Tire

Abstract

To improve wear resistance performance while securing ice and snow performance and wet performance.SOLUTION: In the pneumatic tire 1, the groove depth of the zigzag circumferential groove 41 is smaller than the groove depths of the circumferential main grooves 31A, 32A, and the groove widths of the zigzag circumferential groove 41 are smaller than the groove widths of the circumferential main grooves 31A, 32A. The inner lateral grooves 51 and the outer lateral grooves 52 extend in the same inclination direction with respect to the tire lateral direction and are alternately arranged in the tire circumferential direction, and the lug grooves 53 face the outer lateral grooves 52 across the outer circumferential main groove 32A and extend in an inclination direction opposite to that of the outer lateral grooves 52 with respect to the tire lateral direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to tires. [Background technology]

[0002] For example, the tire described in Patent Document 1 has a tread pattern in which a large number of blocks are arranged, each of which is defined by main grooves, semi-main grooves, and lug grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3488756 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] An object of the present invention is 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 achieve the above object, a tire according to one aspect of the present invention comprises: two inner circumferential main grooves and an outer circumferential main groove that are formed linearly along the tire circumferential direction and adjacent to each other in the tire width direction; an inner land portion defined between the circumferential main grooves; an outer land portion defined on the tire width direction outer side of the outer circumferential main groove and including a ground contact edge; a zigzag circumferential groove in the inner land portion that extends continuously in the tire circumferential direction between the circumferential main grooves and has inclined portions that are inclined in opposite directions to the tire circumferential direction and are alternately provided in the tire circumferential direction and connected by bends; an inner width direction groove that extends in the inner land portion from the bends facing inward in the tire width direction of the zigzag circumferential groove toward the inner side in the tire width direction and communicates with the inner circumferential main groove; and and an outer width direction groove that extends outward in the tire width direction from a bend portion of the zigzag circumferential groove that faces outward in the tire width direction and is connected to the outer circumferential main groove, and a plurality of lug grooves that are connected to the outer circumferential main groove in the outer land portion, extend outward in the tire width direction, and are lined up in the tire circumferential direction, wherein the groove depth of the zigzag circumferential groove is smaller than the groove depth of each of the circumferential main grooves, and the groove width of the zigzag circumferential groove is smaller than the groove width of each of the circumferential main grooves, the inner width direction groove and the outer width direction groove extend in the same inclined direction with respect to the tire width direction and are arranged alternately in the tire circumferential direction, and the lug grooves are arranged opposite to the outer width direction groove with respect to the outer circumferential main groove and extend in an inclined direction opposite to that of the outer width direction groove with respect to the tire width direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve wear resistance while ensuring performance on snow and ice and wet conditions. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment. [Figure 2] FIG. 2 is a plan view of a tread portion of a pneumatic tire according to the embodiment. [Figure 3] FIG. 3 is an enlarged plan view of the inner side in the vehicle width direction of the tread portion of the pneumatic tire according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 5 is an enlarged plan view of the outer side in the vehicle width direction of the tread portion of the pneumatic tire according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along the line BB in FIG. [Figure 7] FIG. 7 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 8] FIG. 8 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 9] FIG. 9 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 10] FIG. 10 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 11] FIG. 11 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of 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 of these embodiments include those that can be substituted and are obvious substitutes while maintaining the identity of the invention. Furthermore, the multiple modifications described in these embodiments can be arbitrarily combined within the scope obvious to those skilled in the art.

[0010] 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 of this embodiment. 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. 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 equator line refers to a line that is on the tire equatorial plane CL and runs along the tire circumferential direction of the pneumatic tire 1. Also, a cross section in the tire meridian direction (meridian cross section) refers to a cross section of the tire cut by a plane including the tire rotation axis.

[0011] As shown in FIG. 1, a pneumatic tire 1 of the embodiment has a tread portion 2, a sidewall portion 8, and a bead portion 10.

[0012] The tread portion 2 is disposed at the outermost portion in the tire radial direction when viewed in a tire meridian cross section. The tread portion 2 has tread rubber 2A 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 running, is formed as a tread contact surface (also referred to as a tread surface) 2B. The tread contact surface 2B forms part of the contour of the pneumatic tire 1. The tread portion 2 has shoulder portions 2C formed at both outer ends in the tire width direction.

[0013] The sidewall portions 8 are disposed on both sides in the tire width direction of the tread portion 2 and on the inner side in the tire radial direction of the shoulder portions 2C. The sidewall portions 8 are disposed in two locations on both sides in the tire width direction of the pneumatic tire 1, and form the outermost exposed portions of the pneumatic tire 1 in the tire width direction.

[0014] The bead portions 10 are disposed on the radially inner side of each sidewall portion 8. Like the sidewall portions 8, the bead portions 10 are disposed at two locations on both sides 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 radially outer side of the bead core 11 in the tire radial direction. The bead core 11 is an annular member formed by bundling bead wires, which are steel wires, into a circular shape. The bead filler 12 is a rubber member disposed on the radially outer side of the bead core 11 in the tire radial direction.

[0015] The pneumatic tire 1 has an internal structure including a belt layer 14 and a carcass layer 13 .

[0016] The belt layer 14 is disposed on the tread rubber 2A of 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, the belt layer 14 has two layers of belts 141, 142 laminated together.

[0017] The belts 141 and 142 are formed by covering a plurality of belt cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling them. The belt angles of the belts 141 and 142, defined as the inclination angle of the belt cords with respect to the tire circumferential direction, are within a predetermined range (for example, 20 degrees or more and 55 degrees or less). The belt angles of the belts 141 and 142 are different from each other. For this reason, the belts 141 and 142 are formed as a so-called cross-ply structure (cross belt) in which the inclination directions of the belt cords are layered so as to cross each other.

[0018] 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. The belt cover 143 has a belt angle, defined as the inclination angle of the belt cover cords with respect to the tire circumferential direction, within a predetermined range (for example, 0 degrees or more and 10 degrees or less). The belt cover 143 is formed, for example, by spirally winding a strip material, made of one or more belt cover cords covered with coating rubber, around the tire radially outer side of the two-layered belts 141 and 142 in the tire circumferential direction.

[0019] The carcass layer 13 is disposed continuously on the radially inner side of the belt layer 14 in the tread portion 2, the sidewall portion 8, and the bead portion 10. Both ends of the carcass layer 13 in the tire width direction are wound back and secured to the outer side in the tire width direction so as to enclose the bead cores 11 and bead fillers 12 of both bead portions 10, and are wound around the tire circumferentially in a toroidal shape to form the tire framework. The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together. The carcass ply of the carcass layer 13 is formed by coating multiple carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, or rayon with coating rubber and rolling them. The carcass cords that make up the carcass ply are arranged side by side at an angle to the tire circumferential direction, with the angle aligned along the tire meridian direction.

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

[0021] 1 and 2, a pneumatic tire 1 of the embodiment has a tread pattern on a tread contact surface 2B of a tread portion 2. Here, each dimension of the tread pattern is measured in an unloaded state with the tire mounted on a specified rim and inflated to a specified internal pressure.

[0022] Specified rim refers to the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. Specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. Specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "load capacity" specified by ETRTO.

[0023] The groove width (also called the open groove width) is measured as the maximum distance between the opposing groove walls at the groove opening at the tread contact surface 2B when the tire is mounted on a specified rim, inflated to a specified internal pressure, and in an unloaded state. In addition, when the groove opening has a notch or chamfer, the groove width is measured using the intersection of an extension of the tread contact surface 2B and an extension of the groove wall as the endpoint in a cross section parallel to the tire width direction and the tire radial direction.

[0024] The groove depth is measured as the maximum distance from the tread contact surface 2B to the groove bottom when the tire is mounted on a specified rim, inflated to a specified internal pressure, and under no load. If the tire has partial unevenness or sipes at the groove bottom, the groove depth is measured excluding these.

[0025] As shown in FIGS. 1 to 4, the pneumatic tire 1 of the embodiment mainly includes an inner circumferential main groove 31 and an outer circumferential main groove 32 as a tread pattern.

[0026] The inner circumferential main groove 31 has an annular structure that extends along the tire circumferential direction and is continuously provided around the entire tire circumference. Two inner circumferential main grooves 31 are provided in parallel in the tire width direction with the tire equatorial plane CL sandwiched therebetween.

