Tire

Abstract

To provide a tire which enables improvement of abrasion resistance while securing ice and snow tire performance and wet performance by optimizing a pattern structure.SOLUTION: A plurality of circumferential major grooves 30 include shoulder major grooves 35 and a center major groove 31, and a plurality of widthwise grooves 50 include shoulder widthwise grooves 55 and second widthwise grooves 51. The second widthwise groove 51 communicates with the shoulder major groove 35 at a position different from a position where the shoulder widthwise groove 55 communicates with the shoulder major groove 35 in a tire circumferential direction and has at least two bending parts 53c where an extending direction in the second widthwise groove 51 changes. A circumferential narrow groove 60 which extends in the tire circumferential direction, communicates at both ends with the second widthwise grooves 51 at positions different from those of the bending parts 53c, and divides a second land part 22 in a tire width direction is disposed between the second widthwise grooves 51 located adjacent to each other in the tire circumferential direction.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Tires mounted on vehicles have grooves formed in the tread portion to ensure various performance characteristics according to the manner in which the tire is used, and performance is improved by devising the shape of the grooves. For example, a pneumatic tire described in Patent Document 1 has lug grooves with a Z-shape or crank shape in which the groove centerline is offset in the tire circumferential direction, and grooves extending in the tire circumferential direction and having one end connected to the bent portion of the lug groove are arranged between the lug grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6107843 Summary of the Invention [Problem to be solved by the invention]

[0004] Traditionally, studless tires have been focused on performance on ice, but there is also a demand for improved performance on snow. Generally, improving performance on ice requires improving adhesion friction, but this is achieved by increasing the actual contact area by reducing the groove area ratio, which has the drawback of worsening performance on snow and wet surfaces. In addition, improved wear resistance is also required for studless tires in recent years.

[0005] The present invention has been made in view of the above, and aims to provide a tire that can improve wear resistance while ensuring snow and ice performance and wet performance by optimizing the pattern configuration. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a tire according to the present invention includes a plurality of circumferential main grooves arranged in a tread portion and extending in a tire circumferential direction, a plurality of widthwise grooves arranged in the tread portion and extending in a tire width direction, and a land portion defined by the circumferential main grooves and the widthwise grooves, wherein the plurality of circumferential main grooves have shoulder main grooves arranged outermost in the tire width direction and a center main groove adjacent to the shoulder main grooves, and the plurality of widthwise grooves include shoulder widthwise grooves arranged outward of the shoulder main grooves in the tire width direction and communicating with the shoulder main grooves, and shoulder widthwise grooves arranged between the shoulder main grooves and the center main groove and second width direction grooves communicating with the shoulder main grooves and the center main groove, the second width direction grooves communicating with the shoulder main grooves at positions in the tire circumferential direction that are different from positions at which the shoulder width direction grooves communicate with the shoulder main grooves, and having at least two bend portions where the extending direction of the second width direction grooves changes, and between the second width direction grooves adjacent in the tire circumferential direction, circumferential narrow grooves are arranged that extend in the tire circumferential direction and communicate with the second width direction grooves at positions different from the bend portions, and that divide in the tire width direction the second land portion that is the land portion defined by the shoulder main grooves and the center main groove. [Effects of the Invention]

[0007] The tire according to the present invention has an effect of improving wear resistance while ensuring performance on snow and ice and wet conditions. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a tire meridian cross-sectional view showing a main part of a pneumatic tire according to an embodiment. [Figure 2] FIG. 2 is a view taken along the line AA in FIG. [Figure 3] FIG. 3 is a detailed view of part B in FIG. [Figure 4] FIG. 4 is a detailed view of part B in FIG. 2, and is an explanatory view of the angle of the groove. [Figure 5]FIG. 5 is a cross-sectional view taken along line CC in FIG. 3, and is a schematic diagram for comparing groove depths. [Figure 6] FIG. 6 is a detailed view of part B in FIG. 2, and is an explanatory view of the inner second land portion. [Figure 7] FIG. 7 is a detailed view of part E in FIG. [Figure 8] FIG. 8 is a detailed view of part E in FIG. 2, and is an explanatory view of the bent portion and the groove width. [Figure 9] FIG. 9 is a cross-sectional view taken along the FF line in FIG. 8, and is a schematic diagram for comparing groove depths. [Figure 10] FIG. 10 is a cross-sectional view taken along line GG in FIG. [Figure 11] FIG. 11 is a detailed view of part E in FIG. 2, and is an explanatory view of the outer second land portion. [Figure 12A] FIG. 12A is a chart showing the results of a performance evaluation test of a pneumatic tire. [Figure 12B] FIG. 12B is a chart showing the results of a performance evaluation test of a pneumatic tire. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a tire according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

[0010] [Embodiment] In the following description, a pneumatic tire 1 will be used as an example of a tire according to the present invention. The pneumatic tire 1, which is an example of a tire, can be filled with air, an inert gas such as nitrogen, or other gases.

[0011] In the following description, the tire radial direction refers to the direction perpendicular to the tire rotational axis (not shown), which is the rotational axis of the pneumatic tire 1, the tire radial inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis. The tire width direction refers to the direction parallel to the tire rotational axis, the tire width inner side refers to the side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is perpendicular to the tire rotational axis and passes through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides in position in the tire width direction with the tire width centerline, which is the center position of the pneumatic tire 1 in the tire width direction. The tire width is the width in the tire width direction between the portions located outermost in the tire width direction, that is, the distance in the tire width direction between the portions farthest from the tire equatorial plane CL. The tire equator line refers to a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1. In the following description, the tire meridian cross section refers to a cross section of the tire cut by a plane that includes the tire rotation axis.

[0012] FIG. 1 is a tire meridian cross-sectional view showing a main portion of a pneumatic tire 1 according to an embodiment. The pneumatic tire 1 according to this embodiment has a specified mounting direction relative to a vehicle, i.e., the direction when mounted on a vehicle. That is, the side of the pneumatic tire 1 according to this embodiment that faces the inside of the vehicle when mounted on the vehicle is the inside of the vehicle mounting direction, and the side that faces the outside of the vehicle when mounted on the vehicle is the outside of the vehicle mounting direction. Note that the designation of the inside of the vehicle mounting direction and the outside of the vehicle mounting direction is not limited to when mounted on a vehicle. For example, when mounted on a rim, the orientation of the rim relative to the inside and outside of the vehicle in the tire width direction is determined. Therefore, when mounted on a rim, the orientation of the pneumatic tire 1 relative to the inside and outside of the vehicle in the tire width direction is specified. The pneumatic tire 1 also has a mounting direction indicator (not shown) that indicates the mounting direction relative to the vehicle. The mounting direction indicator is configured, for example, by a mark or a concavo-convex shape on the sidewall portion 8 of the tire. For example, ECER30 (Article 30 of the Economic Commission for Europe Regulation) requires that a mounting direction indicator be provided on the sidewall portion 8 that is on the outer side in the vehicle mounting direction when mounted on a vehicle. Furthermore, the pneumatic tire 1 according to this embodiment is a pneumatic tire 1 that is mainly used for passenger cars.

[0013] When viewed in meridian section, the pneumatic tire 1 according to this embodiment has a tread portion 2 disposed at the radially outermost portion of the tire, and the tread portion 2 has a tread rubber 4 made of a rubber composition. The surface of the tread portion 2, i.e., the portion that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 is traveling, is formed as a tread contact surface 3, and the tread contact surface 3 constitutes part of the contour of the pneumatic tire 1.

[0014] Shoulder portions 5 are located at both outer ends of the tread portion 2 in the tire width direction, and sidewall portions 8 are arranged on the tire radially inward side of the shoulder portions 5. That is, the sidewall portions 8 are arranged on both sides of the tread portion 2 in the tire width direction. In other words, the sidewall portions 8 are arranged in two locations on both sides of the pneumatic tire 1 in the tire width direction, and form the outermost exposed portions of the pneumatic tire 1 in the tire width direction.

[0015] A bead portion 10 is located on the tire radially inner side of each sidewall portion 8 located on both sides in the tire width direction. Like the sidewall portions 8, the bead portions 10 are located at two positions on both sides of the tire equatorial plane CL; that is, a pair of bead portions 10 are located on both sides of the tire equatorial plane CL in the tire width direction. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided on the tire radially outer side of the bead core 11. The bead core 11 is an annular member formed by bundling bead wires, which are steel wires, into a circular shape, and the bead filler 12 is a rubber member located on the tire radially outer side of the bead core 11.

[0016] A belt layer 14 is also disposed in the tread portion 2. The belt layer 14 has a multi-layer structure in which a plurality of belts 141, 142 and a belt cover 143 are laminated. In this embodiment, two layers of belts 141, 142 are laminated. The belts 141, 142 constituting the belt layer 14 are formed by coating a plurality of belt cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the coated belt cords. The belt angle, defined as the inclination angle of the belt cords with respect to the tire circumferential direction, is within a predetermined range (for example, 20° to 55°). The two-layer belts 141, 142 have different belt angles. Therefore, the belt layer 14 has a so-called cross-ply structure in which the two-layer belts 141, 142 are laminated with the inclination directions of the belt cords crossing each other. In other words, the two-layer belts 141, 142 are provided as so-called cross belts in which the belt cords of the respective belts 141, 142 are arranged in a direction in which they cross each other.

[0017] The belt cover 143 is formed by covering a plurality of belt cover cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the covered cords, and the belt angle, defined as the inclination angle of the belt cover cords with respect to the tire circumferential direction, is within a predetermined range (for example, 0° to 10°). The belt cover 143 is, for example, a strip material formed by covering one or more belt cover cords with coating rubber, and is formed by winding this strip material spirally around the tire rotation axis from the outer side in the tire radial direction of the two-layered belts 141 and 142.

[0018] A carcass layer 13 containing the cords of the radial ply is provided continuously on the tire radially inward side of the belt layer 14 and on the tire equatorial plane CL side of the sidewall portion 8. Therefore, the pneumatic tire 1 according to this embodiment is configured as a so-called radial tire. The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of a plurality of carcass plies stacked together, and is toroidally spanned between a pair of bead portions 10 arranged on both sides in the tire width direction to form the framework of the tire.

[0019] Specifically, the carcass layer 13 is disposed from one of a pair of bead portions 10 located on both sides in the tire width direction to the other bead portion 10, and is wound back along the bead core 11 at the bead portion 10 toward the outside in the tire width direction so as to enclose the bead core 11 and the bead filler 12. The bead filler 12 is made of a rubber material that is disposed in a space formed on the outside in the tire radial direction of the bead core 11 by folding back the carcass layer 13 at the bead portion 10 in this manner. The belt layer 14 is disposed on the outside in the tire radial direction of the portion of the carcass layer 13 that is positioned in the tread portion 2 and that is stretched between the pair of bead portions 10 in this manner. The carcass ply of the carcass layer 13 is formed by covering a plurality of carcass cords made of steel or an organic fiber material such as aramid, nylon, polyester, or rayon with coating rubber and rolling the coated cords. The carcass cords constituting the carcass ply are arranged in parallel at a certain angle relative to the tire circumferential direction, along the tire meridian direction.

