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 a tire. [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, to improve performance on ice, it is necessary to improve adhesion friction, but to achieve this, methods such as reducing the groove area ratio to increase the actual contact area have been used, but this method has the drawback of worsening performance on snow and wet surfaces. In addition, improved wear resistance is also required for recent studless tires.

[0005] An object of the present invention is to provide a tire that can improve wear resistance while ensuring performance on snow and ice and wet conditions by optimizing the pattern configuration. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a tire according to one embodiment 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 an inclined portion inclined in a predetermined direction with respect to the tire circumferential direction that continues in a zigzag pattern along 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 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 arranged misaligned with the widthwise connecting groove. Effect 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 description of the drawings]

[0008] [Figure 1] FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment. [Diagram 2] FIG. 2 is a plan view of a tread portion of a pneumatic tire according to the embodiment. [Diagram 3] FIG. 3 is a partial enlarged view of a tread portion of the pneumatic tire according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA of FIG. [Diagram 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 PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, the components of this embodiment include those that can be substituted and are obvious to be substituted while maintaining the identity of the invention. In addition, the multiple modified examples described in this embodiment 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 a direction perpendicular to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1 of the embodiment, the tire radial inner side refers to the side facing the tire rotation axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to a direction around the tire rotation axis as the central axis. The tire width direction refers to a direction parallel to the tire rotation axis, the tire width inner side refers to the side facing the tire equatorial plane (tire equatorial 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 perpendicular to the tire rotation axis and passing through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides in position in the tire width direction with the tire width centerline which is the center position in the tire width direction of the pneumatic tire 1. The tire equatorial line refers to a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 1. Additionally, a cross section in the tire meridian direction (meridian section) refers to a cross section obtained by cutting the tire along 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 a tread rubber 4 made of a rubber composition. The surface of the tread portion 2, i.e., the portion that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 is running, 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 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 5. 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 inner side of each sidewall portion 8 in the tire radial direction. 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 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 ring shape. The bead filler 12 is a rubber member disposed on the outer side of the bead core 11 in the tire radial direction.

[0015] The pneumatic tire 1 has, as its internal structure, 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 materials such as polyester, rayon, and 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 (e.g., 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 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 (e.g., 0° to 10°). The belt cover 143 is formed, for example, by winding a strip material made of one or more belt cover cords covered with coating rubber in a spiral shape in the tire circumferential direction on the outer side in the tire radial direction of the two-layered belts 141 and 142.

[0019] The carcass layer 13 is disposed continuously on the tire radial inner side of the belt layer 14 in the tread portion 2, the sidewall portion 8, and the bead portion 10. The carcass layer 13 is wound around and engaged on the tire widthwise outer side so as to wrap the bead cores 11 and the bead fillers 12 of both bead portions 10 at both ends in the tire widthwise direction, and is wound around the tire circumferential direction 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 a plurality of carcass plies laminated together. The carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, or rayon with a coating rubber and rolling them. The carcass cords constituting the carcass ply are arranged in parallel at an angle to the tire circumferential direction while being aligned along the tire meridian direction.

[0020] A rim cushion rubber 17 is disposed on the tire radially inner side and tire widthwise outer side of the turnup portion of the carcass layer 13. The rim cushion rubber 17 constitutes 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 a 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] The specified rim refers to the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. The 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 in an unloaded state with the tire mounted on a specified rim and inflated to a specified internal pressure as the maximum distance between the opposing groove walls at the groove opening in the tread contact surface 3. In a configuration in which the groove opening has a notch or chamfer, the groove width is measured with the intersection of an extension of the tread contact surface 3 and an extension of the groove wall as an end point in a cross section parallel to the tire width direction and tire radial direction.