[0027] The outer circumferential main grooves 32 extend circumferentially along the tire and have a continuous annular structure around the entire tire circumference. The two outer circumferential main grooves 32 are arranged in parallel in the tire width direction, on the outer side of the two inner circumferential main grooves 31 in the tire width direction, with the tire equatorial plane CL sandwiched between them. The outer circumferential main grooves 32 are defined as grooves that are required to display a wear indicator as specified by JATMA.

[0028] In the pneumatic tire 1 of the embodiment, a plurality of land portions 20 are defined in the tread portion 2 by two inner circumferential main grooves 31 and two outer circumferential main grooves 32. The land portion 20 includes a central land portion 21, an inner land portion 22, and an outer land portion 23. The central land portion 21 is formed in a single rib-like row along the tire circumferential direction between the two inner circumferential main grooves 31, including the tire equatorial plane CL. The inner land portion 22 is defined between one inner circumferential main groove 31 and one outer circumferential main groove 32, and is formed in a total of two rib-like rows along the tire circumferential direction on both outer sides of the central land portion 21 in the tire width direction. The outer land portions 23 are defined on the outer side of each outer circumferential main groove 32 in the tire width direction, and are formed in a single rib-like row along the tire circumferential direction on the outer side of each inner land portion 22 in the tire width direction, for a total of two rows.

[0029] Furthermore, the pneumatic tire 1 of the embodiment has a specified orientation relative to the vehicle width direction when mounted on a vehicle. The pneumatic tire 1 of the embodiment has a defined orientation relative to the vehicle width direction (tire width direction) when mounted on a vehicle, i.e., a defined inner side in the vehicle width direction and an outer side in the vehicle width direction. Specifically, the pneumatic tire 1 has a mounting direction indicator (not shown) that indicates the tire mounting direction relative to the vehicle. The mounting direction indicator is configured, for example, by a mark or a recess or protrusion on the sidewall of the tire. For example, ECER30 (Article 30 of the Economic Commission for Europe Regulation) requires that a vehicle mounting direction indicator be provided on the sidewall that is on the outer side in the vehicle width direction when mounted on a vehicle.

[0030] The pneumatic tire 1 of the embodiment has an asymmetric tread pattern that is different between the inner side and the outer side in the vehicle width direction in the tire width direction, with the tire equatorial plane CL (central land portion 21) as the boundary.

[0031] First, the tread pattern on the inner side in the vehicle width direction will be described.

[0032] The tread pattern on the inner side in the vehicle width direction includes one inner circumferential main groove 31A corresponding to the inner circumferential main groove 31 and one outer circumferential main groove 32A corresponding to the outer circumferential main groove 32.

[0033] The inner circumferential main groove 31A is formed linearly along the tire circumferential direction without any bends, as shown in Fig. 3. The inner circumferential main groove 31A has a groove width W1a (W1) of 4 mm or more and 10 mm or less, and a groove depth D1a (D1) of 6.5 mm or more and 7.5 mm or less, as shown in Fig. 4.

[0034] The outer circumferential main groove 32A is formed linearly along the tire circumferential direction without any bends, as shown in Fig. 3. The outer circumferential main groove 32A has a groove width W1b (W1) of 5.0 mm or more and 14.0 mm or less, and a groove depth D1b (D1) of 8.0 mm or more and 9.0 mm or less, as shown in Fig. 4.

[0035] The pneumatic tire 1 is defined with a central land portion 21 on the inner side in the tire width direction of the inner circumferential main groove 31A. The pneumatic tire 1 is also defined with an inner land portion 22A between the inner circumferential main groove 31A and the outer circumferential main groove 32A. The pneumatic tire 1 is also defined with an outer land portion 23A on the outer side in the tire width direction of the outer circumferential main groove 32A, the outer land portion 23A including the ground contact edge T, at the outermost side in the tire width direction of the tread pattern.

[0036] Here, the ground contact edges T refer to the outermost ends in the tire width direction in the area where the tread contact surface 2B of the pneumatic tire 1 comes into contact with the road surface when the pneumatic tire 1 is mounted on a standard rim, inflated to a standard internal pressure, and subjected to 70% of a standard load, and are continuous in the tire circumferential direction.

[0037] The pneumatic tire 1 has zigzag circumferential grooves 41, inner widthwise grooves 51, and outer widthwise grooves 52 formed in the inner land portion 22A. The pneumatic tire 1 also has lug grooves 53 and circumferential narrow grooves 71 formed in the outer land portion 23A. The pneumatic tire 1 also has sipes 61 formed in the central land portion 21, the inner land portion 22A, and the outer land portion 23A.

[0038] As shown in Fig. 3, the zigzag circumferential groove 41 is formed in a zigzag shape along the tire circumferential direction between the inner circumferential main groove 31A and the outer circumferential main groove 32A. The zigzag circumferential groove 41 is formed by first inclined portions (sometimes referred to as inclined portions) 41a and second inclined portions (sometimes referred to as inclined portions) 41b, which are inclined in opposite directions relative to the tire circumferential direction, connected by bends 41c and alternately arranged in the tire circumferential direction, so that the zigzag circumferential groove 41 is continuously formed in a zigzag shape along the tire circumferential direction. The first inclined portions 41a and the second inclined portions 41b are formed to extend linearly. Therefore, the zigzag circumferential groove 41 divides the inner land portion 22A into two in the tire width direction. In the zigzag circumferential groove 41, the maximum amplitude A1 in the tire width direction formed by the first inclined portion 41a and the second inclined portion 41b with the bend portion 41c therebetween satisfies the relationship of 0.2≦A1 / A≦0.5, relative to the tire width direction dimension A of the inner land portion 22A (the dimension between adjacent opening edges of the inner circumferential main groove 31A and the outer circumferential main groove 32A). Furthermore, in the zigzag circumferential groove 41, the tire circumferential length La of the first inclined portion 41a forming the amplitude A1 and the tire circumferential length Lb of the second inclined portion 41b forming the amplitude A1 satisfy the relationship of 0.4≦Lb / La≦0.8. That is, the tire circumferential length La of the first inclined portion 41a is longer than the tire circumferential length Lb of the second inclined portion 41b. As shown in Fig. 4, the first inclined portion 41a has a groove width Wa (W) of 1.5 mm or more and 3.5 mm or less, and a groove depth Da (D) of 4.5 mm or more and 5.5 mm or less. As shown in Fig. 4, the second inclined portion 41b has a groove width Wb (W) of 1.8 mm or more and 3.9 mm or less, and a groove depth Db (D) of 4.5 mm or more and 5.5 mm or less.

[0039] As shown in FIG. 3 , one end 51a of the inner widthwise groove 51 is connected to a bent portion 41c of the zigzag circumferential groove 41 facing inward in the tire width direction, extends linearly from the bent portion 41c toward the inner side in the tire width direction, and the other end 51a communicates with the inner circumferential main groove 31A. Therefore, the inner widthwise groove 51 divides the inner side in the tire width direction of the inner land portion 22A divided by the zigzag circumferential groove 41 into multiple blocks 22Aa in the tire circumferential direction. The inner widthwise grooves 51 are provided at an angle with respect to the tire width direction. All of the inner widthwise grooves 51 are formed in the same inclination direction. The angle θ1 of the inner widthwise groove 51 with respect to the tire width direction is in the range of 15 degrees ≦ θ1 ≦ 30 degrees. As shown in FIG. 4, the inner widthwise groove 51 has a groove width W3 of 1.5 mm to 3.5 mm, and a groove depth D3 of 6.5 mm to 7.5 mm.

[0040] As shown in FIG. 3 , one end 52a of the outer widthwise groove 52 is connected to a bent portion 41c of the zigzag circumferential groove 41 facing outward in the tire width direction, extends linearly from the bent portion 41c toward the outer side in the tire width direction, and the other end 52a is connected to the outer circumferential main groove 32A. Therefore, the outer widthwise grooves 52 divide the tire widthwise outer side of the inner land portion 22A divided by the zigzag circumferential grooves 41 into multiple blocks 22Ab in the tire circumferential direction. The outer widthwise grooves 52 are provided at an incline with respect to the tire width direction. All of the outer widthwise grooves 52 are formed in the same inclination direction. The outer widthwise grooves 52 are formed in the same inclination direction as the inner widthwise grooves 51. The outer widthwise grooves 52 and the inner widthwise grooves 51 are also arranged alternately in the tire circumferential direction. Therefore, the outer widthwise groove 52 and the inner widthwise groove 51 connect the inner circumferential main groove 31A and the outer circumferential main groove 32A with the first inclined portion 41a or the second inclined portion 41b of the zigzag circumferential groove 41 therebetween. The outer widthwise groove 52 and the inner widthwise groove 51 are bent and not continuous with the linear connection between the inner circumferential main groove 31A and the outer circumferential main groove 32A with the first inclined portion 41a or the second inclined portion 41b of the zigzag circumferential groove 41 therebetween. The outer widthwise groove 52 has an angle θ2 with respect to the tire width direction in the range of 15°≦θ2≦30°. As shown in FIG. 4, the outer widthwise groove 52 has a groove width W4 of 2.3 mm or more and 4.5 mm or less and a groove depth D4 of 8.0 mm or more and 9.0 mm or less.