[0020] In the bead portion 10, a rim cushion rubber 17 that forms the contact surface of the bead portion 10 with the rim flange is arranged on the tire radially inner side and tire widthwise outer side of the bead core 11 and the turned-up portion of the carcass layer 13. Furthermore, an inner liner 16 is formed along the carcass layer 13 on the inner side of the carcass layer 13 or on the inner side of the carcass layer 13 in the pneumatic tire 1. The inner liner 16 forms a tire inner surface 18, which is the inner surface of the pneumatic tire 1.

[0021] Fig. 2 is a view taken along the arrow AA in Fig. 1. In the tread portion 2, a plurality of circumferential main grooves 30 extending in the tire circumferential direction and a plurality of widthwise grooves 50 extending in the tire width direction are arranged in the tread contact surface 3, and these circumferential main grooves 30 and widthwise grooves 50 define a plurality of land portions 20 on the surface of the tread portion 2. In this embodiment, three circumferential main grooves 30 are arranged side by side in the tire width direction. Specifically, one circumferential main groove 30 is arranged on the inner side of the tire equatorial plane CL in the vehicle mounting direction, and two circumferential main grooves 30 are arranged on the outer side of the tire equatorial plane CL in the vehicle mounting direction.

[0022] Of the two circumferential main grooves 30 arranged on the outer side in the vehicle mounting direction with respect to the tire equatorial plane CL, the circumferential main groove 30 arranged on the inner side in the tire width direction is a center main groove 31, and the circumferential main groove 30 arranged on the outer side in the tire width direction is a shoulder main groove 35. Furthermore, the one circumferential main groove 30 arranged on the inner side in the vehicle mounting direction with respect to the tire equatorial plane CL is approximately the same distance from the tire equatorial plane CL as the shoulder main groove 35 arranged on the outer side in the vehicle mounting direction. For this reason, the one circumferential main groove 30 arranged on the inner side in the vehicle mounting direction with respect to the tire equatorial plane CL is provided as a shoulder main groove 35.

[0023] That is, the pneumatic tire 1 according to this embodiment has three circumferential main grooves 30: two shoulder main grooves 35 arranged on the outermost sides in the tire width direction, and one center main groove 31 adjacent to the shoulder main groove 35 in the tire width direction. The two shoulder main grooves 35 include an inner shoulder main groove 35a, which is the shoulder main groove 35 arranged on the inner side in the vehicle mounting direction, and an outer shoulder main groove 35b, which is the shoulder main groove 35 arranged on the outer side in the vehicle mounting direction. In this embodiment, all three circumferential main grooves 30 are formed to extend linearly in the tire circumferential direction.

[0024] The circumferential main groove 30 here is a longitudinal groove extending in the tire circumferential direction, and has a wear indicator (slip sign) inside that indicates the end of wear. The circumferential main groove 30 thus formed has a groove width in the range of 4.0 mm to 13.5 mm, and a groove depth in the range of 8.0 mm to 9.0 mm.

[0025] Furthermore, in the tread portion 2, a straight groove 40 extending in the tire circumferential direction and having a shallower groove depth than the shoulder main groove 35 is arranged between the shoulder main groove 35 and the center main groove 31 on the inner side of the tire equatorial plane CL in the vehicle mounting direction. That is, the straight groove 40 is arranged between the inner shoulder main groove 35a arranged on the inner side in the vehicle mounting direction and the center main groove 31, and has a shallower groove depth than the inner shoulder main groove 35a.

[0026] The straight grooves 40 have a groove width in the range of 3.0 mm to 7.5 mm, and a groove depth in the range of 6.0 mm to 7.5 mm. The straight grooves 40 do not have a wear indicator and are different from the circumferential main grooves 30. In this embodiment, the straight grooves 40 are formed to extend linearly along the tire circumferential direction, similar to the circumferential main grooves 30.

[0027] The land portions 20 defined by the circumferential main grooves 30 include a center land portion 21, a second land portion 22, and a shoulder land portion 25. Of these, the center land portion 21 is the land portion 20 located between the center main groove 31 disposed on the outer side in the vehicle mounting direction and the straight groove 40 disposed on the inner side in the vehicle mounting direction, and is defined on both sides in the tire width direction by the center main groove 31 and the straight groove 40.

[0028] Furthermore, the second land portion 22 is a land portion 20 on the inner side in the vehicle mounting direction that is defined on both sides in the tire width direction by the shoulder main groove 35 and the straight groove 40, and on the outer side in the vehicle mounting direction that is defined by the shoulder main groove 35 and the center main groove 31. In other words, the inner second land portion 23, which is the second land portion 22 located on the inner side in the vehicle mounting direction, has an inner portion in the tire width direction defined by the straight groove 40 and an outer portion in the tire width direction defined by the inner shoulder main groove 35a. Furthermore, the outer second land portion 24, which is the second land portion 22 located on the outer side in the vehicle mounting direction, has an inner portion in the tire width direction defined by the center main groove 31 and an outer portion in the tire width direction defined by the outer shoulder main groove 35b.

[0029] Additionally, the shoulder land portion 25 is a land portion 20 located on the outer side of the shoulder main groove 35 in the tire width direction, and its inner side in the tire width direction is defined by the shoulder main groove 35. That is, the inner shoulder land portion 25a, which is the shoulder land portion 25 located on the inner side in the vehicle mounting direction, has its inner side in the tire width direction defined by the inner shoulder main groove 35a, and the outer shoulder land portion 25b, which is the shoulder land portion 25 located on the outer side in the vehicle mounting direction, has its inner side in the tire width direction defined by the outer shoulder main groove 35b.

[0030] Of the multiple land portions 20 arranged in the tread portion 2, the second land portion 22 and the shoulder land portion 25 are arranged on both sides of the tire equatorial plane CL in the tire width direction.

[0031] The widthwise grooves 50 include second widthwise grooves 51 and shoulder widthwise grooves 55. Of these, the second widthwise grooves 51 are widthwise grooves 50 disposed at least between the shoulder main grooves 35 and the center main groove 31. The second widthwise grooves 51 include an inner second widthwise groove 52, which is a second widthwise groove 51 disposed on the inner side of the tire equatorial plane CL in the vehicle mounting direction, and an outer second widthwise groove 53, which is a second widthwise groove 51 disposed on the outer side of the tire equatorial plane CL in the vehicle mounting direction.

[0032] The inner second widthwise groove 52 is disposed at least between the inner shoulder main groove 35a and the center main groove 31, with one end communicating with the inner shoulder main groove 35a and the other end terminating within the center land portion 21. In other words, the inner second widthwise groove 52 intersects the straight groove 40 between the inner shoulder main groove 35a and the center main groove 31, and the end of the inner second widthwise groove 52 opposite the end communicating with the inner shoulder main groove 35a terminates within the center land portion 21, which is the land portion 20 located on the opposite side of the straight groove 40 from the side where the inner second land portion 23 is located. By intersecting the straight groove 40 in this way, the inner second widthwise groove 52 also communicates with the straight groove 40.

[0033] The outer second widthwise groove 53 is disposed at least between the outer shoulder main groove 35b and the center main groove 31, with one end communicating with the outer shoulder main groove 35b and the other end terminating within the center land portion 21. In other words, the outer second widthwise groove 53 intersects with the center main groove 31, and the end of the outer second widthwise groove 53 opposite the end communicating with the outer shoulder main groove 35b terminates within the center land portion 21, which is the land portion 20 located on the opposite side of the center main groove 31 from the side where the outer second land portion 24 is located. By intersecting the center main groove 31 in this way, the outer second widthwise groove 53 also communicates with the center main groove 31.

[0034] The inner second widthwise groove 52 communicates with the straight grooves 40 and the inner shoulder main groove 35a that define both sides in the tire width direction of the inner second land portion 23. Therefore, the inner second land portion 23 is defined on both sides in the tire width direction by the straight grooves 40 and the inner shoulder main groove 35a, and on both sides in the tire circumferential direction by the inner second widthwise grooves 52, forming a block-shaped land portion 20.

[0035] The outer second widthwise groove 53 communicates with the center main groove 31 and the outer shoulder main groove 35b, which define both sides in the tire width direction of the outer second land portion 24. Therefore, the outer second land portion 24 is defined on both sides in the tire width direction by the center main groove 31 and the outer shoulder main groove 35b, and on both sides in the tire circumferential direction by the outer second widthwise groove 53, forming a block-shaped land portion 20.

[0036] The shoulder width direction grooves 55 are arranged on the outer side of the shoulder main grooves 35 in the tire width direction, and their inner ends in the tire width direction form width direction grooves 50 that communicate with the shoulder main grooves 35. More specifically, the shoulder width direction grooves 55 include an inner shoulder width direction groove 55a that is a shoulder width direction groove 55 arranged on the outer side of the inner shoulder main groove 35a in the tire width direction, and an outer shoulder width direction groove 55b that is a shoulder width direction groove 55 arranged on the outer side of the outer shoulder main groove 35b in the tire width direction.

[0037] The inner shoulder widthwise groove 55a has an inner end in the tire width direction that communicates with the inner shoulder main groove 35a, and the inner shoulder widthwise groove 55b has an inner end in the tire width direction that communicates with the outer shoulder main groove 35b. The outer ends in the tire width direction of the inner shoulder widthwise groove 55a and the outer shoulder widthwise groove 55b each terminate at a so-called design end, which is an end in the tire width direction of the tread pattern of the tread portion 2.

[0038] The inner shoulder widthwise groove 55a formed between the inner shoulder main groove 35a and the design end serves as a widthwise groove 50 that defines the inner shoulder land portion 25a, which is the shoulder land portion 25 located on the outer side of the inner shoulder main groove 35a in the tire width direction. Therefore, the inner shoulder land portion 25a is defined on the inner side in the tire width direction by the inner shoulder main groove 35a, and on both sides in the tire circumferential direction by the inner shoulder widthwise groove 55a, forming a block-shaped land portion 20.

[0039] Additionally, the outer shoulder widthwise groove 55b formed between the outer shoulder main groove 35b and the design end serves as a widthwise groove 50 that defines the outer shoulder land portion 25b, which is the shoulder land portion 25 located on the outer side of the outer shoulder main groove 35b in the tire width direction. Therefore, the outer shoulder land portion 25b is defined on the inner side in the tire width direction by the outer shoulder main groove 35b, and on both sides in the tire circumferential direction by the outer shoulder widthwise groove 55b, forming a block-shaped land portion 20.

