tire

Abstract

To provide a tire that can secure on-snow performance and wet-performance while suppressing on-ice performance from deteriorating.SOLUTION: THe tire comprises: a plurality of circumferential grooves 30 extending in a tire circumferential direction; a plurality of land parts 20 partitioned by the circumferential grooves 30; and lug grooves 40, arranged in the land parts 20 whose both sides in a tire width direction are partitioned by the circumferential grooves 30, of the land parts 20, which has two or more bent parts 43 whose one ends open to the circumferential grooves 30 and whose other ends terminate in the land parts 20 and whose extending directions vary.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In tires mounted on vehicles, grooves are formed in the tread portion in order to ensure various performances according to the manner of use of the tire, and the performance is improved by devising the shape of the groove. For example, in the pneumatic tire described in Patent Document 1, auxiliary grooves that open into the circumferential groove are arranged at the bending position of the bent narrow groove that bends at a predetermined circumferential pitch and extends in the circumferential direction, thereby improving performance on wet road surfaces and snowy and icy road surfaces. In addition, in the pneumatic tire described in Patent Document 2, both ends of a lateral groove that extends in the tire width direction with one bending point are opened into a main groove that extends in the tire circumferential direction, thereby improving performance on snowy and icy road surfaces.

[0003] In addition, the pneumatic tire described in Patent Document 3 has a secondary groove that is bent at an acute angle and has one end that opens into the circumferential main groove and the other end that terminates within the land portion, thereby reducing the air column resonance generated by the circumferential main groove and improving stone trapping without sacrificing excellent driving stability. In addition, the pneumatic tire described in Patent Document 4 has a plurality of L-shaped bent grooves in the rib, one end of which opens into the circumferential groove and the other end of which terminates within the rib, thereby achieving a high level of harmony between uneven wear resistance, drainage, low noise, and driving stability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-315433 A [Patent Document 2] JP 2013-49335 A [Patent Document 3] JP 2009-137412 A [Patent Document 4] JP 2007-302112 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, the performance required for the grooves formed in the tread portion includes wet performance by ensuring the drainage of water between the tread portion and the road surface when driving on a wet road surface. In addition, for studless tires that are required to drive on snowy road surfaces and icy road surfaces, snow performance and ice performance are also important. In order to improve the snow performance, it is effective to increase the area of ​​the grooves formed in the tread portion and increase the snow column shear force by arranging lug grooves extending in the tire width direction between circumferential grooves adjacent to each other in the tire width direction and connecting the circumferential grooves with the lug grooves. In addition, when the area of ​​the grooves is increased in this way, drainage is also improved, which is also effective in improving wet performance.

[0006] However, when the groove area is increased, the rigidity of the land portion decreases, and the land portion collapses during braking, reducing the contact area and causing a risk of a decline in braking performance on ice. In other words, when the groove area is increased, there is a risk of a decline in performance on ice. For this reason, it has been very difficult to satisfy all the performance requirements for performance on snow, wet conditions, and ice.

[0007] The present invention has been made in view of the above, and has an object to provide a tire that can ensure performance on snow and wet ground while suppressing deterioration of performance on ice. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the tire of the present invention is characterized in comprising a plurality of circumferential grooves extending in a tire circumferential direction, a plurality of land portions defined by the circumferential grooves, and lug grooves, both sides of the land portions in the tire width direction being disposed in the land portions defined by the circumferential grooves, one end opening into the circumferential groove and the other end terminating within the land portion, and having two or more bends where the extension direction changes.

[0009] In the tire, it is preferable that at least one of the plurality of bent portions in one lug groove has a bend angle of 90° or more.

[0010] In the tire, the bent portion is preferably disposed within a range of 40% of the maximum width of the land portion in the tire width direction, centered on the center of the land portion in the tire width direction.

[0011] In addition, in the above tire, it is preferable that a communicating sipe is arranged in the land portion in which the lug groove is arranged, the communicating sipe opening into the lug groove and the circumferential groove different from the circumferential groove on the side where the lug groove opens.

[0012] In the tire, it is preferable that the lug groove has a groove depth that increases from an end side terminating within the land portion toward an end side opening into the circumferential groove.

[0013] In the tire, it is preferable that the lug groove has a groove width that increases from an end side terminating within the land portion toward an end side opening into the circumferential groove.