[0041] The lug grooves 53 are provided in the outer land portion 23A mainly in a straight or arc-shaped manner along the tire width direction without any bends, and multiple lug grooves 53 are provided side by side in the tire circumferential direction. Each lug groove 53 is provided parallel to the other. One end 53a of each lug groove 53 is connected to the outer circumferential main groove 32A. The ends 53a, 52a of each lug groove 53 and each outer width direction groove 52 face each other in the tire width direction, with the outer circumferential main groove 32A as the boundary. "Facing each end 53a, 52a" means that the projection ranges of the groove widths W5 (see FIG. 4) and W4 of each end 53a, 52a onto the tire width direction overlap in the tire circumferential direction. Each lug groove 53 and each outer width direction groove 52 are arranged to extend in a direction inclined opposite to the tire width direction. The same number of each lug groove 53 and each outer width direction groove 52 are arranged in the tire circumferential direction. As shown in FIG. 4, the lug groove 53 has a groove width W5 of 3.0 mm or more and 7.5 mm or less, and a groove depth D5 of 8.0 mm or more and 9.0 mm or less.

[0042] The sipes 61 are provided throughout the land portion 20, including the central land portion 21, the inner land portions 22A and 22B, and the outer land portions 23A and 23B. The sipes 61 extend mainly along the tire width direction, and multiple sipes are provided side by side in the tire circumferential direction. The sipes 61 are formed in a zigzag or wavy shape by repeatedly bending and vibrating in the tire circumferential direction. The ends of each sipe 61 may terminate inside the land portion 20, or may be connected to other grooves as described above and open. By arranging the sipes 61 in the land portions 20 in this manner, the pneumatic tire 1 of the embodiment is applicable to studless tires that ensure driving performance on icy and snowy roads, or all-season tires that ensure driving performance in winter.

[0043] The sipes 61 are formed in the shape of narrow grooves in the tread contact surface 2B, 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 may not come into contact with each other, but 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 portion 20 on which the narrow grooves are formed collapses, 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 portion 20. The sipes 61 have a groove width of 1.0 mm or less and a groove depth of 1.5 mm to 9.0 mm.

[0044] The sipes 61 may be so-called three-dimensional sipes or two-dimensional sipes. The three-dimensional sipes referred to here are sipes 61 that have curved wall surfaces with amplitude in the width direction of the sipe 61 in both a cross-sectional view with the length direction of the sipe 61 as the normal direction (a cross-sectional view including the width direction and depth direction of the sipe 61) and a cross-sectional view with the depth direction of the sipe 61 as the normal direction (a cross-sectional view including the width direction and length direction of the sipe 61). The two-dimensional sipes refer to sipes 61 that have straight wall surfaces in any cross-sectional view with the length direction of the sipe 61 as the normal direction (a cross-sectional view including the width direction and depth direction of the sipe 61).

[0045] The circumferential narrow grooves 71 are arranged in the outer land portion 23A in a straight line without any bends along the tire circumferential direction between the outer circumferential main groove 32A and the ground contact edge T, and are arranged between the lug grooves 53 lined up in the tire circumferential direction, with one end connected to one of the lug grooves 53 and the other end terminating inside the outer land portion 23A. The circumferential narrow grooves 71 are arranged in a line in the tire circumferential direction. The circumferential narrow grooves 71 have a groove width of 0.8 mm to 1.3 mm and a groove depth of 1 mm to 3 mm.

[0046] Next, the tread pattern on the outer side in the vehicle width direction will be described.

[0047] The tread pattern on the outer side in the vehicle width direction includes one inner circumferential main groove 31B corresponding to the inner circumferential main groove 31 and one outer circumferential main groove 32B corresponding to the outer circumferential main groove 32.

[0048] As shown in FIG. 5, the inner circumferential main groove 31B is formed by connecting the ends 31Baa of the inclined portions 31Ba, which are inclined in a predetermined direction with respect to the tire circumferential direction, in a zigzag pattern along the tire circumferential direction. Each inclined portion 31Ba is provided linearly along the tire circumferential direction without any bends, and multiple inclined portions are provided side by side along the tire circumferential direction. The zigzag degree of each inclined portion 31Ba of the inner circumferential main groove 31B (the offset dimension of the connecting portion of the inclined portions / the length of the inclined portion) is 0.05 to 0.15. The inclined portion 31Ba of the inner circumferential main groove 31B has an inclination angle α with respect to the tire circumferential direction as shown in FIG. 5, where α1 in one direction is in the range of -20 degrees ≦ α1(α) ≦ -3 degrees, and α2 in the opposite direction is in the range of 3 degrees ≦ α2(α) ≦ 20 degrees. As described above, the inner circumferential main groove 31B has an inclined portion 31Ba inclined in a predetermined direction relative to the tire circumferential direction. As shown in Fig. 6, the inner circumferential main groove 31B has an inclined portion 31Ba with a groove width W11 of 3.0 mm or more and 10.0 mm or less and a groove depth D11 of 6.0 mm or more and 10.0 mm or less.

[0049] The outer circumferential main groove 32B is formed linearly along the tire circumferential direction without any bends, as shown in Fig. 5. The outer circumferential main groove 32B has a groove width W15 of 4.0 mm or more and 15.0 mm or less, and a groove depth D15 of 6.0 mm or more and 10.0 mm or less, as shown in Fig. 6.

[0050] The pneumatic tire 1 is defined with a central land portion 21 on the inner side in the tire width direction of the inner circumferential main groove 31B. The pneumatic tire 1 is also defined with an inner land portion 22B between the inner circumferential main groove 31B and the outer circumferential main groove 32B. The pneumatic tire 1 is also defined with an outer land portion 23B on the outer side in the tire width direction of the outer circumferential main groove 32B and including the ground contact edge T at the outermost side in the tire width direction of the tread pattern.

[0051] The pneumatic tire 1 has a circumferential auxiliary groove 42, a widthwise connecting groove 54, and a widthwise auxiliary groove 55 formed in the inner land portion 22B. The pneumatic tire 1 also has a lug groove 56 formed in the outer land portion 23B. The pneumatic tire 1 also has sipes 61 formed in the central land portion 21, the inner land portion 22B, and the outer land portion 23B.

[0052] The circumferential auxiliary groove 42 is provided in the inner land portion 22B between the inner circumferential main groove 31B and the outer circumferential main groove 32B. The circumferential auxiliary grooves 42 are provided mainly in a straight line without any bends along the tire circumferential direction, and multiple circumferential auxiliary grooves 42 are provided side by side in the tire circumferential direction. One circumferential auxiliary groove 42 is provided adjacent to each inclined portion 31Ba of the inner circumferential main groove 31B in the tire width direction. Both ends 42a of the circumferential auxiliary groove 42 terminate inside the inner land portion 22B. The circumferential auxiliary groove 42 is provided at an inclination in the opposite direction to the inclined portion 31Ba with respect to the tire circumferential direction. In the inclination angle β of the circumferential auxiliary groove 42 with respect to the tire circumferential direction shown in FIG. 3, the angle β1 in one direction is in the range of 3 degrees ≦ β1(β) ≦ 30 degrees, and the angle β2 in the opposite direction is in the range of -30 degrees ≦ α ≦ -3 degrees. In this way, the circumferential auxiliary groove 42 is inclined in the opposite direction to the tire circumferential direction of the inclined portion 31Ba of the inner circumferential main groove 31B. Also, as shown in Fig. 6, the circumferential auxiliary groove 42 has a groove width W12 of 1.5 mm or more and 6.0 mm or less, and a groove depth D12 of 3.0 mm or more and 7.0 mm or less.