[0040] The second widthwise grooves 51 and shoulder widthwise grooves 55 arranged in this manner communicate with the shoulder main grooves 35 at mutually different positions in the tire circumferential direction. That is, the inner second widthwise groove 52 and the inner shoulder widthwise groove 55a communicate with the inner shoulder main groove 35a at mutually different positions in the tire circumferential direction. Similarly, the outer second widthwise groove 53 and the outer shoulder widthwise groove 55b communicate with the outer shoulder main groove 35b at mutually different positions in the tire circumferential direction.

[0041] Between the circumferentially adjacent second widthwise grooves 51, circumferential narrow grooves 60 are arranged, which extend in the tire circumferential direction across the space between the circumferentially adjacent second widthwise grooves 51 and have both ends communicating with the second widthwise grooves 51. The circumferential narrow grooves 60 include an inner circumferential narrow groove 61 which is a circumferential narrow groove 60 arranged between the inner shoulder main groove 35a and the straight groove 40, and an outer circumferential narrow groove 62 which is a circumferential narrow groove 60 arranged between the outer shoulder main groove 35b and the center main groove 31.

[0042] The inner circumferential narrow grooves 61 are arranged between the inner second widthwise grooves 52 adjacent in the tire circumferential direction, extend in the tire circumferential direction between the inner second widthwise grooves 52, and have both ends connected to the inner second widthwise grooves 52. The outer circumferential narrow grooves 62 are arranged between the outer second widthwise grooves 53 adjacent in the tire circumferential direction, extend in the tire circumferential direction between the outer second widthwise grooves 53, and have both ends connected to the outer second widthwise grooves 53.

[0043] Additionally, shoulder narrow grooves 70 extending in the tire circumferential direction are arranged in the shoulder land portions 25 located on the outer side of the shoulder main grooves 35 in the tire width direction. One end of the shoulder narrow grooves 70 extending in the tire circumferential direction communicates with the shoulder width direction groove 55, and the other end terminates within the shoulder land portion 25. Of the shoulder narrow grooves 70 arranged in the shoulder land portion 25 and located on the same side in the tire width direction with respect to the tire equatorial plane CL, the ends of the shoulder narrow grooves 70 that communicate with the shoulder width direction groove 55 are all on the same side in the tire circumferential direction. In other words, the shoulder narrow grooves 70 arranged in the shoulder land portions 25 defined by the same shoulder main grooves 35 all face the same direction in the tire circumferential direction.

[0044] Specifically, the shoulder narrow groove 70 includes an inner shoulder narrow groove 70a disposed in the inner shoulder land portion 25a and an outer shoulder narrow groove 70b disposed in the outer shoulder land portion 25b. The inner shoulder narrow grooves 70a have circumferentially opposite ends that communicate with the inner shoulder widthwise groove 55a, and the inner shoulder narrow grooves 70a have circumferentially opposite ends that terminate within the inner shoulder land portion 25a. Similarly, the outer shoulder narrow grooves 70b have circumferentially opposite ends that communicate with the outer shoulder widthwise groove 55b, and the outer shoulder narrow grooves 70b have circumferentially opposite ends that terminate within the outer shoulder land portion 25b.

[0045] Furthermore, the inner shoulder narrow groove 70a and the outer shoulder narrow groove 70b have ends on different sides, one communicating with the shoulder widthwise groove 55 and the other terminating within the shoulder land portion 25. In other words, the inner shoulder narrow groove 70a and the outer shoulder narrow groove 70b are oriented in opposite directions in the tire circumferential direction.

[0046] Furthermore, a plurality of sipes 80 extending in the tire width direction are arranged in each land portion 20. The sipes 80 arranged in the land portion 20 are, for example, formed in a zigzag pattern by extending in the tire width direction while repeatedly bending and oscillating in the tire circumferential direction. The ends of each sipe 80 may terminate within the land portion 20, or may be connected to other grooves. The sipes 80 arranged in each land portion 20 are preferably inclined in the same direction in the tire circumferential direction with respect to the tire width direction as the widthwise groove 50 that is positioned at the same position in the tire width direction. In other words, each sipe 80 is preferably arranged in a direction extending approximately parallel to the widthwise groove 50 that is positioned at the same position in the tire width direction.

[0047] By arranging sipes 80 on each land portion 20 in this manner, the pneumatic tire 1 of this embodiment can be used as a studless tire, which is a winter tire that ensures driving performance on icy and snowy roads, or as an all-season tire that ensures driving performance in winter.

[0048] The sipes 80 referred to here are narrow grooves formed in the tread contact surface 3, and when the pneumatic tire 1 is mounted on a specified rim and under a specified internal pressure condition and no load is applied, the wall surfaces constituting the narrow grooves do not come into contact with each other. However, when a load is applied vertically on a flat plate and the narrow grooves are located in a part of the contact surface formed on the flat plate, or when the land portions 20 on which the narrow grooves are formed collapse, the wall surfaces constituting the narrow grooves, or at least a part of the portions provided on the wall surfaces, come into contact with each other due to deformation of the land portions 20. In this embodiment, the sipes 80 have a groove width of 0.4 mm or less, and a maximum depth from the tread contact surface 3 of 6.5 mm to 7.0 mm.

[0049] The specified rim here refers to the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value listed in the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO.

[0050] The sipe 80 may be a so-called three-dimensional sipe or a two-dimensional sipe. The three-dimensional sipe here refers to a sipe 80 having a curved wall surface with amplitude in the width direction of the sipe 80 in both a cross-sectional view in which the length direction of the sipe 80 is the normal direction (a cross-sectional view including the width direction and depth direction of the sipe 80) and a cross-sectional view in which the depth direction of the sipe 80 is the normal direction (a cross-sectional view including the width direction and length direction of the sipe 80). The two-dimensional sipe refers to a sipe 80 having a straight wall surface in any cross-sectional view in which the length direction of the sipe 80 is the normal direction (a cross-sectional view including the width direction and depth direction of the sipe 80).

[0051] Fig. 3 is a detailed view of part B in Fig. 2. The inner second widthwise groove 52 extends in the tire width direction and is inclined in the tire circumferential direction with respect to the tire width direction. The end of the inner second widthwise groove 52 that intersects with the straight groove 40 and terminates within the center land portion 21 is located near the tire equatorial plane CL and on the inner side of the tire equatorial plane CL in the vehicle mounting direction.

[0052] The portion of the inner second widthwise groove 52 between the inner shoulder main groove 35a and the straight groove 40 has a wide portion 52a and a narrow portion 52b with different groove widths. The narrow portion 52b has a groove width narrower than that of the wide portion 52a, is located on both sides of the wide portion 52a in the extension direction of the inner second widthwise groove 52, and communicates with the inner shoulder main groove 35a or the straight groove 40. In other words, the narrow portions 52b are located on the side of the wide portion 52a where the inner shoulder main groove 35a is located and the side where the straight groove 40 is located in the extension direction of the inner second widthwise groove 52.

[0053] The inner narrow portion 52ba, which is the narrow portion 52b arranged on the side of the wide portion 52a where the straight groove 40 is located, is connected to the straight groove 40, and the outer narrow portion 52bb, which is the narrow portion 52b arranged on the side of the wide portion 52a where the inner shoulder main groove 35a is located, is connected to the inner shoulder main groove 35a. The straight grooves 40 that intersect with the inner second widthwise grooves 52 intersect with the inner narrow portions 52ba of the inner second widthwise grooves 52 formed in this manner. Therefore, the inner narrow portions 52ba of the inner second widthwise grooves 52 are arranged on both sides of the straight grooves 40 in the groove width direction at the intersection with the straight grooves 40 and are connected to the straight grooves 40 from both sides in the groove width direction.

[0054] The inner narrow portion 52ba and the outer narrow portion 52bb, which are located on both sides of the wide portion 52a, are offset from each other in the groove width direction of the inner second widthwise groove 52. More specifically, one of the edges on both sides of the inner narrow portion 52ba in the groove width direction is positioned on an extension line of one of the edges on both sides of the wide portion 52a in the groove width direction.

[0055] In contrast, one of the edges of the outer narrow portion 52bb in the groove width direction is located on an extension line of an edge of the wide portion 52a that is different from the edge of the inner narrow portion 52ba on the extension line of the wide portion 52a in the groove width direction. As a result, the inner narrow portion 52ba and the outer narrow portion 52bb of the inner second widthwise groove 52 are shifted from each other in the groove width direction of the inner second widthwise groove 52.

[0056] In the inner second widthwise groove 52 having the wide portion 52a and the narrow portion 52b with different groove widths as described above, the groove width W4a of the inner narrow portion 52ba, which is the narrow portion 52b on the side communicating with the straight groove 40, satisfies the relationship W4a≦0.6W3 relative to the groove width W3 of the wide portion 52a. Similarly, in the inner second widthwise groove 52, the groove width W4b of the outer narrow portion 52bb, which is the narrow portion 52b on the side communicating with the inner shoulder main groove 35a, satisfies the relationship W4b≦0.6W3 relative to the groove width W3 of the wide portion 52a. In this embodiment, the groove width W4a of the inner narrow portion 52ba and the groove width W4b of the outer narrow portion 52bb are the same.

[0057] The inner circumferential narrow groove 61, both ends of which are connected to the inner second widthwise groove 52, is connected to the vicinity of the boundary between the wide portion 52a and the narrow portion 52b of the inner second widthwise groove 52. More specifically, the inner circumferential narrow groove 61 is connected to one of the inner second widthwise grooves 52 adjacent to each other in the tire circumferential direction near the boundary between the wide portion 52a and the outer narrow portion 52bb, and is connected to the other inner second widthwise groove 52 near the boundary between the wide portion 52a and the inner narrow portion 52ba. Therefore, the inner circumferential narrow groove 61 extends in the tire circumferential direction and is inclined in the tire width direction with respect to the tire circumferential direction.

[0058] In this way, the inner circumferential narrow groove 61 communicating with the inner second widthwise groove 52 has a groove width narrower than the groove width of the wide portion 52a of the inner second widthwise groove 52. Specifically, the groove width W5 of the inner circumferential narrow groove 61 and the groove width W3 of the wide portion 52a of the inner second widthwise groove 52 satisfy the relationship W5≦0.6W3.

[0059] 4 is a detailed view of portion B in FIG. 2 and is an explanatory diagram of the groove angles. The inner second widthwise groove 52 and the inner circumferential narrow groove 61, which are respectively arranged at an incline, are inclined in the same direction in the tire width direction relative to the tire circumferential direction. The inclination angle θα of the inner circumferential narrow groove 61 in the tire width direction relative to the tire circumferential direction is within the range of 15°≦θα≦30°. The inclination angle θβ of the inner second widthwise groove 52 in the tire width direction relative to the tire circumferential direction is within the range of 65°≦θβ≦80°. In this case, the angle θα of the inner circumferential narrow groove 61 and the angle θβ of the inner second widthwise groove 52 are each angles on the acute angle side with respect to the tire circumferential direction.

