is desirable that the groove width W10 of the outer shoulder lateral groove 38 is, for example, 1.30 to 1.70 times the groove width W6 of the outer middle lateral groove 23. Such an outer shoulder lateral groove 38 is useful for improving wet performance while maintaining noise performance.

FIG. 5A shows a sectional view taken along line CC of the outer shoulder lateral groove 38. As shown in FIG. 5A, the outer shoulder lateral groove 38 is connected to, for example, a first groove portion 38a on the outer tread end To side and a second groove portion 38a having a depth smaller than that of the first groove portion 38a. It has a groove 38b. The depth d6 of the second groove portion 38b is, for example, 0.60 to 0.75 times the depth d5 of the first groove portion 38a. The second groove 38b can prevent the outer shoulder lateral groove 38 from opening excessively when it touches the ground, and thus can reduce the pumping noise.

As shown in FIG. 4, the outer shoulder lateral groove 39 is inclined in the same direction as, for example, the outer shoulder lateral groove 38. The outer shoulder lateral groove 39 of the present embodiment extends along, for example, the outer shoulder lateral groove 38.

It is desirable that the groove width W11 of the outer shoulder lateral groove 39 is, for example, 0.40 to 0.60 times the groove width W10 of the outer shoulder lateral groove 38. The outer shoulder lateral groove 39 of the present embodiment has, for example, an opening width of 1.5 mm or more on the tread surface of the land portion. However, the present invention is not limited to such an aspect, and the outer shoulder lateral groove 39 may be configured as a sipe. As used herein, "sipe" means a notch with a width of less than 1.5 mm.

FIG. 5B shows a cross-sectional view taken along the line DD of the outer shoulder lateral groove 39. As shown in FIG. 5B, the outer shoulder lateral groove 39 of the present embodiment has, for example, an opening 28 having the above-mentioned opening width and a sipe portion extending in the tire radial direction with a width of less than 1.5 mm. 29 and is included. Such an outer shoulder lateral narrow groove 39 can prevent an excessive decrease in rigidity of the outer shoulder land portion 11 and can improve the initial steering response and the wear resistance in a well-balanced manner.

FIG. 6 shows an enlarged view of the land portion 15 of the crown. As shown in FIG. 6, it is desirable that the land portion 15 of the crown extends continuously, for example, in the tire circumferential direction. Such a crown land portion 15 can increase the rigidity of the tread portion 2 near the tire equator C together with the inner portion 31 of the outer middle land portion 12 described above, and can provide a large cornering force during turning.

It is desirable that the crown land portion 15 is provided with, for example, a plurality of outer recesses 33 and a plurality of inner slots 34. In the present embodiment, the outer recess 33 and the inner slot 34 are provided at the same pitch as the outer middle lateral groove 23. The outer recess 33 is recessed from the edge 15a on the outer tread end To side of the crown land portion 15 to the inner tread end Ti side. The inner slot 34 extends from the edge 15b on the inner tread end Ti side of the crown land portion 15 to the outer tread end To side and is interrupted in the crown land portion 15.

The outer recess 33 includes, for example, a first edge 33a and a second edge 33b that are inclined in opposite directions on the tread of the land portion. The first edge 33a is inclined at an angle θ5 of, for example, 50 to 70 ° with respect to the tire axial direction. The second edge 33b is inclined at an angle θ6 smaller than that of the first edge 33a in the tire axial direction, for example. Specifically, the angle θ6 of the second edge 33b is, for example, 0 to 10 °.

It is desirable that the width W12 of the outer recess 33 in the tire axial direction is smaller than the width W9 of the inner portion 31 of the outer middle land portion 12 in the tire axial direction (shown in FIG. 2). Such an outer recess 33 can be expected to uniformly bring the progress of wear between the crown land portion 15 and the outer middle land portion 12 closer to each other, and thus to improve the wear resistance.

It is desirable that the inner slot 34 is inclined in the same direction as the outer middle lateral groove 23 with respect to the tire axial direction, for example. The angle θ7 of the inner slot 34 with respect to the tire axial direction is preferably, for example, 10 to 25 °.

It is desirable that the length L6 of the inner slot 34 in the tire axial direction is larger than, for example, the width W12 of the outer recess 33. In the present embodiment, the crown land portion 15 is provided on the tire equator C, and the inner slots 34 are arranged so as not to straddle the tire equator C. More specifically, it is desirable that the length L6 of the inner slot 34 is, for example, 0.30 to 0.50 times the width W13 of the crown land portion 15 in the tire axial direction. Such an inner slot 34 makes it easy for the crown land portion 15 to be appropriately deformed, and can reduce the striking sound when the crown land portion 15 touches the ground.