[0053] The widthwise connecting grooves 54 are provided in the inner land portion 22B mainly in a straight line without any bends along the tire width direction, with multiple grooves lined up in the tire circumferential direction. Each widthwise connecting groove 54 is inclined in a predetermined direction with respect to the tire width direction and is provided parallel to each other. Each widthwise connecting groove 54 is provided connecting both ends 31Baa of the inclined portion 31Ba of the inner circumferential main groove 31B to both ends 42a of the circumferential auxiliary groove 42. Each widthwise connecting groove 54 is provided so that its own ends 54a, which connect to the ends 31Baa of the inclined portion 31Ba and the ends 42a of the circumferential auxiliary groove 42, terminate inside the inner land portion 22B. The widthwise connecting grooves 54 form a trapezoidal block-shaped first small land portion 22Bba inside the inner land portion 22B by the one inclined portion 31Ba of the inner circumferential main groove 31B, the one circumferential auxiliary groove 42, and the two widthwise connecting grooves 54 that are aligned in the tire circumferential direction and connect both ends 54a, 42a of the circumferential auxiliary groove 42. A plurality of first small land portions 22Bba are provided consecutively in the tire circumferential direction, with the widthwise connecting groove 54 as a boundary. As shown in FIG. 6, the widthwise connecting groove 54 has a groove width W13 of 1.5 mm or more and 5.0 mm or less, and a groove depth D13 of 4.0 mm or more and 9.0 mm or less.

[0054] The widthwise auxiliary grooves 55 are provided in the inner land portion 22B mainly in a linear manner without any bends along the tire width direction, with multiple grooves lined up in the tire circumferential direction. Each widthwise auxiliary groove 55 is inclined in a predetermined direction with respect to the tire width direction and is provided parallel to each other. Each widthwise auxiliary groove 55 is provided parallel to each widthwise connecting groove 54. Each widthwise auxiliary groove 55 is provided connecting the center of each circumferential auxiliary groove 42 to the outer circumferential main groove 32B. Each widthwise auxiliary groove 55 is provided so that its both ends 55a, which connect to the center of each circumferential auxiliary groove 42 and the outer circumferential main groove 32B, terminate inside the inner land portion 22B. Because the widthwise auxiliary groove 55 connects to the center of the circumferential auxiliary groove 42, it is not directly connected to the widthwise connecting groove 54, which connects to the end 42a of the circumferential auxiliary groove 42, but is arranged misaligned. The widthwise auxiliary grooves 55 are provided to form a block-shaped second small land portion 22Bb inside the inner land portion 22B, which has two bent portions on the opposing side of the outer circumferential main groove 32B, including the outer circumferential main groove 32B, the two circumferential auxiliary grooves 42 aligned in the tire circumferential direction, a portion of the widthwise connecting groove 54 connecting these grooves, and the two widthwise auxiliary grooves 55 aligned in the tire circumferential direction. A plurality of second small land portions 22Bb are provided consecutively in the tire circumferential direction, with the widthwise auxiliary groove 55 as a boundary. As shown in FIG. 6, the widthwise auxiliary groove 55 has a groove width W14 of 2.0 mm or more and 7.0 mm or less, and a groove depth D14 of 6.0 mm or more and 10.0 mm or less.

[0055] The lug grooves 56 are arranged in the outer land portion 23B mainly in a straight or arc-shaped manner along the tire width direction without any bends, and multiple lug grooves are arranged side by side in the tire circumferential direction. Each lug groove 56 is arranged parallel to one another. One end 56a of each lug groove 56 is connected to the outer circumferential main groove 32B. The ends 56a, 55a of each lug groove 56 and each width-direction auxiliary groove 55, which connect to opposite sides of the outer circumferential main groove 32B in the tire width direction, do not face each other and are arranged misaligned in the tire circumferential direction. Each lug groove 56 and each width-direction auxiliary groove 55 are arranged alternately in the tire circumferential direction. Note that when the groove position relationship between the lug grooves 56 and the width-direction auxiliary grooves 55 coincides at the centers of their groove widths, which is defined as 0% and 100%, the respective groove position relationship is in the range of 30% to 70%. The lug grooves 56 have a groove width of 2.5 mm or more and 6.5 mm or less, and a groove depth of 2.5 mm or more and 10.0 mm or less, in the tread contact surface 2B.

[0056] The circumferential narrow grooves 72 are arranged in the outer land portion 23B in a straight line without any bends along the tire circumferential direction between the outer circumferential main groove 32B and the ground contact edge T, and are arranged between the lug grooves 56 lined up in the tire circumferential direction, with one end connected to one lug groove 56 and the other end terminating inside the outer land portion 23B. The circumferential narrow grooves 72 are arranged in a line in the tire circumferential direction. The circumferential narrow grooves 72 have a groove width of 0.8 mm to 1.3 mm and a groove depth of 1 mm to 3 mm.

[0057] The pneumatic tire 1 of the embodiment does not have any grooves other than the grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, 56, 71, and 72 and the sipes 61 described above.

[0058] 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. When a vehicle mounted with the pneumatic tire 1 runs, the pneumatic tire 1 rotates while the lower tread contact surface 2B of the tread portion 2 comes into contact with the road surface. When a vehicle mounted with the pneumatic tire 1 runs on a dry road surface, the vehicle runs by transmitting driving force and braking force to the road surface and generating turning force mainly due to friction between the tread contact surface 2B and the road surface.

[0059] Furthermore, when traveling on a wet road surface, water between the tread contact surface 2B and the road surface enters each of the grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, 56 and the sipes 61, and the water between the tread contact surface 2B and the road surface is drained while traveling. This makes it easier for the tread contact surface 2B to make contact with the road surface, and the friction between the tread contact surface 2B and the road surface provides wet performance, enabling the vehicle to travel.

[0060] Furthermore, when traveling on snowy roads, the pneumatic tire 1 compacts snow on the road surface with the tread contact surface 2B, and the snow on the road surface enters each of the grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, and 56, compacting the snow within the grooves. In this state, when driving or braking forces act 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 and braking forces to be transmitted to the road surface, ensuring snow traction and snow performance. This allows the vehicle to travel on snowy roads.

[0061] Furthermore, when traveling on snowy or icy road surfaces, the tire also utilizes the edge effect of the grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, and 56 and the sipes 61. That is, when traveling on snowy or icy road surfaces, the tire also utilizes the resistance created by the edges of the grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, and 56 and the sipes 61 catching on the snow or ice surface. Furthermore, when traveling on icy road surfaces, the sipes 61 absorb water on the surface of the icy road surface, removing the water film between the icy road surface and the tread contact surface 2B, thereby facilitating contact between the icy road surface and the tread contact surface 2B. As a result, the resistance between the tread contact surface 2B and the icy road surface increases due to frictional force and the edge effect, thereby providing ice performance. This allows the vehicle to travel on icy road surfaces.

[0062] The grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, 56 and sipes 61 formed in the tread portion 2 contribute to ensuring driving performance when traveling on wet, snowy, or icy road surfaces, and therefore, in order to improve wet performance, i.e., driving performance on wet road surfaces, it is effective to increase the groove area of ​​the tread portion 2. In other words, if the groove area of ​​the grooves 31, 32, 33, 34, 35, 36, etc. is increased, water on the road surface can easily enter the grooves when traveling on a wet road surface, thereby improving the drainage of water between the tread contact surface 2B and the road surface and improving wet performance.

[0063] Increasing the groove area is also effective in improving snow performance, which is driving performance on snowy roads. In other words, increasing the groove area increases the amount of snow that can enter each groove 31, 32, 41, 42, 51, 52, 53, 54, 55, and 56 when driving on snowy roads, thereby increasing the snow column shear force acting on the snow that has entered the grooves. This improves snow traction when driving on snowy roads, and improves snow performance.

[0064] Here, when the groove area of ​​the tread portion 2 is increased, the volume of the land portions 20 defined by the grooves 31, 32, 41, 42, 51, 52, 53, 54, 55, and 56 decreases as the groove area increases. When the volume of the land portions 20 decreases, the rigidity of the land portions 20 decreases, and when the rigidity of the land portions 20 decreases, the land portions 20 become more likely to deform and collapse when a load is applied. When the land portions 20 collapse, the contact area of ​​the collapsed land portions 20 decreases, which may make it difficult to ensure driving performance.