[0060] In other words, the inner circumferential narrow groove 61 communicates with the inner second widthwise groove 52 at an angle θα relative to the inner shoulder main groove 35a that is within the range of 15°≦θα≦30°. The inner second widthwise groove 52 also communicates with the inner shoulder main groove 35a at an angle θβ relative to the inner shoulder main groove 35a that is within the range of 65°≦θβ≦80°.

[0061] The inclination angle θα of the inner circumferential narrow groove 61 in the tire width direction relative to the tire circumferential direction is preferably within the range of 20°≦θα≦25°, and the inclination angle θβ of the inner second widthwise groove 52 in the tire width direction relative to the tire circumferential direction is preferably within the range of 70°≦θβ≦75°.

[0062] The straight groove 40 has a narrower groove width than the circumferential main groove 30. Specifically, the groove width W2 of the straight groove 40 satisfies the relationship W2≦0.75W1 with respect to the groove width W1 of the inner shoulder main groove 35a. Preferably, the relationship between the groove width W2 of the straight groove 40 and the groove width W1 of the inner shoulder main groove 35a is within the range of 0.60W1≦W2≦0.90W1.

[0063] Figure 5 is a cross-sectional view taken along CC in Figure 3, and is a schematic diagram for comparing groove depths. Figure 5 is a schematic diagram illustrating, in a single cross-sectional view, the inner second widthwise groove 52 and the inner shoulder main groove 35a, which are located at different positions in the tire circumferential direction. The straight groove 40 has a groove depth D2 that is shallower than the groove depth D1 of the inner shoulder main groove 35a, and the groove depth D2 of the straight groove 40 satisfies the relationship D2≦0.8D1 relative to the groove depth D1 of the inner shoulder main groove 35a.

[0064] The inner second widthwise grooves 52 communicating with the inner shoulder main groove 35a and the straight groove 40 have the same groove depths at the portions communicating with the inner shoulder main groove 35a and the straight groove 40 as the groove depths of the inner shoulder main groove 35a and the straight groove 40. That is, the inner second widthwise groove 52 has a groove depth D4b of an outer narrow portion 52bb communicating with the inner shoulder main groove 35a that is the same as the groove depth D1 of the inner shoulder main groove 35a, and a groove depth D4a of an inner narrow portion 52ba communicating with the straight groove 40 that is the same as the groove depth D2 of the straight groove 40.

[0065] Therefore, the inner second widthwise groove 52 has a shallower groove depth at the inner narrow portion 52ba communicating with the straight groove 40 than at the outer narrow portion 52bb communicating with the inner shoulder main groove 35a. The groove depth D3 of the wide portion 52a of the inner second widthwise groove 52 is the same as the groove depth D4b of the outer narrow portion 52bb. Therefore, the inner second widthwise groove 52 and the inner shoulder main groove 35a are formed to the same depth from the inner shoulder main groove 35a to the wide portion 52a of the inner second widthwise groove 52.

[0066] The inner circumferential narrow groove 61, which is the circumferential narrow groove 60 communicating with the inner second widthwise groove 52, has a groove depth D5 that is shallower than the groove depth D1 of the inner shoulder main groove 35a and the groove depth D2 of the straight groove 40. Specifically, the groove depth D5 of the inner circumferential narrow groove 61 and the groove depth D2 of the straight groove 40 satisfy the relationship D5≦0.75D2.

[0067] Here, two inner circumferential narrow grooves 61 communicate with the inner second widthwise groove 52 from both sides in the groove width direction of the inner second widthwise groove 52, and in the portion of the inner second widthwise groove 52 where the inner circumferential narrow grooves 61 communicate with each other near the boundary between the wide portion 52a and the inner narrow portion 52ba, the groove depth of the inner second widthwise groove 52 is the same as the groove depth of the inner circumferential narrow groove 61.

[0068] The inner circumferential narrow groove 61 has a groove depth D5 that is shallower than the inner shoulder main groove 35a and the straight groove 40, and the wide portion 52a and the inner narrow portion 52ba of the inner second widthwise groove 52 have the same groove depth as the inner shoulder main groove 35a and the straight groove 40. Therefore, the portion of the inner second widthwise groove 52 that has the same groove depth as the inner circumferential narrow groove 61 has a groove bottom that is raised to match the groove depth of the inner circumferential narrow groove 61.

[0069] In addition, the inner shoulder widthwise groove 55a communicates with the inner shoulder main groove 35a from the outer side in the tire width direction, and the groove depth D6 of the inner shoulder widthwise groove 55a communicating with the inner shoulder main groove 35a is the same as the groove depth D1 of the inner shoulder main groove 35a.

[0070] Here, the portion of the inner second widthwise groove 52 formed in a bottom-up shape is, in other words, a portion divided by the inner circumferential narrow groove 61, and the inner second widthwise groove 52 communicates with the inner circumferential narrow groove 61 from both sides in the groove width direction of the inner circumferential narrow groove 61. Therefore, the inner circumferential narrow groove 61 extending in the tire circumferential direction across between the inner second widthwise grooves 52 adjacent in the tire circumferential direction has one end in the extension direction of the inner circumferential narrow groove 61 communicate with one inner second widthwise groove 52 and the other end divides the other inner second widthwise groove 52.

[0071] That is, the inner circumferential narrow grooves 61 divide the inner second widthwise grooves 52 at positions in the extension direction of the inner second widthwise grooves 52 that are different from positions at which inner circumferential narrow grooves 61 adjacent in the tire circumferential direction communicate with the inner second widthwise grooves 52. That is, one end of the inner circumferential narrow groove 61 communicates with the inner second widthwise groove 52 near the boundary between the wide portion 52a and the outer narrow portion 52bb of the inner second widthwise groove 52, and the other end divides the inner second widthwise groove 52 near the boundary between the wide portion 52a and the inner narrow portion 52ba of the inner second widthwise groove 52 adjacent in the tire circumferential direction to the inner second widthwise groove 52. Therefore, the wide portion 52a and the inner narrow portion 52ba of the inner second widthwise groove 52 divided by the inner circumferential narrow groove 61 communicate with the inner circumferential narrow groove 61 from both sides in the groove width direction of the inner circumferential narrow groove 61.

[0072] 2, and is an explanatory diagram of the inner second land portion 23. The inner second land portion 23 is formed into a block-shaped land portion 20 by arranging inner second widthwise grooves 52 across the inner shoulder main groove 35a and the straight groove 40, and further, inner circumferential narrow grooves 61 are arranged between the inner second widthwise grooves 52, so that each block is divided in the tire width direction by the inner circumferential narrow grooves 61. Therefore, the inner second land portion 23 has a first block portion 23a and a second block portion 23b divided by the inner circumferential narrow groove 61 between the inner second widthwise grooves 52 adjacent in the tire circumferential direction.

[0073] The first block portion 23a is defined by two circumferentially adjacent inner second widthwise grooves 52, a straight groove 40, and an inner circumferential narrow groove 61. The second block portion 23b is defined by two circumferentially adjacent inner second widthwise grooves 52, an inner shoulder main groove 35a, and an inner circumferential narrow groove 61. As described above, the area AA of the first block portion 23a and the area AB of the second block portion 23b of the inner second land portion 23 satisfy the relationship 0.9AB≦AA≦1.1AB. That is, the first block portion 23a and the second block portion 23b of the inner second land portion 23 are formed to have approximately the same area.

[0074] Fig. 7 is a detailed view of part E in Fig. 2. The outer second widthwise groove 53 extends in the tire width direction and is inclined in the tire circumferential direction with respect to the tire width direction. The end of the outer second widthwise groove 53 that intersects with the center main groove 31 and terminates within the center land portion 21 is located near the tire equatorial plane CL and outboard of the tire equatorial plane CL in the vehicle mounting direction.

[0075] The outer second widthwise groove 53 has at least two bent portions 53c at which the extending direction of the second widthwise groove 51 changes. In this embodiment, the outer second widthwise groove 53 has two bent portions 53c, and the two bent portions 53c bend in opposite directions when directed in one direction in the extending direction of the outer second widthwise groove 53. Therefore, the outer second widthwise groove 53 is formed in a so-called crank shape by the two bent portions 53c.

[0076] The bent portion 53c of the outer second widthwise groove 53 is disposed at a position where the distance Wk from the center line CB in the tire width direction of the outer second land portion 24 is within the range of 0≦Wk≦0.25WB, where WB in the tire width direction of the outer second land portion 24 is the width WB of the outer second land portion 24. In this case, the distance Wk of the bent portion 53c from the center line CB in the tire width direction of the outer second land portion 24 is the distance at the portion of the bent portion 53c that is farthest from the center line CB of the outer second land portion 24 in the tire width direction.

[0077] The two bent portions 53c of the outer second widthwise groove 53 are both disposed at positions where the distance Wk from the center line CB of the outer second land portion 24 is within the range of 0≦Wk≦0.25WB, where WB is the width WB of the outer second land portion 24. In other words, the two bent portions 53c of the outer second widthwise groove 53 are both disposed near the center of the outer second land portion 24 in the tire width direction.

[0078] It is preferable that the distance Wk from the center line CB of the outer second land portion 24 to the bent portion 53c relative to the width WB of the outer second land portion 24 is within the range of 0≦Wk≦0.1WB.

[0079] In the outer second widthwise groove 53 provided with the two bent portions 53c, the inclination angle θs of the outer groove portion 53a, which is the portion of the outer second widthwise groove 53 between the portion communicating with the outer shoulder main groove 35b and the bent portion 53c, in the tire circumferential direction with respect to the tire width direction is within the range of 0°≦θs≦60°. In this case, the bent portion 53c is the bent portion 53c of the two bent portions 53c that is located on the outer shoulder main groove 35b side in the direction along which the outer second widthwise groove 53 extends.

[0080] Additionally, the outer second widthwise groove 53 has an inner groove portion 53b, which is a portion of the outer second widthwise groove 53 between the portion communicating with the central main groove 31 and the bent portion 53c, whose inclination angle θc in the tire circumferential direction with respect to the tire width direction is within the range of 0°≦θc≦60°. In this case, the bent portion 53c is the bent portion 53c of the two bent portions 53c that is located closer to the central main groove 31 in the direction along which the outer second widthwise groove 53 extends.

[0081] Furthermore, in the outer second widthwise groove 53, the inclination angle θs of the outer groove portion 53a and the inclination angle θc of the inner groove portion 53b satisfy the relationship θc-5°≦θs≦θc+5°. That is, the outer groove portion 53a and the inner groove portion 53b of the outer second widthwise groove 53 have approximately the same inclination angles in the tire circumferential direction with respect to the tire width direction.

