Pneumatic tire

Abstract

To provide a pneumatic tire having side blocks on a sidewall, which achieves both enhancement in traction performance in muddy terrain and prevention of fracture caused by cut damage.SOLUTION: A tire 1 includes a plurality of side blocks 30 that protrude side by side in the tire circumferential direction from a sidewall reference surface, on at least one of a pair of sidewalls 5. A plurality of dimples, each longer in the tire radial direction than in the tire circumferential direction, are formed in each side block side by side along the tire circumferential direction. The plurality of dimples include a first dimple having a tire circumferential width of a first length and a second dimple having a tire circumferential width of a second length smaller than the first length. A tire circumferential width at a top surface of a second wall adjacent to a first side in the tire circumferential direction of the second dimple is greater than a tire circumferential width at a top surface of a first wall adjacent to a second side in the tire circumferential direction of the first dimple.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire including a tread and a pair of sidewalls, wherein at least one of the pair of sidewalls includes a plurality of side blocks protruding side by side in the tire circumferential direction from a sidewall reference plane.

Background Art

[0002] Conventionally, side blocks protruding outward in the tire axial direction from a sidewall reference plane are provided on the side surface in the tire axial direction of a tire. The side blocks can improve the cut resistance performance for suppressing the occurrence of cut scars when stones, rocks, etc. collide with the sidewall.

[0003] For example, Patent Document 1 describes that a plurality of side protectors corresponding to side blocks are provided on the sidewall on the side surface in the tire axial direction so as to be divided in the tire circumferential direction and bulge outward in the tire axial direction. The side protectors are provided with grooves, notches, and sipes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the tire described in Patent Document 1, there is room for improvement in terms of achieving both an improvement in traction performance on muddy ground and suppression of breakage due to cut scars.

[0006] An object of the present invention is to achieve both an improvement in traction performance on muddy ground and suppression of breakage due to cut scars in a pneumatic tire having side blocks on the sidewall.

Means for Solving the Problems

[0007] The pneumatic tire according to the present invention includes a tread and a pair of sidewalls, and at least one of the pair of sidewalls is a pneumatic tire including a plurality of side blocks protruding side by side in the tire circumferential direction from a sidewall reference plane, wherein a plurality of dimples that are longer in the tire radial direction than in the tire circumferential direction are formed side by side in the tire circumferential direction in each of the plurality of side blocks, the plurality of dimples include a first dimple having a first length in the tire circumferential direction width and a second dimple having a second length smaller than the first length in the tire circumferential direction width, and the tire circumferential direction width at the top surface of a second wall adjacent to a first side in the tire circumferential direction of the second dimple is larger than the tire circumferential direction width at the top surface of a first wall adjacent to a second side in the tire circumferential direction of the first dimple.

Advantages of the Invention

[0008] According to the pneumatic tire of the present invention, in a pneumatic tire having side blocks on the sidewalls, it is possible to achieve both an improvement in traction performance on muddy ground and suppression of breakage due to cut damage.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0010] Hereinafter, with reference to the drawings, an example of an embodiment of a pneumatic tire according to the present invention will be described in detail. The embodiment described below is merely an example, and the present invention is not limited to the following embodiments.

[0011] FIG. 1 is a perspective view showing a partial circumferential direction of a pneumatic tire 1 which is an example of the embodiment. FIG. 2 is a view of the upper part of the tire side surface 13 of FIG. 1 seen in the tire axial direction. FIG. 3 is a view showing a tire contour shape with side blocks omitted in the meridian cross section of the pneumatic tire 1. FIG. 4 is a view showing only a partial circumferential direction of the side block taken out from FIG. 2 and extending the tire circumferential direction in the left-right direction. FIG. 5 is an enlarged view showing the shape per pitch of the shape in the tire side view taken out from FIG. 4. FIG. 6 is a sectional view taken along line A-A of FIG. 5. FIG. 7 is a sectional view taken along line B-B of FIG. 5. FIG. 8 is a sectional view taken along line C-C of FIG. 5. Hereinafter, the "pneumatic tire 1" will be referred to as "tire 1".