[0065] For example, when driving on an icy road surface, in addition to the edge effect of the groove edge components, the frictional force caused by the tread contact surface 2B contacting the icy road surface is also important. However, if the rigidity of the land portion 20 is reduced by increasing the groove area of ​​the tread portion 2, the land portion 20 will be more likely to collapse when a load is applied, which will likely reduce the contact area and make it difficult to ensure driving performance due to frictional force. Therefore, if the rigidity of the land portion 20 is reduced by increasing the groove area of ​​the tread portion 2, the land portion 20 will be more likely to collapse when braking while driving on an icy road surface, which will likely reduce the contact area and make it difficult to ensure braking performance on an icy road surface.

[0066] The pneumatic tire 1 of the embodiment is characterized in that, on the inner side in the vehicle width direction, the groove depth D of the zigzag circumferential groove 41 is smaller than the groove depth D1 of each of the circumferential main grooves 31A, 32A, the groove width W of the zigzag circumferential groove 41 is smaller than the groove width W1 of each of the circumferential main grooves 31A, 32A, the inner width grooves 51 and the outer width grooves 52 extend in the same inclined direction with respect to the tire width direction and are arranged alternately in the tire circumferential direction, and the lug grooves 53 are arranged opposite to the outer width grooves 52 across the outer circumferential main groove 32A and extend in the opposite inclined direction with respect to the tire width direction of the outer width grooves 52.

[0067] According to the pneumatic tire 1 of the embodiment, by arranging the outer width direction groove 52 opposite to each other on the extension line through the outer circumferential direction main groove 32A of the lug groove 53, the drainage performance from the inner land portion 22A to the outer land portion 23A is improved. Further, according to the pneumatic tire 1 of the embodiment, by inclining the outer width direction groove 52 and the lug groove 53 in opposite directions with the outer circumferential direction main groove 32A as a boundary, the snow performance can be improved without being biased at a specific angle. Further, according to the pneumatic tire 1 of the embodiment, by having the zigzag circumferential groove 41 and arranging the positions of the inner width direction groove 51 and the outer width direction groove 52 shifted in the tire circumferential direction, an improvement in the snow turning performance (STI90 [deg]) can be realized. Further, according to the pneumatic tire 1 of the embodiment, regarding the wear resistance performance, by making the groove depth and groove width of the zigzag circumferential groove 41 shallower and narrower than those of the circumferential direction main grooves 31A and 32A, and ensuring the edge amount, the wear resistance performance can be improved. As a result, this pneumatic tire 1 can improve the wear resistance performance while ensuring the ice and snow performance and the wet performance.

[0068] In the pneumatic tire 1 of the embodiment, the groove depth D (Da or Db) of the zigzag circumferential groove 41, the groove depth D1a of the inner circumferential direction main groove 31A, and the groove depth D1b of the outer circumferential direction main groove 32A satisfy the relationship of D < D1a < D1b and 0.5 ≦ D / D1a ≦ 0.8.

[0069] According to the pneumatic tire 1 of the embodiment, since the groove depth D of the zigzag circumferential groove 41 is shallower than the groove depth D1a of the inner circumferential direction main groove 31A and the groove depth D1b of the outer circumferential direction main groove 32A, the rigidity of the inner land portion 22A (block 22Aa) can be ensured, and the wear resistance performance can be improved. Further, according to the pneumatic tire 1 of the embodiment, since the groove depth D1a of the inner circumferential main groove 31A is shallower than the groove depth D1b of the outer circumferential main groove 32A, the rigidity on the center side in the tire width direction can be ensured and the wear resistance performance can be improved. And when D / D1a is less than 0.5, the groove depth D of the zigzag circumferential groove 41 is too shallow and the drainage property deteriorates, and the wet performance tends to deteriorate. When it exceeds 0.8, the groove depth D of the zigzag circumferential groove 41 is too deep and the block rigidity decreases, and the wear resistance performance tends to deteriorate. Therefore, it is set within the above range. Further, according to the pneumatic tire 1 of the embodiment, by satisfying the relationship of 0.6 ≦ D / D1a ≦ 0.75, the above effects can be remarkably obtained, which is preferable.

[0070] In the pneumatic tire 1 of the embodiment, the groove widths Wa, Wb of the reverse inclined portions 41a, 41b with the bent portion 41c of the zigzag circumferential groove 41 as the boundary, the groove width W1a of the inner circumferential main groove 31A, and the groove width W1b of the outer circumferential main groove 32A satisfy the relationship of Wa < Wb < W1a < W1b. The groove widths Wa, Wb of the inclined portions 41a, 41b satisfy the relationship of 0.8 ≦ Wa / Wb ≦ 0.9. The groove width Wa of the narrower inclined portion 41a and the groove width W1a of the inner circumferential main groove 31A satisfy the relationship of 0.3 ≦ Wa / W1a ≦ 0.6.

[0071] In the pneumatic tire 1 of the embodiment, the groove widths Wa, Wb of the oppositely oriented inclined portions 41a, 41b separated by the bent portion 41c of the zigzag circumferential groove 41 are different, so that the narrow inclined portion 41a contributes to ensuring rigidity, while the wide inclined portion 41b contributes to ensuring drainage, thereby improving the balance between snow and ice performance, wet performance, and wear resistance. Also, in the pneumatic tire 1 of the embodiment, the groove widths Wa, Wb of the oppositely oriented inclined portions 41a, 41b separated by the bent portion 41c of the zigzag circumferential groove 41 are narrower than the groove width W1a of the inner circumferential main groove 31A and the groove width W1b of the outer circumferential main groove 32A, so that the rigidity of the inner land portion 22A (blocks 22Aa) can be ensured, and wear resistance can be improved. Furthermore, in the pneumatic tire 1 of this embodiment, the groove width W1a of the inner circumferential main groove 31A is narrower than the groove width W1b of the outer circumferential main groove 32A, ensuring rigidity at the tire widthwise center and improving wear resistance. Furthermore, if Wa / Wb is less than 0.8, the groove width Wa is too narrow, which tends to impair drainage and wet performance. If it exceeds 0.9, the difference between the groove widths Wa and Wb is too small, which tends to make it difficult to achieve the above-mentioned effects. Furthermore, if Wa / W1a is less than 0.3, the inclined portion 41a is too narrow, which tends to impair drainage and wet performance. If it exceeds 0.6, the inclined portion 41a is too wide, which tends to reduce block rigidity and impair wear resistance. Furthermore, in the pneumatic tire 1 of this embodiment, satisfying the relationship 0.35≦Wa / W1a≦0.5 is preferable because it significantly achieves the above-mentioned effects.

[0072] In the pneumatic tire 1 of the embodiment, the angle θ1 of the inner widthwise groove 51 relative to the tire width direction and the angle θ2 of the outer widthwise groove 52 relative to the tire width direction are in the ranges of 15 [deg]≦θ1≦40 [deg] and 15 [deg]≦θ2≦40 [deg].

[0073] According to the pneumatic tire 1 of the embodiment, when the angles θ1 and θ2 are less than 15 [deg], the drainage performance tends to decrease, and when it exceeds 40 [deg], the edge amount cannot be obtained and the ice and snow performance tends to decrease. Therefore, the above range is set. Further, according to the pneumatic tire 1 of the embodiment, by satisfying the relationship of 20 [deg] ≤ θ1, θ2 ≤ 30 [deg], the above effects can be remarkably obtained, which is preferable.

[0074] In the pneumatic tire 1 of the embodiment, the amplitude A1 in the tire width direction of the zigzag shape formed by the inclined portions 41a and 41b in the reverse direction of the zigzag circumferential groove 41 and the tire width direction dimension A of the inner land portion 22A satisfy the relationship of 0.2 ≤ A1 / A ≤ 0.5, and the tire circumferential lengths La and Lb of the inclined portions 41a and 41b forming the amplitude A1 of the zigzag circumferential groove 41 satisfy the relationship of 0.4 ≤ Lb / La ≤ 0.8.

[0075] According to the pneumatic tire 1 of the embodiment, when the amplitude A1 is less than 0.2 with respect to the tire width direction dimension A of the inner land portion 22A, the groove area ratio and the edge amount cannot be ensured, and the ice and snow performance and the wet T performance tend to decrease. When it exceeds 0.5, the block rigidity decreases and the wear resistance performance tends to deteriorate. Therefore, the above range is set. Further, according to the pneumatic tire 1 of the embodiment, by satisfying the relationship of 0.3 ≤ A1 / A ≤ 0.4, the above effects can be remarkably obtained, which is preferable. Moreover, according to the pneumatic tire 1 of the embodiment, if the tire circumferential lengths La and Lb of the inclined portions 41a and 41b of the zigzag circumferential groove 41 change too much, the balance between the drainage performance and the rigidity tends to deteriorate. Therefore, the above range is set.

