tire

Abstract

To improve abrasion resistance while securing on-ice and-snow performance and wet performance.SOLUTION: A pneumatic tire 1 includes: a circumferential main groove 31 formed linearly along a tire circumferential direction; a circumferential groove 32, formed along the tire circumferential direction, in which an inclining part 32A inclining in a predetermined direction with respect to the tire circumferential direction extends zigzag in the tire circumferential direction; a circumferential auxiliary groove 33, formed between the circumferential groove 32 and the circumferential main groove 31, which is made adjacent in a tire width direction to the inclining part 32A and inclines in an opposite direction of the tire circumferential direction with respect to the inclining part 32A; width-directional connection grooves 34 connecting respective ends 32Aa and 33a of the inclining part 32A and the circumferential auxiliary groove 33 and partitioning blocks extending continuously in the tire circumferential direction; and width-directional auxiliary grooves 35 which connect a center part of the circumferential auxiliary groove 33 to the circumferential main groove 31 and are arranged so as not to match the width-directional connection grooves 34.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 block-shaped land portions defined by circumferential grooves extending in the tire circumferential direction, narrow circumferential grooves extending in the tire circumferential direction, and a plurality of lug grooves extending in the tire width direction, and the circumferential grooves and narrow circumferential grooves are formed in a zigzag shape having long and short portions of relatively different lengths by extending in the tire circumferential direction and oscillating in the tire width direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 025172 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 includes a circumferential main groove formed in a straight line along the tire circumferential direction; a circumferential groove formed along the tire circumferential direction and having inclined portions inclined in a predetermined direction with respect to the tire circumferential direction that continue in a zigzag pattern around the tire; a circumferential auxiliary groove provided between the circumferential groove and the circumferential main groove, adjacent to the inclined portion in the tire width direction and inclined in the opposite direction to the tire circumferential direction; a widthwise connecting groove connecting both ends of the inclined portion and the circumferential auxiliary groove to define blocks that are continuous in the tire circumferential direction; and a widthwise auxiliary groove that connects a center portion of the circumferential auxiliary groove to the circumferential main groove and is positioned misaligned with the widthwise connecting groove. [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 a partially enlarged view of a tread portion of a 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 a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 6] FIG. 6 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 7] FIG. 7 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 radially outermost portion of the tire when viewed in a meridian cross section of the tire. The tread portion 2 has 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 in motion, is formed as a tread contact surface 3. The tread contact surface 3 forms part of the contour of the pneumatic tire 1. The tread portion 2 has shoulder portions 5 formed at both outer ends in the tire width direction.

[0013] The sidewall portions 8 are arranged on both sides of the tread portion 2 in the tire width direction and on the inner side in the tire radial direction of the shoulder portions 5. 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.

[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 4 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° to 55°). 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, between 0° and 10°). 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-layer 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 3 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 in the tread contact surface 3 when the tire is mounted on a specified rim, inflated to a specified internal pressure, and in an unloaded state. In addition, in a configuration in which the groove opening has a notch or chamfer, the groove width is measured using the intersection of an extension of the tread contact surface 3 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 3 to the groove bottom when the tire is mounted on a specified rim, inflated to a specified internal pressure, and under no load. In addition, 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, a pneumatic tire 1 of the embodiment mainly includes a circumferential main groove 31 and a circumferential groove 32 as a tread pattern.

[0026] The circumferential main grooves 31 extend along the tire circumferential direction and have an annular structure that is continuously provided around the entire tire circumference. Two circumferential main grooves 31 are provided in parallel in the tire width direction with the tire equatorial plane CL sandwiched between them. The circumferential main grooves 31 are defined as grooves that are required to display a wear indicator as specified by JATMA. In this embodiment, as shown in FIG. 4, the circumferential main grooves 31 have a groove width W5 of 4.0 mm or more and 15.0 mm or less, and a groove depth d5 ​​of 6.0 mm or more and 10.0 mm or less.