[0012] The tire 1 includes a tread 10 which is a portion in contact with the road surface. The tread 10 has a tread pattern including a plurality of blocks such as shoulder blocks 2a and 2b, and is formed in an annular shape along the tire circumferential direction. A plurality of grooves 3a and 3b for partitioning the blocks are formed in the tread 10. In FIG. 3, the illustration of the grooves is omitted. The tread 10 has a grounding end T (FIG. 3). In FIGS. 1, 2, 4, and 5, the first side in the tire circumferential direction is indicated by X1, the second side in the tire circumferential direction is indicated by X2, the outer side in the tire radial direction is indicated by Y1, and the inner side in the tire radial direction is indicated by Y2.

[0013] Hereinafter, the structure of the tire 1 will be described centering on the portion on the first side in the tire axial direction. The tire 1 may have a symmetric shape on both sides in the tire axial direction with the center of the tire axial direction center, or the shape on the second side in the tire axial direction, for example, the shape of the side surface facing the axial direction on the second side in the tire axial direction may be different from the first side in the tire axial direction.

[0014] At both ends in the tire axial direction, the tire 1 is provided with a pair of sidewalls 5 that are provided at the ends outside the tread 10 in the tire axial direction and bulge most outward in the tire axial direction, and a bead (not shown) fixed to the rim of the wheel. The sidewall 5 and the bead are formed in an annular shape along the tire circumferential direction. The sidewall 5 extends from both ends in the tire axial direction of the tread 10 inward in the tire radial direction Y2. As shown in FIG. 3, at the inner end in the radial direction Y of the tire 1, a rim strip 18 that forms the outer surface of the bead is provided adjacent to the sidewall 5.

[0015] The tire 1 is a pneumatic tire filled with air at a predetermined pressure. The tread 10 is composed of tread rubber. The sidewall 5 is composed of a different type of sidewall rubber from the tread rubber.

[0016] In this specification, unless otherwise specified, the dimensions of each part of the tire are the dimensions measured in the unloaded normal state in which the unused tire is mounted on the regular rim and filled with air so as to reach the regular internal pressure.

[0017] The "ground contact end T" means both ends in the tire axial direction Z of the region that contacts the flat road surface when a load of 88% of the regular load at the regular internal pressure is applied in a state where the unused tire 1 is mounted on the regular rim and filled with air so as to reach the regular internal pressure.

[0018] Here, the "regular rim" is the rim defined by the tire standard, which is the "standard rim" in JATMA, the "Design Rim" in TRA, and the "Measuring Rim" in ETRTO. The "regular internal pressure" is the "maximum air pressure" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "INFLATION PRESSURE" in ETRTO. The "regular load" is the "maximum load capacity" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "LOAD CAPACITY" in ETRTO.

[0019] Tire 1 includes a carcass and a belt layer. The carcass is a cord layer covered with rubber, forming the framework of Tire 1 that withstands loads, impacts, air pressure, etc. The belt layer is a reinforcing band disposed between the tread rubber and the carcass. The belt layer tightly compresses the carcass to increase the rigidity of Tire 1. The belt layer is formed by a plurality of belts overlapping in the tire radial direction. Each belt is formed by covering a plurality of cords arranged in a direction inclined with respect to the tire circumferential direction with rubber. In adjacent belts, the cords are inclined in opposite directions with respect to the tire circumferential direction so that the cords of each other cross. The cords are formed of steel or the like.

[0020] Between the belt layer and the tread rubber, a belt reinforcing layer extending in the tire circumferential direction and covering the entire tire axial direction Z of the belt layer is provided. The belt reinforcing layer is formed by covering cords extending substantially in the tire circumferential direction with rubber. The cords are formed of organic fibers or the like.

[0021] In addition, as part of the rim strip rubber that forms the rim strip 18, a rim protector 23 that protrudes outward in the tire axial direction is provided. The rim line 24 is provided annularly along the tire circumferential direction at the apex located at the outer end in the tire axial direction of the rim protector 23. The rim protector 23 has a function of protecting the rim from damage. The rim line 24 is a line for confirming, with the gap from the rim, that the tire 1 is properly mounted on the rim. In FIG. 3, the rim protector 23 is provided, but as shown by the two-dot chain line in FIG. 3, a configuration without the rim protector 23 may also be used. Even in this case, a rim line, which is a protrusion formed in an annular shape and protruding outward in the tire axial direction, is provided on the tire side surface for confirming that the tire 1 is properly mounted on the rim.