[0076] In the pneumatic tire 1 of the embodiment, the groove widths Wa and Wb of the inclined portions 41a and 41b in the reverse direction with the bent portion 41c of the zigzag circumferential groove 41 as the boundary, the groove width W3 of the inner width direction groove 51, the groove width W4 of the outer width direction groove 52, and the groove width W5 of the lug groove 53 satisfy the relationships of Wa < Wb < W3 < W4 ≤ W5 and 1.5 ≤ W4 / W3 ≤ 2.0.

[0077] According to the pneumatic tire 1 of the embodiment, since the groove width W3 of the inner widthwise groove 51 is narrower than the groove width W4 of the outer widthwise groove 52, the rigidity on the center side in the tire width direction can be ensured, and the wear resistance performance can be improved. On the center side in the tire width direction, it is necessary to secure a ground contact area for improving the braking force. Also, according to the pneumatic tire 1 of the embodiment, by making the groove width W5 of the lug groove 53 equal to or greater than the groove width W4 of the outer widthwise groove 52, the drainage performance can be improved. Further, when W4 / W3 is less than 1.5, the block rigidity decreases and the wear resistance performance tends to deteriorate, and when it exceeds 2.0, the groove area ratio decreases and the snow performance and wet performance tend to deteriorate. Therefore, it is within the above range. Also, according to the pneumatic tire 1 of the embodiment, by satisfying the relationship of 1.7≦W4 / W3≦1.9, the above effects can be significantly obtained, which is preferable.

[0078] In the pneumatic tire 1 of the embodiment, the groove depth D of the zigzag circumferential groove, the groove depth D3 of the inner widthwise groove 51, the groove depth D4 of the outer widthwise groove 52, and the groove depth D5 of the lug groove 53 satisfy the relationships of D<D3<D4≦D5 and 1.1≦D4 / D3≦1.5.

[0079] According to the pneumatic tire 1 of the embodiment, in order to ensure the block rigidity on the center side in the tire width direction, the grooves closer to the center side in the tire width direction are shallower grooves. Also, according to the pneumatic tire 1 of the embodiment, by satisfying the relationship of 1.2≦D4 / D3≦1.4, the above effects can be significantly obtained, which is preferable.

[0080] In the pneumatic tire 1 of the embodiment, the angle θ3 of the outer widthwise groove 52 with respect to the tire circumferential direction and the angle θ4 of the lug groove 53 with respect to the tire circumferential direction satisfy the relationship of θ3<θ4.

[0081] According to the pneumatic tire 1 of the embodiment, since the angle θ4 of the lug groove 53 with respect to the tire circumferential direction is larger than the angle θ3 of the outer widthwise groove 52 with respect to the tire circumferential direction, an edge effect can be obtained and the snow performance can be improved.

[0082] In the pneumatic tire 1 of the embodiment, each land portion 20 has a sipe 61 extending along the tire width direction, and the tire can be used as a winter tire or an all-season tire.

[0083] In the pneumatic tire 1 of the embodiment, the orientation relative to the vehicle width direction when mounted on a vehicle is specified, and each of the circumferential main grooves 31A, 32A, inner land portion 22A, outer land portion 23A, zigzag circumferential groove 41, inner width direction groove 51, outer width direction groove 52, and lug groove 53 is positioned on the inner side in the vehicle width direction, with the tire equatorial plane CL as the boundary.

[0084] According to the pneumatic tire 1 of the embodiment, the above-mentioned effect can be obtained more significantly by disposing the above-mentioned configuration on the inner side in the vehicle width direction.

[0085] The pneumatic tire 1 of the embodiment is characterized by including, on the inner side in the vehicle width direction, an outer circumferential main groove 32B formed in a straight line along the tire circumferential direction; an inner circumferential main groove 31B formed along the tire circumferential direction and having inclined portions 31Ba inclined in a predetermined direction with respect to the tire circumferential direction continuing in a zigzag pattern around the tire circumferential direction; a circumferential auxiliary groove 42 provided between the outer circumferential main groove 32B and the inner circumferential main groove 31B, adjacent to the inclined portions 31Ba in the tire width direction and inclined in the opposite direction to the inclined portions 31Ba with respect to the tire circumferential direction; a widthwise connecting groove 54 connecting both ends 31Baa, 42a of the inclined portions 31Ba and the circumferential auxiliary groove 42 to define blocks that are continuous in the tire circumferential direction; and a widthwise auxiliary groove 55 connecting the central portion of the circumferential auxiliary groove 42 to the outer circumferential main groove 32B and the outer circumferential main groove 32B and arranged misaligned with the widthwise connecting groove 54.

[0086] According to the pneumatic tire 1 of the embodiment, the inner circumferential main groove 31B is zigzag-shaped to ensure sufficient edge width and improve ice performance, while the circumferential auxiliary groove 42 is provided in the opposite direction to the zigzag groove, improving snow shear force without biasing the Snow Traction Index (STI) component to a specific angle. Furthermore, according to the pneumatic tire 1 of the embodiment, the inner circumferential main groove 31B and the circumferential auxiliary groove 42 are connected by the widthwise connecting groove 54, and the circumferential auxiliary groove 42 and the outer circumferential main groove 32B are connected by the widthwise connecting groove 55, thereby improving drainage and wet performance. Furthermore, according to the pneumatic tire 1 of the embodiment, the widthwise auxiliary groove 55 does not coincide with the widthwise connecting groove 54, thereby suppressing a decrease in rigidity of the land portion 20 (inner land portion 22B) and improving wear resistance. As a result, the pneumatic tire 1 of the embodiment can improve wear resistance while ensuring snow and ice performance and wet performance.

[0087] In the pneumatic tire 1 of the embodiment, the circumferential auxiliary grooves 42 are preferably formed in a straight line without any bends. For example, bends increase the amount of edge, but on the other hand, this may result in a decrease in the rigidity of the land portion 20 (inner land portion 22B). In this regard, in the pneumatic tire 1, the amount of edge is ensured by the zigzag-shaped inner circumferential main groove 31B, and the circumferential auxiliary grooves 42 are formed in a straight line, thereby preventing a decrease in the rigidity of the land portion 20 (inner land portion 22B) and improving wear resistance.

[0088] In addition, in the pneumatic tire 1 of the embodiment, the widthwise auxiliary grooves 55 connected to the outer circumferential main grooves 32B do not face the lug grooves 56 connected to the opposite side of the outer circumferential main grooves 32B in the tire width direction, and are arranged misaligned with each other in the tire circumferential direction.

[0089] According to this pneumatic tire 1, by making the widthwise auxiliary grooves 55 not coincide with the lug grooves 56 that are bordered by the outer circumferential main groove 32B, a decrease in rigidity of the land portion 20 (inner land portion 22B) is suppressed, thereby improving wear resistance.

[0090] In addition, in the pneumatic tire 1 of the embodiment, the widthwise connecting groove 54 is connected to the inner circumferential main groove 31B and the circumferential auxiliary groove 42, and terminates inside the land portion 20 (inner land portion 22B) defined by the outer circumferential main groove 32B and the inner circumferential main groove 31B.

[0091] According to this pneumatic tire 1, the widthwise connecting grooves 54 terminate, thereby suppressing a decrease in rigidity of the land portion 20 (inner land portion 22B) and improving wear resistance.

[0092] In the pneumatic tire 1 of the embodiment, the angle α of the inclined portion 31Ba relative to the tire circumferential direction is in the range of −20°≦α≦−3° or 3°≦α≦20°.

[0093] With this pneumatic tire 1, when the angle α of the inclined portion 31Ba is ±3° or more, an edge component is obtained, improving snow and ice performance. Furthermore, with this pneumatic tire 1, when the angle α of the inclined portion 31Ba is ±20° or less, the deterioration of drainage caused by a larger inclination is suppressed, ensuring wet performance. By setting the angle α preferably within the range of 5°≦α≦10°, snow and ice performance and wet performance can be improved.

[0094] In the pneumatic tire 1 of the embodiment, the angle β of the circumferential auxiliary groove 42 with respect to the tire circumferential direction is in the range of 3°≦β≦30° or −30°≦α≦−3°.