[0027] The circumferential groove 32 has an annular structure extending along the tire circumferential direction and continuously provided around the entire tire circumference. Two circumferential grooves 32 are provided in parallel in the tire width direction, on the tire widthwise inner side of the two circumferential main grooves 31, with the tire equatorial plane CL sandwiched between them. As shown in FIG. 3 , the circumferential groove 32 is formed in a continuous zigzag pattern along the tire circumferential direction by connecting inclined portions 32A inclined in a predetermined direction with respect to the tire circumferential direction at their ends 32Aa. Each inclined portion 32A is provided linearly along the tire circumferential direction without any bends, and a plurality of inclined portions are provided side by side in the tire circumferential direction. The zigzag degree formed by each inclined portion 32A (the offset dimension of the connecting portion of the inclined portions / the length of the inclined portion) is set to a relationship of 0.05 to 0.15. In the embodiment, the inclined portion 32A of the circumferential groove 32 has an inclination angle α with respect to the tire circumferential direction shown in Fig. 3, where the angle α1 in one direction is in the range of -20°≦α1(α)≦-3°, and the angle α2 in the opposite direction is in the range of 3°≦α2(α)≦20°. In this manner, the circumferential groove 32 is provided with the inclined portion 32A inclined in a predetermined direction with respect to the tire circumferential direction. In the embodiment, as shown in Fig. 4, the circumferential groove 32 has a groove width W1 of 3.0 mm or more and 10.0 mm or less and a groove depth d1 of 6.0 mm or more and 10.0 mm or less.

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

[0029] In the pneumatic tire 1, a circumferential auxiliary groove 33, a widthwise connecting groove 34, and a widthwise auxiliary groove 35 are formed in the second land portion 22. In addition, in the pneumatic tire 1, lug grooves 36 are formed in the shoulder land portion 23. In addition, in the pneumatic tire 1, sipes 37 are formed in the land portion 20.

[0030] The circumferential auxiliary groove 33 is provided in the second land portion 22 between the circumferential main groove 31 and the circumferential groove 32. The circumferential auxiliary groove 33 is provided mainly in a straight line without any bends along the tire circumferential direction, and a plurality of circumferential auxiliary grooves 33 are provided side by side in the tire circumferential direction. One circumferential auxiliary groove 33 is provided adjacent to each inclined portion 32A of the circumferential groove 32 in the tire width direction. The circumferential auxiliary groove 33 is provided such that both ends 33a terminate inside the second land portion 22. The circumferential auxiliary groove 33 is provided so as to be inclined in the opposite direction to the inclined portion 32A with respect to the tire circumferential direction. In this embodiment, the circumferential auxiliary groove 33 has an inclination angle β with respect to the tire circumferential direction shown in FIG. 3, where the angle β1 in one direction is in the range of 3°≦β1(β)≦30°, and the angle β2 in the opposite direction is in the range of −30°≦α≦−3°. In this way, the circumferential auxiliary groove 33 is provided so as to be inclined in the opposite direction relative to the tire circumferential direction to the inclined portion 32A of the circumferential groove 32. In the embodiment, as shown in Fig. 4, the circumferential auxiliary groove 33 has a groove width W2 of 1.5 mm or more and 6.0 mm or less, and a groove depth d2 of 3.0 mm or more and 7.0 mm or less.