[0082] The inclination angle θs of the outer groove portion 53a of the outer second widthwise groove 53 is preferably within the range of 10°≦θs≦30°, and the inclination angle θc of the inner groove portion 53b is also preferably within the range of 10°≦θc≦30°. The relationship between the inclination angle θs of the outer groove portion 53a and the inclination angle θc of the inner groove portion 53b is preferably within the range of θc-3°≦θs≦θc+3°.

[0083] The outer circumferential narrow grooves 62 arranged between the outer second widthwise grooves 53 adjacent in the tire circumferential direction and communicating with the respective outer second widthwise grooves 53 have both ends communicating with the outer second widthwise grooves 53 at positions different from the bend portions 53c. More specifically, of the two outer second widthwise grooves 53 whose both ends communicate with each other, the outer circumferential narrow groove 62 communicates with the outer groove portion 53a for one of the outer second widthwise grooves 53 and communicates with the inner groove portion 53b for the other outer second widthwise groove 53.

[0084] An end of the outer circumferential narrow groove 62 that communicates with the outer groove portion 53a joins the outer groove portion 53a near the bend 53c of the outer groove portion 53a, and an end of the outer circumferential narrow groove 62 that communicates with the inner groove portion 53b joins the inner groove portion 53b near the bend 53c of the inner groove portion 53b. With one end of the outer circumferential narrow groove 62 thus communicating with the outer groove portion 53a of the outer second widthwise groove 53 and the other end communicating with the inner groove portion 53b of the outer second widthwise groove 53, the outer circumferential narrow groove 62 extends in the tire circumferential direction while inclining in the tire widthwise direction with respect to the tire circumferential direction.

[0085] The outer circumferential narrow groove 62 and the outer second widthwise groove 53, which are inclined with respect to the tire circumferential direction, are inclined in opposite directions in the tire width direction with respect to the tire circumferential direction. In other words, the outer circumferential narrow groove 62 and the outer second widthwise groove 53 are inclined in opposite directions in the tire circumferential direction with respect to the tire width direction. The inclination angle θn of the outer circumferential narrow groove 62, which is inclined in this manner and in the tire width direction with respect to the tire circumferential direction, is within the range of 5°≦θn≦40°.

[0086] 8 is a detailed view of portion E in FIG. 2 and is an explanatory diagram of the bent portion 53c and the groove width. The outer second widthwise groove 53 has a raised bottom portion 53d at a position including the bent portion 53c. The raised bottom portion 53d of the outer second widthwise groove 53 is disposed in a portion between the two bent portions 53c of the outer second widthwise groove 53, near the bent portion 53c of the outer groove portion 53a, and near the bent portion 53c of the inner groove portion 53b.

[0087] The outer circumferential narrow groove 62 communicating with the outer second widthwise groove 53 communicates with the outer second widthwise groove 53 at a position where the raised bottom portion 53d of the outer second widthwise groove 53 is arranged. That is, the end of the outer circumferential narrow groove 62 that communicates with the outer groove portion 53a of the outer second widthwise groove 53 communicates with the outer groove portion 53a at a position where the raised bottom portion 53d of the outer groove portion 53a is arranged. Similarly, the end of the outer circumferential narrow groove 62 that communicates with the inner groove portion 53b of the outer second widthwise groove 53 communicates with the inner groove portion 53b at a position where the raised bottom portion 53d of the inner groove portion 53b is arranged.

[0088] The outer shoulder main groove 35b, which is the shoulder main groove 35 located on the outer side in the vehicle mounting direction, has a groove width Ws within a range of 3.0 mm≦Ws≦10.0 mm. The groove width Ws of the outer shoulder main groove 35b is wider than the groove width Wc of the center main groove 31, the groove width Wm of the outer second widthwise groove 53, and the groove width Wn of the outer circumferential narrow groove 62.

[0089] Specifically, the groove width Wc of the center main groove 31 satisfies the relationship 0.7Ws≦Wc≦0.9Ws relative to the groove width Ws of the outer shoulder main groove 35b. The groove width Wm of the outer second widthwise groove 53 satisfies the relationship 0.5Ws≦Wm≦0.7Ws relative to the groove width Ws of the outer shoulder main groove 35b. The groove width Wn of the outer circumferential narrow groove 62 satisfies the relationship 0.3Ws≦Wn≦0.5Ws relative to the groove width Ws of the outer shoulder main groove 35b.

[0090] Figure 9 is an FF cross-sectional view of Figure 8, and is a schematic diagram for comparing groove depths. Figure 10 is a GG cross-sectional view of Figure 8. The outer second widthwise groove 53 having the raised bottom portion 53d has a groove depth dr at the raised bottom portion 53d that is within a range of 0.5D≦dr≦0.7D relative to the groove depth D of the circumferential main groove 30. The outer second widthwise groove 53 has a groove depth dm at a position other than the raised bottom portion 53d that is within a range of 0.7D≦dm≦1.0D relative to the groove depth D of the circumferential main groove 30. In this case, the groove depth D of the circumferential main groove 30 includes the groove depths of both the outer shoulder main groove 35b and the center main groove 31, which are connected to the outer second widthwise groove 53.

[0091] The groove depth dr at the position of the bottom-raised portion 53d of the outer second widthwise groove 53 is preferably within a range of 0.55D≦dr≦0.65D relative to the groove depth D of the circumferential main groove 30. The groove depth dm at a position other than the bottom-raised portion 53d of the outer second widthwise groove 53 is preferably within a range of 0.8D≦dm≦1.0D relative to the groove depth D of the circumferential main groove 30.

[0092] In addition, the groove depth dn of the outer circumferential narrow groove 62 that communicates with the outer second widthwise groove 53 at the position of the raised bottom portion 53d of the outer second widthwise groove 53 is the same as the groove depth dr at the position of the raised bottom portion 53d of the outer second widthwise groove 53.

[0093] 11 is a detailed view of portion E in FIG. 2 and is an explanatory diagram of the outer second land portion 24. The outer second land portion 24 is formed into a block-shaped land portion 20 by arranging outer second widthwise grooves 53 across the outer shoulder main groove 35b and the center main groove 31, and further, outer circumferential narrow grooves 62 are arranged between the outer second widthwise grooves 53, so that each block is divided in the tire width direction by the outer circumferential narrow grooves 62. Therefore, the outer second land portion 24 has outer block portions 24a and inner block portions 24b divided by the outer circumferential narrow grooves 62 between outer second widthwise grooves 53 adjacent in the tire circumferential direction.

[0094] The outer block portion 24a is defined by two outer second widthwise grooves 53 adjacent to each other in the tire circumferential direction, an outer shoulder main groove 35b, and an outer circumferential narrow groove 62. The inner block portion 24b is defined by two outer second widthwise grooves 53 adjacent to each other in the tire circumferential direction, a center main groove 31, and an outer circumferential narrow groove 62. As described above, the outer block portion 24a and the inner block portion 24b of the outer second land portion 24 have an area As of the outer block portion 24a and an area Ac of the inner block portion 24b that satisfy the relationship 1.0Ac≦As≦1.2Ac.

[0095] The relationship between the area As of the outer block portion 24a and the area Ac of the inner block portion 24b of the outer second land portion 24 is preferably within the range of 1.0Ac≦As≦1.1Ac. The outer block portion 24a and the inner block portion 24b of the outer second land portion 24 have approximately the same area, or the outer block portion 24a is slightly larger than the inner block portion 24b.

[0096] When mounting the pneumatic tire 1 according to this embodiment on a vehicle, the pneumatic tire 1 is mounted on a rim wheel, filled with air, and mounted on the vehicle in an inflated state. Since the mounting direction of the pneumatic tire 1 according to this embodiment relative to the vehicle is specified, the tire is mounted on the vehicle in the specified direction. That is, the tire is mounted on the vehicle in the direction specified by the mounting direction indicators attached to the sidewall portions 8. As a result, the pneumatic tire 1 is mounted on the vehicle in an orientation such that the side of the tire equatorial plane CL on which the inner second widthwise groove 52 having the wide portion 52a and the narrow portion 52b is disposed is located on the inner side in the vehicle mounting direction, and the side on which the outer second widthwise groove 53 having the bent portion 53c is located is located on the outer side in the vehicle mounting direction.

[0097] When a vehicle equipped with pneumatic tire 1 travels, the pneumatic tire 1 rotates while the lower part of the tread contact surface 3 of the tread portion 2 comes into contact with the road surface. When a vehicle equipped with pneumatic tire 1 travels on a dry road surface, the vehicle travels by transmitting driving force and braking force to the road surface and generating turning force mainly due to the frictional force between the tread contact surface 3 and the road surface.

[0098] Furthermore, when traveling on a wet road surface, water between the tread contact surface 3 and the road surface enters grooves such as the circumferential main grooves 30 and widthwise grooves 50, and the sipes 80, and these grooves drain the water between the tread contact surface 3 and the road surface while traveling. This makes it easier for the tread contact surface 3 to make contact with the road surface, and the frictional force between the tread contact surface 3 and the road surface enables the vehicle to travel.

[0099] Furthermore, when traveling on snowy roads, the pneumatic tire 1 compacts snow on the road surface with the tread contact surface 3, and the snow on the road surface also compacts within the grooves as it enters the circumferential main grooves 30 and widthwise grooves 50. In this state, when driving force or braking force acts on the pneumatic tire 1, or when a force acts in the tire width direction due to turning of the vehicle, a shear force acting on the snow in the grooves, known as snow column shear force, is generated between the pneumatic tire 1 and the snow. When traveling on snowy roads, this snow column shear force generates resistance between the pneumatic tire 1 and the road surface, allowing driving force and braking force to be transmitted to the road surface, ensuring snow traction. This allows the vehicle to travel on snowy roads.

[0100] Furthermore, when traveling on snowy or icy road surfaces, the tire also utilizes the edge effects of the circumferential main grooves 30, widthwise grooves 50, and sipes 80. That is, when traveling on snowy or icy road surfaces, the tire also utilizes the resistance caused by the edges of the circumferential main grooves 30, widthwise grooves 50, and sipes 80 catching on the snow or ice surface. Furthermore, when traveling on icy road surfaces, the sipes 80 absorb water on the surface of the icy road surface, removing the water film between the icy road surface and the tread contact surface 3, making it easier for the tread contact surface 3 to come into contact with the icy road surface. As a result, the resistance between the tread contact surface 3 and the icy road surface increases due to the adhesive friction force and edge effect between the tread contact surface 3 and the icy road surface, thereby ensuring the driving performance of a vehicle equipped with the pneumatic tire 1.