[0022] In this example, a plurality of side blocks 30 shown in FIGS. 1, 2, 4 to 6 are provided on the tire side surface 13, which is the outer surface in the tire axial direction Z on the tire radial inner side Y2 from the ground contact end T of the tread 10 and on the tire radial outer side Y1 from the rim line 24.

[0023] Specifically, as shown in FIGS. 1, 2, 4 to 6, a plurality of side blocks 30 are provided on the tire side surface 13 so as to bulge outward in the tire axial direction from the sidewall reference surface 5a, which is the profile surface of the sidewall 5. The plurality of side blocks 30 are arranged in the tire circumferential direction. The "sidewall reference surface 5a" means the surface of the sidewall 5 facing outward in the tire axial direction when the side blocks 30 are not formed. Each side block 30 is provided along the tire circumferential direction. Each side block 30 improves the cut resistance performance of the tire side surface 13 and the traction performance during uneven road running. In this example, each side block 30 has the same shape.

[0024] The tire 1 is suitable for, for example, a tire for a light truck. Note that light trucks include pickup trucks, sports utility vehicles (SUVs), and the like. An example of the size of the tire 1 is LT275 / 60R20.

[0025] On the tire 1, a side rib 6 is formed near the tread 10 on the tire side surface 13. The side rib 6 is a convex portion protruding toward the outer side in the tire axial direction and is formed in an annular shape along the tire circumferential direction. In the present embodiment, the side rib 6 is formed along the tire circumferential direction in the vicinity of the outer peripheral edge portion of the side block 30. The side rib 6 is disposed, for example, outside the tire maximum width position P (FIG. 3) in the outer side in the tire radial direction Y. In this specification, the "tire maximum width position P" means a position where the tire axial length is maximum on the sidewall reference plane 5a.

[0026] Further, a portion from the outer axial end of the surface of the shoulder blocks 2a and 2b facing the outer side in the tire radial direction Y to the side rib 6 is defined as a buttless region, and a portion from the bead to the side rib 6 is defined as the sidewall 5. For this reason, the side block 30 is provided on the sidewall 5. Further, the inner end in the tire radial direction of the buttless region and the outer end in the tire radial direction of each side block 30 are connected at substantially the same position in the tire axial direction via the side rib 6.

[0027] The buttless region may be made of the same rubber as the tread 10 or may be made of different rubber. On the other hand, side blocks 30 having the same shape or different shapes from each other may be provided on a pair of sidewalls 5 on both sides in the tire axial direction. The tire 1 may be a tire without a specified mounting direction. On the other hand, the tire 1 may be configured such that the mounting direction is specified, and the side blocks 30 shown in FIGS. 1, 2, 4 to 6 may be provided only on the outer axial surface of the portion on the outer side of the vehicle.

[0028] Hereinafter, the side block 30 will be described in detail. The side block 30 can be formed between the side rib 6 and the tire maximum width position P. In this case, it becomes easy to ensure good side traction performance and cut (protection) performance of the tire side surface 13.

[0029] The plurality of side blocks 30 are arranged at predetermined intervals in the tire circumferential direction. The predetermined intervals are constant. Note that the side blocks 30 may also have a variable pitch in which the intervals between the blocks and the circumferential length of the blocks are slightly changed in units of a predetermined number. Also, the number of pitches in the shape of the tire side view is preferably 40 or more and 60 or less.

[0030] The plurality of side blocks 30 are formed at a plurality of equally spaced positions in the tire circumferential direction of an annular block formed along the entire circumference in the tire circumferential direction, and have a shape divided in the tire circumferential direction by recesses 31 extending from the inner end in the tire radial direction toward the outer side in the tire radial direction. In this example, as shown in FIG. 2, inside the recess 31, at the center in the tire circumferential direction of the recess 31 and at a position that enters from the outer end Y1 in the tire radial direction of the recess 31 toward the inner side Y2 in the tire radial direction, a bottom surface 32 is formed, and three inclined surfaces 33 and 35 that are continuous from the three sides of the opening end of the recess 31, are inclined with respect to the top surfaces of the side block 30 and the vicinity of the side rib 6, and are connected to the bottom surface 32 are formed. The bottom surface 32 is an elongated rectangle whose shape in the tire side view extends in the tire radial direction and coincides with the sidewall reference plane 5a. The tire circumferential width of the recess 31 can be made to substantially coincide with the maximum tire circumferential width d1 or the second largest tire circumferential width d2 among the tire circumferential widths of the plurality of dimples 40a, 40b, 40c, 40d, 40e shown in FIG. 4 described later.