[0095] With this pneumatic tire 1, when the angle β of the circumferential auxiliary groove 42 is ±3° or more, the small inclination prevents an edge component from being obtained, resulting in poor snow and ice performance. However, the edge component is obtained, improving snow and ice performance. Furthermore, with this pneumatic tire 1, when the angle β of the circumferential auxiliary groove 42 is ±30° or less, the inclination prevents a decrease in block rigidity and ensures wear resistance. By setting the angle β preferably within the range of 10°≦α≦20°, both snow and ice performance and wear resistance can be achieved.

[0096] In the pneumatic tire 1 of the embodiment, the groove depth D11 of the inclined portion 31Ba and the groove depth D12 of the circumferential auxiliary groove 42 satisfy the relationship 0.5≦D12 / D11≦0.7.

[0097] According to this pneumatic tire 1, when D12 / D11 is 0.5 or more, sufficient groove depth can be ensured and water drainage is achieved, improving wet performance. Furthermore, according to this pneumatic tire 1, when D12 / D11 is 0.7 or less, a decrease in block rigidity is suppressed and wear resistance is ensured. By setting D12 / D11 within the range of 0.55≦D12 / D11≦0.65, both wet performance and wear resistance can be achieved.

[0098] In the pneumatic tire 1 of the embodiment, the groove depth D11 of the inclined portion 31Ba and the groove depth D13 of the widthwise connecting groove 54 satisfy the relationship 0.7≦D13 / D11≦0.9.

[0099] With this pneumatic tire 1, when D13 / D11 is 0.7 or more, sufficient groove depth can be ensured and water drainage is achieved, improving wet performance. Furthermore, with this pneumatic tire 1, when D13 / D11 is 0.9 or less, a decrease in block rigidity is suppressed and wear resistance is ensured. By setting D13 / D11 within the range of 0.75≦D13 / D11≦0.85, both wet performance and wear resistance can be achieved.

[0100] In the pneumatic tire 1 of the embodiment, the groove width W11 of the inclined portion 31Ba and the groove width W12 of the circumferential auxiliary groove 42 are in the ranges of 3.0 mm≦W11≦10.0 mm and 1.5 mm≦W12≦6.0 mm.

[0101] With this pneumatic tire 1, when W11 is 3.0 mm or more and W12 is 1.5 mm or more, the groove width can be secured and drainage is achieved, improving wet performance. Also, with this pneumatic tire 1, when W11 is 10.0 mm or less and W12 is 6.0 mm or less, a decrease in block rigidity is suppressed and wear resistance is ensured.

[0102] In the pneumatic tire 1 of the embodiment, the groove width W13 of the widthwise connecting groove 54 and the groove width W14 of the widthwise auxiliary groove 55 are in the ranges of 1.5 mm≦W13≦5.0 mm and 2.0 mm≦W14≦7.0 mm.

[0103] With this pneumatic tire 1, when W13 is 1.5 mm or more and W14 is 2.0 mm or more, the groove width can be secured and drainage is achieved, improving wet performance. Also, with this pneumatic tire 1, when W13 is 5.0 mm or less and W14 is 7.0 mm or less, a decrease in block rigidity is suppressed and wear resistance is ensured.

[0104] In the pneumatic tire 1 of the embodiment, a plurality of sipes 61 extending along the tire width direction are arranged in the inner land portion 22B defined by the inner circumferential main groove 31B and the outer circumferential main groove 32B.

[0105] According to this pneumatic tire 1, the arrangement of the sipes 61 can improve performance on ice, and the tire can be applied to a studless tire or an all-season tire.

[0106] In the pneumatic tire 1 of the embodiment, the sipes 61 are arranged parallel to at least one of the widthwise connecting grooves 54 and the widthwise auxiliary grooves 55 .

[0107] According to this pneumatic tire 1, the sipes 61 are arranged in parallel with the widthwise connecting grooves 54 and the widthwise auxiliary grooves 55, thereby aligning the edge components and improving snow and ice performance.

[0108] In the present embodiment, as described above, a pneumatic tire 1 has been described as an example of a tire. The pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, or other gases. However, the tread pattern configuration of the pneumatic tire 1 described in the present embodiment can be applied to other tires as desired within the scope of what is obvious to those skilled in the art. Examples of other tires include airless tires and solid tires. [Example]

[0109] 7 to 11 are tables showing the results of performance tests of pneumatic tires according to the embodiment. Performance evaluation tests conducted on a conventional pneumatic tire and an example pneumatic tire according to the embodiment will be described below. The performance evaluation tests were conducted on ice performance, snow performance, wet performance, and uneven wear resistance.

[0110] 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 240 kPa for the front wheels and 240 kPa for the rear wheels, and running the evaluation vehicle.

[0111] To evaluate ice performance, a test vehicle fitted with the test tires is subjected to a braking test on an icy test course, measuring the braking distance. Based on the results of these tests, the reciprocal of the tire's braking distance is calculated as an index, with the conventional tire being used as the benchmark (100). The higher the index value, above 95, the better.

[0112] To evaluate snow performance, a vehicle fitted with the test tires is subjected to a braking test on a snowy test course, measuring the braking distance. Based on the results of these tests, the reciprocal of the tire is used to create an index rating, with the conventional tire being used as the benchmark (100). The higher the rating, above 95, the better.

[0113] The wet performance evaluation test involves a braking test on a test vehicle fitted with a test tire on a wet road test course with 1mm of water depth, and the braking distance is measured. Based on the measurement results, the reciprocal of the tire is used to evaluate the tire's performance on an index basis, with the conventional tire being used as the standard (100). The higher the evaluation value, the better.

[0114] The wear resistance evaluation test involves measuring the amount of wear after a test vehicle fitted with a test tire has driven 10,000 km on a dry asphalt test course. Based on the results of this measurement, the reciprocal of the tire's wear is used to evaluate the tire's performance, with the conventional tire being used as the standard (100). The higher the evaluation value, the better.

[0115] The conventional pneumatic tire has a tread pattern on one side in the vehicle width direction that includes two straight circumferential main grooves, a zigzag circumferential groove, an inner width groove, an outer width groove, and lug grooves, but this does not fall within the specified range. The tread pattern on the other side in the vehicle width direction has the configuration shown in Figure 5.

[0116] The pneumatic tire of the example has a tread pattern on one side in the vehicle width direction that includes two straight circumferential main grooves, a zigzag circumferential groove, an inner width groove, an outer width groove, and lug grooves, and is formed within a specified range. The tread pattern on the other side in the vehicle width direction has the configuration shown in Figure 5.

[0117] As shown in the test results, the pneumatic tire of this example has improved ice performance, snow performance, wet braking performance, and wear resistance compared to the conventional tire.