[0101] The circumferential main grooves 30, widthwise grooves 50, and sipes 80 formed in the tread portion 2 contribute to ensuring running performance when running on wet, snowy, and icy road surfaces, and therefore, in order to improve wet performance, which is running performance on wet road surfaces, for example, it is effective to increase the groove area ratio of the tread portion 2. In other words, if the groove area ratio, which is the ratio of the area of ​​grooves such as the circumferential main grooves 30 and widthwise grooves 50 in the contact patch, is increased, water on the road surface will more easily enter the grooves when running on a wet road surface, thereby improving the drainage of water between the tread contact surface 3 and the road surface and improving wet performance.

[0102] Increasing the groove area ratio is also effective in improving snow performance, which is driving performance on snowy roads. In other words, when the groove area ratio is increased, the amount of snow that can be trapped in the circumferential main grooves 30 and the widthwise grooves 50 when driving on snowy roads can be increased, thereby increasing the snow column shear force acting on the snow trapped in the grooves. This improves snow traction when driving on snowy roads, and improves snow performance.

[0103] However, when the groove area ratio is increased, the volume of the land portion 20 is relatively reduced, which reduces the rigidity of the land portion 20. If the rigidity of the land portion 20 is reduced, the land portion 20 becomes more susceptible to wear, which may lead to a reduction in wear resistance. Therefore, in order to prevent a reduction in wear resistance, it is preferable to reduce the groove area ratio to ensure the rigidity of the land portion 20.

[0104] Furthermore, when the groove area ratio is reduced, the actual contact area can be relatively increased, and the increased actual contact area can improve adhesion friction and ice performance, which is the driving performance on icy roads. However, when the groove area ratio is reduced, the amount of water and snow on the road surface that can enter the circumferential main grooves 30 and widthwise grooves 50 decreases, which may lead to a deterioration in wet performance and snow performance.

[0105] In contrast, in the pneumatic tire 1 according to this embodiment, the outer second widthwise groove 53 communicates with the outer shoulder main groove 35b at a position in the tire circumferential direction that is different from the position at which the outer shoulder widthwise groove 55b communicates with the outer shoulder main groove 35b. This allows the outer second widthwise groove 53 and the outer shoulder widthwise groove 55b to have different edge positions in the tire circumferential direction. This allows the edge components to be dispersed in the tire circumferential direction, thereby enhancing the edge effect. This improves driving performance on snowy and icy roads, ensuring good snow and ice performance.

[0106] Furthermore, because the positions at which the outer second widthwise groove 53 and the outer shoulder widthwise groove 55b communicate with the outer shoulder main groove 35b differ in the tire circumferential direction, stress concentration can be suppressed in the outer second land portion 24 and the outer shoulder land portion 25b near the portions where the outer second widthwise groove 53 and the outer shoulder widthwise groove 55b communicate with the outer shoulder main groove 35b. That is, near the portion where the outer second widthwise groove 53 communicates with the outer shoulder main groove 35b, the load acting on this portion can be borne by the outer shoulder land portion 25b, and near the portion where the outer shoulder widthwise groove 55b communicates with the outer shoulder main groove 35b, the load acting on this portion can be borne by the outer second land portion 24. This suppresses stress concentration in the outer second land portion 24 and the outer shoulder land portion 25b, reducing wear associated with stress concentration and improving wear resistance.

[0107] Furthermore, because the outer second widthwise groove 53 has two bent portions 53c, the length of the outer second widthwise groove 53 can be increased, thereby increasing the edge component of the outer second widthwise groove 53. This improves driving performance on snowy and icy surfaces, ensuring performance on snow and ice. Furthermore, because the outer second widthwise groove 53 has two bent portions 53c, the length of the outer second widthwise groove 53 can be increased, thereby increasing the groove area ratio of the range in which the outer second land portion 24 is disposed. This improves drainage in the outer second widthwise groove 53, and the high drainage of the outer second widthwise groove 53, whose ends communicate with the center main groove 31 and the outer shoulder main groove 35b, improves wet performance.

[0108] Furthermore, outer circumferential narrow grooves 62 that divide the outer second land portion 24 in the tire width direction are arranged between the outer second widthwise grooves 53 adjacent in the tire circumferential direction, and therefore the outer circumferential narrow grooves 62 can increase the edge component and groove area ratio at the position of the outer second land portion 24. As a result, the increased edge component can improve performance on snow and ice, and the increased groove area ratio can improve wet performance.

[0109] Furthermore, because the outer circumferential narrow grooves 62 communicate with the outer second widthwise grooves 53 at positions different from the bends 53c, the outer circumferential narrow grooves 62 can be arranged while suppressing a decrease in rigidity of the outer second land portion 24. This makes it possible to improve performance on snow, ice, and wet surfaces while suppressing a decrease in wear resistance. As a result, optimizing the pattern configuration makes it possible to improve wear resistance while ensuring snow and ice performance and wet surface performance.

[0110] Furthermore, the bent portion 53c of the outer second widthwise groove 53 is disposed at a position where the distance Wk from the center line CB of the outer second land portion 24, relative to the width WB of the outer second land portion 24, is within the range of 0≦Wk≦0.25WB. This allows the bent portion 53c to be provided in the outer second widthwise groove 53 while achieving non-uniform rigidity in the outer second land portion 24. This increases the edge component of the outer second widthwise groove 53 while suppressing a decrease in wear resistance, thereby increasing the groove area ratio of the range in which the outer second land portion 24 is disposed. As a result, wear resistance can be improved while more reliably ensuring snow and ice performance and wet performance.

[0111] Furthermore, in the outer second widthwise groove 53, the inclination angle θs of the outer groove portion 53a in the tire circumferential direction with respect to the tire width direction is within the range of 0°≦θs≦60°, and the inclination angle θc of the inner groove portion 53b in the tire circumferential direction with respect to the tire width direction is within the range of 0°≦θc≦60°, and the inclination angle θs and the inclination angle θc satisfy the relationship θc-5°≦θs≦θc+5°, thereby making it possible to appropriately exert the edge effect while suppressing a decrease in rigidity of the outer second land portion 24. As a result, it is possible to improve wear resistance while more reliably ensuring ice and snow performance.

[0112] Furthermore, since the outer second widthwise groove 53 and the outer circumferential narrow groove 62 are inclined in opposite directions in the tire width direction relative to the tire circumferential direction, the directions in which the outer second widthwise groove 53 and the outer circumferential narrow groove 62 exert their edge effects can be dispersed. This improves performance on snow and ice. Furthermore, since the outer second widthwise groove 53 and the outer circumferential narrow groove 62 are inclined in opposite directions, it is possible to prevent a decrease in rigidity of the outer second land portion 24 while arranging the outer circumferential narrow groove 62 that communicates with the outer second widthwise groove 53. As a result, it is possible to improve wear resistance while more reliably ensuring snow and ice performance.

[0113] Furthermore, the outer second land portion 24 has outer block portions 24a and inner block portions 24b that are partitioned by the outer circumferential narrow groove 62, and the area As of the outer block portion 24a and the area Ac of the inner block portion 24b satisfy the relationship 1.0Ac≦As≦1.2Ac, thereby reducing the difference in rigidity between the outer block portions 24a and the inner block portions 24b. This makes it possible to suppress uneven wear caused by the difference in rigidity between the outer block portions 24a and the inner block portions 24b.

[0114] Furthermore, by making the area As of the outer block portion 24a and the area Ac of the inner block portion 24b satisfy the relationship 1.0Ac≦As≦1.2Ac, the rigidity of the outer block portion 24a is prevented from being lower than the rigidity of the inner block portion 24b. This ensures the rigidity of the outer block portion 24a, which is located outward in the vehicle mounting direction and is therefore more likely to be subjected to a relatively large load. This prevents uneven wear, in which the outer block portion 24a wears out earlier than the inner block portion 24b. As a result, uneven wear resistance can be improved.

[0115] Furthermore, the outer second widthwise groove 53 has a bottom-up portion 53d at a position including the bent portion 53c, and the outer circumferential narrow groove 62 communicates with the outer second widthwise groove 53 at the position where the bottom-up portion 53d is arranged, so that the outer circumferential narrow groove 62 can be arranged while suppressing a decrease in rigidity of the outer second land portion 24. This makes it possible to more reliably suppress a decrease in wear resistance when arranging the outer circumferential narrow groove 62. As a result, it is possible to more reliably improve wear resistance while ensuring snow and ice performance and wet performance.

[0116] Furthermore, the groove depth dr of the outer second widthwise groove 53 at the position of the raised bottom portion 53d is within a range of 0.5D≦dr≦0.7D relative to the groove depth D of the circumferential main groove 30, and therefore it is possible to suppress a decrease in the rigidity of the outer second land portion 24 while ensuring drainage in the outer second widthwise groove 53. In other words, if the groove depth dr of the outer second widthwise groove 53 at the position of the raised bottom portion 53d is dr<0.5D relative to the groove depth D of the circumferential main groove 30, the groove depth dr at the position of the raised bottom portion 53d is too shallow, and it may be difficult to ensure drainage in the outer second widthwise groove 53. Furthermore, if the groove depth dr at the position of the bottom-raised portion 53d of the outer second widthwise groove 53 is dr > 0.7D relative to the groove depth D of the circumferential main groove 30, the groove depth dr at the position of the bottom-raised portion 53d is too deep, so even if the bottom-raised portion 53d is provided in the outer second widthwise groove 53, it may be difficult to suppress a decrease in rigidity of the outer second land portion 24 at the position where the outer circumferential narrow groove 62 communicates with the outer second widthwise groove 53.

[0117] In contrast, when the groove depth dr at the bottom-raised portion 53d of the outer second widthwise groove 53 is within a range of 0.5D≦dr≦0.7D relative to the groove depth D of the circumferential main groove 30, it is possible to suppress a decrease in rigidity of the outer second land portion 24 at the position where the outer circumferential narrow groove 62 communicates with the outer second widthwise groove 53 while ensuring drainage in the outer second widthwise groove 53. As a result, it is possible to improve wear resistance while more reliably ensuring wet performance.

[0118] Furthermore, because the groove width Ws of the outer shoulder main groove 35b is within the range of 3.0 mm≦Ws≦10.0 mm, the outer shoulder main groove 35b can ensure the rigidity of the outer second land portion 24 and the outer shoulder land portion 25b while ensuring the drainage performance of the outer shoulder main groove 35b. In other words, if the groove width Ws of the outer shoulder main groove 35b is less than 3.0 mm, the groove width Ws of the outer shoulder main groove 35b is too narrow, which may make it difficult to ensure the drainage performance of the outer shoulder main groove 35b. On the other hand, if the groove width Ws of the outer shoulder main groove 35b is greater than 10.0 mm, the groove width Ws of the outer shoulder main groove 35b may be too wide. In this case, it may be difficult to ensure the rigidity of the outer second land portion 24 and the outer shoulder land portion 25b defined by the outer shoulder main groove 35b, which may make it difficult to ensure the wear resistance performance.