[0031] The widthwise connecting grooves 34 are provided in the second land portion 22 mainly in a straight line without any bends along the tire width direction, with multiple widthwise connecting grooves 34 lined up in the tire circumferential direction. Each widthwise connecting groove 34 is inclined in a predetermined direction with respect to the tire width direction and is provided parallel to each other. Each widthwise connecting groove 34 is provided connecting both ends 32Aa of the inclined portion 32A of the circumferential groove 32 to both ends 33a of the circumferential auxiliary groove 33. Each widthwise connecting groove 34 is provided so that its own ends 34a, which connect to the ends 32Aa of the inclined portion 32A and the ends 33a of the circumferential auxiliary groove 33, terminate inside the second land portion 22. The provision of the widthwise connecting grooves 34 forms a trapezoidal block-shaped first small land portion 22A inside the second land portion 22 by one inclined portion 32A of the circumferential groove 32, one circumferential auxiliary groove 33, and two widthwise connecting grooves 34 lined up in the tire circumferential direction and connecting the both ends 34a, 33a. A plurality of first land portions 22A are provided continuously in the tire circumferential direction, with the widthwise connecting groove 34 as a boundary. In the embodiment, as shown in Fig. 4, the widthwise connecting groove 34 has a groove width W3 of 1.5 mm or more and 5.0 mm or less, and a groove depth d3 of 4.0 mm or more and 9.0 mm or less.

[0032] The widthwise auxiliary grooves 35 are provided in the second land portion 22 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 auxiliary groove 35 is inclined in a predetermined direction with respect to the tire width direction and is provided parallel to each other. Each widthwise auxiliary groove 35 is provided parallel to each widthwise connecting groove 34. Each widthwise auxiliary groove 35 is provided connecting the center of each circumferential auxiliary groove 33 to the circumferential main groove 31. Each widthwise auxiliary groove 35 is provided so that its both ends 35a, which connect to the center of each circumferential auxiliary groove 33 and the circumferential main groove 31, terminate inside the second land portion 22. Because the widthwise auxiliary groove 35 connects to the center of the circumferential auxiliary groove 33, it is not directly connected to the widthwise connecting groove 34 that connects to the end 33a of the circumferential auxiliary groove 33 and is arranged misaligned. By providing the widthwise auxiliary grooves 35, a block-shaped second small land portion 22B having two bends on the opposing side of the circumferential main groove 31 is formed inside the second land portion 22 by the circumferential main groove 31, two circumferential auxiliary grooves 33 aligned in the tire circumferential direction, a part of the widthwise connecting groove 34 connecting these grooves, and two widthwise auxiliary grooves 35 aligned in the tire circumferential direction. A plurality of second small land portions 22B are provided consecutively in the tire circumferential direction, with the widthwise auxiliary groove 35 as a boundary. In this embodiment, as shown in FIG. 4, the widthwise auxiliary groove 35 has a groove width W4 of 2.0 mm or more and 7.0 mm or less, and a groove depth d4 of 6.0 mm or more and 10.0 mm or less.

[0033] The lug grooves 36 are provided in the shoulder land portions 23 mainly in a straight or arc-shaped manner along the tire width direction without any bends, and multiple lug grooves 36 are provided side by side in the tire circumferential direction. Each lug groove 36 is provided parallel to one another. One end 36a of each lug groove 36 is connected to the circumferential main groove 31. The ends 36a, 35a of each lug groove 36 and each width-direction auxiliary groove 35, which connect to opposite sides of the circumferential main groove 31 in the tire width direction, do not face each other and are arranged misaligned in the tire circumferential direction. Each lug groove 36 and each width-direction auxiliary groove 35 are arranged alternately in the tire circumferential direction. Note that when the groove position relationship between the lug grooves 36 and the width-direction auxiliary grooves 35 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%. In the embodiment, the lug grooves 36 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 3.

[0034] The sipes 37 are provided throughout the land portion 20, including the center land portion 21, the second land portion 22, and the shoulder land portions 23. The sipes 37 extend mainly along the tire width direction, and multiple sipes are provided side by side in the tire circumferential direction. The sipes 37 are formed in a zigzag or wavy shape by repeatedly bending and vibrating in the tire circumferential direction. The ends of each sipe 37 may terminate inside the land portion 20, or may be connected to other grooves as described above and open. By arranging the sipes 37 in the land portions 20 in this manner, the pneumatic tire 1 of the embodiment can be used as a studless tire that ensures driving performance on icy and snowy roads, or as an all-season tire that ensures driving performance in winter.