[0118] The present disclosure includes the following inventions. [Invention 1] two inner circumferential main grooves and an outer circumferential main groove formed linearly along the tire circumferential direction and adjacent to each other in the tire width direction; an inner land portion defined between each of the circumferential main grooves; an outer land portion defined on the outer side of the outer circumferential main groove in the tire width direction and including a ground contact edge; a zigzag circumferential groove in the inner land portion, in which inclined portions extending continuously in the tire circumferential direction between the circumferential main grooves and inclined in opposite directions to the tire circumferential direction are alternately provided in the tire circumferential direction and connected by bent portions; an inner widthwise groove extending inward in the tire width direction from a bent portion of the zigzag circumferential groove facing inward in the tire width direction in the inner land portion and communicating with the inner circumferential main groove; On the inner land portion, an outer width-direction groove that extends outward in the tire width direction from a bent portion facing the outer side in the tire width direction of the zigzag circumferential groove and communicates with the outer circumferential main groove; On the outer land portion, lug grooves that communicate with the outer circumferential main groove, extend outward in the tire width direction, and are arranged in a plurality in the tire circumferential direction; comprising the groove depth of the zigzag circumferential groove is smaller than the groove depth of each of the circumferential main grooves; the groove width of the zigzag circumferential groove is smaller than the groove width of each of the circumferential main grooves; the inner width-direction groove and the outer width-direction groove extend in the same inclination direction with respect to the tire width direction and are alternately arranged in the tire circumferential direction; the lug grooves face the outer width-direction groove with the outer circumferential main groove as a boundary and are arranged to extend in an inclination direction opposite to that of the outer width-direction groove with respect to the tire width direction; a tire. [Invention 2] The groove depth D of the zigzag circumferential groove, the groove depth D1a of the inner circumferential main groove, and the groove depth D1b of the outer circumferential main groove satisfy the relationship D < D1a < D1b and 0.5 ≦ D / D1a ≦ 0.8; The tire according to Invention 1. [Invention 3] The groove widths Wa and Wb of the inclined portions in opposite directions with the bent portion of the zigzag circumferential groove as a boundary, the groove width W1a of the inner circumferential main groove, and the groove width W1b of the outer circumferential main groove satisfy the relationship Wa < Wb < W1a < W1b; the groove widths Wa and Wb of each of the inclined portions satisfy the relationship 0.8 ≦ Wa / Wb ≦ 0.9; the groove width Wa of the inclined portion with a narrow width and the groove width W1a of the inner circumferential main groove satisfy the relationship 0.3 ≦ Wa / W1a ≦ 0.6; The tire according to Invention 1 or 2. [Invention 4] The angle θ1 of the inner width-direction groove with respect to the tire width direction and the angle θ2 of the outer width-direction groove with respect to the tire width direction are in the range of 15[deg] ≦ θ1 ≦ 40[deg] and 15[deg] ≦ θ2 ≦ 40[deg]; The tire according to any one of Inventions 1 to 3. [Invention 5] The tire-width direction amplitude A1 of the zigzag shape formed by each of the inclined portions in the opposite direction of the zigzag circumferential groove and the tire-width direction dimension A of the inner land portion satisfy the relationship of 0.2 ≦ A1 / A ≦ 0.5, The tire circumferential direction lengths La and Lb of each of the inclined portions forming the amplitude A1 of the zigzag circumferential groove satisfy the relationship of 0.4 ≦ Lb / La ≦ 0.8. The tire according to any one of Inventions 1 to 4. [Invention 6] The groove widths Wa and Wb of each of the inclined portions in the opposite direction with the bent portion of the zigzag circumferential groove as a boundary, the groove width W3 of the inner width direction groove, the groove width W4 of the outer width direction groove, and the groove width W5 of the lug groove satisfy the relationships of Wa < Wb < W3 < W4 ≦ W5 and 1.5 ≦ W4 / W3 ≦ 2.0. The tire according to any one of Inventions 1 to 5. [Invention 7] The groove depth D of the zigzag circumferential groove, the groove depth D3 of the inner width direction groove, the groove depth D4 of the outer width direction groove, and the groove depth D5 of the lug groove satisfy the relationships of D < D3 < D4 ≦ D5 and 1.1 ≦ D4 / D3 ≦ 1.5. The tire according to any one of Inventions 1 to 6. [Invention 8] The angle θ3 of the outer width direction groove with respect to the tire circumferential direction and the angle θ4 of the lug groove with respect to the tire circumferential direction satisfy the relationship of θ3 < θ4. The tire according to any one of Inventions 1 to 7. [Invention 9] A winter tire or an all-season tire having sipes extending along the tire width direction in each of the land portions. The tire according to any one of Inventions 1 to 8. [Invention 10] The direction with respect to the vehicle width direction when mounted on a vehicle is specified, Each of the circumferential main grooves, the inner land portion, the outer land portion, the zigzag circumferential groove, the inner width direction groove, the outer width direction groove, and the lug groove are arranged on the inner side in the vehicle width direction with the tire equatorial plane as a boundary. The tire according to any one of Inventions 1 to 9. [Explanation of symbols]

[0119] 1. Pneumatic tires (tires) 22A Inner land area 23A Outer land area 31A Inner circumferential main groove 32A Outer circumferential main groove 41 Zigzag circumferential groove 41a First slope part (slope part) 41b Second slope part (slope part) 41c Bend part 51 Inner width direction groove 52 Outer width groove 53 Lug groove 61 Sipe

Claims

1. two inner circumferential main grooves and two outer circumferential main grooves that are linearly formed along the tire circumferential direction and adjacent to each other in the tire width direction; an inner land portion defined between each of the circumferential main grooves; an outer land portion defined on the outer side of the outer circumferential main groove in the tire width direction and including a ground contact edge; a zigzag circumferential groove in the inner land portion, in which inclined portions extending continuously in the tire circumferential direction between the circumferential main grooves and inclined in opposite directions to the tire circumferential direction are alternately provided in the tire circumferential direction and connected by bent portions; an inner widthwise groove extending inward in the tire width direction from a bent portion of the zigzag circumferential groove facing inward in the tire width direction in the inner land portion and communicating with the inner circumferential main groove; an outer widthwise groove extending from a bent portion of the zigzag circumferential groove facing outward in the tire width direction in the inner land portion toward the outer side in the tire width direction and communicating with the outer circumferential main groove; a plurality of lug grooves arranged in the tire circumferential direction in the outer land portion, the lug grooves communicating with the outer circumferential main groove and extending outward in the tire width direction; Including, a groove depth of the zigzag circumferential groove is smaller than a groove depth of each of the circumferential main grooves, a groove width of the zigzag circumferential groove is smaller than a groove width of each of the circumferential main grooves, the inner widthwise grooves and the outer widthwise grooves extend in the same inclined direction with respect to the tire width direction and are alternately arranged in the tire circumferential direction, the lug grooves are arranged to face the outer width direction grooves across the outer circumferential main groove, and to extend in an inclined direction opposite to that of the outer width direction grooves with respect to the tire width direction; tire.

2. a groove depth D of the zigzag circumferential groove, a groove depth D1a of the inner circumferential main groove, and a groove depth D1b of the outer circumferential main groove satisfy the relationships D<D1a<D1b and 0.5≦D / D1a≦0.8; 2. The tire of claim 1.

3. groove widths Wa and Wb of the inclined portions of the zigzag circumferential groove that are in opposite directions with respect to the bent portion, a groove width W1a of the inner circumferential main groove, and a groove width W1b of the outer circumferential main groove satisfy the relationship Wa<Wb<W1a<W1b, the groove widths Wa and Wb of the inclined portions satisfy the relationship 0.8≦Wa / Wb≦0.9, a groove width Wa of the narrow inclined portion and a groove width W1a of the inner circumferential main groove satisfy a relationship of 0.3≦Wa / W1a≦0.6, 2. The tire of claim 1.

4. The angle θ1 of the inner width direction groove with respect to the tire width direction and the angle θ2 of the outer width direction groove with respect to the tire width direction are in the ranges of 15 [deg]≦θ1≦40 [deg] and 15 [deg]≦θ2≦40 [deg], 2. The tire of claim 1.

5. an amplitude A1 in the tire width direction of a zigzag shape formed by each of the inclined portions facing in opposite directions of the zigzag circumferential groove and a dimension A in the tire width direction of the inner land portion satisfy a relationship of 0.2≦A1 / A≦0.5, lengths La and Lb in the tire circumferential direction of each of the inclined portions forming the amplitude A1 of the zigzag circumferential groove satisfy a relationship of 0.4≦Lb / La≦0.8; 2. The tire of claim 1.

6. groove widths Wa and Wb of the inclined portions of the zigzag circumferential groove in opposite directions with respect to the bent portion, a groove width W3 of the inner widthwise groove, a groove width W4 of the outer widthwise groove, and a groove width W5 of the lug groove satisfy the relationships Wa<Wb<W3<W4≦W5 and 1.5≦W4 / W3≦2.0, 2. The tire of claim 1.

7. a groove depth D of the zigzag circumferential groove, a groove depth D3 of the inner widthwise groove, a groove depth D4 of the outer widthwise groove, and a groove depth D5 of the lug groove satisfy the relationships D<D3<D4≦D5 and 1.1≦D4 / D3≦1.5, 2. The tire of claim 1.

8. an angle θ3 of the outer widthwise groove with respect to the tire circumferential direction and an angle θ4 of the lug groove with respect to the tire circumferential direction satisfy a relationship of θ3<θ4; 2. The tire of claim 1.

9. The tire is a winter tire or an all-season tire having sipes extending along the tire width direction in each of the land portions.

2. The tire of claim 1.

10. The direction relative to the vehicle width when installed is specified. the circumferential main grooves, the inner land portion, the outer land portion, the zigzag circumferential groove, the inner widthwise groove, the outer widthwise groove, and the lug grooves are arranged on the inner side in the vehicle width direction with respect to the tire equatorial plane; 2. The tire of claim 1.

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