JP7775656B2 - tire - Google Patents

Description

The present invention relates to a tire.

Patent Document 1 below describes a pneumatic tire in which a land portion is provided with a first lateral groove and a sipe. The first lateral groove has an inner end that extends from a first circumferential edge of the land portion and terminates within the land portion. A tie bar is provided at the inner end. The sipe includes a first sipe portion that extends from a second circumferential edge of the land portion to the first lateral groove, and a second sipe portion that extends over the tie bar.

Japanese Patent Application Laid-Open No. 2021-88344

While tires like those described above can ensure traction on low-μ surfaces, there is still room for improvement in terms of resistance to uneven wear.

This disclosure was devised in light of the above-mentioned circumstances, and its primary objective is to provide a tire that can further improve uneven wear resistance while maintaining driving performance on low μ roads.

The present disclosure relates to a tire having a tread portion, the tread portion including a first land portion including a first circumferential edge extending in the tire circumferential direction, a second circumferential edge extending in the tire circumferential direction, and a tread surface therebetween, the first land portion being composed of a rib that is not provided with a lateral groove (defined as having a width of 2 mm or more) that completely crosses the first land portion in the tire axial direction, and the first land portion including a first sipe extending in the tire axial direction and a second sipe extending in the tire axial direction and adjacent to the first sipe in the tire circumferential direction. The tire includes two sipes, wherein the first sipes include a pair of first shallow portions that include both longitudinal ends and a first deep portion that connects the pair of first shallow portions and has a depth greater than that of the pair of first shallow portions, and the second sipes include a pair of second deep portions that include both longitudinal ends and a second shallow portion that connects the pair of second deep portions and has a depth less than that of the pair of second deep portions, and the first deep portion and the pair of second deep portions are misaligned in the tire axial direction.

By adopting the above configuration, the tire disclosed herein can further improve uneven wear resistance while maintaining driving performance on low μ roads.

FIG. 2 is a plan view of a first land portion according to an embodiment of the present disclosure. 1A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 1B is a cross-sectional view taken along line BB in FIG. FIG. 2 is a development view of the entire tread portion. 4A is a cross-sectional view taken along line CC in FIG. 3, and FIG. 4B is a cross-sectional view taken along line DD in FIG. FIG. FIG. FIG.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.
1 is an expanded plan view of a tread portion 2 of a tire 1 according to this embodiment. The present disclosure is applied to an all-season pneumatic tire mounted on a light truck that can run on paved roads such as asphalt roads as well as low-μ roads such as steel roads and icy roads. The present disclosure may also be applied to pneumatic tires 1 for passenger cars and heavy-duty vehicles, as well as tires 1 of other categories.

As shown in FIG. 1, the tread portion 2 of this embodiment includes a first land portion 3 that includes a first circumferential edge e1 extending in the tire circumferential direction, a second circumferential edge e2 extending in the tire circumferential direction, and a tread surface 3a between them.

The first land portion 3 is formed from a rib 3R that does not have a lateral groove that completely crosses the first land portion 3 in the tire axial direction. Such a first land portion 3 has a relatively large contact area, improving driving performance on low-μ roads. In this specification, lateral grooves are groove-like bodies with a groove width of 2 mm or more. Furthermore, sipes, which will be described later, are notched bodies with a width of less than 2 mm.

The first land portion 3 is provided with first sipes 4 extending in the tire axial direction and second sipes 5 extending in the tire axial direction and adjacent to the first sipes 4 in the tire circumferential direction. These first sipes 4 and second sipes 5 generate a large traction force on low μ roads, thereby maintaining basic driving performance on low μ roads. In this embodiment, the first land portion 3 has the first sipes 4 and second sipes 5 arranged alternately in the tire circumferential direction.

Figure 2(a) is a cross-sectional view taken along line A-A in Figure 1. Figure 2(b) is a cross-sectional view taken along line B-B in Figure 1. As shown in Figures 1 and 2, the first sipe 4 includes a pair of first shallow portions 6, 6 that include both longitudinal ends 4e, and a first deep portion 7 that connects the pair of first shallow portions 6, 6 and has a depth d2 that is greater than the depth d1 of the pair of first shallow portions 6. The second sipe 5 includes a pair of second deep portions 8, 8 that include both longitudinal ends 5e, and a second shallow portion 9 that connects the pair of second deep portions 8, 8 and has a depth d4 that is less than the depth d3 of the pair of second deep portions 8.

The first deep bottom portion 7 and the pair of second deep bottom portions 8 are misaligned in the tire axial direction. This prevents a large difference in rigidity between the first sipe 4 and second sipe 5 of the first land portion 3, improving uneven wear resistance.

