pneumatic tires

Abstract

To suppress uneven wear of a shoulder land portion in which a plurality of sipes extending in a tire axial direction are formed on a tread surface.SOLUTION: A pneumatic tire: includes a shoulder-land 15A having a tread surface 11 and an outside surface 12; a plurality of lateral grooves 21 provided on the shoulder-land 15A; a plurality of sipes 23A, 23B provided between a pair of lateral grooves 21; and a plurality of recesses 25 provided on the outside surface 12. A plurality of recesses 25 are respectively disposed at different positions in a tire circumferential direction TC with respect to the sipes 23A, 23B and include an inner recess 26 located on a center side in the tire circumferential direction TC and an outer recess 27 located on a lateral groove 21 side, at an interval between the pair of lateral grooves 21. A size Sr1 of the inner recess 26 in a tire radial direction TR is shorter than a size Sr2 of the outer recess 27 in the tire radial direction TR. Each of the inner recess 26 and the outer recess 27 has a bent shape having one or more inflection points 26e as viewed from a tire axial direction TA.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire. [Background technology]

[0002] In Patent Document 1, for the purpose of suppressing wear at the shoulder land of the tread, first sipes are formed on the outer surface located at the axially outer end of the shoulder land, recessed axially inward, extending radially and terminating at a distance from the tread surface. Patent Document 1 also discloses a configuration in which second sipes are provided between adjacent first sipes in the tire circumferential direction, recessed radially inward from the tread surface of the shoulder land, extending axially and opening at the outer surface of the shoulder land. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-506 Summary of the Invention [Problem to be solved by the invention]

[0004] When a shoulder land has multiple lateral grooves extending radially inward from the outer surface at intervals around the tire, and multiple second sipes are provided on the tread, uneven wear is likely to occur in the center between a pair of circumferentially adjacent lateral grooves. This is because, when a force acts on the shoulder land from the outside to the inside in the tire axial direction, the center between the pair of lateral grooves is more likely to have reduced rigidity due to the second sipes than the circumferentially outer portions, and the amount of relative displacement is also greater. Therefore, the pneumatic tire of Patent Document 1 has room for improvement in terms of measures to prevent uneven wear at the axially outer ends of the tread.

[0005] An object of the present invention is to provide a pneumatic tire that can suppress uneven wear on a shoulder land having a plurality of sipes formed on the tread surface extending in the tire axial direction. [Means for solving the problem]

[0006] One aspect of the present invention is a tire having a tread surface at the outer end in the tire radial direction and an outer surface at the outer end in the tire axial direction, the tread having a shoulder land located at the outer end in the tire axial direction of the tread; a plurality of lateral grooves provided on the shoulder land at intervals in the tire circumferential direction, recessed from the tread surface inward in the tire radial direction, extending in the tire axial direction and opening at the outer surface; a plurality of sipes provided at intervals in the tire circumferential direction between a pair of lateral grooves adjacent in the tire circumferential direction of the shoulder land, each recessed from the tread surface inward in the tire radial direction, extending in the tire axial direction and terminating at a position spaced from the outer surface; Provided is a pneumatic tire comprising: a plurality of recesses provided on an outer surface, recessed inward in the tire axial direction, and extending in the tire radial direction; the plurality of recesses are arranged at different positions in the tire circumferential direction relative to the sipes; the plurality of recesses each include an inner recess located closer to the center of the tire circumferential direction within the spacing between the pair of lateral grooves, and an outer recess located closer to the lateral groove than the inner recess; the tire radial dimension of the inner recess is shorter than the tire radial dimension of the outer recess; and at least one of the inner recess and the outer recess has a curved shape having one or more inflection points when viewed in the tire axial direction.

[0007] The inner and outer recesses are provided at different positions around the tire circumferential direction relative to the sipes on the tread. This prevents excessive reduction in shoulder stiffness compared to when the sipes and recesses are provided at the same position around the tire circumferential direction, thereby reducing the occurrence of cracks originating from the sipes and recesses.

[0008] The radial dimension of the inner recess is shorter than the radial dimension of the outer recess. Therefore, the rigidity of the outer circumferential portion of the shoulder land between a pair of lateral grooves can be made lower than the rigidity of the circumferential center portion. This optimizes the circumferential rigidity balance between the pair of lateral grooves. This averages out the amount of circumferential displacement when a force acts from the outer side to the inner side in the tire axial direction, effectively suppressing uneven wear in the circumferential center portion of the tire.

[0009] At least one of the inner and outer recesses has a curved shape with one or more inflection points, allowing the curved recess to elastically absorb forces from two or more different directions. This allows for a more optimized circumferential rigidity balance between the pair of lateral grooves, effectively suppressing uneven wear even when the pneumatic tire is mounted on a steering wheel of a vehicle.

[0010] The inner recess or the outer recess of the bent shape has a first portion extending in a first direction and a second portion extending in a second direction intersecting the first direction, and the angle between the first portion and the second portion is greater than or equal to 90 degrees and less than or equal to 150 degrees.

[0011] The angle between the first and second portions of the inner or outer recess of the bent shape is between 90 and 150 degrees. This prevents cracks from forming at the inflection point, which is likely to occur when the angle between the first and second portions is too small. Furthermore, the effect of mitigating lateral forces from different directions, which is difficult to achieve when the angle between the first and second portions is too large, can be reliably achieved.

[0012] The inner recess and the outer recess each have an outer end located on the outer side in the tire radial direction and an inner end located on the inner side in the tire radial direction, and a straight line connecting the outer end of the inner recess to the inner end of the inner recess, and a straight line connecting the outer end of the outer recess to the inner end of the outer recess, each incline from the outer side to the inner side in the tire radial direction, toward the center of the tire circumferential direction within the gap between the pair of lateral grooves.

[0013] The straight lines connecting the outer and inner ends of the inner and outer recesses are inclined from the outer side to the inner side in the tire radial direction toward the center in the tire circumferential direction between the pair of lateral grooves. This makes the inclination of the inner and outer recesses an obtuse angle with respect to the direction of rotation of the pneumatic tire, which reduces damage originating from the inner and outer recesses when the tire comes into contact with a curb, step, etc.

[0014] The inclination angle of each of the straight lines relative to a reference line extending in the tire radial direction is equal to or greater than 5 degrees and equal to or less than 15 degrees.

[0015] The inclination angle of the line connecting the outer end and inner end of each of the inner and outer recesses is between 5 and 15 degrees relative to a reference line extending in the tire radial direction. This prevents the short inner recess and the long outer recess from overlapping when viewed from the outside in the tire radial direction. This prevents excessive reduction in shoulder rigidity due to the overlap of the inner and outer recesses.

[0016] The dimension of the outer recess in the tire radial direction is 1.25 to 1.75 times the depth of the sipe in the tire radial direction.

[0017] The radial dimension of the outer recess is between 1.25 and 1.75 times the radial depth of the sipe, which effectively reduces the rigidity of the outer circumferential portion of the tire between a pair of lateral grooves, optimizing the rigidity balance of the shoulder area and suppressing uneven wear.

[0018] The radial dimension of the inner recess is 0.25 to 0.45 times the radial dimension of the outer recess.