[0035] The sipes 37 are formed in the shape of narrow grooves 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 may 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 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. In this embodiment, the sipes 37 have a groove width of 1.0 mm or less and a groove depth of 1.5 mm to 9.0 mm.

[0036] The sipes 37 may be so-called three-dimensional sipes or two-dimensional sipes. The three-dimensional sipes referred to here are sipes 37 that have curved wall surfaces with amplitude in the width direction of the sipe 37 in both a cross-sectional view in which the length direction of the sipe 37 is the normal direction (a cross-sectional view including the width direction and depth direction of the sipe 37) and a cross-sectional view in which the depth direction of the sipe 37 is the normal direction (a cross-sectional view including the width direction and length direction of the sipe 37). The two-dimensional sipes refer to sipes 37 that have straight wall surfaces in any cross-sectional view in which the length direction of the sipe 37 is the normal direction (a cross-sectional view including the width direction and depth direction of the sipe 37).

[0037] The pneumatic tire 1 of the embodiment does not have any grooves other than the grooves 31, 32, 33, 34, 35, 36 and sipes 37 described above.

[0038] The pneumatic tire 1 of the embodiment has a symmetrical tread pattern with respect to the tire equatorial plane CL. In the pneumatic tire 1 of the embodiment, the inclined portions 32A of the circumferential grooves 32 and the circumferential auxiliary grooves 33 are inclined in opposite directions, and the first land portions 22A have a side where they converge and a side where they diverge in the tire circumferential direction. The pneumatic tire 1 of the embodiment defines the rotational direction so that the side where the inclined portions 32A of the circumferential grooves 32 and the circumferential auxiliary grooves 33 converge is the leading side (or toe side) and the side where they diverge is the trailing side (or heel side), thereby achieving a significant traction effect on icy and snowy road surfaces. The defined rotational direction is defined as the rotational direction of the vehicle when mounted on the vehicle and moving forward. The rotational direction is indicated by the pneumatic tire 1 having a rotational direction indicator (not shown) that indicates the tire rotational direction. The rotation direction indicator is configured by, for example, a mark or a concave or convex portion provided on the sidewall portion 8 of the pneumatic tire 1.

[0039] 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 part of the tread contact surface 3 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 3 and the road surface.

[0040] Furthermore, when driving on a wet road surface, water between the tread contact surface 3 and the road surface enters each of the grooves 31, 32, 33, 34, 35, 36 and the sipes 37, and the water is drained from between the tread contact surface 3 and the road surface while driving. This makes it easier for the tread contact surface 3 to make contact with the road surface, and the friction between the tread contact surface 3 and the road surface provides wet performance, enabling the vehicle to drive.

[0041] 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 31, 32, 33, 34, 35, and 36 as it enters them. 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, 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.

[0042] Furthermore, when traveling on snowy or icy road surfaces, the tire also utilizes the edge effect of the grooves 31, 32, 33, 34, 35, and 36 and the sipes 37. 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, 33, 34, 35, and 36 and the sipes 37 catching on the snow or ice surface. Furthermore, when traveling on icy road surfaces, the sipes 37 absorb water on the surface of the icy road, removing the water film between the icy road surface and the tread contact surface 3, making it easier for the icy road surface and the tread contact surface 3 to come into contact. As a result, the resistance between the tread contact surface 3 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.

[0043] The grooves 31, 32, 33, 34, 35, 36 and sipes 37 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 3 and the road surface and improving wet performance.

[0044] Increasing the groove area also effectively improves 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, 33, 34, 35, and 36 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.

[0045] 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, 33, 34, 35, and 36 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.

[0046] For example, when driving on an icy road surface, in addition to the edge effect due to the edge components of the grooves, the frictional force caused by the tread contact surface 3 contacting the icy road surface is also important. However, if the rigidity of the land portions 20 is reduced by increasing the groove area of ​​the tread portion 2, the land portions 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 portions 20 is reduced by increasing the groove area of ​​the tread portion 2, the land portions 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.