More specifically, in this embodiment, the first deep bottom portion 7 has no portion that coincides with the pair of second deep bottom portions 8 in the tire axial direction. This effectively achieves the above-mentioned effect. If the first deep bottom portion 7 and the pair of second deep bottom portions 8 are separated too far in the tire axial direction, for example, the axial length L2 of the first shallow bottom portion 6 will be large and the axial length L3 of the first deep bottom portion 7 will be small, which could result in the scratching force not being exerted over an extended period of time. For this reason, the axial separation distance La between the first deep bottom portion 7 and the second deep bottom portion 8 is preferably 2% or more of the maximum axial width Wa of the first land portion 3, more preferably 3% or more, more preferably 7% or less, and even more preferably 6% or less.

Figure 3 is a plan view of the tread portion 2 of this embodiment, with the tread edges Te, Te unfolded. The "tread edge Te" is defined as the axially outermost contact point when the tire 1 is in a normal state, is loaded with a normal load, and is placed on a flat surface with a camber angle of 0 degrees. The axial distance between the tread edges Te, Te is the tread width TW.

The "normal condition" refers to a tire 1 mounted on a normal rim (not shown), inflated to the normal internal pressure, and unloaded. Unless otherwise specified, the dimensions of each part of tire 1 are values measured in this normal condition.

The above-mentioned "genuine rim" refers to the rim specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, this refers to a "standard rim," for TRA, it refers to a "design rim," and for ETRTO, it refers to a "measuring rim."

The "normal internal pressure" mentioned above refers to the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, this is the "maximum air pressure," for TRA, this is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, this is the "INFLATION PRESSURE."

The above-mentioned "normal load" refers to the load specified for each tire in each standard, including the standard on which the tire is based. For JATMA, this is "maximum load capacity," for TRA, this is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is "LOAD CAPACITY."

As shown in Figure 3, the tread portion 2 of this embodiment includes multiple main grooves 10 extending continuously in the circumferential direction of the tire and land portions 11 separated by the main grooves 10.

The main grooves 10 in this embodiment include a pair of shoulder main grooves 10A located closest to the tread edge Te, and one crown main groove 10B located between the pair of shoulder main grooves 10A. As a result, the land portion 11 in this embodiment includes a pair of shoulder land portions 12 defined between the shoulder main grooves 10A and the tread edge Te, and a pair of crown land portions 13 defined between the shoulder main groove 10A and the crown main groove 10B.

In this embodiment, the first land portion 3 is the crown land portion 13. The crown land portion 13 is a land portion that is subjected to greater ground pressure during straight-line driving than the shoulder land portions 12. By configuring such a crown land portion 13 as the first land portion 3 consisting of a rib, high driving performance is achieved on low μ roads. In the rest of this specification, the first land portion 3 will be described as the crown land portion 13. Note that the first land portion 3 may also form the shoulder land portion 12.

In this embodiment, the shoulder main grooves 10A and crown main grooves 10B extend in a zigzag pattern along the tire circumferential direction. Because these shoulder main grooves 10A and crown main grooves 10B have an axial component, they exert a scratching force on low-μ roads. The shoulder main grooves 10A and crown main grooves 10B are formed, for example, with the same number of zigzag pitches. The shoulder main grooves 10A and crown main grooves 10B may extend, for example, in a wavy or arcuate pattern, or they may extend linearly.

The groove width W2 of the crown main groove 10B is, for example, larger than the groove width W1 of the shoulder main groove 10A. Although not particularly limited, in this embodiment, the groove width W1 of the shoulder main groove 10A and the groove width W2 of the crown main groove 10B are preferably 2% or more of the tread width TW, more preferably 3% or more, more preferably 7% or less, and even more preferably 6% or less.

Figure 4(a) is a cross-sectional view taken along line CC in Figure 3. Figure 4(b) is a cross-sectional view taken along line DD in Figure 3. As shown in Figure 4, the angle θ1 of the groove wall 10a of the shoulder main groove 10A relative to the tread normal n is preferably 4 degrees or greater, more preferably 8 degrees or greater, and preferably 20 degrees or less, and even more preferably 16 degrees or less. The angle θ2 of the groove wall 10b of the crown main groove 10B relative to the tread normal n is preferably 4 degrees or greater, more preferably 8 degrees or greater, and preferably 20 degrees or less, and even more preferably 16 degrees or less. This reduces stone trapping in each main groove 10A, 10B. In this specification, the tread normal n extends in a direction perpendicular to the tread surfaces 12a, 13a of each land portion 12, 13.

In this embodiment, the groove bottom of the crown main groove 10B is provided with protrusions 14 that protrude radially outward. These protrusions 14 further reduce stone trapping. The protrusions 14 are spaced apart along the length of the crown main groove 10B. In this embodiment, no protrusions are provided at the groove bottom of the shoulder main groove 10A.

Figure 5 is an enlarged view of the crown land portion 13 in Figure 3. As shown in Figure 5, the first circumferential edge e1 is, for example, the edge where the groove wall 10a of the shoulder main groove 10A (shown in Figure 4) intersects with the tread surface 13a of the crown land portion 13. The second circumferential edge e2 is, for example, the edge where the groove wall 10b of the crown main groove 10B intersects with the tread surface 13a.