In a more preferred embodiment, the length L6 of the inner slot 34 is smaller than the tire axial length L5 of the outer middle lateral groove 23. Specifically, it is desirable that the length L6 of the inner slot 34 is 0.45 to 0.65 times the length L5 of the outer middle lateral groove 23. Such an inner slot 34 helps to evenly approach the progress of wear between the crown land portion 15 and the outer middle land portion 12.

FIG. 7 shows a sectional view taken along line EE of the outer recess 33 and the inner slot 34. As shown in FIG. 7, it is desirable that the maximum depth d8 of the outer recess 33 is 0.25 to 0.47 times the maximum depth d7 of the main groove.

It is desirable that the inner slot 34 gradually increases in depth toward, for example, the inner tread end Ti side. The maximum depth d9 of the inner slot 34 is greater than, for example, the maximum depth d8 of the outer recess 33. In a more preferred embodiment, the depth d9 of the inner slot 34 is, for example, 1.30 to 1.70 times the depth d2 (shown in FIG. 3A) of the first groove portion 23a of the outer middle lateral groove 23. .. Such an inner slot 34 can reduce the striking sound when the crown land portion 15 touches the ground while maintaining steering stability.

FIG. 8 shows an enlarged view of the inner middle land portion 14 and the inner shoulder land portion 13. As shown in FIG. 8, the inner middle land portion 14 is provided with, for example, a plurality of inner middle lateral grooves 41 and a plurality of inner middle sipes 42. In the present embodiment, the inner middle lateral grooves 41 and the inner middle sipes 42 are alternately provided in the tire circumferential direction.

The inner middle lateral groove 41 completely crosses, for example, the inner middle land portion 14. The inner middle lateral groove 41 is inclined in the same direction as the inner slot 34 with respect to the tire axial direction, for example. The angle θ8 of the inner middle lateral groove 41 with respect to the tire axial direction is preferably, for example, 10 to 18 °.

In the present embodiment, the inner middle lateral groove 41 is slightly curved, and the angle of the groove center line with respect to the tire axial direction gradually decreases toward the inner tread end Ti. The maximum angle θ9 of the groove center line of the inner middle lateral groove 41 with respect to the tire axial direction (corresponding to the angle at the end of the outer tread end To side in the present embodiment) is, for example, with respect to the tire axial direction of the outer middle lateral groove 23. It is desirable that the angle θ2 is 0.20 to 0.30 times. As a result, the rigidity of the land portion in the vicinity of the inner middle lateral groove 41 in the tire axial direction is increased, and a large cornering force can be obtained in the middle of turning.

As shown in FIG. 1, it is desirable that the inner middle lateral groove 41 is smoothly continuous with the inner slot 34 via the inner crown main groove 8. Such an inner middle lateral groove 41 can exhibit high drainage together with the inner slot 34. The phrase "provided at a position where the grooves or slots are smoothly continuous" includes at least an embodiment in which a region in which one groove or slot is virtually extended intersects with a region in which the other groove or slot is virtually extended. As a more desirable embodiment, in the present embodiment, a region in which the inner middle lateral groove 41 is virtually extended intersects with the end portion of the inner slot 34 on the inner crown main groove 8 side. Further, a region in which the inner slot 34 is virtually extended intersects with the end portion of the inner middle lateral groove 41 on the inner crown main groove 8 side.

FIG. 9A shows a sectional view taken along line FF of the inner middle lateral groove 41 of FIG. As shown in FIG. 9A, the inner middle lateral groove 41 includes a shallow bottom groove portion 41b having a depth smaller than each end portion 41a between the end portions 41a on both sides in the tire axial direction. The depth d11 of the shallow bottom groove portion 41b is, for example, 0.30 to 0.40 times the depth d10 of the end portion 41a. Such an inner middle lateral groove 41 can improve the wet performance while maintaining the rigidity of the inner middle land portion 14.

As shown in FIG. 8, the inner middle sipe 42 completely crosses, for example, the inner middle land portion 14. The inner middle sipe 42 is inclined in the same direction as the inner middle lateral groove 41 with respect to the tire axial direction, for example, and extends along the inner middle lateral groove 41 in a more desirable embodiment.