[0047] The pneumatic tire 1 of the embodiment is characterized by including a circumferential main groove 31 formed in a straight line along the tire circumferential direction, a circumferential groove 32 formed along the tire circumferential direction and having inclined portions 32A inclined in a predetermined direction with respect to the tire circumferential direction that continue in a zigzag pattern around the tire circumferential direction, a circumferential auxiliary groove 33 provided between the circumferential groove 32 and the circumferential main groove 31, adjacent to the inclined portion 32A in the tire width direction and inclined in the opposite direction to the tire circumferential direction of the inclined portion 32A, a widthwise connecting groove 34 connecting both ends 32Aa, 33a of the inclined portion 32A and the circumferential auxiliary groove 33 to define blocks that are continuous in the tire circumferential direction, and a widthwise auxiliary groove 35 connecting the center of the circumferential auxiliary groove 33 to the circumferential main groove 31 and arranged misaligned with the widthwise connecting groove 34.

[0048] According to the pneumatic tire 1 of the embodiment, the circumferential grooves 32 are zigzag-shaped to ensure sufficient edge volume and improve ice performance, while the circumferential auxiliary grooves 33 are provided in the opposite direction to the zigzag grooves, 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 circumferential grooves 32 and the circumferential auxiliary grooves 33 are connected by widthwise connecting grooves 34, and the circumferential auxiliary grooves 33 and the circumferential main grooves 31 are connected by widthwise auxiliary grooves 35, thereby improving drainage and wet performance. Furthermore, according to the pneumatic tire 1 of the embodiment, the widthwise auxiliary grooves 35 are not aligned with the widthwise connecting grooves 34, thereby suppressing a decrease in rigidity of the land portions 20 (second land portions 22) 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.

[0049] In the pneumatic tire 1 of the embodiment, the circumferential auxiliary grooves 33 are preferably formed in a straight line without any bends. For example, bends increase the edge amount, but on the other hand, this can cause a decrease in the rigidity of the land portion 20 (second land portion 22). In this regard, according to the pneumatic tire 1, the edge amount is ensured by the zigzag-shaped circumferential grooves 32, and the circumferential auxiliary grooves 33 are formed in a straight line, thereby preventing a decrease in the rigidity of the land portion 20 (second land portion 22) and improving wear resistance.

[0050] In addition, in the pneumatic tire 1 of the embodiment, the widthwise auxiliary grooves 35 connected to the circumferential main grooves 31 do not face the lug grooves 36 connected to the opposite side of the circumferential main grooves 31 in the tire width direction, and are arranged misaligned with each other in the tire circumferential direction.

[0051] According to this pneumatic tire 1, by making the widthwise auxiliary grooves 35 not coincide with the lug grooves 36 that are separated by the circumferential main grooves 31, a decrease in rigidity of the land portion 20 (second land portion 22) is suppressed, and wear resistance is improved.

[0052] In addition, in the pneumatic tire 1 of the embodiment, the widthwise connecting groove 34 connects to the circumferential groove 32 and the circumferential auxiliary groove 33, and terminates inside the land portion 20 (second land portion 22) defined by the circumferential main groove 31 and the circumferential groove 32.

[0053] According to this pneumatic tire 1, the widthwise connecting grooves 34 terminate, thereby suppressing a decrease in rigidity of the land portion 20 (second land portion 22) and improving wear resistance.

[0054] In the pneumatic tire 1 of the embodiment, the angle α of the inclined portion 32A relative to the tire circumferential direction is in the range of −20°≦α≦−3° or 3°≦α≦20°.

[0055] With this pneumatic tire 1, when the angle α of the inclined portion 32A 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 32A 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.

[0056] In the pneumatic tire 1 of the embodiment, the angle β of the circumferential auxiliary groove 33 relative to the tire circumferential direction is in the range of 3°≦β≦30° or −30°≦α≦−3°.