[0024] The groove depth is measured as the maximum distance from the tread contact surface 3 to the bottom of the groove 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 depth has a configuration in which partial unevenness or sipes are present at the bottom of the groove, 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 groove 31 has an annular structure that extends along the tire circumferential direction and is continuously provided around the entire tire circumference. The 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 stipulated by JATMA. In the embodiment, as shown in FIG. 4, the circumferential main groove 31 has 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 that extends along the tire circumferential direction and is continuously provided around the entire tire circumference. The circumferential groove 32 is provided in parallel in the tire width direction on the inner side of the two circumferential main grooves 31 in the tire width direction, sandwiching the tire equatorial plane CL between them. As shown in FIG. 3, the circumferential groove 32 is formed in a zigzag shape continuously along the tire circumferential direction by connecting the ends 32Aa of the inclined portions 32A inclined in a predetermined direction with respect to the tire circumferential direction. Each inclined portion 32A is provided in a straight line without a bend along the tire circumferential direction, and a plurality of inclined portions are provided side by side in the tire circumferential direction. The zigzag degree of each inclined portion 32A (shift dimension of the connection part of the inclined portion / 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, in which the angle α1 in one direction is in the range of -20°≦α1(α)≦-3°, and the angle α2 in the opposite other 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 has a center land portion 21, a second land portion 22, and a shoulder land portion 23. The center land portion 21 is formed in one rib-like row along the tire circumferential direction between the two circumferential grooves 32, 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 total of two rows, one rib-like row along the tire circumferential direction on both outer sides in the tire width direction of the center land portion 21. The shoulder land portion 23 is defined on the outer side in the tire width direction of each circumferential main groove 31, and is formed in a total of two rows, one rib-like row along the tire circumferential direction on the outer side in the tire width direction of each second land portion 22.

[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, a lug groove 36 is formed in the shoulder land portion 23. In addition, in the pneumatic tire 1, a sipe 37 is formed in the land portion 20.

[0030] The circumferential auxiliary groove 33 is provided between the circumferential main groove 31 and the circumferential groove 32 in the second land portion 22. The circumferential auxiliary groove 33 is provided mainly in a straight line without a bent portion along the tire circumferential direction, and a plurality of circumferential auxiliary grooves 33 are provided side by side in the tire circumferential direction. The circumferential auxiliary grooves 33 are provided adjacent to each of the inclined portions 32A of the circumferential grooves 32 in the tire width direction. The circumferential auxiliary grooves 33 are provided such that both ends 33a terminate inside the second land portion 22. The circumferential auxiliary grooves 33 are provided inclined in the opposite direction to the inclined portion 32A with respect to the tire circumferential direction. In the embodiment, the circumferential auxiliary groove 33 has an inclination angle β with respect to the tire circumferential direction shown in FIG. 3, in which the angle β1 in one direction is in the range of 3°≦β1(β)≦30°, and the angle β2 in the opposite other direction is in the range of -30°≦α≦-3°. In this way, the circumferential auxiliary groove 33 is provided inclined in the opposite direction to the tire circumferential direction of the inclined portion 32A of the circumferential groove 32. In the embodiment, 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, as shown in Fig. 4.

[0031] The widthwise connecting grooves 34 are provided in the second land portion 22 mainly in a straight line without bending portions along the tire width direction, and a plurality of widthwise connecting grooves 34 are provided side by side in the tire circumferential direction. Each widthwise connecting groove 34 is provided by connecting both ends 32Aa of the inclined portion 32A of the circumferential groove 32 and both ends 33a of the circumferential auxiliary groove 33. Each widthwise connecting groove 34 is provided such that both ends 34a thereof, 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. By providing the widthwise connecting grooves 34, a trapezoidal block-shaped first small land portion 22A is formed 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 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 width direction auxiliary grooves 35 are provided in the second land portion 22 mainly in a straight line without bending portions along the tire width direction, and a plurality of width direction auxiliary grooves 35 are provided in the tire circumferential direction. Each width direction auxiliary groove 35 is provided in parallel to each other, inclined in a predetermined direction with respect to the tire width direction. Each width direction auxiliary groove 35 is provided parallel to each width direction connecting groove 34. Each width direction auxiliary groove 35 is provided by connecting the center of each circumferential auxiliary groove 33 to the circumferential main groove 31. Each width direction auxiliary groove 35 is provided such that both ends 35a thereof connected to the center of each circumferential auxiliary groove 33 and the circumferential main groove 31 terminate inside the second land portion 22. Since the width direction auxiliary groove 35 is connected to the center of the circumferential auxiliary groove 33, it is arranged in a mismatched manner without being directly connected to the width direction connecting groove 34 connected to the end 33a of the circumferential auxiliary groove 33. By providing the width direction auxiliary groove 35, the circumferential main groove 31, the two circumferential auxiliary grooves 33 aligned in the tire circumferential direction, a part of the width direction connecting groove 34 connecting them, and the two width direction auxiliary grooves 35 aligned in the tire circumferential direction form a block-shaped second land portion 22B inside the second land portion 22. The second land portion 22B is provided in a plurality of consecutive positions in the tire circumferential direction, with the width direction auxiliary groove 35 as a boundary. In the embodiment, the width direction 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, as shown in FIG.