[0031] In each side block 30, a plurality of rectangular dimples 40a, 40b, 40c, 40d, 40e that are longer in the tire radial direction than in the tire circumferential direction in the tire side view are formed side by side in the tire circumferential direction. The outer edge and the inner edge in the tire radial direction of the rectangle of each dimple 40a, 40b, 40c, 40d, 40e are straight lines substantially along the tire circumferential direction. The first side edge and the second side edge in the tire circumferential direction of the rectangle of each dimple 40a, 40b, 40c, 40d, 40e are straight lines substantially along the tire radial direction. As will be described later, the tire circumferential widths of the plurality of dimples 40a, 40b, 40c, 40d, 40e in each side block 30 gradually decrease toward the dimples 40b, 40c, 40d, 40e on the first side X1 in the tire circumferential direction.

[0032] Each of the dimples 40a, 40b, 40c, 40d, and 40e is provided so as to be recessed at a plurality of positions on the top surface 60 facing the outer side in the tire axial direction of the side block 30. Thereby, since the mud in the muddy ground can be sheared at a plurality of positions, the traction performance in the muddy ground can be improved. In particular, since each of the dimples 40a, 40b, 40c, 40d, and 40e is long in the tire radial direction, the edge effect at the corner of the wall adjacent to the end in the tire circumferential direction of the dimple can be enhanced. Also, the breakage due to the cut damage of the tire can be suppressed by the wall having a large width in the tire circumferential direction. Thereby, both the improvement of the traction performance in the muddy ground and the suppression of breakage due to cut damage can be achieved. Hereinafter, the plurality of dimples 40b, 40c, 40d, and 40e may be collectively referred to as the dimple 40 in some cases.

[0033] Also, a predetermined annular region having a plurality of side blocks 30 in the tire side view (an annular region whose length in the tire radial direction is indicated by the arrow α in FIG. 2) has a shape that is repeated in the tire circumferential direction at the same pitch. For example, FIG. 5 shows the shape for one pitch when the shape is repeated in the tire circumferential direction in the side block 30. Also, two or more and five or less dimples 40 can be provided in the side block 30 per pitch in the tire side view. In FIG. 4, five dimples 40 are provided per pitch, but two or more and four or less dimples may be provided in the side block per pitch. Thereby, it is possible to prevent the opening area of each dimple 40 from becoming too large and the length of each dimple 40 in the tire circumferential direction from becoming too small, so that it becomes easier to achieve both the traction performance and the suppression of breakage due to cut damage.

[0034] In each side block 30, the tire circumferential width of the plurality of dimples 40 decreases in order toward the dimple 40 on the first side X1 in the tire circumferential direction. Specifically, among the plurality of dimples 40 in each side block 30, the tire circumferential width of the dimple 40a at the end of the second side X2 in the tire circumferential direction is the longest first length d1. And the tire circumferential width of the dimple 40b adjacent to the first side X1 in the tire circumferential direction of the dimple 40a is a second length d2 smaller than the first length d1. Further, the tire circumferential width of the dimple 40c arranged adjacent to the first side X1 in the tire circumferential direction, which is on the side opposite to the dimple 40a of the dimple 40b, is a third length d3 smaller than the second length d2.

[0035] And similarly, the tire circumferential widths of the dimples 40d and 40e arranged on the first side X1 in the tire circumferential direction of the dimple 40c decrease in order toward the dimples 40d and 40e on the first side X1. In this example, the dimple 40a corresponds to the first dimple, the dimple 40b corresponds to the second dimple, and the dimple 40c corresponds to the third dimple. On the other hand, the tire radial widths of the plurality of dimples 40 in each side block 30 are the same.

[0036] Also, the tire circumferential width W2 of the top surface 60 of the wall 50b adjacent to the first side X1 in the tire circumferential direction of the dimple 40b is larger than the tire circumferential width W1 of the top surface 60 of the wall 50a adjacent to the first side X1 in the tire circumferential direction of the dimple 40a. Further, the tire circumferential width W3 of the top surface of the wall 50c adjacent to the first side in the tire circumferential direction of the dimple 40c is larger than the tire circumferential width W2 of the top surface 60 of the wall 50b adjacent to the first side X1 in the tire circumferential direction of the dimple 40b. Thereby, the tire circumferential widths increase in order for the walls 50a, 50b, 50c arranged side by side toward the first side X1 in the tire circumferential direction.