[0019] The radial dimension of the inner recess is between 0.25 and 0.45 times the radial dimension of the outer recess. This prevents excessive reduction in rigidity in the circumferential center portion of the tire between a pair of lateral grooves, thereby optimizing the rigidity balance in the shoulder area and suppressing uneven wear.

[0020] The outer side surface has a chamfer at the portion in contact with the tread that is inclined from the inside in the tire radial direction to the outside toward the inside in the tire axial direction, and the distance from the outer end of the sipe in the tire axial direction to the outer end of the chamfer in the tire axial direction is 1.5 times or more the dimension of the chamfer in the tire axial direction.

[0021] The distance from the outer edge of the sipe to the outer edge of the chamfer is 1.5 times or more the axial dimension of the chamfer, which helps to prevent cracks from occurring at the outer edge of the sipe.

[0022] The outer ends of the inner recess and the outer recess in the tire radial direction are opened at the chamfers.

[0023] The outer ends of the inner and outer recesses are open within the chamfer, which can prevent cracks from occurring at the outer ends, which may occur if the outer ends of the inner and outer recesses are closed.

[0024] The depth of each of the inner recess and the outer recess in the tire axial direction is 0.25 to 0.75 times the dimension of the chamfer in the tire axial direction.

[0025] The depth of the inner and outer recesses is 0.25 to 0.75 times the axial dimension of the chamfer. This prevents the reduction in shoulder land rigidity, which can occur when the inner and outer recess depths are too small relative to the chamfer dimensions, and improves the rigidity balance between a pair of lateral grooves. Furthermore, it prevents cracks from occurring when the inner and outer recess depths are too large relative to the chamfer dimensions, which can occur when the tire comes into contact with a curb or step, ensuring external damage resistance.

[0026] The ratio of the width of the inner recess in the tire circumferential direction to the depth of the inner recess in the tire axial direction is 0.5 to 1.0, and the ratio of the width of the outer recess in the tire circumferential direction to the depth of the outer recess in the tire axial direction is 0.5 to 1.0.

[0027] The ratio of the width of the inner recess and the outer recess to the depth of each recess is 0.5 to 1.0. This prevents insufficient reduction in stiffness of the shoulder land, which can occur when the ratio of the width to the depth of the recess is too small. Also, it prevents excessive reduction in stiffness of the shoulder land, which can occur when the ratio of the width to the depth of the recess is too large.

[0028] The tread comprises main grooves spaced apart on the inner side of the outer surface in the tire axial direction, recessed radially inward, and extending circumferentially; and a circumferential groove formed between the main groove and the outer surface, recessed radially inward, and extending circumferentially. The shoulder land comprises a rib defined by the outer surface and a sidewall of the main groove, a plurality of first blocks formed on the outer side of the rib in the tire radial direction and defined by the outer surface, the sidewall of the circumferential groove, and the sidewalls of a pair of circumferentially adjacent lateral grooves, and a plurality of second blocks formed on the outer side of the rib in the tire radial direction and defined by the sidewall of the circumferential groove, the sidewall of the main groove, and the sidewalls of a pair of circumferentially adjacent lateral grooves, and the sipes and the recesses are formed in each of the plurality of first blocks.

[0029] The shoulder land has a rib, multiple first blocks, and multiple second blocks, with a recess formed in the first block. With this type of shoulder land, when a force acts from the outside to the inside of the tire axial direction, the rib has difficulty absorbing the force, so the impact on the first block is significant. However, because the recess is formed in the first block, the rigidity balance of the first block can be optimized, and uneven wear can be suppressed.

[0030] The number of the recesses is equal to or greater by one than the number of the sipes, and is an even number of 4 or greater.

[0031] The number of recesses is the same as the number of sipes or is one more than the number of sipes, and is an even number of 4 or more. In this way, since the number of recesses is an even number of 4 or more, with the upper limit being one more than the number of sipes, the rigidity balance between a pair of lateral grooves can be easily optimized. [Effects of the Invention]

[0032] The present invention can suppress uneven wear on the shoulder land where a plurality of sipes extending in the tire axial direction are formed on the tread. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a perspective view showing a portion of a pneumatic tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the tread pattern of the pneumatic tire of FIG. 1. [Figure 3] Enlarged view of part III in Figure 2. [Figure 4] Cross-sectional view of line IV-IV in Figure 3. [Figure 5] FIG. 3 is a side view showing a portion of the pneumatic tire of FIG. 2. [Figure 6] Enlarged view of part VI in Figure 5. [Figure 7] FIG. 7 is an enlarged view similar to FIG. 6 of a pneumatic tire according to a modified example. [Figure 8] FIG. 7 is an enlarged view similar to FIG. 6 of a pneumatic tire according to a modified example. [Figure 9] FIG. 10 is a perspective view showing a portion of a modified pneumatic tire. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0035] 1 and 2 show a portion of a tread 10 of a pneumatic tire (hereinafter simply referred to as "tire") 1 according to an embodiment of the present invention. The tire 1 of this embodiment is a studless tire for passenger cars, but the tire 1 may also be for light trucks or trucks and buses.

[0036] 1 and 2, a tire 1 includes a tread 10, a pair of sidewalls (not shown), and a pair of bead portions (not shown). Of these, the sidewalls are connected to both ends of the tread 10 in the tire axial direction TA and extend inward in the tire radial direction TR (downward in FIG. 1). The bead portions are connected to the inner ends of the sidewalls in the tire radial direction TR.

[0037] The tread 10 is cylindrical, extends in the tire axial direction TA, and continues endlessly in the tire circumferential direction TC. The tread 10 is defined by a tread surface 11 located at the outer end in the tire radial direction TR and a pair of outer side surfaces 12 located at the outer ends of the tire in the tire axial direction TA. The tread 10 is provided with a plurality of lateral grooves 21 extending in the tire axial direction TA at intervals in the tire circumferential direction TC. In this embodiment, recesses 25 are provided in each of the pair of outer side surfaces 12 to suppress uneven wear between a pair of lateral grooves 21 adjacent in the tire circumferential direction TC.

[0038] Specifically, the tread 10 is provided with a plurality of annular main grooves 14 recessed inward in the tire radial direction TR from the tread surface 11 and extending in the tire circumferential direction TC at intervals in the tire axial direction TA. Referring to Fig. 4, each main groove 14 is defined by a pair of side walls 14a facing each other in the tire axial direction TA and bottom walls 14b continuing to the inner ends of the pair of side walls 14a in the tire radial direction TR.

[0039] 2, the tread 10 has a plurality of lands 15 arranged in the tire axial direction TA by a plurality of main grooves 14. In this embodiment, four rows of lands 15 are formed by three main grooves 14, but the number of main grooves 14 and the number of lands 15 can be changed as needed.

[0040] In the following description, of the multiple lands 15, the two located at the outermost sides in the tire axial direction TA in Figure 2 will be referred to as shoulder lands 15A, and the lands other than the shoulder lands 15A located between the pair of main grooves 14 will be referred to as center lands 15B. The outer side in the tire axial direction TA means the side away from the center line CL1 that divides the tread 10 in half in the tire axial direction TA, and the inner side in the tire axial direction TA means the side closer to the center line CL1.