[0057] With this pneumatic tire 1, when the angle β of the circumferential auxiliary groove 33 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 33 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.

[0058] In the pneumatic tire 1 of the embodiment, the groove depth d1 of the inclined portion 32A and the groove depth d2 of the circumferential auxiliary groove 33 satisfy the relationship 0.5≦d2 / d1≦0.7.

[0059] According to this pneumatic tire 1, when d2 / d1 is 0.5 or more, sufficient groove depth can be ensured and water drainage is achieved, improving wet performance. Also, according to this pneumatic tire 1, when d2 / d1 is 0.7 or less, a decrease in block rigidity is suppressed and wear resistance is ensured. By setting d2 / d1 preferably within the range of 0.55≦d2 / d1≦0.65, both wet performance and wear resistance can be achieved.

[0060] In the pneumatic tire 1 of the embodiment, the groove depth d1 of the inclined portion 32A and the groove depth d3 of the widthwise connecting groove 34 satisfy the relationship 0.7≦d3 / d1≦0.9.

[0061] According to this pneumatic tire 1, when d3 / d1 is 0.7 or more, sufficient groove depth can be ensured and water drainage is achieved, improving wet performance. Also, according to this pneumatic tire 1, when d3 / d1 is 0.9 or less, a decrease in block rigidity is suppressed and wear resistance is ensured. By setting d3 / d1 preferably within the range of 0.75≦d3 / d1≦0.85, both wet performance and wear resistance can be achieved.

[0062] In the pneumatic tire 1 of the embodiment, the groove width W1 of the inclined portion 32A and the groove width W2 of the circumferential auxiliary groove 33 are in the ranges of 3.0 mm≦W1≦10.0 mm and 1.5 mm≦W2≦6.0 mm.

[0063] With this pneumatic tire 1, when W1 is 3.0 mm or more and W2 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 W1 is 10.0 mm or less and W2 is 6.0 mm or less, a decrease in block rigidity is suppressed and wear resistance is ensured.

[0064] In the pneumatic tire 1 of the embodiment, the groove width W3 of the widthwise connecting groove 34 and the groove width W4 of the widthwise auxiliary groove 35 are in the ranges of 1.5 mm≦W3≦5.0 mm and 2.0 mm≦W4≦7.0 mm.

[0065] With this pneumatic tire 1, when W3 is 1.5 mm or more and W4 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 W3 is 5.0 mm or less and W4 is 7.0 mm or less, a decrease in block rigidity is suppressed and wear resistance is ensured.

[0066] In the pneumatic tire 1 of the embodiment, a plurality of sipes 37 extending along the tire width direction are arranged in the second land portion 22 defined by the circumferential groove 32 and the circumferential main groove 31 .

[0067] According to this pneumatic tire 1, the arrangement of the sipes 37 can improve performance on ice, and the tire can be applied to a studless tire or an all-season tire.

[0068] In the pneumatic tire 1 of the embodiment, the sipes 37 are arranged parallel to at least one of the widthwise connecting grooves 34 and the widthwise auxiliary grooves 35 .

[0069] According to this pneumatic tire 1, the sipes 37 are arranged in parallel with the widthwise connecting grooves 34 and the widthwise auxiliary grooves 35, thereby aligning the edge components and improving snow and ice performance.

[0070] 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]

[0071] 5 to 7 are tables showing the results of performance tests of pneumatic tires according to the embodiment. Performance evaluation tests conducted on a conventional pneumatic tire, a comparative 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.

[0072] 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.

[0073] To evaluate ice performance, a test vehicle fitted with the test tires is subjected to a braking test on an icy test course, and the braking distance is measured. Based on the results of these tests, the reciprocal of the tire's braking distance is used to evaluate the tire's performance, with the conventional tire being used as the benchmark (100). The higher the evaluation value, the better.

[0074] The evaluation test for snow performance involves braking tests on a test vehicle fitted with test tires on a snowy test course, measuring the braking distance. Based on the results of these tests, the reciprocal of the tire's braking distance 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.