FIG. 9B shows a sectional view taken along line GG of the inner middle sipe 42 of FIG. As shown in FIG. 9B, the inner middle sipe 42 includes, for example, a shallow bottom sipe 42b having a depth smaller than each end 42a between the ends 42a on both sides in the tire axial direction. There is. The depth d13 of the shallow bottom sipe portion 42b is, for example, 0.40 to 0.55 times the depth d12 of the end portion 42a. Such an inner middle sipe 42 can improve the initial responsiveness and the wear resistance in a well-balanced manner.

In a more preferred embodiment, the depth d12 of the end 42a of the inner middle sipe 42 is smaller than the depth d10 of the end 41a of the inner middle lateral groove 41. On the other hand, the depth d13 of the shallow bottom sipe portion 42b of the inner middle sipe 42 is larger than the depth d11 of the shallow bottom groove portion 41b of the inner middle lateral groove 41. Such an inner middle lateral groove 41 and an inner middle sipe 42 can suppress uneven wear of the inner middle land portion 14.

As shown in FIG. 8, the inner shoulder land portion 13 is provided with, for example, a plurality of inner shoulder lateral grooves 43 and a plurality of inner shoulder sipes 44. In the present embodiment, the inner shoulder lateral grooves 43 and the inner shoulder sipes 44 are alternately provided in the tire circumferential direction.

The inner shoulder lateral groove 43 completely crosses, for example, the inner shoulder land portion 13. The inner middle lateral groove 41 is inclined in the same direction as the inner middle lateral groove 41 with respect to the tire axial direction, for example. The angle θ10 of the inner shoulder lateral groove 43 with respect to the tire axial direction is preferably less than, for example, 10 °.

In the present embodiment, the inner shoulder lateral groove 43 is slightly curved, and the angle of the groove center line with respect to the tire axial direction gradually decreases toward the inner tread end Ti. The maximum angle θ11 of the groove center line of the inner shoulder lateral groove 43 with respect to the tire axial direction (corresponding to the angle at the end on the outer tread end To side in the present embodiment) is, for example, with respect to the tire axial direction of the inner middle lateral groove 41. It is desirable that the angle is smaller than the maximum angle θ9.

It is desirable that the inner shoulder lateral groove 43 is smoothly continuous with the inner middle lateral groove 41 via the inner shoulder main groove 6. As a more desirable embodiment, in the present embodiment, a region in which the inner shoulder lateral groove 43 is virtually extended intersects with the end portion of the inner middle lateral groove 41 on the inner shoulder main groove 6 side. Further, a region in which the inner middle lateral groove 41 is virtually extended intersects with the end portion of the inner shoulder lateral groove 43 on the inner shoulder main groove 6 side. Such an inner shoulder lateral groove 43 can exhibit excellent drainage.

In the present embodiment, the inner slot 34, the inner middle lateral groove 41 and the inner shoulder lateral groove 43 are smoothly continuous via the main groove, and the angle with respect to the tire axial direction thereof gradually decreases from the inner end of the inner slot 34 to the inner tread end Ti. It is desirable to do. Such a lateral groove arrangement helps to further enhance wet performance.

FIG. 9 (c) shows a sectional view taken along line OH of the inner shoulder lateral groove 43. As shown in FIG. 9 (c), the inner shoulder lateral groove 43 includes, for example, a first groove portion 43a and a second groove portion 43b connected to the inner shoulder main groove 6 and having a depth smaller than that of the first groove portion 43a. I'm out. The depth d15 of the second groove portion 43b is, for example, 0.60 to 0.70 times the depth d14 of the first groove portion 43a. Such an inner shoulder lateral groove 43 can reduce the pumping noise.

As shown in FIG. 8, the inner shoulder sipe 44 completely crosses, for example, the inner shoulder land portion 13. The inner shoulder sipe 44 is inclined, for example, in the same direction as the inner shoulder lateral groove 43 with respect to the tire axial direction, and more preferably extends along the inner shoulder lateral groove 43.

It is desirable that the inner shoulder sipe 44 is smoothly continuous with the inner middle sipe 42, for example, via the inner shoulder main groove 6. Such an inner shoulder sipe 44 can moderately easily deform the inner shoulder land portion 13 and enhance the initial responsiveness.

As shown in FIG. 1, the land ratio LT of the tread portion 2 is preferably, for example, 60% to 70%. In the present specification, the “land ratio” is the ratio Sb / Sa of the actual total ground contact area Sb to the total area Sa of the virtual ground contact surface that fills all the grooves, sipes, and slots provided in the tread portion 2. Is.