In a plan view of the tread, the first circumferential edge e1 and the second circumferential edge e2 have, for example, multiple peaks 15 that protrude toward the outside of the crown land portion 13. Furthermore, in a plan view of the tread, the first circumferential edge e1 and the second circumferential edge e2 also include, for example, multiple recesses 16 that recess toward the inside of the first land portion 3. In this embodiment, the first circumferential edge e1 and the second circumferential edge e2 each have peaks 15 and recesses 16 that alternate in the tire circumferential direction. The peaks 15 and recesses 16 coincide with the zigzag peaks of the shoulder main grooves 10A and the crown main grooves 10B, respectively.

In a plan view of the tread, each peak 15 is formed by an arc S with a radius of curvature r1 of 2 mm or more. This increases the rigidity of the crown land portion 13 in the area where high ground contact pressure acts (peak 15), thereby improving uneven wear resistance. While not particularly limited, it is desirable for the radius of curvature r1 to be 5 mm or less.

The crown land portion 13 is formed with a plurality of first lateral grooves 17 extending from the first circumferential edge e1 and having ends 17e that terminate within the crown land portion 13. The crown land portion 13 also is formed with a plurality of second lateral grooves 18 extending from the second circumferential edge e2 and having ends 18e that terminate within the crown land portion 13. In this embodiment, the first lateral grooves 17 are connected to the shoulder main grooves 10A. The second lateral grooves 18 are connected to the crown main grooves 10B.

In this embodiment, the first sipes 4 extend from the discontinuous end 17e to the second circumferential edge e2. In this embodiment, the second sipes 5 extend from the discontinuous end 18e to the first circumferential edge e1. In this way, in this embodiment, the first sipes 4 are connected to the crown main groove 10B. The second sipes 5 are connected to the shoulder main groove 10A.

The first sipe 4 is connected, for example, to the apex 15 of the second circumferential edge e2. The second sipe 5 is connected, for example, to the apex 15 of the first circumferential edge e1. Because the first sipe 4 and the second sipe 5 are connected to the apex 15 formed by the arc S in this way, a decrease in the rigidity of the crown land portion 13 is suppressed.

In this embodiment, the first sipes 4 and the second sipes 5 extend linearly. For example, the first sipes 4 are inclined in the same direction as the second sipes 5 relative to the tire axial direction. This reduces the difference in rigidity between the first sipes 4 and the second sipes 5 in the crown land portion 13, suppressing uneven wear. The first sipes 4 and the second sipes 5 may extend in a zigzag pattern along the longitudinal direction or along the tire radial direction, for example.

To effectively achieve the above-mentioned effect, the absolute value of the difference |α1 - α2| between the angle α1 of the first sipe 4 relative to the tire axial direction and the angle α2 of the second sipe 5 relative to the tire axial direction is preferably 20 degrees or less, and more preferably 10 degrees or less. While not particularly limited, the angle α1 of the first sipe 4 and the angle α2 of the second sipe 5 are preferably between 10 and 30 degrees.

The axial length L1 of the first sipe 4 is preferably 20% or more of the maximum width Wa (shown in Figure 1) of the crown land portion 13, more preferably 30% or more, and preferably 80% or less, and even more preferably 70% or less. Similarly, the axial length L4 of the second sipe 5 is preferably 20% or more of the maximum width Wa of the first land portion 3, more preferably 30% or more, and preferably 80% or less, and even more preferably 70% or less.

The pair of first shallow portions 6, 6 includes, for example, a lateral groove-side first shallow portion 6A connected to the first lateral groove 17. The axial length L2a of the lateral groove-side first shallow portion 6A is preferably 10% or more of the maximum radial thickness h1 (shown in Figure 2) of the crown land portion 13. This ensures a sufficient distance between the first deep portion 7 and the first lateral groove 17, reducing the rigidity step in the axially outer region of the crown land portion 13, which is subjected to relatively large lateral forces, and suppressing uneven wear originating from the first lateral groove 17. If the length L2a of the lateral groove-side first shallow portion 6A is excessively large, the axial length L3 of the first deep portion 7 will be reduced, which will shorten the length of the first sipe 4 at the end of wear, potentially resulting in an inability to maintain driving performance on low-μ roads. For this reason, the length of the lateral groove-side first shallow bottom portion 6A is preferably 15% or more of the maximum thickness h1 of the first land portion 3, more preferably 30% or less, and even more preferably 25% or less.

One of the pair of first shallow portions 6 in the axial direction (the right side in Figure 5) 6A, in other words, the lateral groove-side first shallow portion 6A, overlaps, for example, with the other of the pair of second deep portions 8 in the axial direction (the left side in Figure 5) 8B. This prevents a rigidity step from occurring.