[0014] In the above tire, it is preferable that a plurality of sipes extending in the tire width direction are arranged in the land portion. Effect of the Invention

[0015] The tire according to the present invention has an effect of ensuring performance on snow and wet ground while suppressing deterioration of performance on ice. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a tire meridian cross-sectional view showing a main part of a pneumatic tire according to an embodiment. [Diagram 2] FIG. 2 is a view taken along the line AA in FIG. [Diagram 3] FIG. 3 is a detailed view of part B in FIG. [Figure 4] FIG. 4 is a schematic diagram of a cross section taken along the extending direction of the bent lug groove shown in FIG. [Diagram 5] FIG. 5 is a detailed view of part C in FIG. [Figure 6] FIG. 6 is a chart showing the results of a performance evaluation test of pneumatic tires. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of a tire according to 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 in the following embodiments include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

[0018] [Embodiment] In the following description, a pneumatic tire 1 will be used as an example of a tire according to the present invention. The pneumatic tire 1, which is an example of a tire, can be filled with air, an inert gas such as nitrogen, and other gases.

[0019] 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, 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 the 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 with a tire width centerline which is the center position of the pneumatic tire 1 in the tire width direction. The tire width is the width in the tire width direction between the portions located outermost in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line refers to a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1. In the following description, the tire meridian section refers to a section obtained by cutting the tire with a plane that includes the tire rotation axis.

[0020] 1 is a tire meridian cross-section showing a main part of a pneumatic tire 1 according to an embodiment. When viewed in tire meridian cross-section, the pneumatic tire 1 according to this embodiment has a tread portion 2 disposed on the outermost part in the tire radial direction, and the tread portion 2 has a tread rubber 4 made of a rubber composition. The surface of the tread portion 2, i.e., the portion that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 is traveling, is formed as a tread contact surface 3, and the tread contact surface 3 constitutes a part of the contour of the pneumatic tire 1.

[0021] Shoulder portions 5 are located at both outer ends of the tread portion 2 in the tire width direction, and sidewall portions 8 are disposed on the tire radially inner sides of the shoulder portions 5. That is, the sidewall portions 8 are disposed on both sides in the tire width direction of the tread portion 2. In other words, the sidewall portions 8 are disposed 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.

[0022] A bead portion 10 is located on the tire radially inner side of each sidewall portion 8 located on both sides in the tire width direction. The bead portions 10 are disposed at two locations on both sides of the tire equatorial plane CL, similar to the sidewall portions 8, i.e., a pair of the bead portions 10 are disposed on both sides of the tire equatorial plane CL in the tire width direction. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided on the tire radially outer side of the bead core 11. The bead core 11 is an annular member formed by bundling bead wires, which are steel wires, into a circular ring shape, and the bead filler 12 is a rubber member disposed on the tire radially outer side of the bead core 11.

[0023] Further, the belt layer 14 is disposed in the tread portion 2. The belt layer 14 is configured by a multi-layer structure in which a plurality of belts 141, 142 and a belt cover 143 are laminated, and in this embodiment, two layers of belts 141, 142 are laminated. The belts 141, 142 constituting the belt layer 14 are configured 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, and the belt angle defined as the inclination angle of the belt cords with respect to the tire circumferential direction is within a predetermined range (for example, 20° or more and 55° or less). In addition, the two layers of belts 141, 142 have different belt angles. Therefore, the belt layer 14 is configured as a so-called cross-ply structure in which the two layers of belts 141, 142 are laminated with the inclination directions of the belt cords crossing each other. That is, the two-layer belts 141, 142 are provided as so-called cross belts in which the belt cords of the respective belts 141, 142 are arranged in a direction crossing each other.

[0024] The belt cover 143 is formed by covering a plurality of belt cover cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the covered cords, and the belt angle, defined as the inclination angle of the belt cover cords with respect to the tire circumferential direction, is within a predetermined range (for example, 0° to 10°). The belt cover 143 is, for example, a strip material made of one or more belt cover cords covered with coating rubber, and is formed by winding the strip material in a spiral shape around the tire rotation axis from the outer side in the tire radial direction of the two-layered belts 141 and 142.

[0025] A carcass layer 13 containing the cords of the radial ply is provided continuously on the inner side in the tire radial direction of the belt layer 14 and on the tire equatorial plane CL side of the sidewall portion 8. Therefore, the pneumatic tire 1 according to this embodiment is configured as a so-called radial tire. The carcass layer 13 has a single-layer structure consisting of one carcass ply, or a multi-layer structure consisting of a plurality of carcass plies stacked together, and is toroidally spanned between a pair of bead portions 10 arranged on both sides in the tire width direction to form the framework of the tire.

[0026] Specifically, the carcass layer 13 is disposed from one bead portion 10 to the other bead portion 10 of a pair of bead portions 10 located on both sides in the tire width direction, and is wound back along the bead core 11 at the bead portion 10 toward the outside in the tire width direction so as to envelop the bead core 11 and the bead filler 12. The bead filler 12 is a rubber material disposed in a space formed on the outside in the tire radial direction of the bead core 11 by folding back the carcass layer 13 at the bead portion 10 in this manner. The belt layer 14 is disposed on the outside in the tire radial direction of the portion of the carcass layer 13 that is stretched between the pair of bead portions 10 and that is located in the tread portion 2. The carcass ply of the carcass layer 13 is formed by covering a plurality of carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, rayon, etc. with a coating rubber and rolling the covered cords. The carcass cords constituting the carcass ply are arranged in parallel at a certain angle to the tire circumferential direction while being aligned along the tire meridian direction.