[0037] Similarly, a plurality of dimples 40d and 40e arranged on the first side X1 in the tire circumferential direction of the dimple 40c, and the tire circumferential widths of the walls 50d and 50e adjacent to the first side X1 in the tire circumferential direction of the dimples 40d and 40e increase in the order of the walls 50d and 50e arranged side by side toward the first side X1 in the tire circumferential direction. In this example, the wall 50a corresponds to the first wall, the wall 50b corresponds to the second wall, and the wall 50c corresponds to the third wall. Hereinafter, the plurality of walls 50a, 50b, 50c, 50d, and 50e may be collectively referred to as the wall 50.

[0038] Also, among the plurality of walls 50 and 50z arranged in the tire circumferential direction of each side block 30, the tire circumferential width Wz of the wall 50z located at the second side X2 end in the tire circumferential direction is the smallest. Thereby, in each side block 30, each of the plurality of dimples 40 and the plurality of walls 50 and 50z is arranged in a gradation in the tire circumferential direction. For this reason, the traction performance on muddy ground can be increased with dimples having a large tire circumferential width, and the effect of suppressing breakage due to cut damage can be increased with walls having a large tire circumferential width.

[0039] In this example, in each side block 30, the center of each of the plurality of dimples 40 in the tire circumferential direction is located at equal intervals in the tire circumferential direction, but the present invention is not limited thereto, and they may be arranged at unequal intervals.

[0040] Also, the ratio ((d5 / d1)×100) of the maximum tire circumferential width d1 to the minimum tire circumferential width d5 of the plurality of dimples 40 in each side block 30 is 35% or more and 55% or less.

[0041] Furthermore, each dimple 40 is provided with radial inclined surfaces 41 and 42 inclined with respect to the top surface 60 so as to be continuous from the top surface 60 of the side block 30 where the dimple 40 is provided and the depth increases toward the center in the tire radial direction of the dimple 40. In particular, in this example, the dimple 40 is provided with an outer radial inclined surface 41 on the outer side in the tire radial direction and an inner radial inclined surface 42 on the inner side in the tire radial direction as the radial inclined surfaces.

[0042] Further, each dimple 40 is provided with circumferential inclined surfaces 43 and 44 that are continuous from the top surface 60 of the side block 30 where the dimple 40 is provided and inclined with respect to the top surface 60 so that the depth increases toward the center in the tire circumferential direction of the dimple 40. In particular, in this example, the dimple 40 is provided with a first circumferential inclined surface 43 on the first side X1 in the tire circumferential direction and a second circumferential inclined surface 44 on the second side X2 in the tire circumferential direction as the circumferential inclined surfaces.

[0043] Furthermore, a bottom surface 45 parallel to the sidewall reference plane 5a is provided at the center of the bottom of each dimple 40. In this example, the bottom surface 45 substantially coincides with the sidewall reference plane 5a, but the bottom surface may be arranged outside the sidewall reference plane 5a in the tire axial direction as long as it is parallel to the sidewall reference plane 5a.

[0044] As shown in FIG. 6, the opening angles θa and θb of the outer radial inclined surface 41 and the inner radial inclined surface 42 of each dimple 40 are each 60 degrees or more and 85 degrees or less. The opening angles θa and θb may be made the same. The opening angles θa and θb for the radial inclined surfaces are the angles formed by the straight lines La and Lb orthogonal to the bottom surface 45 and the respective radial inclined surfaces 41 and 42 at the positions where the respective radial inclined surfaces 41 and 42 intersect the bottom surface 45 in the tire meridian cross-section passing through the bottom surface 45 of the dimple 40. In FIG. 6, the dimple 40a at the second side X2 end in the tire circumferential direction of the side block 30 is shown, but the opening angles of the outer and inner radial inclined surfaces 41 and 42 of the other dimples 40b, 40c, 40d, and 40e are also the same. Since the opening angle is thus restricted to be large, unlike the case of 0 degrees with no opening angle, distortion of the wall adjacent to the dimple in the tire radial direction is less likely to occur. Therefore, the rigidity of the side block 30 can be improved, thereby improving durability.