[0075] To evaluate wet performance, a test vehicle fitted with the test tire is subjected to a braking test on a test course with a wet road surface in 1mm of water, and the braking distance is measured. Based on the results of this test, an index is calculated using the reciprocal of the tire's braking distance, with the conventional tire being used as the standard (100). The higher the index value, the better, and a value of 97 or higher is desirable in terms of achieving both good wear resistance and good braking performance.

[0076] 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.

[0077] The conventional pneumatic tire has a straight circumferential main groove, a zigzag circumferential groove, a circumferential auxiliary groove, a widthwise connecting groove, and a widthwise auxiliary groove, and the circumferential groove and the circumferential auxiliary groove are inclined in opposite directions, but the widthwise auxiliary groove is aligned with the widthwise connecting groove.

[0078] The comparative example pneumatic tire has a straight circumferential main groove, a zigzag circumferential groove, a circumferential auxiliary groove, a widthwise connecting groove, and a widthwise auxiliary groove, and the widthwise auxiliary groove does not coincide with the widthwise connecting groove, but the circumferential groove and the circumferential auxiliary groove are inclined in the same direction.

[0079] The pneumatic tire of the embodiment has a straight circumferential main groove, a zigzag circumferential groove, a circumferential auxiliary groove, a widthwise connecting groove, and a widthwise auxiliary groove, and the circumferential groove and the circumferential auxiliary groove are inclined in opposite directions, and the circumferential groove and the circumferential auxiliary groove are inclined in the same direction.

[0080] 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 example and comparative example.

[0081] The present disclosure includes the following inventions. [Invention 1] a circumferential main groove formed linearly along the tire circumferential direction; a circumferential groove formed along the tire circumferential direction, in which inclined portions inclined in a predetermined direction with respect to the tire circumferential direction are continuous in a zigzag pattern in the tire circumferential direction; a circumferential auxiliary groove provided between the circumferential groove and the circumferential main groove, adjacent to the inclined portion in the tire width direction, and inclined in the opposite direction to the inclined portion with respect to the tire circumferential direction; a widthwise connecting groove that connects both ends of the inclined portion and the circumferential auxiliary groove to define a block that is continuous in the tire circumferential direction; a width-direction auxiliary groove that connects a center portion of the circumferential auxiliary groove and the circumferential main groove and is arranged misaligned with the width-direction connecting groove; Including, tire. [Invention 2] the width direction auxiliary grooves connected to the circumferential main grooves do not face lug grooves connected to the opposite sides of the circumferential main grooves in the tire width direction, and are arranged misaligned with each other in the tire circumferential direction; A tire according to invention 1. [Invention 3] the widthwise connecting groove is connected to the circumferential groove and the circumferential auxiliary groove, and terminates inside a land portion defined by the circumferential main groove and the circumferential groove; The tire according to claim 1 or 2. [Invention 4] The inclined portion has an angle α with respect to the tire circumferential direction in the range of −20°≦α≦−3° or 3°≦α≦20°. A tire according to any one of inventions 1 to 3. [Invention 5] The circumferential auxiliary groove has an angle β with respect to the tire circumferential direction in the range of 3°≦β≦30° or −30°≦α≦−3°. A tire according to any one of inventions 1 to 4. [Invention 6] a groove depth d1 of the inclined portion and a groove depth d2 of the circumferential auxiliary groove satisfy the relationship 0.5≦d2 / d1≦0.7; A tire according to any one of inventions 1 to 5. [Invention 7] a groove depth d1 of the inclined portion and a groove depth d3 of the width-direction connecting groove satisfy the relationship 0.7≦d3 / d1≦0.9; A tire according to any one of inventions 1 to 6. [Invention 8] The groove width W1 of the inclined portion and the groove width W2 of the circumferential auxiliary groove are in the ranges of 3.0 mm ≦ W1 ≦ 10.0 mm and 1.5 mm ≦ W2 ≦ 6.0 mm, A tire according to any one of inventions 1 to 7. [Invention 9] The groove width W3 of the width-direction connecting groove and the groove width W4 of the width-direction auxiliary groove are in the ranges of 1.5 mm ≦ W3 ≦ 5.0 mm and 2.0 mm ≦ W4 ≦ 7.0 mm, A tire according to any one of inventions 1 to 8. [Invention 10] a plurality of sipes extending along the tire width direction are arranged in a land portion defined by the circumferential groove and the circumferential main groove; A tire according to any one of claims 1 to 9. [Invention 11] The sipes are arranged parallel to at least one of the widthwise connecting grooves and the widthwise auxiliary grooves. A tire according to invention 10. [Explanation of symbols]