[0033] The lug grooves 36 are provided in the shoulder land portion 23 mainly in a straight or arc shape without a bend along the tire width direction, and a plurality of lug grooves are provided in the tire circumferential direction. The lug grooves 36 are provided in parallel to each other. One end 36a of each lug groove 36 is provided to be connected to the circumferential main groove 31. The lug grooves 36 and the width direction auxiliary grooves 35 are arranged so that their ends 36a, 35a connected to the opposite sides of the circumferential main groove 31 in the tire width direction do not face each other and are misaligned with each other in the tire circumferential direction. The lug grooves 36 and the width direction auxiliary grooves 35 are arranged alternately one by one in the tire circumferential direction. When the groove position relationship between the lug grooves 36 and the width direction auxiliary grooves 35 coincides with each other at the center of the groove width, which is 0% and 100%, the groove position relationship is in the range of 30% to 70%. In the embodiment, the lug groove 36 has 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 in the entire land portion 20 including the center land portion 21, the second land portion 22, and the shoulder land portion 23. The sipes 37 extend mainly along the tire width direction, and a plurality of sipes are provided in a row in the tire circumferential direction. The sipes 37 are formed in a zigzag or wavy shape by repeatedly bending and oscillating in the tire circumferential direction. The ends of each sipe 37 may terminate inside the land portion 20, or may be connected to the other grooves described above and open. The pneumatic tire 1 of the embodiment is applied to a studless tire that ensures driving performance on icy and snowy roads, or an all-season tire that ensures driving performance in winter, by arranging the sipes 37 in the land portion 20 in this way.

[0035] The sipes 37 are formed in the shape of narrow grooves on the tread contact surface 3, and when the pneumatic tire 1 is mounted on a specified rim and under a specified internal pressure condition, the wall surfaces constituting the narrow grooves may not come into contact with each other when no load is applied, but when the narrow grooves are located in a part of the contact surface formed on a flat plate when a load is applied vertically 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 portion 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 sipe 37 may be a so-called three-dimensional sipe or a two-dimensional sipe. The three-dimensional sipe is a sipe 37 having a curved wall surface with an 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 sipe is a sipe 37 having a straight wall surface 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 the 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 portion 32A of the circumferential groove 32 and the circumferential auxiliary groove 33 are inclined in opposite directions, and the first land portion 22A has a side where they narrow and a side where they widen in the tire circumferential direction. The pneumatic tire 1 of the embodiment can obtain a remarkable traction effect on an icy and snowy road surface by defining the rotation direction such that the side where the inclined portion 32A of the circumferential groove 32 and the circumferential auxiliary groove 33 narrow is the leading side (or toe side) and the side where they widen is the trailing side (or heel side). The definition of the rotation direction is defined as the rotation direction when the vehicle is mounted on the vehicle and the vehicle moves forward. The rotation direction is indicated by the pneumatic tire 1 having a rotation direction indicator (not shown) that indicates the tire rotation direction. The indication of the rotation direction is configured by, for example, a mark or an unevenness provided on the sidewall portion 8 of the pneumatic tire 1.