The first deep portion 7 has a length greater than the first shallow portion 6. The second shallow portion 9 has a length greater than the second deep portion 8. As a result, the rigidity near the first sipe 4 tends to be lower than the rigidity near the second sipe 5. Therefore, by making the width W3 of the first sipe 4 smaller than the width W4 of the second sipe 5, the difference in rigidity between the first sipe 4 and the second sipe 5 is reduced, improving uneven wear resistance. To effectively achieve this effect, the width W3 of the first sipe 4 is preferably 50% or more of the width W4 of the second sipe 5, more preferably 55% or more, more preferably 75% or less, and even more preferably 70% or less. The width W3 of the first sipe 4 is preferably 0.4 mm or more, more preferably 0.6 mm or more, preferably 0.9 mm or less, and even more preferably 0.7 mm or less.

The axial length L3 of the first deep bottom portion 7 is preferably 30% or more of the axial length L1 of the first sipe 4, more preferably 40% or more, and preferably 70% or less, and even more preferably 60% or less. The axial length L6 of the second shallow bottom portion 9 is preferably 30% or more of the axial length L4 of the second sipe 5, more preferably 40% or more, and preferably 70% or less, and even more preferably 60% or less.

As shown in FIG. 2, the depth d1 of the first shallow portion 6 and the depth d4 of the second shallow portion 9 are preferably 10% or more of the maximum thickness h1 of the crown land portion 13, more preferably 20% or more, and preferably 50% or less, and even more preferably 40% or less. Because the depth d1 of the first shallow portion 6 and the depth d4 of the second shallow portion 9 are 10% or more of the maximum thickness h1 of the crown land portion 13, scratching force on low μ roads is maintained. Because the depth d1 of the first shallow portion 6 and the depth d4 of the second shallow portion 9 are 50% or less of the maximum thickness h1 of the crown land portion 13, a significant decrease in rigidity of the crown land portion 13 is suppressed.

The depth d2 of the first deep bottom portion 7 and the depth d3 of the second deep bottom portion 8 are preferably 70% or more of the maximum thickness h1 of the crown land portion 13, more preferably 75% or more, and more preferably 90% or less, and even more preferably 85% or less. Because the depth d2 of the first deep bottom portion 7 and the depth d3 of the second deep bottom portion 8 are 70% or more of the maximum thickness h1 of the crown land portion 13, the tire 1 maintains its scratching force on low μ roads until the end of wear. Because the depth d2 of the first deep bottom portion 7 and the depth d3 of the second deep bottom portion 8 are 90% or less of the maximum thickness h1 of the crown land portion 13, the rigidity between the first sipe 4 and the second sipe 5 is maintained.

Figure 6 is an enlarged view of the crown land portion 13 in Figure 3. As shown in Figure 6, in this embodiment, the first lateral grooves 17 and the second lateral grooves 18 are alternately arranged in the tire circumferential direction. The shortest circumferential distance L7 between the first lateral grooves 17 and the second lateral grooves 18 is preferably 30% or more, more preferably 40% or more, more preferably 70% or less, and even more preferably 60% or less of the circumferential distance L8 between the first lateral grooves 17, 17. Because the shortest distance L7 is 30% or more and 70% or less of the circumferential distance L8 between the first lateral grooves 17, 17, the bias in rigidity of the crown land portion 13 is reduced, and uneven wear resistance is improved.

In this embodiment, the first lateral grooves 17 and second lateral grooves 18 are inclined relative to the tire axial direction. For example, the first lateral grooves 17 and second lateral grooves 18 are inclined in the same direction. Because these first lateral grooves 17 and second lateral grooves 18 also have a circumferential component, they improve snow performance during cornering and driving performance on low-μ roads. The absolute value |α3-α4| of the difference between the angle α3 of the first lateral groove 17 relative to the tire axial direction and the angle α4 of the second lateral groove 18 relative to the tire axial direction is preferably 20 degrees or less, and more preferably 10 degrees or less. This improves uneven wear resistance.

The first lateral grooves 17 are, for example, inclined in the same direction relative to the tire axial direction as the first sipes 4. Such first lateral grooves 17 enhance the edge effect of the first sipes 4. The absolute value |α1-α3| of the difference between the angle α3 of the first lateral grooves 17 and the angle α1 of the first sipes 4 (shown in FIG. 5) is preferably 20 degrees or less, and more preferably 10 degrees or less. In this embodiment, the absolute value |α1-α3| is 0 degrees. Similarly, the absolute value |α2-α4| of the difference between the angle α4 of the second lateral grooves 18 and the angle α2 of the second sipes 5 is preferably 20 degrees or less, and more preferably 10 degrees or less.

The first lateral groove 17 is connected to, for example, the recessed portion 16 of the first circumferential edge e1. The second lateral groove 18 is connected to, for example, the recessed portion 16 of the second circumferential edge e2. Such first lateral grooves 17 and second lateral grooves 18 eliminate the rigidity step of the recessed portion 16 and improve wear resistance.

The axial length L9 of the first lateral groove 17 and the axial length L10 of the second lateral groove 18 are each preferably 20% or more of the maximum width Wa of the crown land portion 13, more preferably 30% or more, and more preferably 70% or less, and even more preferably 60% or less.

Although not particularly limited, the groove width W5 of the first lateral groove 17 and the groove width W6 of the second lateral groove 18 are, for example, 10% to 20% of the maximum length Wa of the crown land portion 13.