[0045] As shown in FIGS. 7 and 8, the opening angles θ1 and θ2 of the first circumferential direction inclined surface 43 and the second circumferential direction inclined surface 44 of each dimple 40 are each 13 degrees or more and 80 degrees or less. The opening angle of the circumferential direction inclined surface is the angle formed by a straight line orthogonal to the bottom surface 45 and each of the circumferential direction inclined surfaces 43, 44 at the position where each of the circumferential direction inclined surfaces 43, 44 intersects the bottom surface 45 in a cross section in the circumferential direction tangent direction of the tire passing through the center in the tire circumferential direction of the bottom surface 45 in the dimple 40. Since it is regulated so that the opening angle becomes large in this way, unlike the case of 0 degrees where there is no opening angle, distortion of the wall adjacent to the dimple in the tire circumferential direction is less likely to occur. Also by this, since the rigidity of the side block 30 can be improved, the durability can be improved.

[0046] In FIG. 7, the dimple 40a at the second side X2 end in the tire circumferential direction of the side block 30 is shown, and in FIG. 8, the dimple 40e at the first side X1 end in the tire circumferential direction of the side block 30 is shown. As shown in FIGS. 7 and 8, the opening angle θ1 of each circumferential direction inclined surface 43, 44 of the dimple 40a at the second side end in the tire circumferential direction is larger than the opening angle θ2 of each circumferential direction inclined surface 43, 44 of the dimple 40e at the first side X1 end in the tire circumferential direction. The opening angles of the circumferential direction inclined surfaces 43, 44 of the other dimples 40b, 40c, 40d of the side block 30 are between the opening angle θ1 and the opening angle θ2. In any case, the opening angles of the circumferential direction inclined surfaces 43, 44 of each dimple 40 are each 13 degrees or more and 80 degrees or less.

[0047] Furthermore, the height from the sidewall reference plane 5a of the side block 30 gradually increases toward the inner side Y2 in the tire radial direction. For example, as shown in FIG. 6, in a cross section including the dimple 40a at the second side X2 end in the tire circumferential direction of the side block 30, the height from the sidewall reference plane 5a to the top surface 60 gradually increases toward the inner side Y2 in the tire radial direction.

[0048] Also, near the inner edge in the tire radial direction of each side block 30, an inner rib 61 is formed that bulges so that the height rapidly increases and extends along the tire circumferential direction X. The inner rib may be omitted.

[0049] The height of each side block 30 from the side wall reference plane 5a is 3.0 mm or more and 5.0 mm or less throughout the tire radial direction.

[0050] Also, the maximum depth of each of the plurality of dimples 40 is 2.0 mm or more and 5.0 mm or less.

[0051] According to the above tire 1, in the tire 1 having the side blocks 30 on the sidewall 5, it is possible to achieve both an improvement in traction performance on muddy ground and suppression of breakage due to cut damage.

[0052] FIG. 9 is a view corresponding to FIG. 4 in a pneumatic tire which is another example of the embodiment. In the configuration of this example, the plurality of dimples 40 and the plurality of walls 50, 50z provided in each side block 30a are arranged in the reverse order in the tire circumferential direction compared to the configuration of FIGS. 1 to 8. In this example, other configurations and operations are the same as those of the configurations of FIGS. 1 to 8.

[0053] In addition, in each of the above examples, in each of the side blocks 30, 30a, the plurality of dimples and the plurality of walls are arranged in a gradation in the tire circumferential direction, but the arrangement is not limited to this. For example, in each side block, only two dimples, a first dimple and a second dimple, may be formed. The second length, which is the tire circumferential width of the second dimple, is smaller than the first length, which is the tire circumferential width of the first dimple. Also, the tire circumferential width at the top surface of the second wall adjacent to the first side in the tire circumferential direction of the second dimple is larger than the tire circumferential width at the top surface of the first wall adjacent to the second side in the tire circumferential direction of the first dimple.