[0039] When the pneumatic tire 1 according to this embodiment is mounted on a vehicle, the pneumatic tire 1 is mounted on a rim wheel and inflated with air inside. When a vehicle equipped with the pneumatic tire 1 runs, the pneumatic tire 1 rotates while the lower tread contact surface 3 of the tread portion 2 comes into contact with the road surface. When a vehicle equipped 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] In addition, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters each of the grooves 31, 32, 33, 34, 35, 36 and the sipes 37, and the water between the tread surface 3 and the road surface is drained while traveling. This makes it easier for the tread surface 3 to come into contact with the road surface, and the friction between the tread surface 3 and the road surface provides wet performance, enabling the vehicle to travel.

[0041] In addition, when traveling on a snowy road surface, the pneumatic tire 1 compacts the snow on the road surface with the tread contact surface 3, and the snow on the road surface enters each groove 31, 32, 33, 34, 35, 36, so that the snow is also compacted in the grooves. In this state, when a driving force or braking force acts on the pneumatic tire 1, or when a force acts in the tire width direction due to the turning of the vehicle, a shear force acting on the snow in the grooves, so-called snow column shear force, is generated between the pneumatic tire 1 and the snow. When traveling on a snowy road surface, this snow column shear force generates resistance between the pneumatic tire 1 and the road surface, so that the driving force and braking force can be transmitted to the road surface, snow traction can be ensured, and snow performance can be achieved. This allows the vehicle to travel on a snowy road surface.

[0042] In addition, when traveling on a snowy road surface or an icy road surface, the vehicle also uses the edge effect of each groove 31, 32, 33, 34, 35, 36 and the sipes 37. That is, when traveling on a snowy road surface or an icy road surface, the vehicle also uses the resistance caused by the edges of each groove 31, 32, 33, 34, 35, 36 and the sipes 37 catching on the snowy or icy surface. In addition, when traveling on an icy road surface, the sipes 37 absorb water on the surface of the icy road surface, and the water film between the icy road surface and the tread contact surface 3 is removed, so that the icy road surface and the tread contact surface 3 can easily come into contact with each other. As a result, the resistance between the tread contact surface 3 and the icy road surface increases due to frictional force and edge effect, and the vehicle has ice performance. This allows the vehicle to travel on an icy road surface.

[0043] Since the grooves 31, 32, 33, 34, 35, 36 and sipes 37 formed in the tread portion 2 contribute to ensuring running performance when running on wet road surfaces, snowy road surfaces, and icy road surfaces, for example, in order to improve wet performance, which is running performance on wet road surfaces, it is effective to increase the groove area of ​​the tread portion 2. In other words, when the groove area of ​​the grooves 31, 32, 33, 34, 35, 36, etc. is increased, water on the road surface easily enters the grooves when running on a wet road surface, so that the drainage of water between the tread contact surface 3 and the road surface can be improved, and the wet performance can be improved.

[0044] Increasing the groove area is also effective in improving snow performance, which is the driving performance on snowy roads. In other words, when the groove area is increased, the amount of snow that can be put into each groove 31, 32, 33, 34, 35, 36 when driving on a snowy road can be increased, and the snow column shear force acting on the snow that has entered the groove can be increased. This improves snow traction when driving on a snowy road, and improves snow performance.

[0045] Here, when the groove area of ​​the tread portion 2 is increased, the volume of the land portion 20 defined by each of the grooves 31, 32, 33, 34, 35, 36 decreases with the increase in the groove area. When the volume of the land portion 20 decreases, the rigidity of the land portion 20 decreases, and when the rigidity of the land portion 20 decreases, the land portion 20 becomes more likely to deform and collapse when a load is applied. When the land portion 20 collapses, the contact area of ​​the collapsed land portion 20 decreases, so that it may become difficult to ensure driving performance.