[0082] 1. Pneumatic tires (tires) 31 Circumferential main groove 32 Circumferential groove 32A Slope 32Aa end 33 Circumferential auxiliary groove 33a edge 34 Width direction connection groove 35 Width direction auxiliary groove 36 Lug groove 37 Sipe W1 Groove width W2 groove width W3 Groove width W4 groove width α angle β angle

Claims

1. a circumferential main groove formed linearly along the tire circumferential direction; a circumferential groove formed along the tire circumferential direction, in which inclined portions inclined in a predetermined direction with respect to the tire circumferential direction are continuous in a zigzag pattern in the tire circumferential direction; a circumferential auxiliary groove that is provided linearly without a bent portion between the circumferential groove and the circumferential main groove, adjacent to the inclined portion in the tire width direction, and inclined in the opposite direction to the inclined portion with respect to the tire circumferential direction; a widthwise connecting groove that connects both ends of the inclined portion and the circumferential auxiliary groove to define a block that is continuous in the tire circumferential direction; a width-direction auxiliary groove that connects a center portion of the circumferential auxiliary groove and the circumferential main groove and is arranged misaligned with the width-direction connecting groove; Including, tire.

2. the width direction auxiliary grooves connected to the circumferential main grooves do not face lug grooves connected to the opposite sides of the circumferential main grooves in the tire width direction, and are arranged misaligned with each other in the tire circumferential direction; 2. The tire of claim 1.

3. the widthwise connecting groove is connected to the circumferential groove and the circumferential auxiliary groove, and terminates inside a land portion defined by the circumferential main groove and the circumferential groove; 2. The tire of claim 1.

4. the inclined portion has an angle α with respect to the tire circumferential direction in the range of −20°≦α≦−3° or 3°≦α≦20°; 2. The tire of claim 1.

5. the circumferential auxiliary groove has an angle β with respect to the tire circumferential direction in the range of 3°≦β≦30° or −30°≦α≦−3°; 2. The tire of claim 1.

6. a groove depth d1 of the inclined portion and a groove depth d2 of the circumferential auxiliary groove satisfy a relationship of 0.5≦d2 / d1≦0.7; 2. The tire of claim 1.

7. a groove depth d1 of the inclined portion and a groove depth d3 of the width-direction connecting groove satisfy the relationship 0.7≦d3 / d1≦0.9; 2. The tire of claim 1.

8. a groove width W1 of the inclined portion and a groove width W2 of the circumferential auxiliary groove are in the ranges of 3.0 mm≦W1≦10.0 mm and 1.5 mm≦W2≦6.0 mm, 2. The tire of claim 1.

9. a groove width W3 of the width-direction connecting groove and a groove width W4 of the width-direction auxiliary groove are in the ranges of 1.5 mm≦W3≦5.0 mm and 2.0 mm≦W4≦7.0 mm, 2. The tire of claim 1.

10. a plurality of sipes extending along the tire width direction are arranged in a land portion defined by the circumferential groove and the circumferential main groove; 2. The tire of claim 1.

11. The sipes are arranged parallel to at least one of the widthwise connecting grooves and the widthwise auxiliary grooves.

11. The tire of claim 10.

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