[0054] In addition, in each side block, a combination of the first dimple, the second dimple, the first wall, and the second wall may be repeatedly formed a plurality of times in the tire circumferential direction. Further, in each side block, among the plurality of dimples, the dimples arranged on the second side in the tire circumferential direction are arranged such that the tire circumferential width increases in order toward the first side in the tire circumferential direction, and the dimples arranged on the first side in the tire circumferential direction are arranged such that the tire circumferential width decreases in order toward the first side in the tire circumferential direction. In this case, the plurality of walls arranged on the second side in the tire circumferential direction are arranged such that the tire circumferential width increases in order toward the first side in the tire circumferential direction. Also, the plurality of walls arranged on the first side in the tire circumferential direction are arranged such that the tire circumferential width decreases in order toward the first side in the tire circumferential direction.

[0055] In addition, in each of the above examples, in each dimple 40 provided in each side block 30, a configuration in which both the radial inclined surface and the circumferential inclined surface are formed inward has been described, but a configuration in which only one of the radial inclined surface and the circumferential inclined surface is formed may also be used. Further, as the radial inclined surface, only one of the outer radial inclined surface and the inner radial inclined surface may be formed, and as the circumferential inclined surface, only one of the first circumferential inclined surface and the second circumferential inclined surface may be formed.

[0056] The present disclosure will be further described by the following embodiments. Configuration 1: A pneumatic tire including a tread and a pair of sidewalls, at least one of the pair of sidewalls including a plurality of side blocks protruding side by side in the tire circumferential direction from a sidewall reference plane, wherein a plurality of dimples longer in the tire radial direction than in the tire circumferential direction are formed side by side in the tire circumferential direction in each of the plurality of side blocks, the plurality of dimples having a first dimple with a tire circumferential width of a first length and a second dimple with a tire circumferential width of a second length smaller than the first length, A pneumatic tire in which the tire circumferential width at the top surface of the second wall adjacent to the first side in the tire circumferential direction of the second dimple is larger than the tire circumferential width at the top surface of the first wall adjacent to the second side in the tire circumferential direction of the first dimple. Configuration 2: The plurality of dimples include a third dimple disposed on the side opposite to the first dimple of the second dimple, The tire circumferential widths of the first dimple, the second dimple, and the third dimple decrease in this order, A third wall is adjacent to the first side in the tire circumferential direction of the third dimple, The tire circumferential widths of the first wall, the second wall, and the third wall increase in this order. The pneumatic tire according to Configuration 1. Configuration 3: The ratio between the maximum tire circumferential width and the minimum tire circumferential width of the plurality of dimples in each side block is 35% or more and 55% or less. The pneumatic tire according to Configuration 2. Configuration 4: At least one of a radial inclined surface inclined with respect to the top surface so as to be continuous from the top surface of the side block and increase in depth toward the center in the tire radial direction of the dimple, and a circumferential inclined surface inclined with respect to the top surface so as to be continuous from the top surface of the side block and increase in depth toward the center in the tire circumferential direction of the dimple is provided in the dimple. The pneumatic tire according to any one of Configurations 1 to 3. Configuration 5: In the dimple, an outer radial inclined surface on the outer side in the tire radial direction and an inner radial inclined surface on the inner side in the tire radial direction are provided as the radial inclined surfaces, and a first circumferential inclined surface on the first side in the tire circumferential direction and a second circumferential inclined surface on the second side in the tire circumferential direction are provided as the circumferential inclined surfaces. The pneumatic tire according to Configuration 4. Configuration 6: A bottom surface parallel to the sidewall reference plane is provided at the center bottom of the dimple. The pneumatic tire according to Configuration 5. Configuration 7: The opening angles of the outer diameter direction inclined surface and the inner diameter direction inclined surface of the dimple are each 60 degrees or more and 85 degrees or less. The pneumatic tire according to Configuration 5 or Configuration 6. Configuration 8: The opening angles of the first circumferential direction inclined surface and the second circumferential direction inclined surface of the dimple are each 13 degrees or more and 80 degrees or less. The pneumatic tire according to any one of Configurations 5 to 7. Configuration 9: The predetermined annular region having the plurality of side blocks in a side view of the tire has a shape that is repeated in the tire circumferential direction at the same pitch. The plurality of dimples provided in the plurality of side blocks are 2 or more and 5 or less per pitch. The pneumatic tire according to any one of Configurations 1 to 8. Configuration 10: The height of the side block from the sidewall reference plane gradually increases toward the inner side in the tire radial direction. The pneumatic tire according to any one of Configurations 1 to 9. Configuration 11: The height of the side block from the sidewall reference plane is 3.0 mm or more and 5.0 mm or less throughout the tire radial direction. The pneumatic tire according to Configuration 10. Configuration 12: The maximum depth of the plurality of dimples is 2.0 mm or more and 5.0 mm or less. The pneumatic tire according to any one of Configurations 1 to 11.