[0119] In contrast, when the groove width Ws of the outer shoulder main groove 35b is within the range of 3.0 mm≦Ws≦10.0 mm, the drainage performance of the outer shoulder main groove 35b can be ensured while ensuring the rigidity of the outer second land portion 24 and the outer shoulder land portion 25b.

[0120] Furthermore, the groove width Wc of the center main groove 31 satisfies the relationship 0.7Ws≦Wc≦0.9Ws relative to the groove width Ws of the outer shoulder main groove 35b, so that the center main groove 31 can ensure drainage while ensuring the rigidity of the center land portion 21 and the outer second land portion 24. In other words, if the groove width Wc of the center main groove 31 is less than 0.7Ws relative to the groove width Ws of the outer shoulder main groove 35b, the groove width Wc of the center main groove 31 is too narrow, which may make it difficult to ensure drainage. If the groove width Wc of the center main groove 31 is greater than 0.9Ws relative to the groove width Ws of the outer shoulder main groove 35b, the groove width Wc of the center main groove 31 may be too wide. In this case, it may be difficult to ensure the rigidity of the center land portion 21 and the outer second land portion 24 defined by the center main groove 31, which may make it difficult to ensure wear resistance.

[0121] In contrast, when the groove width Wc of the center main groove 31 is within the range of 0.7Ws≦Wc≦0.9Ws relative to the groove width Ws of the outer shoulder main groove 35b, the drainage performance of the center main groove 31 can be ensured while ensuring the rigidity of the center land portion 21 and the outer second land portion 24.

[0122] Furthermore, the groove width Wm of the outer second widthwise groove 53 satisfies the relationship 0.5Ws≦Wm≦0.7Ws relative to the groove width Ws of the outer shoulder main groove 35b, so that the drainage performance of the outer second widthwise groove 53 can be ensured while ensuring the rigidity of the outer second land portion 24. That is, if the groove width Wm of the outer second widthwise groove 53 is Wm<0.5Ws relative to the groove width Ws of the outer shoulder main groove 35b, the groove width Wm of the outer second widthwise groove 53 is too narrow, which may make it difficult to ensure the drainage performance of the outer second widthwise groove 53. If the groove width Wm of the outer second widthwise groove 53 is Wm>0.7Ws relative to the groove width Ws of the outer shoulder main groove 35b, the groove width Wm of the outer second widthwise groove 53 may be too wide. In this case, it may be difficult to ensure the rigidity of the outer second land portion 24 defined by the outer second widthwise groove 53, which may make it difficult to ensure wear resistance.

[0123] In contrast, when the groove width Wm of the outer second widthwise groove 53 is within the range of 0.5Ws≦Wm≦0.7Ws relative to the groove width Ws of the outer shoulder main groove 35b, the rigidity of the outer second land portion 24 can be ensured while ensuring drainage in the outer second widthwise groove 53.

[0124] Furthermore, the groove width Wn of the outer circumferential narrow groove 62 satisfies the relationship 0.3Ws≦Wn≦0.5Ws relative to the groove width Ws of the outer shoulder main groove 35b, so that the drainage performance of the outer circumferential narrow groove 62 can be ensured while ensuring the rigidity of the outer second land portion 24. That is, if the groove width Wn of the outer circumferential narrow groove 62 is Wn<0.3Ws relative to the groove width Ws of the outer shoulder main groove 35b, the groove width Wn of the outer circumferential narrow groove 62 is too narrow, which may make it difficult to ensure the drainage performance of the outer circumferential narrow groove 62. If the groove width Wn of the outer circumferential narrow groove 62 is Wn>0.5Ws relative to the groove width Ws of the outer shoulder main groove 35b, the groove width Wn of the outer circumferential narrow groove 62 may be too wide. In this case, it may be difficult to ensure the rigidity of the outer second land portion 24 in which the outer circumferential narrow groove 62 is disposed, which may make it difficult to ensure wear resistance.

[0125] In contrast, when the groove width Wn of the outer circumferential narrow groove 62 is within the range of 0.3Ws≦Wn≦0.5Ws relative to the groove width Ws of the outer shoulder main groove 35b, the rigidity of the outer second land portion 24 can be ensured while ensuring the drainage performance of the outer circumferential narrow groove 62.

[0126] Furthermore, the outer second widthwise groove 53 intersects the center main groove 31, and the end of the outer second widthwise groove 53 opposite to the end that connects to the outer shoulder main groove 35b terminates within the center land portion 21, ensuring the rigidity of the center land portion 21. This increases the rigidity of the center land portion 21, which is prone to receive large loads during vehicle travel, and reduces wear of the center land portion 21, which is prone to receive large loads. As a result, wear resistance can be improved more reliably.

[0127] Furthermore, since the land portion 20 is provided with a plurality of sipes 80 extending in the tire width direction, the amount of edge can be increased by the plurality of sipes 80, and the increased edge effect can improve driving performance on snowy and icy road surfaces. As a result, snow and ice performance can be improved more reliably.

[0128] Furthermore, the sipes 80 arranged in the land portions 20 are inclined in the same direction in the tire circumferential direction relative to the tire width direction as the widthwise grooves 50 that are located at the same positions in the tire width direction. This makes it possible to suppress changes in the distance between the sipes 80 and the widthwise grooves 50 in the land portions 20 and between adjacent sipes 80, thereby preventing the occurrence of portions where the distance between the sipes 80 and the widthwise grooves 50 or between adjacent sipes 80 becomes extremely small. This prevents the occurrence of portions where the rigidity is low in the land portions 20, and ensures appropriate rigidity in the portions between the sipes 80 and the widthwise grooves 50 in the land portions 20 and between adjacent sipes 80. As a result, wear resistance can be improved more reliably.

[0129] [Variations] In the above-described embodiment, the outer second widthwise groove 53 has two bent portions 53c, but the outer second widthwise groove 53 may have three or more bent portions 53c. By having at least two bent portions 53c, the length of the outer second widthwise groove 53 is increased, which increases the edge amount of the outer second widthwise groove 53 and increases the groove area of ​​the outer second widthwise groove 53. This improves snow and ice performance and wet performance.

[0130] In the above-described embodiment, the tread pattern is different between the inner side and the outer side in the vehicle mounting direction with respect to the tire equatorial plane CL, but the tread pattern may be formed in the same pattern on both sides of the tire equatorial plane CL. For example, the tread pattern on the outer side in the vehicle mounting direction in the embodiment may be formed on the outer side in the vehicle mounting direction in line symmetry with respect to the tire equatorial plane CL. That is, second widthwise grooves 51 having multiple bends 53c may also be arranged on the inner side in the vehicle mounting direction.

[0131] Furthermore, in the above-described embodiment, the pneumatic tire 1 is described using a tire having a specified mounting direction on a vehicle, but the pneumatic tire 1 does not have to have a specified mounting direction on a vehicle. Furthermore, in the above-described embodiment, the pneumatic tire 1 is described using an example of a tire according to the present invention, but the tire according to the present invention may be a tire other than the pneumatic tire 1. The tire according to the present invention may be, for example, a so-called airless tire that can be used without being filled with gas.

[0132] [Example] 12A and 12B are tables showing the results of performance evaluation tests of pneumatic tires. Performance evaluation tests conducted on the conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and a comparative pneumatic tire compared to the pneumatic tire 1 according to the present invention will be described below. The performance evaluation tests were conducted on ice performance, snow performance, wet performance, and wear resistance.

[0133] The performance evaluation test was carried out by mounting a pneumatic tire 1 having a tire nominal size of 195 / 65R15 91Q as specified by JATMA on a JATMA standard rim wheel having a rim size of 15 x 6.5J, mounting the test tire on a front-wheel drive evaluation vehicle with an engine displacement of 1800cc, adjusting the air pressure to 240kPa, and running the evaluation vehicle.

[0134] The evaluation method for each test item was as follows: for ice performance, a braking test was conducted on an icy test course using an evaluation vehicle fitted with test tires, and the reciprocal of the braking distance was expressed as an index, with the conventional example (described below) set at 100. The higher the index, the shorter the braking distance on icy roads, indicating better ice performance.

[0135] Snow performance was evaluated by conducting braking tests on a test course on snowy roads using an evaluation vehicle fitted with the test tires, and expressing the reciprocal of the braking distance as an index, with the conventional example (described below) set at 100. The higher the index, the shorter the braking distance on snowy roads, indicating better snow performance.

[0136] Wet performance was evaluated by conducting a braking test on an asphalt test course where a test tire was fitted to an evaluation vehicle and water was sprayed to a depth of 1.0 mm, and expressing the reciprocal of the braking distance as an index, with the conventional example (described later) set at 100. The higher the index, the shorter the braking distance on a wet road surface, indicating better wet performance.

[0137] Wear resistance was evaluated by measuring the groove depth after a 10,000 km road test was conducted by a test driver on an evaluation vehicle fitted with the test tires. Wear resistance was evaluated by expressing the measured groove depth as an index, with the conventional example (described below) being set at 100, and the higher the index, the better the wear resistance.

[0138] The performance evaluation test was conducted on 19 types of pneumatic tires, including a conventional pneumatic tire, Examples 1 to 17 which are pneumatic tire 1 according to the present invention, and a comparative example which is a pneumatic tire compared to pneumatic tire 1 according to the present invention. Of these, in the conventional example, the second widthwise groove does not have a bent portion, and the second widthwise groove and the shoulder widthwise groove are aligned at positions where they communicate with the shoulder main groove. In the comparative example, the second widthwise groove has a bent portion, but the position where the circumferential narrow groove communicates with the second widthwise groove is aligned at the bent portion, and the position where the second widthwise groove and the shoulder widthwise groove are aligned at the shoulder main groove is also aligned.

[0139] In contrast, in Examples 1 to 17, which are examples of the pneumatic tire 1 according to the present invention, the second widthwise grooves 51 all have bent portions 53c, the position where the circumferential narrow groove 60 communicates with the second widthwise groove 51 does not coincide with the bent portion 53c, and the position where the second widthwise groove 51 communicates with the shoulder widthwise groove 55 does not coincide with the shoulder main groove 35. Furthermore, in the pneumatic tires 1 according to Examples 1 to 17, the ratio Wk / WB of the distance Wk of the bent portion 53c from the center line CB of the second land portion 22 to the width WB of the second land portion 22, the inclination direction of the second widthwise groove 51 and the circumferential narrow groove 60, the ratio As / Ac of the area As of the outer block portion 24a to the area Ac of the inner block portion 24b of the second land portion 22, the presence or absence of the bottom-up portion 53d of the second widthwise groove 51, the groove depth D of the circumferential main groove 30, the width of the second widthwise groove 51 ... The ratio dr / D of the groove depth dr at the bottom-up portion 53d, the groove width Ws of the shoulder main groove 35, the ratio Wc / Ws of the groove width Wc of the center main groove 31 to the groove width Ws of the shoulder main groove 35, the ratio Wm / Ws of the groove width Wm of the second widthwise groove 51 to the groove width Ws of the shoulder main groove 35, the ratio Wn / Ws of the groove width Wn of the circumferential narrow groove 60 to the groove width Ws of the shoulder main groove 35, and whether the second widthwise groove 51 terminates within the center land portion 21 are all different.