[0041] 2, the shoulder land 15A is defined by the outer surface 12 and the sidewall 14a of the main groove 14 closest to the outer surface 12. The center land 15B is defined by the sidewall 14a of each main groove 14 adjacent to the outer surface 12 in the tire axial direction TA. Each land 15 has one circumferential groove 20 and multiple lateral grooves 21 formed therein.

[0042] 1 and 4, the circumferential grooves 20 are provided between the main grooves 14 and the outer surface 12 and between the pair of main grooves 14, recessed inward in the tire radial direction TR from the tread surface 11, and extending annularly in the tire circumferential direction TC. The circumferential groove 20 is defined by a pair of side walls 20a facing each other in the tire axial direction TA, and bottom walls 20b respectively continuing to the inner ends of the pair of side walls 20a in the tire radial direction TR.

[0043] The lateral grooves 21 are recessed inward in the tire radial direction TR from the tread surface 11, extend in the tire axial direction TA, and are provided at intervals in the tire circumferential direction TC. Each lateral groove 21 is defined by a pair of side walls 21a facing each other in the tire circumferential direction TC and a bottom wall 21b continuing to the inner ends of the pair of side walls 21a in the tire radial direction TR.

[0044] One end of each lateral groove 21 in the tire axial direction TA opens at the side wall 20a of the circumferential groove 20 and is connected to the circumferential groove 20. On the outer side of the circumferential groove 20 of the shoulder land 15A in the tire axial direction TA, the other end of the lateral groove 21 in the tire axial direction TA opens at the outer surface 12 and is open to the outside. On the inner side of the circumferential groove 20 of the shoulder land 15A in the tire axial direction TA and at the center land 15B, the other end of the lateral groove 21 in the tire axial direction TA opens at the side wall 14a of the main groove 14 and is connected to the main groove 14.

[0045] 2 and 3, the groove width of the lateral groove 21 in the tire circumferential direction TC, which is the distance between a pair of side walls 21a, is smaller than the groove width of the main groove 14 in the tire axial direction TA, which is the distance between a pair of side walls 14a. Also, the groove width of the circumferential groove 20 in the tire axial direction TA, which is the distance between a pair of side walls 20a, is smaller than the groove width of the lateral groove 21.

[0046] 4, the depth of the circumferential groove 20 in the tire radial direction TR, i.e., the dimension from the tread 11 to the bottom wall 20b, is shallower than the depth Dr1 of the main groove 14 in the tire radial direction. The depth Dr2 of the lateral groove 21 in the tire radial direction TR, i.e., the dimension from the tread 11 to the bottom wall 21b, is shallower than the depth Dr1 of the main groove 14. In this embodiment, the depth of the circumferential groove 20 is the same as the depth Dr2 of the lateral groove 21. However, the depths of the circumferential groove 20 and the lateral groove 21 may be different as long as they are shallower than the depth Dr1 of the main groove 14.

[0047] 1 and 4, each land 15 is formed by the main grooves 14, the circumferential grooves 20, and the lateral grooves 21, with a rib 16 and a plurality of blocks 17 located outside the rib 16 in the tire radial direction TR. For each land 15, a plurality of blocks 17 are provided at intervals in the tire circumferential direction TC, and are also provided in two rows at intervals in the tire axial direction TA.

[0048] 2, the rib 16 of the shoulder land 15A is defined by the outer surface 12 and the sidewall 14a of the main groove 14 closest to the outer surface 12. The rib 16 of the center land 15B is defined by the sidewall 14a of each of the adjacent main grooves 14.

[0049] Referring to Figures 1 and 4, two rows of blocks 18 protruding from each rib 16 are separated by a circumferential groove 20, and the multiple blocks 17 included in each block row 18 are separated by multiple lateral grooves 21.

[0050] In the following description, of the two block rows 18, the one located on the outer side in the tire axial direction TA may be referred to as the outer block row 18A, and the one located on the inner side in the tire axial direction TA may be referred to as the inner block row 18B. Of the multiple blocks 17, the blocks that make up the outer block row 18A of the shoulder land 15A, i.e., the blocks (first blocks) located at the outer ends of the tread 10 in the tire axial direction TA, may be referred to as 17A, and the blocks other than 17A may be referred to as 17B (second blocks).

[0051] The block 17A is defined by the outer surface 12, the sidewalls 20a of the circumferential groove 20, and the sidewalls 21a of a pair of lateral grooves 21 adjacent to each other in the tire circumferential direction TC. The block 17B is defined by the sidewalls 14a of the main groove 14, the sidewalls 20a of the circumferential groove 20, and the sidewalls 21a of a pair of lateral grooves 21 adjacent to each other in the tire circumferential direction TC.

[0052] 2 and 3, the positions in the tire circumferential direction TC of the lateral grooves 21 of the outer block row 18A and the positions in the tire circumferential direction TC of the lateral grooves 21 of the inner block row 18B are different from each other. As a result, the positions in the tire circumferential direction TC of the blocks 17 of the outer block row 18A and the positions in the tire circumferential direction TC of the blocks 17 of the inner block row 18B are also different from each other.

[0053] In this embodiment, the shape of the blocks 17 is rectangular when viewed from the outside in the tire radial direction TR, but this can be changed as necessary. In other words, the circumferential grooves 20 are provided linearly in the tire circumferential direction TC, but may be formed in a wavy shape with repeated concave and convex portions in the tire axial direction TA along the tire circumferential direction TC. Furthermore, the lateral grooves 21 are provided linearly in the tire axial direction TA, but may be inclined with respect to a straight line (not shown) extending in the tire axial direction TA, or may be formed in a wavy shape with repeated concave and convex portions in the tire circumferential direction TC along the tire axial direction TA.

[0054] 2 to 4, each block 17 is formed with a sipe 23 that is recessed inward in the tire radial direction TR from the tread 11 and extends in the tire axial direction TA. The sipe 23 is defined by a pair of side walls 23a facing each other in the tire circumferential direction TC and a bottom wall 23b that is continuous with the inner ends of the pair of side walls 23a in the tire radial direction TR. Each sipe 23 is provided linearly along the tire axial direction TA, but may be inclined with respect to a straight line (not shown) extending in the tire axial direction TA, or may have a wavy shape with repeated concave and convex shapes in the tire circumferential direction TC along the tire axial direction TA.

[0055] A plurality of sipes 23, more specifically, three or more sipes 23 are provided at intervals in the tire circumferential direction TC between a pair of lateral grooves 21 that define the block 17. In this embodiment, four sipes 23 are formed for a block 17 having a circumferential length of 35 mm.

[0056] The spacing between adjacent sipes 23 in the tire circumferential direction TC is preferably set to 5 mm or more and 8 mm or less. If the spacing between the sipes 23 is made too small, the rigidity of the tread surface 11 will be excessively reduced, while if the spacing between the sipes 23 is made too large, the rigidity of the tread surface 11 will not be sufficiently reduced, making it difficult to obtain an appropriate grip force. To prevent these inconveniences, the spacing between adjacent sipes 23 is preferably set within the above-specified range.