[0027] In the bead portion 10, a rim cushion rubber 17 that constitutes the contact surface of the bead portion 10 with the rim flange is disposed on the inner side in the tire radial direction and the outer side in the tire width direction of the bead core 11 and the turned-up portion of the carcass layer 13. Also, an inner liner 16 is formed along the carcass layer 13 on the inner side of the carcass layer 13 or on the inner side of the carcass layer 13 in the pneumatic tire 1. The inner liner 16 forms a tire inner surface 18 that is the inner surface of the pneumatic tire 1.

[0028] 2 is a view taken along the line AA in FIG. 1. In the tread portion 2, a plurality of circumferential grooves 30 extending in the tire circumferential direction and a plurality of lug grooves 40 extending in the tire width direction are formed on the tread ground contact surface 3, and a plurality of land portions 20 are defined on the surface of the tread portion 2 by these circumferential grooves 30 and lug grooves 40. In this embodiment, four circumferential grooves 30 are formed in a line in the tire width direction. In detail, the circumferential grooves 30 have four grooves: two inner circumferential grooves 31 arranged on both sides of the tire equatorial plane CL in the tire width direction, and two outer circumferential grooves 35 arranged one on each side of the two inner circumferential grooves 31 in the tire width direction. The groove width of these circumferential grooves 30 is within a range of 3.5 mm to 12 mm, and the groove depth is within a range of 6.0 mm to 10.0 mm.

[0029] The land portion 20 defined by the circumferential groove 30 includes a center land portion 21, a second land portion 22, and a shoulder land portion 23. The center land portion 21 is a land portion 20 located between the inner circumferential grooves 31, and both sides in the tire width direction are defined by the inner circumferential grooves 31. The second land portion 22 is a land portion 20 located between the inner circumferential groove 31 and the outer circumferential groove 35 adjacent in the tire width direction, and the inner portion in the tire width direction is defined by the inner circumferential groove 31, and the outer portion in the tire width direction is defined by the outer circumferential groove 35. The shoulder land portion 23 is a land portion 20 located on the outer side in the tire width direction of the outer circumferential groove 35, and the inner side in the tire width direction is defined by the outer circumferential groove 35. The second land portion 22 and the shoulder land portion 23 are disposed on both sides in the tire width direction of the tire equatorial plane CL.

[0030] Of the four circumferential grooves 30, the two outer circumferential grooves 35 are each formed to extend linearly along the tire circumferential direction. On the other hand, of the four circumferential grooves 30, the two inner circumferential grooves 31 are each formed in a zigzag shape with at least one of the groove walls on both sides in the groove width direction extending in the tire circumferential direction and oscillating in the tire width direction.

[0031] Specifically, when the two inner circumferential grooves 31 are the first inner circumferential groove 31a and the second inner circumferential groove 31b, the first inner circumferential groove 31a has a groove wall on the outer side in the tire width direction formed in a zigzag shape among the groove walls on both sides in the groove width direction, and the groove wall on the inner side in the tire width direction formed in a straight line extending along the tire circumferential direction. The second inner circumferential groove 31b is formed in a zigzag shape by the second inner circumferential groove 31b extending in the tire circumferential direction and oscillating in the tire width direction as a whole. Therefore, the second inner circumferential groove 31b has both groove walls on both sides in the groove width direction formed in a zigzag shape while maintaining a constant groove width.

[0032] The lug grooves 40 include a center lug groove 41, a bent lug groove 42, a communicating lug groove 44, and a shoulder lug groove 45. Of these, the center lug groove 41 is disposed between two inner circumferential grooves 31. The center lug groove 41 extends in the tire width direction and is inclined in the tire circumferential direction with respect to the tire width direction, with both ends opening into the inner circumferential groove 31. For this reason, the center land portion 21 defined by the inner circumferential groove 31 and the center lug groove 41 is a block-shaped land portion 20 defined on both sides in the tire width direction by the inner circumferential groove 31 and on both sides in the tire circumferential direction by the center lug groove 41.

[0033] The bent lug groove 42 is disposed between the first inner circumferential groove 31a and the outer circumferential groove 35 adjacent to the first inner circumferential groove 31a. In other words, the bent lug groove 42 is disposed in the first second land portion 22a, which is the second land portion 22 located between the first inner circumferential groove 31a and the outer circumferential groove 35, among the second land portions 22 disposed on both sides in the tire width direction of the tire equatorial plane CL. In this way, the bent lug groove 42, which is the lug groove 40 disposed in the land portion 20 partitioned by the circumferential groove 30 on both sides in the tire width direction, is formed by bending at multiple points, with one end opening to the circumferential groove 30 and the other end terminating within the land portion 20. That is, the bent lug groove 42 is a lug groove 40 that opens on one side, with one end opening to the circumferential groove 30 and the other end not opening.