[0140] 12A and 12B, performance evaluation tests were conducted using these pneumatic tires 1. As a result, it was found that the pneumatic tires 1 according to Examples 1 to 17 were able to improve wear resistance compared to the conventional tire without deteriorating any of the performance on ice, snow, and wet surfaces compared to the conventional tire. In other words, the pneumatic tires 1 according to Examples 1 to 17 were able to improve wear resistance while ensuring snow and ice performance and wet surface performance.

[0141] The present disclosure encompasses the following inventions. Invention[1] A plurality of circumferential main grooves disposed in the tread portion and extending in the tire circumferential direction; A plurality of widthwise grooves disposed in the tread portion and extending in the tire width direction; a land portion defined by the circumferential main groove and the widthwise groove; Equipped with The plurality of circumferential main grooves are a shoulder main groove disposed outermost in the tire width direction; a center main groove adjacent to the shoulder main groove; and The plurality of widthwise grooves are a shoulder width direction groove disposed on the outer side of the shoulder main groove in the tire width direction and communicating with the shoulder main groove; a second widthwise groove disposed between the shoulder main groove and the center main groove and communicating with the shoulder main groove and the center main groove; and the second widthwise groove communicates with the shoulder main groove at a position in the tire circumferential direction that is different from a position at which the shoulder widthwise groove communicates with the shoulder main groove, and has at least two bend portions at which the extending direction of the second widthwise groove changes, A tire characterized in that a circumferential narrow groove is arranged between the second widthwise grooves adjacent in the tire circumferential direction, the narrow groove extending in the tire circumferential direction and having both ends connected to the second widthwise groove at positions different from the bend portion, and dividing the second land portion, which is the land portion defined by the shoulder main groove and the center main groove, in the tire width direction. Invention[2] The tire according to the invention [1], wherein the bent portion of the second widthwise groove is positioned at a position where the distance Wk from the center line of the second land portion in the tire width direction is within the range of 0≦Wk≦0.25WB relative to the width WB of the second land portion in the tire width direction. Invention[3] The second widthwise groove is a tilt angle θs in the tire circumferential direction with respect to the tire width direction of a portion of the second widthwise groove between a portion communicating with the shoulder main groove and the bent portion is within a range of 0°≦θs≦60°, a tilt angle θc in the tire circumferential direction with respect to the tire width direction of a portion of the second widthwise groove between a portion communicating with the center main groove and the bent portion is within a range of 0°≦θc≦60°, The tire according to invention [1] or invention [2], wherein the inclination angle θs and the inclination angle θc satisfy the relationship θc-5°≦θs≦θc+5°. Invention[4] The tire according to any one of the inventions [1] to [3], wherein the second widthwise groove and the circumferential narrow groove are inclined in opposite directions in the tire width direction relative to the tire circumferential direction. Invention[5] the second land portion has an outer block portion defined by two second widthwise grooves adjacent to each other in the tire circumferential direction, the shoulder main groove, and the circumferential narrow groove, and an inner block portion defined by two second widthwise grooves adjacent to each other in the tire circumferential direction, the center main groove, and the circumferential narrow groove, The tire according to any one of Inventions [1] to [4], wherein the outer block portion and the inner block portion have an area As of the outer block portion and an area Ac of the inner block portion that satisfy the relationship 1.0Ac≦As≦1.2Ac. Invention[6] the second widthwise groove has a bottom-raised portion at a position including the bent portion, The tire according to any one of the inventions [1] to [5], wherein the circumferential narrow groove is connected to the second widthwise groove at a position where the bottom-up portion of the second widthwise groove is disposed. Invention[7] The tire according to the invention [6], wherein the second widthwise groove has a groove depth dr at the position of the bottom raised portion, where the groove depth D of the circumferential main groove is in the range of 0.5D≦dr≦0.7D. Invention[8] the shoulder main groove has a groove width Ws in the range of 3.0 mm≦Ws≦10.0 mm, the center main groove has a groove width Wc relative to the shoulder main groove width Ws satisfying the relationship 0.7Ws≦Wc≦0.9Ws, the second widthwise groove has a groove width Wm relative to the groove width Ws of the shoulder main groove satisfying the relationship 0.5Ws≦Wm≦0.7Ws, The tire according to any one of inventions [1] to [7], wherein the groove width Wn of the circumferential narrow groove satisfies the relationship 0.3Ws≦Wn≦0.5Ws with respect to the groove width Ws of the shoulder main groove. Invention[9] the second widthwise groove intersects with the center main groove, A tire according to any one of inventions [1] to [8], wherein the end of the second widthwise groove opposite to the end that communicates with the shoulder main groove terminates within the land portion located on the opposite side of the center main groove from the side where the second land portion is located. Invention

[10] The tire according to any one of Inventions [1] to [9], wherein the tire is a winter tire or an all-season tire in which a plurality of sipes extending in the tire width direction are arranged in the land portion. Invention

[11] The tire according to the invention

[10] , wherein the sipes are inclined in the same direction as the widthwise grooves, which are positioned at the same position in the tire width direction, in the tire circumferential direction relative to the tire width direction. [Explanation of symbols]

[0142] 1 pneumatic tire 2 Tread section 3 Tread contact surface 5 Shoulder section 8 Sidewall 10 Bead section 13 Carcass layer 14 Belt Layer 20 Land 21 Center Land Division 22 Second Land Club 23 Inner second land area 24 Outer second land area 24a outer block 24b Inner block 25 Shoulder land area 30 Circumferential main groove 31 Center main groove 35 Shoulder main groove 35a inner shoulder main groove 35b Outer shoulder main groove 40 Straight groove 50 Width groove 51 Second width direction groove 52 Inner second widthwise groove 53 Outer second widthwise groove 53a Outer groove 53b Inner groove 53c Bend part 53d Bottom raised part 55 Shoulder width groove 60 Circumferential thin groove 61 Inner circumferential narrow groove 62 Outer circumferential narrow groove 70 Shoulder narrow groove 80 sipes

Claims

1. a plurality of circumferential main grooves disposed in the tread portion and extending in the tire circumferential direction; A plurality of widthwise grooves disposed in the tread portion and extending in the tire width direction; a land portion defined by the circumferential main groove and the widthwise groove; Equipped with The plurality of circumferential main grooves are a shoulder main groove disposed outermost in the tire width direction; a center main groove adjacent to the shoulder main groove; and The plurality of widthwise grooves are a shoulder width direction groove disposed on the outer side of the shoulder main groove in the tire width direction and communicating with the shoulder main groove; a second widthwise groove disposed between the shoulder main groove and the center main groove and communicating with the shoulder main groove and the center main groove; and the second widthwise groove communicates with the shoulder main groove at a position in the tire circumferential direction that is different from a position at which the shoulder widthwise groove communicates with the shoulder main groove, and has at least two bend portions at which an extending direction of the second widthwise groove changes, A tire characterized in that a circumferential narrow groove is arranged between the second widthwise grooves adjacent in the tire circumferential direction, the narrow groove extending in the tire circumferential direction and having both ends connected to the second widthwise groove at positions different from the bend portion, and dividing the second land portion, which is the land portion defined by the shoulder main groove and the center main groove, in the tire width direction.

2. 2. The tire according to claim 1, wherein the bent portion of the second widthwise groove is positioned at a position where a distance Wk from a center line in the tire width direction of the second land portion is within a range of 0≦Wk≦0.25WB relative to a width WB of the second land portion in the tire width direction.

3. The second widthwise groove is a tilt angle θs in the tire circumferential direction with respect to the tire width direction of a portion of the second widthwise groove between a portion communicating with the shoulder main groove and the bent portion is within a range of 0°≦θs≦60°, a tilt angle θc in the tire circumferential direction with respect to the tire width direction of a portion of the second widthwise groove between a portion communicating with the center main groove and the bent portion is within a range of 0°≦θc≦60°, The tire according to claim 1, wherein the inclination angle θs and the inclination angle θc satisfy the relationship θc - 5° ≦ θs ≦ θc + 5°.

4. The tire according to claim 1 , wherein the second widthwise groove and the circumferential narrow groove are inclined in opposite directions in the tire width direction with respect to the tire circumferential direction.

5. the second land portion has an outer block portion defined by two second widthwise grooves adjacent to each other in the tire circumferential direction, the shoulder main groove, and the circumferential narrow groove, and an inner block portion defined by two second widthwise grooves adjacent to each other in the tire circumferential direction, the center main groove, and the circumferential narrow groove, 2. The tire according to claim 1, wherein the area As of the outer block portion and the area Ac of the inner block portion satisfy the relationship 1.0Ac≦As≦1.2Ac.

6. the second widthwise groove has a bottom-raised portion at a position including the bent portion, The tire according to claim 1 , wherein the circumferential narrow groove communicates with the second widthwise groove at a position where the bottom-up portion of the second widthwise groove is disposed.

7. The tire according to claim 6, wherein the second widthwise groove has a groove depth dr at the position of the bottom raised portion, where D is a groove depth of the circumferential main groove, within a range of 0.5D≦dr≦0.7D.

8. the shoulder main groove has a groove width Ws in the range of 3.0 mm≦Ws≦10.0 mm, the center main groove has a groove width Wc relative to the shoulder main groove width Ws satisfying the relationship 0.7Ws≦Wc≦0.9Ws, the second widthwise groove has a groove width Wm relative to the groove width Ws of the shoulder main groove satisfying the relationship 0.5Ws≦Wm≦0.7Ws, The tire according to claim 1, wherein the circumferential narrow groove has a groove width Wn that satisfies the relationship 0.3Ws≦Wn≦0.5Ws relative to the groove width Ws of the shoulder main groove.

9. the second widthwise groove intersects with the center main groove, 2. The tire according to claim 1, wherein an end portion of the second widthwise groove opposite to an end portion thereof that communicates with the shoulder main groove terminates within the land portion located on the opposite side of the center main groove from the side where the second land portion is located.

10. The tire according to claim 1 , wherein the tire is a winter tire or an all-season tire, and a plurality of sipes extending in the tire width direction are arranged in the land portion.

11. The tire according to claim 10 , wherein the sipes are inclined in the same direction in the tire circumferential direction with respect to the tire width direction as the widthwise grooves that are positioned at the same positions in the tire width direction.

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