[0057] Of the sipes 23 formed in the block 17A, outer ends 23c located on the outer surface 12 side terminate at a position spaced apart from the ridge 13 at the outer end of the outer surface 12 in the tire radial direction TR. Of the sipes 23 of the block 17A, inner ends 23d located on the circumferential groove 20 side terminate at a position spaced apart from the sidewall 20a of the circumferential groove 20. Of the sipes 23 of the block 17B, one end terminates at a position spaced apart from the sidewall 20a of the circumferential groove 20, and the other end terminates at a position spaced apart from the sidewall 14a of the main groove 14.

[0058] 4, the depth Dr3 of the sipes 23 in the tire radial direction TR, i.e., the dimension from the tread surface 11 to the bottom wall 23b, is shallower than both the depth Dr1 of the main groove 14 and the depth Dr2 of the lateral grooves 21. In this embodiment, the depth Dr3 of the sipes 23 is the same for all lands 15 or block rows 18, but may be different for each land 15 or block row 18.

[0059] In the case of the block 17A having the sipes 23 formed in this manner, when a force acts from the outside toward the inside in the tire axial direction TA during running, uneven wear is likely to occur in the center portion in the tire circumferential direction TC of the ridge 13 between the tread surface 11 and the outer side surface 12. To suppress such uneven wear on the ridge 13, a recess 25 is provided in the outer side surface 12 of this embodiment.

[0060] The recess 25 formed in the outer surface 12 will be specifically described below with reference to Figures 1, 4, and 5. Note that Figure 5 shows the tread surface 11 and the outer surface 12 of the outer block row 18A of the shoulder land 15A in an expanded state.

[0061] 1 and 4, the outer surface 12 is inclined inward in the tire axial direction TA from the inner side to the outer side in the tire radial direction TR in a meridian cross section.

[0062] The outer surface 12 has a chamfer 12a on the outer side in the tire radial direction TR and a continuous portion 12b on the inner side in the tire radial direction TR.

[0063] The chamfer 12a is provided on the portion of the outer surface 12 that connects to the tread surface 11. In a meridian cross section, the chamfer 12a is inclined inward in the tire axial direction TA from the inner side to the outer side in the tire radial direction TR. The inclination angle of the chamfer 12a with respect to a reference line RL1 extending in the tire radial direction TR is larger than the inclination angle of the main portion of the outer surface 12 (the portion between the chamfer 12a and the continuous portion 12b) with respect to the reference line RL1. The dimension of the chamfer 12a in the tire radial direction TR is smaller than the depth Dr1 of the main groove 14, the depth Dr2 of the lateral grooves 21, and the depth Dr3 of the sipes 23.

[0064] The continuous portion 12b is provided at a portion of the outer surface 12 that connects to the sidewall. In a meridian cross section, the continuous portion 12b is a curved surface that contacts the sidewall on the inner side of the lateral groove 21 in the tire radial direction TR.

[0065] 4, the distance Sw1 from the outer end 23c of the sipe 23 to the outer end of the chamfer 12a in the tire axial direction TA is set to be 1.5 times or more the dimension Sw2 of the chamfer 12a. If the ratio of the distance Sw1 to the dimension Sw2 is made too small, cracks may occur starting from the outer end 23c of the sipe 23. To prevent such cracks from occurring, it is preferable to set the ratio of the distance Sw1 to the dimension Sw2 to be equal to or greater than the above value.

[0066] 5, each block 17A of this embodiment has four sipes 23. If two of the sipes located on the inside in the tire circumferential direction TC are sipes 23A and two of the sipes located on the outside in the tire circumferential direction TC are sipes 23B, the block 17A can be divided in the tire circumferential direction TC into a central region 17a located between the pair of sipes 23A, a pair of intermediate regions 17b located between the sipes 23A and 23B, and an outer region 17c located on the outside of the sipes 23B in the tire circumferential direction TC.

[0067] 1 and 4, the recesses 25 are formed between the chamfers 12a and the continuous portions 12b of the outer surface 12 so as to recess inward in the tire axial direction TA from the outer surface 12 and extend in the tire radial direction TR. In order to optimize the rigidity balance of the block 17A in the tire circumferential direction TC, the recesses 25 of this embodiment include a pair of inner recesses 26 and a pair of outer recesses 27, and are formed in total in the same number as the number of sipes 23, which is four (an even number).

[0068] 5, the inner recess 26 is formed in the space between the pair of lateral grooves 21, closer to a center line CL2 that passes through the center of the block 17A in the tire circumferential direction TC and extends in the tire radial direction TR. Referring to FIGS. 4 and 6, the inner recess 26 is a groove defined by a pair of side walls 26a facing each other in the tire circumferential direction TC and bottom walls 26b that are continuous with the inner ends of the pair of side walls 26a in the tire axial direction TA. The inner recess 26 has an outer end 26c located on the tread surface 11 side and on the outer side in the tire radial direction TR, and an inner end 26d located inward of the outer end 26c in the tire radial direction TR.

[0069] 5, the outer recess 27 is formed closer to the lateral groove 21 (away from the center line CL2) than the inner recess 26 within the space between the pair of lateral grooves 21. Referring to FIGS. 4 and 6, the outer recess 27 is a groove defined by a pair of side walls 27a facing each other in the tire circumferential direction TC and bottom walls 27b connected to the inner ends of the pair of side walls 27a in the tire axial direction TA. The outer recess 27 has an outer end 27c located on the tread surface 11 side and on the outer side in the tire radial direction TR, and an inner end 27d located inward in the tire radial direction TR than the outer end 27c.

[0070] 1 and 5, the outer ends 26c, 27c of the recesses 26, 27 open at the chamfer 12a and are open outward in the tire radial direction TR. More specifically, the outer ends 26c, 27c of the recesses 26, 27 are both located on a reference line RL2 extending in the tire circumferential direction TC. The inner ends 26d, 27d of the recesses 26, 27 are located outward in the tire radial direction TR from the continuous portion 12b.

[0071] As shown most clearly in Figure 5, the recesses 26, 27 are both located at different positions in the tire circumferential direction relative to the sipes 23. More specifically, the outer end 26c of the inner recess 26 and the outer end 27c of the outer recess 27 are located at different positions in the tire circumferential direction TC relative to the outer ends 23c of the sipes 23. The outer end 26c of the inner recess 26 is located between adjacent sipes 23A, 23B, i.e., in the middle region 17b of the block 17A. The outer end 27c of the outer recess 27 is located outside the sipe 23B in the tire circumferential direction TC, i.e., in the outer region 17c of the block 17A. Neither of the outer ends 26c, 27c of the recesses 26, 27 is located between a pair of sipes 23A, i.e., in the central region 17a of the block 17A.

[0072] 5, the dimension Sr1 of the inner recess 26 in the tire radial direction TR is shorter than the dimension Sr2 of the outer recess 27 in the tire radial direction TR. The dimension Sr1 of the inner recess 26 means the distance in the tire radial direction TR from the outer end 26c to the inner end 26d of the inner recess 26, and the dimension Sr2 of the outer recess 27 means the distance in the tire radial direction TR from the outer end 27c to the inner end 27d of the outer recess 27. Due to the difference in dimensions between the inner recess 26 and the outer recess 27, the rigidity of the block 17A is configured to gradually decrease from the central region 17a to the outer region 17c.