The tread portion 2 includes an outer tread portion 2A between the outer tread end To and the tire equator C, and an inner tread portion 2B between the inner tread end Ti and the tire equator C. The outer tread portion 2A preferably has a larger land ratio than the inner tread portion 2B. Specifically, the land ratio LA of the outer tread portion 2A is preferably, for example, 60% to 80%. The land ratio LB of the inner tread portion 2B is preferably, for example, 55% to 75%. Such a tread portion 2 can exhibit a large cornering force in the middle of turning while exhibiting excellent initial responsiveness.

Although the tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and may be modified into various embodiments.

A tire of size 215 / 60R16 having the basic pattern of FIG. 1 was prototyped. As a comparative example, as shown in FIG. 10, the middle vertical groove b provided in the outer middle land portion a is located on the outer tread end side (left side in FIG. 10) of the groove center line of the outer middle land portion a. The arranged tires were prototyped. In this tire, the outer middle lateral groove d extends from the inner crown main groove to the middle vertical narrow groove b. The tread portion of the tire of the comparative example is substantially the same as the tread portion shown in FIG. 1 except for the above points. The noise performance and steering stability of each test tire were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 16 x 6.5J
Tire internal pressure: 210kPa
Test vehicle: Displacement 2500cc, rear-wheel drive vehicle Tire mounting position: All wheels

<Noise performance>
The noise inside the vehicle was measured when the test vehicle traveled on a dry road surface at a speed of 100 km / h. The result is an index with the value of the comparative example as 100, and the smaller the value, the smaller and better the noise inside the vehicle.

<Maneuvering stability>
The steering stability of the test vehicle when traveling on a dry road surface was evaluated by the driver's sensuality. The result is a score with a comparative example of 100, and the larger the value, the better the steering stability.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the tire of the example exhibited excellent noise performance. It was also confirmed that the tires of the examples had improved steering stability.

2 Tread part 3 Main groove 4 Land part 5 Outer shoulder main groove 12 Outer middle land part 30 Middle vertical narrow groove 31 Inner part

Claims (8)

A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion extends continuously in the tire circumferential direction with an outer tread end located on the outside of the vehicle when mounted on the vehicle and an inner tread end located on the inside of the vehicle when mounted on the vehicle, and has a groove width of 2% or more of the tread width. Including a plurality of main ditches having and a plurality of land areas divided by the main ditches,
The main groove includes an outer shoulder main groove arranged on the outermost side of the outer tread.
The outer shoulder main groove has the smallest groove width among the plurality of main grooves.
The land portion includes an outer middle land portion adjacent to the inner tread end side of the outer shoulder main groove.
The outer middle land portion includes a middle vertical groove extending continuously in the tire circumferential direction on the inner tread end side of the center position of the outer middle land portion in the tire axial direction, and the inner tread of the middle vertical groove. Including the inner part divided on the end side,
The middle longitudinal groove has a groove width of less than 2% of the tread width and 3% to 10% of the tire axial width of the outer middle land portion.
The inner portion is a plain rib without grooves and sipes .
The groove width of the outer shoulder main groove is 0.50 to 0.65 times the maximum groove width of the plurality of main grooves.
tire.
The tire according to claim 1, wherein the outer shoulder main groove has the smallest groove depth among the plurality of main grooves. The tire according to claim 1 or 2, wherein the depth of the middle vertical groove is 0.30 to 0.45 times the depth of the outer shoulder main groove. The tire according to any one of claims 1 to 3, wherein the width of the inner portion in the tire axial direction is 0.20 to 0.40 times the width of the outer middle land portion in the tire axial direction. The land portion includes a crown land portion adjacent to the inner tread end side of the outer middle land portion.
The tire according to any one of claims 1 to 4, wherein the crown land portion is provided with an outer recess recessed from the edge on the outer tread end side to the inner tread end side. The tire according to claim 5, wherein the maximum depth of the outer recess is 0.25 to 0.47 times the maximum depth of the main groove. The tire according to claim 5 or 6, wherein the width of the outer concave portion in the tire axial direction is smaller than the width of the inner portion in the tire axial direction. The outer recess includes a first edge and a second edge that are inclined in opposite directions on the land tread.
The tire according to any one of claims 5 to 7, wherein the second edge is inclined at an angle smaller than that of the first edge in the tire axial direction.

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