[0046] For example, when traveling 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 touching 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 is likely to collapse when a load is applied, which may lead to a reduction in the contact area and make it difficult to ensure the running performance due to the frictional force. For this reason, if the rigidity of the land portion 20 is reduced by increasing the groove area of ​​the tread portion 2, the land portion 20 is likely to collapse when braking while traveling on an icy road surface, which may lead to a reduction in the contact area and make it difficult to ensure the braking performance on the 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 along 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 that connects a central portion of the circumferential auxiliary groove 33 to the circumferential main groove 31 and is arranged misaligned with the widthwise connecting groove 34.

[0048] According to the pneumatic tire 1 of the embodiment, the circumferential groove 32 is zigzag-shaped to ensure the edge amount and obtain the performance on ice, while the circumferential auxiliary groove 33 is provided in the opposite direction to the zigzag groove to improve the shear force in snow without the snow traction index (STI) component being biased to a specific angle. Also, according to the pneumatic tire 1 of the embodiment, the circumferential groove 32 and the circumferential auxiliary groove 33 are connected by the widthwise connecting groove 34, and the circumferential auxiliary groove 33 and the circumferential main groove 31 are connected by the widthwise auxiliary groove 35, so that the drainage can be improved and the wet performance can be improved. Also, according to the pneumatic tire 1 of the embodiment, the widthwise auxiliary groove 35 is not aligned with the widthwise connecting groove 34, so that the decrease in rigidity of the land portion 20 (second land portion 22) is suppressed and the wear resistance is improved. As a result, the pneumatic tire 1 of the embodiment can improve the wear resistance while ensuring the snow and ice performance and the wet performance.

[0049] In the pneumatic tire 1 of the embodiment, the circumferential auxiliary groove 33 is preferably formed in a straight line without a bent portion. For example, a bent portion increases the edge amount, but on the other hand, this may 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 groove 32, and the circumferential auxiliary groove 33 is formed in a straight line, thereby preventing a decrease in the rigidity of the land portion 20 (second land portion 22) and improving the 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 bordered 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 groove 34 terminates, so that a decrease in rigidity of the land portion 20 (second land portion 22) is suppressed, and wear resistance is improved.

[0054] In the pneumatic tire 1 of the embodiment, the inclined portion 32A has an angle α with respect to the tire circumferential direction 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. Also, 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 large inclination is suppressed, and wet performance is ensured. By setting the angle α within the range of preferably 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 with respect 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 inclination is small and no edge component is obtained, resulting in poor snow and ice performance. However, the edge component is obtained, improving snow and ice performance. Also, 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] Furthermore, 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, the groove depth can be secured and drainage can be obtained, improving wet performance. Also, according to this pneumatic tire 1, when d2 / d1 is 0.7 or less, the decrease in block rigidity is suppressed and wear resistance is secured. By setting d2 / d1 within the range of 0.55≦d2 / d1≦0.65, it is possible to achieve both wet performance and wear resistance.

[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, the groove depth can be secured and drainage can be obtained, improving wet performance. Also, according to this pneumatic tire 1, when d3 / d1 is 0.9 or less, the decrease in block rigidity is suppressed and wear resistance is secured. By setting d3 / d1 within the range of 0.75≦d3 / d1≦0.85, it is possible to achieve both wet performance and wear resistance.

[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] According to 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 can be obtained, improving wet performance. Also, according to this pneumatic tire 1, when W1 is 10.0 mm or less and W2 is 6.0 mm or less, the decrease in block rigidity is suppressed and wear resistance is secured.

[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] According to 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 can be obtained, improving wet performance. Also, according to this pneumatic tire 1, when W3 is 5.0 mm or less and W4 is 7.0 mm or less, the decrease in block rigidity is suppressed and wear resistance is secured.

[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 used as 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, thereby improving the snow and ice performance.

[0070] In the present embodiment, as described above, the 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, and other gases. However, the tread pattern configuration of the pneumatic tire 1 described in the present embodiment can be arbitrarily applied to other tires within the scope of obviousness to those skilled in the art. Examples of other tires include airless tires and solid tires. EXAMPLES

[0071] 5 to 7 are tables showing the results of performance tests of the pneumatic tires according to the embodiment. Below, 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. The performance evaluation tests were conducted on ice performance, snow performance, wet performance, and uneven wear resistance.