[0073] The dimension Sr1 of the inner recess 26 is set to be 0.25 to 0.45 times the dimension Sr2 of the outer recess 27. If the dimensional ratio of the inner recess 26 to the outer recess 27 is made too small, the rigidity of the intermediate region 17b will not be reduced sufficiently, which may result in uneven wear in the outer region 17c. If the dimensional ratio of the inner recess 26 to the outer recess 27 is made too large, the rigidity of the intermediate region 17b will be reduced too much, which may result in uneven wear in the central region 17a. To prevent these inconveniences, it is preferable to set the dimensional ratio of the inner recess 26 to the outer recess 27 within the above-specified range.

[0074] The inner recess 26 and the outer recess 27 each have a curved shape with one or more inflection points 26e, 27e. As described above, the inner recess 26 and the outer recess 27 have different dimensions in the tire radial direction TR, so in this embodiment, the shorter inner recess 26 has one inflection point 26e and the longer outer recess 27 has five inflection points 27e. However, the number of inflection points 26e of the inner recess 26 and the number of inflection points 27e of the outer recess 27 can be changed as necessary.

[0075] Specifically, referring to FIG. 6 , the inner recess 26 includes a first portion 26f and a second portion 26g that connects to the inner end of the first portion 26f in the tire radial direction TR. The first portion 26f is inclined in a direction (first direction) away from the center line CL2 of the block 17A as it moves from the outer side to the inner side in the tire radial direction TR. The second portion 26g is inclined in a direction (second direction) approaching the center line CL2 of the block 17A as it moves from the outer side to the inner side in the tire radial direction TR. The inclination directions of the first portion 26f and the second portion 26g are different from the tire axial direction TA, the tire radial direction TR, and the tire circumferential direction TC. The point where the first portion 26f and the second portion 26g connect is an inflection point 26e. The groove width of the first portion 26f and the groove width of the second portion 26g in the tire circumferential direction TC are the same. In other words, the groove width of the inner recess 26 is uniform.

[0076] The outer recess 27 includes three first portions 27f and three second portions 27g that are connected to the inner ends of the first portions 27f in the tire radial direction TR. The first portions 27f are inclined in a direction (first direction) away from the center line CL2 of the blocks 17A as they move from the outer side to the inner side in the tire radial direction TR. The second portions 27g are inclined in a direction (second direction) approaching the center line CL2 of the blocks 17A as they move from the outer side to the inner side in the tire radial direction TR. The inclination directions of the first portions 27f and the second portions 27g are different from the tire axial direction TA, the tire radial direction TR, and the tire circumferential direction TC. The point where the first portions 27f and the second portions 27g join is an inflection point 27e. The groove width of the first portions 27f and the groove width of the second portions 27g in the tire circumferential direction TC are the same. In other words, the groove width of the outer recess 27 in the tire circumferential direction TC is uniform.

[0077] Continuing with reference to FIG. 6 , the angle between the first portion 26f and the second portion 26g of the inner recess 26 is α, and the angle between the first portion 27f and the second portion 27g of the outer recess 27 is β. Both of these angles α and β are set to be greater than or equal to 90 degrees and less than or equal to 150 degrees. If the angles α and β are set too small, the first portions 26f and 27f and the second portions 26g and 27g bend at an acute angle, making it more likely that cracks will occur originating from the inflection points 26e and 27e. On the other hand, if the angles α and β are set too large, the first portions 26f and 27f and the second portions 26g and 27g will approach a straight line, reducing the effect of mitigating lateral forces from different directions. To prevent these problems, it is preferable to set the angles α and β within the above-specified range.

[0078] In this embodiment, the inclination angles of the first portions 26f and 27f with respect to the center line CL2 are the same, and the inclination angles of the second portions 26g and 27g with respect to the center line CL2 are also set to be the same. Therefore, the angle α of the inner recess 26 and the angle β of the outer recess 27 are also set to be the same. However, as long as the angles α and β are within the above-specified ranges, the inclination angles of the first portions 26f and 27f with respect to the center line CL2 may be different, the inclination angles of the second portions 26g and 27g with respect to the center line CL2 may be different, and the angles α and β may also be different.

[0079] The length La1 of the first portion 26f of the inner recess 26 in the tire radial direction TR is set to be equal to or greater than the length La2 of the second portion 26g. The length Lb1 of the first portion 27f of the outer recess 27 in the tire radial direction TR is set to be equal to or greater than the length Lb2 of the second portion 27g.

[0080] The length La1 of the first portion 26f of the inner recess 26 is set to be equal to or greater than the length Lb1 of the first portion 27f of the outer recess 27, and the length La2 of the second portion 26g of the inner recess 26 is set to be equal to or greater than the length Lb2 of the second portion 27g of the outer recess 27. In other words, the pitch of the inner recess 26 including the first portion 26f and the second portion 26g is the same as or longer than the pitch of the outer recess 27, each of which includes one first portion 27f and one second portion 27g.

[0081] The amplitude of the inner recess 26 is defined by the length La1 of the first portion 26f, the length La2 of the second portion 26g, and the angle α. The amplitude of the outer recess 27 is defined by the length Lb1 of the first portion 27f, the length Lb2 of the second portion 27g, and the angle β. The amplitude of the inner recess 26 is set to be equal to or smaller than the amplitude of the outer recess 27, i.e., the same as or smaller than the amplitude of the outer recess 27.

[0082] 6, the inner recess 26 and the outer recess 27 are each inclined from the outer side to the inner side in the tire radial direction TR toward the center in the tire circumferential direction TC between the pair of lateral grooves 21. More specifically, an imaginary line (straight line) VL1 connecting the outer end 26c and the inner end 26d of the inner recess 26, and an imaginary line (straight line) VL2 connecting the outer end 27c and the inner end 27d of the outer recess 27 are each inclined in a direction approaching the center line CL2 of the block 17A as they move from the outer side to the inner side in the tire radial direction TR.

[0083] The inclination angle θ1 of the imaginary line VL1 of the inner recess 26 is set to be 5 degrees or more and 15 degrees or less with respect to the center line CL2, and the inclination angle θ2 of the imaginary line VL2 of the outer recess 27 is set to be 5 degrees or more and 15 degrees or less with respect to the center line CL2. If the inclination angles θ1 and θ2 of the recesses 26 and 27 are excessively small, the recesses 26 and 27 will extend along the center line CL2, making it difficult to gradually reduce the rigidity from the central region 17a to the outer region 17c of the block 17A. If the inclination angles θ1 and θ2 of the recesses 26 and 27 are excessively large, an overlap will occur between the short inner recess 26 and the long outer recess 27 when viewed from the outside in the tire radial direction TR, resulting in an excessive reduction in rigidity in the middle region 17b. To prevent these problems, it is preferable to set the inclination angles θ1 and θ2 of the recesses 26 and 27 within the above-specified range. In this embodiment, the inclination angles θ1 and θ2 of the recesses 26 and 27 are set to be the same, but may be different as long as they are within the above-defined range.