In this embodiment, the first lateral groove 17 includes a first raised portion 20 where the groove bottom 17s is raised. The second lateral groove 18 includes a second raised portion 21 where the groove bottom 18s is raised. The first raised portion 20 extends from the interrupted end 17e toward the shoulder main groove 10A and ends without connecting to the shoulder main groove 10A. The second raised portion 21 extends from the interrupted end 18e toward the crown main groove 10B and ends without connecting to the crown main groove 10B.

The axial length L11 of the first raised portion 20 is preferably 70% or more of the length L9 of the first lateral groove 17, more preferably 75% or more, and more preferably 90% or less, and even more preferably 85% or less. The axial length L12 of the second raised portion 21 is preferably 70% or more of the length L10 of the second lateral groove 18, more preferably 75% or more, and more preferably 90% or less, and even more preferably 85% or less. The depth d7 (shown in Figure 2) of the first raised portion 20 and the depth d8 of the second raised portion 21 are preferably 30% or more of the maximum thickness h1 of the crown land portion 13, more preferably 40% or more, and more preferably 70% or less, and even more preferably 60% or less.

The second raised portion 21 is provided with a groove bottom sipe 24 that connects to the second sipe 5. On the other hand, the first raised portion 20 is not provided with a groove bottom sipe. This maintains even higher rigidity in the axially outer region of the crown land portion 13, suppressing uneven wear originating from the first lateral groove 17. Furthermore, during straight-ahead driving, this promotes deformation of the second lateral groove 18, which is located on the axially inner side of the crown land portion 13 and is subjected to high ground contact pressure, further increasing the scratching force and improving driving performance on low-μ roads.

As shown in FIG. 3 , the crown land portion 13 is provided with closed sipes 26, the ends 26e of which are interrupted within the crown land portion 13. The closed sipes 26 extend, for example, in a zigzag pattern. In this embodiment, the closed sipes 26 are provided between first sipes 4 and second sipes 5 that are arranged alternately in the tire circumferential direction. For example, one closed sipe 26 is provided between each first sipe 4 and second sipe 5.

The axial length L13 of the closed sipe 26 is preferably 30% or more of the maximum length Wa (shown in Figure 1) of the crown land portion 13, more preferably 35% or more, and more preferably 50% or less, and even more preferably 45% or less. Because the length L13 of the closed sipe 26 is 30% or more of the maximum length Wa of the crown land portion 13, driving performance on low μ roads is improved. Because the length 135 of the closed sipe 26 is 50% or less of the maximum length Wa of the crown land portion 13, high wear resistance is maintained.

The closed sipes 26 are, for example, inclined relative to the tire axial direction. In this embodiment, the closed sipes 26 are inclined in the same direction as the first sipes 4. The absolute value |α1-α5| of the difference between the angle α5 of the closed sipes 26 relative to the tire axial direction and the angle α1 of the first sipes 4 (shown in FIG. 5) is preferably 20 degrees or less, and more preferably 10 degrees or less. In this embodiment, the absolute value |α1-α5| is 0 degrees. The angle α5 of the closed sipes 26 is the angle at the center line of the zigzag amplitude.

The maximum width Wa of the crown land portion 13 is preferably smaller than the maximum width Wb (shown in Figure 7) of the shoulder land portion 12. The maximum width Wa of the crown land portion 13 is preferably 30% or more of the maximum width Wb of the shoulder land portion 12, more preferably 40% or more, more preferably 90% or less, and even more preferably 80% or less. The maximum width Wa of the crown land portion 13 is preferably 15% or more of the tread width TW, more preferably 20% or more, more preferably 35% or less, and even more preferably 30% or less.

Figure 7 is a plan view of the shoulder land portion 12. As shown in Figure 7, the shoulder land portion 12 is provided with shoulder lateral grooves 35 that cross the shoulder land portion 12 and shoulder sipes 36 that connect to the shoulder main grooves 10A. As a result, the shoulder land portion 12 is divided into multiple shoulder blocks 12B by the shoulder main grooves 10A, the tread edge Te, and the shoulder lateral grooves 35. The shoulder lateral grooves 35 connect to zigzag apexes 38A that convex on the axially outer side of the shoulder main grooves 10A. The shoulder sipes 36 connect to zigzag apexes 38b that convex on the axially inner side of the shoulder main grooves 10A. The shape of the shoulder land portion 12 is not limited to this embodiment; for example, shoulder sipes 36 may not be provided.

The shoulder lateral grooves 35 have a groove width W7 that continuously increases toward the tread edge Te. The shoulder lateral grooves 35 extend, for example, along the tire axial direction. The groove depth (not shown) of the shoulder lateral grooves is preferably 30% or less, and more preferably 25% or less, of the groove depth D1 (same as the maximum thickness h1 of the crown land portion 13) of the shoulder main groove 10A. Such shoulder lateral grooves 35 prevent excessive reduction in the rigidity of the shoulder land portion 12. To ensure the basic performance of the tire 1, the groove depth of the shoulder lateral grooves 35 is preferably 5% or more, and more preferably 10% or more, of the groove depth of the shoulder main groove 10A.