[0072] The performance evaluation test was performed by mounting a pneumatic tire 1 having a tire nominal size of 195 / 65R15 91Q specified by JATMA on a JATMA standard rim wheel having a rim size of 15 x 6.5J, mounting the test tire on a front-wheel drive evaluation vehicle with an engine displacement of 1800cc, adjusting the air pressure to 240kPa for the front wheels and 240kPa for the rear wheels, and running the evaluation vehicle.

[0073] The evaluation test for ice performance is conducted by carrying out a braking test on an ice test course with an evaluation vehicle fitted with the test tires, and measuring the braking distance. Then, based on the measurement results, an index is calculated by taking the reciprocal of the results and setting the conventional example as the standard (100). The higher the value, the better the evaluation.

[0074] The evaluation test for snow performance is conducted by carrying out a braking test on a test course on a snowy road surface with an evaluation vehicle fitted with the test tires, and measuring the braking distance. Then, based on the measurement results, an index evaluation is performed using the reciprocal of the result as the standard (100) for the conventional example. The higher the value, the better the evaluation.

[0075] For the wet performance evaluation test, a vehicle equipped with the test tire is used to carry out a braking test on a test course with a wet road surface with water 1mm deep, and the braking distance is measured. Then, based on the measurement results, an index evaluation is performed using the reciprocal of the measurement results with the conventional example set as the standard (100). The higher the evaluation value, the better, and a value of 97 or higher is preferable in terms of achieving compatibility with wear resistance performance.

[0076] The wear resistance evaluation test is conducted by measuring the amount of wear after driving a test vehicle equipped with a test tire for 10,000 km on a dry asphalt test course. Then, based on the measurement results, an index evaluation is performed using the reciprocal of the conventional example as the standard (100). The higher the value, the better the evaluation.

[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 coincides with the widthwise connecting groove.

[0078] The comparative 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, 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 by the test results, the pneumatic tire of this embodiment has improved performance on ice, performance on snow, wet braking performance, and wear resistance compared to the conventional example and the comparative example.

[0081] The present disclosure includes the following inventions. [Invention 1] A circumferential main groove formed linearly along the circumferential direction of the tire; a circumferential groove formed along the circumferential direction of the tire, the slanted portion being slanted in a predetermined direction with respect to the circumferential direction of the tire and continuing in a zigzag pattern in the circumferential direction of 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 a direction opposite 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 not aligned with the width direction connecting groove; Including, tire. [Invention 2] The width direction auxiliary groove connected to the circumferential main groove is not opposed to a lug groove connected to the opposite side of the circumferential main groove in the tire width direction, and is arranged so as to be misaligned with each other in the tire circumferential direction. A tire according to claim 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. 3. 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 claims 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 claims 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 claims 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 claims 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 claims 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 claims 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 sipe is arranged parallel to at least one of the widthwise connecting groove and the widthwise auxiliary groove. A tire according to claim 10. [Explanation of symbols]

[0082] 1. Pneumatic tires (tires) 31 Circumferential main groove 32 Circumferential groove 32A Slope 32Aa edge 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 circumferential direction of the tire; a circumferential groove formed along the circumferential direction of the tire, the slanted portion being slanted in a predetermined direction with respect to the circumferential direction of the tire and continuing in a zigzag pattern in the circumferential direction of 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 a direction opposite 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 not aligned with the width direction connecting groove; Including, tire.

2. The width direction auxiliary groove connected to the circumferential main groove is not opposed to a lug groove connected to the opposite side of the circumferential main groove in the tire width direction, and is arranged so as to be 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 a 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 a relationship of 0.7≦d3 / d1≦0.9; 2. The tire of claim 1.

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.

2. The tire of claim 1.

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.

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 sipe is arranged parallel to at least one of the widthwise connecting groove and the widthwise auxiliary groove.

11. The tire of claim 10.

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