[0084] 6, the width Wc1 of the inner recess 26 in the tire circumferential direction TC is set to be the same as the width Wc2 of the outer recess 27 in the tire circumferential direction TC. Here, the widths Wc1 and Wc2 in the tire circumferential direction TC do not strictly refer to the distance between the sidewalls 26a and the distance between the sidewalls 27a in the direction along the tire circumferential direction TC, but rather refer to the distance between the sidewalls 26a in a direction perpendicular to the sidewalls 26a and the distance between the sidewalls 27a in a direction perpendicular to the sidewalls 27a. It is preferable that the widths Wc1 and Wc2 of the recesses 26 and 27 are both 3 mm or less.

[0085] 4, the depth Dw1 of the inner recess 26 in the tire axial direction TA is set to be the same as the depth Dw2 of the outer recess 27 in the tire axial direction TA. Here, the depths Dw1 and Dw2 in the tire axial direction TA do not mean the depths of the recesses 26 and 27 in the direction strictly along the tire axial direction TA, but rather the depths in a direction perpendicular to the slope of the outer side surface 12, that is, the shortest distance from the surface of the outer side surface 12 to the bottom walls 26b and 27b.

[0086] However, the widths Wc1 and Wc2 of the recesses 26 and 27 and the depths Dw1 and Dw2 of the recesses 26 and 27 are not limited to being identical in a strict geometric sense, and may be slightly different as long as the appearance (shading) of the inner recess 26 and the outer recess 27 appears similar.

[0087] 4 and 6, the ratio of the width Wc1 of the inner recess 26 in the tire circumferential direction TC to the depth Dw1 of the inner recess 26 in the tire axial direction TA is set to be 0.5 to 1.0. The ratio of the width Wc2 of the outer recess 27 in the tire circumferential direction TC to the depth Dw2 of the outer recess 27 in the tire axial direction TA is set to be 0.5 to 1.0. If the ratios of the widths Wc1 and Wc2 to the depths Dw1 and Dw2 are made too small, the rigidity reduction of the block 17A (shoulder land 15A) will be insufficient. If the ratios of the widths Wc1 and Wc2 to the depths Dw1 and Dw2 are made too large, the rigidity reduction of the block 17A will be excessive. To avoid these disadvantages and obtain an appropriate rigidity reduction effect for the block 17A, it is preferable that the ratios of the widths Wc1 and Wc2 to the depths Dw1 and Dw2 of the recesses 26 and 27 be set within the above-specified range. In this embodiment, the ratio of the width Wc1 to the depth Dw1 of the inner recess 26 and the ratio of the width Wc2 to the depth Dw2 of the outer recess 27 are set to be the same, but they may be different as long as they are within the above-specified range.

[0088] 4, the depths Dw1 and Dw2 of the recesses 26 and 27 in the tire axial direction TA are set to be 0.25 to 0.75 times the dimension Sw2 of the chamfer 12a in the tire axial direction TA. If the ratio of the depths Dw1 and Dw2 of the recesses 26 and 27 to the dimension Sw2 of the chamfer 12a is made too small, the reduction in rigidity at the outer surface 12 of the block 17A will be insufficient. If the ratio of the depths Dw1 and Dw2 of the recesses 26 and 27 to the dimension Sw2 of the chamfer 12a is made too large, the resistance of the recesses 26 and 27 to external damage caused by curbs, steps, etc. will be reduced. To prevent these problems, it is preferable to set the ratio of the depths Dw1 and Dw2 of the recesses 26 and 27 to the dimension Sw2 of the chamfer 12a within the above-specified range. In this embodiment, the ratio of the depth Dw1 of the inner recess 26 to the dimension Sw2 of the chamfer 12a and the ratio of the depth Dw2 of the outer recess 27 to the dimension Sw2 of the chamfer 12a are set to be the same, but they may be different as long as they are within the above-specified range.

[0089] 4 and 5, the dimension Sr2 of the outer recess 27 in the tire radial direction TR is set to be 1.25 to 1.75 times the depth Dr3 of the sipe 23 in the tire radial direction TR. If the ratio of the dimension Sr2 of the outer recess 27 to the depth Dr3 of the sipe 23 is set too small, the rigidity reduction in the outer region 17c of the block 17A will be insufficient. If the ratio of the dimension Sr2 of the outer recess 27 to the depth Dr3 of the sipe 23 is set too large, the rigidity reduction in the outer region 17c of the block 17A will be excessive. To prevent these inconveniences, it is preferable that the ratio of the dimension Sr2 of the outer recess 27 to the depth Dr3 of the sipe 23 be set within the above-specified range.

[0090] As described above, in this embodiment, the outer surface 12 of the block 17A, which includes the multiple sipes 23, is provided with the inner recess 26 and the outer recess 27, whose radial dimensions Sr1 and Sr2 are different. Without these recesses 26 and 27, the sipes 23 cause the rigidity of the outer surface 12 of the block 17A to be lowest at the center in the tire circumferential direction TC. This results in the largest displacement due to a force acting from the outer side toward the inner side in the tire axial direction TA, making uneven wear more likely to occur. In contrast, in this embodiment, the recesses 26 and 27 allow the rigidity of the outer surface 12 of the block 17A to gradually decrease from the center line CL2 of the block 17A toward the outer side in the tire circumferential direction TC, thereby optimizing the rigidity balance of the block 17A in the tire circumferential direction TC. As a result, uneven wear in the central region 17a of the block 17A can be suppressed. Furthermore, a decrease in rigidity in the central region 17a of the block 17A from the initial to intermediate stages of wear can also be prevented.

[0091] In particular, the shoulder land 15A of this embodiment has a configuration in which multiple blocks 17 are provided on the outer side of the rib 16 in the tire radial direction TR. In the case of such a shoulder land 15A, when a force acts from the outer side toward the inner side in the tire axial direction TA, the rib 16 has difficulty absorbing the force, and the effect on the blocks 17A is large. However, because the recesses 26, 27 are formed in the blocks 17A, the rigidity balance of the blocks 17A can be optimized, and uneven wear can be suppressed.

[0092] Furthermore, when the pneumatic tire 1 is mounted on a steered wheel of a vehicle, it is more susceptible to lateral forces during cornering than when it is mounted on a drive wheel. This lateral force occurs not only in the tire axial direction TA but also in directions intersecting the tire axial direction TA, i.e., along the tire circumferential direction TC and along the tire radial direction TR, making the outer surface 12 prone to uneven wear. In contrast, the inner recess 26 and the outer recess 27 of this embodiment have curved shapes with one or more inflection points 26e, 27e, and therefore can elastically absorb lateral forces from two or more different directions. Therefore, uneven wear can be effectively suppressed even when the pneumatic tire 1 is mounted on a steered wheel of a vehicle.

[0093] The pneumatic tire 1 configured in this manner has the following features.

[0094] The inner recess 26 and the outer recess 27 are provided at different positions in the tire circumferential direction TC relative to the sipe 23 of the tread surface 11. Therefore, compared to when the sipe 23 and the recesses 26, 27 are formed at the same position in the tire circumferential direction TC, excessive reduction in rigidity of the shoulder land 15A can be suppressed, and the occurrence of cracks originating from the sipe 23 and the recesses 26, 27 can be suppressed.