The shoulder lateral groove 35 includes a first widened portion 35A extending from the shoulder main groove 10A and a second widened portion 35B in which the rate of change in groove width W7 relative to the longitudinal direction is greater than that of the first widened portion 35A. The axial length L15 of the second widened portion 35B is preferably 10% or more of the maximum width Wb of the shoulder land portion 12, more preferably 15% or more, more preferably 30% or less, and even more preferably 25% or less.

In this embodiment, the shoulder sipe 36 includes an axial portion 36A extending axially from the shoulder main groove 10A, and a circumferential portion 36B that connects to the axial portion 36A and extends circumferentially. In a plan view of the tread, the shoulder sipe 36 is formed in a generally L-shape. The circumferential portion 36B terminates within the shoulder block 12B without connecting to the shoulder lateral groove 35. One shoulder sipe 36 is provided per shoulder block 12B.

The shoulder sipes 36 are terminated, for example, axially inward of the second widened portion 35B. In this embodiment, the shoulder sipes 36 extend toward the tread edge Te from the axially intermediate position 12c of the shoulder land portion 12. In this specification, the intermediate position 12c is the middle of the maximum width Wb. The distance L16 between the axially outer end 36e of the shoulder sipe 36 and the tread edge Te is preferably 30% or more of the maximum width Wb of the shoulder land portion 12, more preferably 35% or more, more preferably less than 50%, and even more preferably 45% or less.

The land ratio of the shoulder land portion 12 is preferably 70% or more, more preferably 75% or more, and more preferably 90% or less, and even more preferably 85% or less. The land ratio is the ratio (Sb/Sa) of the tread area Sb of the shoulder land portion 12 to the virtual tread area Sa of the shoulder land portion 12 obtained by filling all lateral grooves and sipes provided in the shoulder land portion 12, such as the shoulder lateral grooves 35 and shoulder sipes 36.

The maximum circumferential length L18 of the shoulder block 12B is preferably 75% or more of the circumferential separation distance L8 between the first lateral grooves 17, 17, more preferably 80% or more, and preferably 95% or less, and even more preferably 90% or less.

The above describes in detail a particularly preferred embodiment of the present disclosure, but the present disclosure is not limited to the illustrated embodiment and can be modified and implemented in various ways.

Tires having the basic pattern shown in Figure 3 were prototyped based on the specifications in Tables 1 and 2. Each test tire was then tested for running performance on a low μ road and uneven wear resistance. The common specifications and test methods for each test tire are as follows:
Tire size: 205/85R16 117/115L
Rim size: 16 x 5.5J
Air pressure: 600kPa (front and rear wheels)
Load: Empty

<Driving performance on low μ roads>
The test tires were mounted on all wheels of a light truck with an engine displacement of 3000 cc. A test driver drove the vehicle on iron and icy roads, and evaluated the driving performance on each road surface while driving straight and while cornering by the test driver's senses. The results were expressed as a score with Example 1 being 100. The higher the score, the better the driving performance on low μ roads.

<Uneven wear resistance>
A test driver drove the vehicle on a dry asphalt road surface. The test driver then evaluated the occurrence of uneven wear (heel-and-toe wear, etc.) on the crown land portion by sensory evaluation. The results were expressed as a score based on Example 1 being 100. The larger the score, the more the occurrence of uneven wear was suppressed and the better the uneven wear resistance performance.
Mileage: 20,000 km
The test results are shown in Tables 1 and 2.
In Table 1, the La/Wa value of "-1" indicates that the first deep bottom portion and the second deep bottom portion are not misaligned in the tire axial direction.
In each example, a score of 95 or above is a pass, and a score below 95 is a fail.

The tires of the examples have improved wear resistance compared to the tires of the comparative examples. Furthermore, the tires of the examples have excellent driving performance on low μ roads.

[Note]
The present disclosure includes the following aspects.