Explanation of Signs

[0057] 1 pneumatic tire (tire), 2 shoulder block, 3 groove, 5 sidewall, 5a sidewall reference plane, 6 side rib, 10 tread, 13 tire side surface, 18 rim strip, 23 rim protector, 24 rim line, 30, 30a side block, 31 recess, 32 bottom surface, 33, 35 inclined surface, 40a - 40e dimple, 41 outer diameter direction inclined surface, 42 inner diameter direction inclined surface, 43 first circumferential direction inclined surface, 44 second circumferential direction inclined surface, 45 bottom surface, 50a - 50e, 50z wall, 60 top surface, 61 inner rib, P tire maximum width position, T ground contact end.

Claims

1. A pneumatic tire comprising a tread and a pair of sidewalls, at least one of the pair of sidewalls including a plurality of side blocks protruding side by side in the tire circumferential direction from a sidewall reference plane, wherein in each of the plurality of side blocks, a plurality of dimples longer in the tire radial direction than in the tire circumferential direction are formed side by side in the tire circumferential direction, the plurality of dimples include first dimples having a first length which is the tire circumferential width and second dimples having a second length smaller than the first length, a pneumatic tire in which the tire circumferential width at the top surface of a second wall adjacent to a first side in the tire circumferential direction of the second dimples is larger than the tire circumferential width at the top surface of a first wall adjacent to a second side in the tire circumferential direction of the first dimples.

2. the plurality of dimples include third dimples disposed on a side opposite to the first dimples of the second dimples, the tire circumferential widths of the first dimples, the second dimples, and the third dimples decrease in this order, a third wall is adjacent to a first side in the tire circumferential direction of the third dimples, the tire circumferential widths of the first wall, the second wall, and the third wall increase in this order, The pneumatic tire according to claim 1.

3. The ratio of the maximum tire circumferential width to the minimum tire circumferential width of the plurality of dimples in each of the side blocks is 35% or more and 55% or less, The pneumatic tire according to claim 2.

4. at least one of a radial inclined surface inclined with respect to the top surface so as to be continuous from the top surface of the side block and increase in depth toward the center in the tire radial direction of the dimple and a circumferential inclined surface inclined with respect to the top surface so as to be continuous from the top surface of the side block and increase in depth toward the center in the tire circumferential direction of the dimple is provided in the dimple, The pneumatic tire according to claim 1.

5. the dimple is provided with an outer radial inclined surface on the outer side in the tire radial direction and an inner radial inclined surface on the inner side in the tire radial direction as the radial inclined surfaces, and a first circumferential inclined surface on a first side in the tire circumferential direction and a second circumferential inclined surface on a second side in the tire circumferential direction as the circumferential inclined surfaces, The pneumatic tire according to claim 4.

6. a bottom surface parallel to the sidewall reference plane is provided at the center of the bottom of the dimple. The pneumatic tire according to claim 5.

7. The opening angle of each of the outer diameter direction inclined surface and the inner diameter direction inclined surface of the dimple is 60 degrees or more and 85 degrees or less. The pneumatic tire according to claim 5.

8. The opening angle of each of the first circumferential direction inclined surface and the second circumferential direction inclined surface of the dimple is 13 degrees or more and 80 degrees or less. The pneumatic tire according to claim 5.

9. The predetermined annular region having the plurality of side blocks in a side view of the tire has a shape that is repeated in the tire circumferential direction at the same pitch. The plurality of dimples provided in the plurality of side blocks are 2 or more and 5 or less per pitch. The pneumatic tire according to claim 1.

10. The height of the side block from the sidewall reference plane gradually increases toward the inner side in the tire radial direction. The pneumatic tire according to claim 1.

11. The height of the side block from the sidewall reference plane is 3.0 mm or more and 5.0 mm or less over the entire tire radial direction. The pneumatic tire according to claim 10.

12. The maximum depth of the plurality of dimples is 2.0 mm or more and 5.0 mm or less. The pneumatic tire according to claim 1.

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