[0095] The dimension Sr1 of the inner recess 26 in the tire radial direction TR is shorter than the dimension Sr2 of the outer recess 27 in the tire radial direction TR. Therefore, the rigidity of the outer side in the tire circumferential direction TC between the pair of lateral grooves 21 of the shoulder land 15A can be made lower than the rigidity of the central portion in the tire circumferential direction TC. This makes it possible to optimize the rigidity balance in the tire circumferential direction TC between the pair of lateral grooves 21. Therefore, it is possible to average out the amount of displacement in the tire circumferential direction TC when a force acts from the outer side to the inner side in the tire axial direction TA, and to effectively suppress uneven wear in the central portion in the tire circumferential direction TC.

[0096] Since the inner recess 26 and the outer recess 27 have a curved shape with one or more inflection points 26e, 27e, they can elastically absorb forces from two or more different directions, thereby effectively suppressing uneven wear even when the pneumatic tire 1 is mounted on a steering wheel of a vehicle.

[0097] The angles α and β formed by the first portions 26f and 27f and the second portions 26g and 27g of the recesses 26 and 27 are between 90 and 150 degrees. This prevents cracks from forming at the inflection points 26e and 27e, which tend to occur when the angles α and β are excessively small. Furthermore, the effect of mitigating lateral forces from different directions, which is difficult to achieve when the angles α and β are excessively large, can be reliably achieved.

[0098] Imaginary lines (straight lines) VL1, VL2 connecting the outer ends 26c, 27c and the inner ends 26d, 27d of the recesses 26, 27 are inclined from the outer side to the inner side in the tire radial direction TR toward the center line CL2 (center side) in the tire circumferential direction TC between the pair of lateral grooves 21. This results in an obtuse angle of inclination of the entire recesses 26, 27 with respect to the rotational direction of the pneumatic tire 1, making it possible to suppress damage originating from the recesses 26, 27 when coming into contact with a curb, a step, or the like.

[0099] The inclination angles θ1, θ2 of the imaginary lines (straight lines) VL1, VL2 of the recesses 26, 27 are between 5 degrees and 15 degrees relative to the center line (reference line) CL2 extending in the tire radial direction TR. This prevents the short inner recess 26 and the long outer recess 27 from overlapping when viewed from the outside in the tire radial direction TR. This prevents an excessive decrease in rigidity of the shoulder land 15A due to the inner recess 26 and the outer recess 27 overlapping each other.

[0100] The dimension Sr2 of the outer recess 27 in the tire radial direction TR is 1.25 to 1.75 times the depth Dr3 of the sipe 23 in the tire radial direction TR. This effectively reduces the rigidity at the outer portion in the tire circumferential direction TC between the pair of lateral grooves 21, thereby optimizing the rigidity balance of the shoulder land 15A and suppressing uneven wear.

[0101] The dimension Sr1 in the tire radial direction TR of the inner recess 26 is 0.25 to 0.45 times the dimension Sr2 in the tire radial direction TR of the outer recess 27. This makes it possible to prevent an excessive decrease in rigidity at the center portion in the tire circumferential direction TC between the pair of lateral grooves 21, thereby optimizing the rigidity balance of the shoulder land 15A and suppressing uneven wear.

[0102] The distance Sw1 from the outer end 23c of the sipe 23 to the outer end of the chamfer 12a is 1.5 times or more the dimension Sw2 of the chamfer 12a in the tire axial direction TA, thereby suppressing the occurrence of cracks originating from the outer end 23c of the sipe 23.

[0103] The outer ends 26c, 27c of the recesses 26, 27 are each open to the outside in the tire radial direction TR within the chamfer 12a, which can prevent cracks from occurring at the outer ends 26c, 27c, which may occur if the outer ends 26c, 27c of the recesses 26, 27 are closed.

[0104] The depths Dw1 and Dw2 of the recesses 26 and 27 are 0.25 to 0.75 times the dimension Sw2 of the chamfer 12a in the tire axial direction TA. This prevents a decrease in the rigidity reduction effect of the shoulder land 15A, which can occur when the depths Dw1 and Dw2 of the recesses 26 and 27 are made too small relative to the dimension Sw2 of the chamfer 12a, and improves the rigidity balance between the pair of lateral grooves 21. Furthermore, it is possible to prevent cracks from occurring when the tire comes into contact with a curb, step, or the like, which can occur when the depths Dw1 and Dw2 of the recesses 26 and 27 are made too large relative to the dimension Sw2 of the chamfer 12a, thereby ensuring external damage resistance.

[0105] The ratio of the widths Wc1, Wc2 of the recesses 26, 27 to the depths Dw1, Dw2 of the recesses 26, 27 is 0.5 to 1.0. This prevents an insufficient reduction in stiffness of the shoulder land 15A, which may occur when the ratio of the widths Wc1, Wc2 to the depths Dw1, Dw2 of the recesses 26, 27 is excessively small. Also, it prevents an excessive reduction in stiffness of the shoulder land 15A, which may occur when the ratio of the widths Wc1, Wc2 to the depths Dw1, Dw2 of the recesses 26, 27 is excessively large.

[0106] The shoulder land 15A includes a rib 16, multiple first blocks 17A, and multiple second blocks 17B, with the first blocks 17A having recesses 26 and 27. When a force acts from the outside to the inside of the tire axial direction TA, the rib 16 has difficulty absorbing the force, which increases the impact on the first blocks 17A. However, because the recesses 26 and 27 are formed in the first blocks 17A, the rigidity balance of the first blocks 17A can be optimized, and uneven wear can be suppressed.

[0107] The number of recesses 26, 27 is an even number, the same as the number of sipes 23. Therefore, the rigidity balance between the pair of lateral grooves 21 can be easily optimized.

[0108] The widths Wc1 and Wc2 of the recesses 26 and 27 are the same, and the depths Dw1 and Dw2 are also the same, so that the appearance (shading) of the inner recess 26 and the outer recess 27 is the same, thereby improving the aesthetic appearance of the pneumatic tire 1.

[0109] The outer ends 26c, 27c of the recesses 26, 27 in the tire radial direction TR are located on a reference line RL2 extending in the tire circumferential direction TC, which makes it possible to easily optimize the rigidity balance between the pair of lateral grooves 21 and improve the aesthetic appearance of the pneumatic tire 1.

[0110] The present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

[0111] 7, the first portions 26f, 27f and the second portions 26g, 27g of the recesses 26, 27 may be connected via arc-shaped third portions (radii) 26h, 27h. In this case, the arc-shaped third portions 26h, 27h form inflection points 26e, 27e.

[0112] 8, the inner recess 26 may extend linearly from the outer end 26c to the inner end 26d, and only the outer recess 27 may be curved. Alternatively, only the inner recess 26 may be curved, and the outer recess 27 may extend linearly from the outer end 27c to the inner end 27d. In other words, it is sufficient that at least one of the inner recess 26 and the outer recess 27 has a curved shape with one or more inflection points.