[Disclosure 1]
A tire having a tread portion,
the tread portion includes a first land portion including a first circumferential edge extending in the tire circumferential direction, a second circumferential edge extending in the tire circumferential direction, and a tread surface therebetween,
the first land portion is formed by a rib that is not provided with a lateral groove that completely crosses the first land portion in the tire axial direction,
the first land portion includes a first sipe extending in the tire axial direction and a second sipe extending in the tire axial direction and adjacent to the first sipe in the tire circumferential direction,
The first sipe includes a pair of first shallow bottom portions including both ends in the longitudinal direction, and a first deep bottom portion connecting the pair of first shallow bottom portions and having a depth greater than a depth of the pair of first shallow bottom portions,
The second sipe includes a pair of second deep bottom portions including both ends in the longitudinal direction, and a second shallow bottom portion connecting the pair of second deep bottom portions and having a depth smaller than a depth of the pair of second deep bottom portions,
The first deep bottom portion and the pair of second deep bottom portions are misaligned in the tire axial direction.
tire.
[Disclosure 2]
The tire described in the present disclosure 1, wherein one of the pair of first shallow bottom portions in the tire axial direction overlaps with the other of the pair of second deep bottom portions in the tire axial direction.
[Disclosure 3]
a plurality of first lateral grooves are formed in the first land portion, the first lateral grooves extending from the first circumferential edge and having ends that terminate within the first land portion;
The tire according to Disclosure 1 or 2, wherein the first sipe extends from the interrupted end to the second circumferential edge.
[Disclosure 4]
the first transverse groove includes a first raised portion at the groove bottom,
The tire of Disclosure 3, wherein the first raised portion is not provided with a groove bottom sipe.
[Disclosure 5]
the pair of first shallow bottom portions includes a lateral groove-side first shallow bottom portion connected to the first lateral groove,
The tire according to Disclosure 3 or 4, wherein the length in the tire axial direction of the lateral groove-side first shallow bottom portion is 10% or more of the maximum thickness in the tire radial direction of the first land portion.
[Disclosure 6]
a plurality of second lateral grooves are formed in the first land portion, the second lateral grooves extending from the second circumferential edge and having ends that terminate within the first land portion;
The tire according to any one of disclosures 1 to 5, wherein the second sipe extends from the interrupted end to the first circumferential edge.
[Disclosure 7]
the second lateral groove includes a second raised portion at the groove bottom,
The tire of the present disclosure 6, wherein the second raised portion is provided with a groove bottom sipe that connects to the second sipe.
[Disclosure 8]
The tire according to any one of Disclosures 1 to 7, wherein the first land portion is a crown land portion disposed closest to the tire equator.
[Disclosure 9]
The tire according to any one of Disclosures 1 to 8, wherein the depth of the first shallow portion and the depth of the second shallow portion are 10% to 50% of the maximum thickness of the first land portion in the tire radial direction.
[Disclosure 10]
A tire described in any one of Disclosures 1 to 9, wherein the depth of the first deep bottom portion and the depth of the second deep bottom portion are 70% to 90% of the maximum thickness of the first land portion in the tire radial direction.
[Disclosure 11]
The tire according to any one of disclosures 1 to 10, wherein the width of the first sipes is smaller than the width of the second sipes.
[Disclosure 12]
the first circumferential edge and the second circumferential edge have a plurality of apexes that are convex toward an outer side of the first land portion,
The tire according to any one of Disclosures 1 to 11, wherein, in a plan view of the tread, each of the plurality of apexes is formed by an arc having a curvature radius of 2 mm or more.
[Disclosure 13]
The tire described in the present disclosure 12, wherein each of the plurality of peaks is connected to either the first sipe or the second sipe.

REFERENCE SIGNS LIST 1 Tire 3 First land portion 4 First sipe 5 Second sipe 6 First shallow bottom portion 7 First deep bottom portion 8 Second deep bottom portion 9 Second shallow bottom portion

Claims (16)