[0113] The recesses 25 may be composed of three or more types of recesses with different dimensions in the tire radial direction TR. In this case, the three or more types of recesses are arranged on the outer surface 12 of the block 17A so that their dimensions gradually increase from the center toward the outside in the tire circumferential direction TC. The number of sipes 23 may be the same as the number of recesses 25 or may be one recess less. In other words, the number of recesses 25 may be the same as the number of sipes 23 or may be one recess more than the number of sipes 23, as long as it is an even number of four or greater.

[0114] The imaginary lines (straight lines) VL1, VL2 of the recesses 26, 27 may be inclined from the outer side to the inner side in the tire radial direction TR in a direction away from the center line CL2 of the block 17A, and the inclination direction can be changed as necessary.

[0115] The recess 25 may be provided on the outer surface 12 of the rib 16 without providing the block 17 on the shoulder land 15A. That is, in a pneumatic tire in which multiple ribs are formed by main grooves, multiple lateral grooves extending inward from the outer ends of the tire in the axial direction may be provided at intervals in the tire circumferential direction in the ribs at both ends in the tire axial direction, and the recess 25 may be provided between adjacent lateral grooves in the tire circumferential direction.

[0116] The pneumatic tire 1 is not limited to a tapered shoulder type in which the outer surface 12 is provided with a chamfer 12a, but may be a box shoulder type without a chamfer 12a, as shown in FIG. [Explanation of symbols]

[0117] 1 pneumatic tire 10 Tread 11 Tread 12 External surface 12a Chamfer 12b Continuous section 13 Ridge 14 Main groove 14a side wall 14b Bottom wall 15 land 15A Shoulder Land 15B Center Land 16 Ribs 17 blocks Block 17A (1st Block) Block 17B (2nd Block) 17a central area 17b Middle area 17c outer area 18 Block Row 18A Outer Block Row 18B Inner Block Row 20 Circumferential groove 20a Sidewall 20b bottom wall 21 Yokomizo 21a side wall 21b Bottom wall 23, 23A, 23B sipes 23a side wall 23b Bottom wall 23c outer end 23d inner edge 25 dent 26 Inner recess 26a side wall 26b Bottom wall 26c outer end 26d inner end 26e Inflection point 26f Part 1 26g 2nd portion 26h 3rd part 27 Outer dent 27a side wall 27b Bottom wall 27c outer end 27d inner end 27e Inflection point 27f Part 1 27g 2nd portion 27h 3rd part TA Tire axial direction TR Tire radial direction TC: Tire Circumferential Direction CL2 Center line (reference line) VL1, VL2 Virtual line (straight line)

Claims

1. a shoulder land having a tread surface at an outer end in the tire radial direction and an outer surface at an outer end in the tire axial direction, the shoulder land being located at the outer end of the tire axial direction of the tread; a plurality of lateral grooves provided at intervals in the tire circumferential direction on the shoulder land, recessed inward in the tire radial direction from the tread surface, extending in the tire axial direction, and opening at the outer surface; a plurality of sipes provided at intervals in the tire circumferential direction between pairs of circumferentially adjacent lateral grooves on the shoulder land, each recessed radially inward from the tread surface, extending in the tire axial direction, and terminating at a position spaced apart from the outer surface; a plurality of recesses provided on the outer surface, recessed inward in the tire axial direction and extending in the tire radial direction; Equipped with the plurality of recesses are arranged at different positions in the tire circumferential direction with respect to the sipes, and include an inner recess located closer to the center in the tire circumferential direction within the interval between the pair of lateral grooves, and an outer recess located closer to the lateral groove than the inner recess, a dimension of the inner recess in the tire radial direction is shorter than a dimension of the outer recess in the tire radial direction; At least one of the inner recess and the outer recess has a curved shape having one or more inflection points when viewed from the tire axial direction.

2. the inner recess or the outer recess of the bent shape has a first portion extending in a first direction and a second portion extending in a second direction intersecting the first direction, The angle between the first portion and the second portion is greater than or equal to 90 degrees and less than or equal to 150 degrees. The pneumatic tire according to claim 1 .

3. the inner recess and the outer recess each have an outer end located on the outer side in the tire radial direction and an inner end located on the inner side in the tire radial direction, a straight line connecting the outer end of the inner recess and the inner end of the inner recess, and a straight line connecting the outer end of the outer recess and the inner end of the outer recess, each inclined from the outer side to the inner side in the tire radial direction toward a center side in the tire circumferential direction of the interval between the pair of lateral grooves, The pneumatic tire according to claim 1 or 2.

4. The pneumatic tire according to claim 3 , wherein the inclination angle of each of the straight lines with respect to a reference line extending in the tire radial direction is equal to or greater than 5 degrees and equal to or less than 15 degrees.

5. The pneumatic tire according to claim 1 , wherein a dimension of the outer recess in the tire radial direction is 1.25 to 1.75 times a depth of the sipe in the tire radial direction.

6. The pneumatic tire according to claim 1 , wherein the radial dimension of the inner recess is 0.25 to 0.45 times the radial dimension of the outer recess.

7. the outer surface has a chamfer inclined from the inner side in the tire radial direction to the outer side in the tire axial direction at a portion in contact with the tread surface, a distance from an outer end of the sipe in the tire axial direction to an outer end of the chamfer in the tire axial direction is 1.5 times or more the dimension of the chamfer in the tire axial direction; The pneumatic tire according to any one of claims 1 to 6.

8. The pneumatic tire according to claim 7 , wherein outer ends in the tire radial direction of the inner recess and the outer recess are opened by the chamfer.

9. The pneumatic tire according to claim 7 or 8, wherein the axial depth of each of the inner recess and the outer recess is 0.25 to 0.75 times the axial dimension of the chamfer.

10. a ratio of a width of the inner recess in the tire circumferential direction to a depth of the inner recess in the tire axial direction is 0.5 to 1.0, The ratio of the width of the outer recess in the tire circumferential direction to the depth of the outer recess in the tire axial direction is 0.5 to 1.

0. The pneumatic tire according to any one of claims 1 to 9.

11. The tread is main grooves provided at intervals on the inner side in the tire axial direction of the outer surface, recessed inward in the tire radial direction, and extending in the tire circumferential direction; a circumferential groove provided between the main groove and the outer surface, recessed inward in the tire radial direction, and extending in the tire circumferential direction; Equipped with The shoulder land is a rib defined by the outer surface and a sidewall of the main groove; a plurality of first blocks provided on the outer side of the rib in the tire radial direction and defined by the outer surface, a side wall of a circumferential groove, and a pair of side walls of lateral grooves adjacent to each other in the tire circumferential direction; a plurality of second blocks provided on the outer side of the rib in the tire radial direction and defined by the side wall of the circumferential groove, the side wall of the main groove, and side walls of a pair of lateral grooves adjacent in the tire circumferential direction; and The sipes and the recesses are formed in each of the plurality of first blocks. The pneumatic tire according to any one of claims 1 to 10.

12. The pneumatic tire according to claim 1 , wherein the number of the recesses is the same as the number of the sipes or is one more than the number of the sipes, and is an even number of four or more.

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