A tire having a tread portion,
the tread portion includes a first land portion including a first circumferential edge extending in the tire circumferential direction, a second circumferential edge extending in the tire circumferential direction, and a tread surface therebetween,
the first land portion is formed by a rib that is not provided with a lateral groove that completely crosses the first land portion in the tire axial direction,
the first land portion includes a first sipe extending in the tire axial direction and a second sipe extending in the tire axial direction and adjacent to the first sipe in the tire circumferential direction,
The first sipe includes a pair of first shallow bottom portions including both ends in the longitudinal direction, and a first deep bottom portion connecting the pair of first shallow bottom portions and having a depth greater than a depth of the pair of first shallow bottom portions,
The second sipe includes a pair of second deep bottom portions including both ends in the longitudinal direction, and a second shallow bottom portion connecting the pair of second deep bottom portions and having a depth smaller than a depth of the pair of second deep bottom portions,
the first deep bottom portion and the pair of second deep bottom portions are misaligned in the tire axial direction,
one of the pair of first shallow portions in the tire axial direction overlaps with the other of the pair of second deep portions in the tire axial direction;
tire. A tire having a tread portion,
the tread portion includes a first land portion including a first circumferential edge extending in the tire circumferential direction, a second circumferential edge extending in the tire circumferential direction, and a tread surface therebetween,
the first land portion is formed by a rib that is not provided with a lateral groove that completely crosses the first land portion in the tire axial direction,
the first land portion includes a first sipe extending in the tire axial direction and a second sipe extending in the tire axial direction and adjacent to the first sipe in the tire circumferential direction,
The first sipe includes a pair of first shallow bottom portions including both ends in the longitudinal direction, and a first deep bottom portion connecting the pair of first shallow bottom portions and having a depth greater than a depth of the pair of first shallow bottom portions,
The second sipe includes a pair of second deep bottom portions including both ends in the longitudinal direction, and a second shallow bottom portion connecting the pair of second deep bottom portions and having a depth smaller than a depth of the pair of second deep bottom portions,
the first deep bottom portion and the pair of second deep bottom portions are misaligned in the tire axial direction,
a plurality of first lateral grooves are formed in the first land portion, the first lateral grooves extending from the first circumferential edge and having discontinuous ends within the first land portion;
The first sipe extends from the interrupted end to the second circumferential edge.
tire. A tire having a tread portion,
the tread portion includes a first land portion including a first circumferential edge extending in the tire circumferential direction, a second circumferential edge extending in the tire circumferential direction, and a tread surface therebetween,
the first land portion is formed by a rib that is not provided with a lateral groove that completely crosses the first land portion in the tire axial direction,
the first land portion includes a first sipe extending in the tire axial direction and a second sipe extending in the tire axial direction and adjacent to the first sipe in the tire circumferential direction,
The first sipe includes a pair of first shallow bottom portions including both ends in the longitudinal direction, and a first deep bottom portion connecting the pair of first shallow bottom portions and having a depth greater than a depth of the pair of first shallow bottom portions,
The second sipe includes a pair of second deep bottom portions including both ends in the longitudinal direction, and a second shallow bottom portion connecting the pair of second deep bottom portions and having a depth smaller than a depth of the pair of second deep bottom portions,
the first deep bottom portion and the pair of second deep bottom portions are misaligned in the tire axial direction,
a plurality of second lateral grooves are formed in the first land portion, the second lateral grooves extending from the second circumferential edge and having discontinuous ends within the first land portion;
The second sipe extends from the interrupted end to the first circumferential edge.
tire. A tire having a tread portion,
the tread portion includes a first land portion including a first circumferential edge extending in the tire circumferential direction, a second circumferential edge extending in the tire circumferential direction, and a tread surface therebetween,
the first land portion is formed by a rib that is not provided with a lateral groove that completely crosses the first land portion in the tire axial direction,
the first land portion includes a first sipe extending in the tire axial direction and a second sipe extending in the tire axial direction and adjacent to the first sipe in the tire circumferential direction,
The first sipe includes a pair of first shallow bottom portions including both ends in the longitudinal direction, and a first deep bottom portion connecting the pair of first shallow bottom portions and having a depth greater than a depth of the pair of first shallow bottom portions,
The second sipe includes a pair of second deep bottom portions including both ends in the longitudinal direction, and a second shallow bottom portion connecting the pair of second deep bottom portions and having a depth smaller than a depth of the pair of second deep bottom portions,
the first deep bottom portion and the pair of second deep bottom portions are misaligned in the tire axial direction,
the first circumferential edge and the second circumferential edge have a plurality of apexes that are convex toward an outer side of the first land portion,
In a plan view of the tread, each of the plurality of peaks is formed by an arc having a curvature radius of 2 mm or more,
Each of the plurality of apexes is connected to either the first sipe or the second sipe.
tire. A tire described in any one of claims 2 to 4, wherein one of the pair of first shallow bottom portions axially overlaps the other of the pair of second deep bottom portions axially. a plurality of first lateral grooves are formed in the first land portion, the first lateral grooves extending from the first circumferential edge and having discontinuous ends within the first land portion;
The tire according to claim 1 , wherein the first sipe extends from the discontinued end of the first lateral groove to the second circumferential edge. a plurality of second lateral grooves are formed in the first land portion, the second lateral grooves extending from the second circumferential edge and having discontinuous ends within the first land portion;
The tire according to claim 1 , wherein the second sipe extends from the discontinued end of the second lateral groove to the first circumferential edge. the first circumferential edge and the second circumferential edge have a plurality of apexes that are convex toward an outer side of the first land portion,
The tire according to claim 1 , wherein, in a plan view of the tread, each of the plurality of apexes is formed by an arc having a curvature radius of 2 mm or more. The tire according to claim 8 , wherein each of the plurality of apexes is connected to either the first sipe or the second sipe. the first transverse groove includes a first raised portion at the groove bottom,
The tire according to claim 2 or 6, wherein the first raised portion is not provided with a groove bottom sipe. the pair of first shallow bottom portions includes a lateral groove-side first shallow bottom portion connected to the first lateral groove,
The tire according to claim 2 , wherein the axial length of the lateral groove-side first shallow bottom portion is 10% or more of the maximum radial thickness of the first land portion. the second lateral groove includes a second raised portion where the groove bottom is raised,
The tire according to claim 3 or 7, wherein the second raised portion is provided with a groove bottom sipe that is connected to the second sipe. The tire described in any one of claims 1 to 12, wherein the first land portion is a crown land portion located closest to the tire equator. A tire described in any one of claims 1 to 13, wherein the depth of the first shallow bottom portion and the depth of the second shallow bottom portion are 10% to 50% of the maximum thickness of the first land portion in the tire radial direction. A tire described in any one of claims 1 to 14, wherein the depth of the first deep bottom portion and the depth of the second deep bottom portion are 70% to 90% of the maximum thickness of the first land portion in the tire radial direction. A tire described in any one of claims 1 to 15, wherein the width of the first sipe is smaller than the width of the second sipe.