[0034] Specifically, the bent lug groove 42 has one end opening into the outer circumferential groove 35 and the other end terminating in the first second land portion 22a, and is bent at two points between the end opening into the outer circumferential groove 35 and the end terminating in the first second land portion 22a. That is, the bent lug groove 42 opens into the outer circumferential groove 35 that defines the outer side in the tire width direction of the two circumferential grooves 30 that define both sides of the first second land portion 22a in the tire width direction. A plurality of bent lug grooves 42 are arranged side by side in the tire circumferential direction in the same form. In addition, since one end of the bent lug groove 42 in the extension direction of the bent lug groove 42 terminates in the first second land portion 22a, the first second land portion 22a is not divided in the tire circumferential direction by the bent lug groove 42. For this reason, the first second land portion 22a is a rib-shaped land portion 20 that is continuously formed in the tire circumferential direction.

[0035] The communicating lug groove 44 is disposed between the second inner circumferential groove 31b and the outer circumferential groove 35 adjacent to the second inner circumferential groove 31b. The communicating lug groove 44 extends in the tire width direction and is inclined in the tire circumferential direction with respect to the tire width direction, with one end opening into the second inner circumferential groove 31b and the other end opening into the outer circumferential groove 35. In this manner, the communicating lug groove 44 disposed between the second inner circumferential groove 31b and the outer circumferential groove 35 is a lug groove 40 that defines the second second land portion 22b, which is the second land portion 22 located between the second inner circumferential groove 31b and the outer circumferential groove 35. For this reason, the second second land portion 22b is a block-shaped land portion 20 that is defined by the second inner circumferential groove 31b and the outer circumferential groove 35 on both sides in the tire width direction and by the communicating lug groove 44 on both sides in the tire circumferential direction.

[0036] The shoulder lug grooves 45 are disposed on the outer side in the tire width direction of the outer circumferential grooves 35 located on both sides in the tire width direction of the tire equatorial plane CL. Each shoulder lug groove 45 is formed extending in the tire width direction, with the inner end in the tire width direction opening into the outer circumferential groove 35 and the outer end in the tire width direction terminating at the so-called design end, which is the end in the tire width direction of the tread pattern of the tread portion 2. In this way, the shoulder lug grooves 45 formed between the outer circumferential groove 35 and the design end form the lug grooves 40 that define the shoulder land portion 23 together with the outer circumferential groove 35. Therefore, the shoulder land portion 23 is a block-shaped land portion 20 defined by the shoulder lug grooves 45 on both sides in the tire circumferential direction.

[0037] The lug grooves 40 thus formed have a groove width within a range of 3.0 mm or more and 8.0 mm or less, and a groove depth within a range of 6.0 mm or more and 9.0 mm or less.

[0038] Furthermore, a circumferential narrow groove 50 is disposed in the second second land portion 22b located between the second inner circumferential groove 31b and the outer circumferential groove 35. The circumferential narrow groove 50 has a groove width narrower than the groove width of the circumferential groove 30, and is formed with a groove width in the range of 1.5 mm to 4 mm. The groove depth of the circumferential narrow groove 50 is in the range of 3.5 mm to 7.0 mm.

[0039] The circumferential narrow groove 50 extends in the tire circumferential direction and is disposed in the second second land portion 22b, and both ends in the tire circumferential direction open to the communicating lug grooves 44 that define the second second land portion 22b. The circumferential narrow groove 50 is formed to have a portion that extends in the tire circumferential direction and bends in the tire width direction, and in this embodiment, the circumferential narrow groove 50 is bent at two points to be disposed in the second second land portion 22b in a crank-like shape.

[0040] In addition, a shoulder narrow groove 55 extending in the tire circumferential direction is disposed in the shoulder land portion 23 located on the outer side in the tire width direction of the outer circumferential groove 35. One end of the shoulder narrow groove 55 extending in the tire circumferential direction opens into the shoulder lug groove 45, and the other end terminates in the shoulder land portion 23. The shoulder narrow grooves 55 disposed in the shoulder land portion 23 and located on the same side in the tire width direction with respect to the tire equatorial plane CL all have ends on the same side in the tire circumferential direction that open into the shoulder lug groove 45. That is, the shoulder narrow grooves 55 disposed in the shoulder land portion 23 partitioned by the same outer circumferential groove 35 all face the same direction in the tire circumferential direction.

[0041] Moreover, the shoulder narrow groove 55 arranged on one side of the tire equatorial plane CL in the tire width direction and the shoulder narrow groove 55 arranged on the other side have ends on different sides, one opening into the shoulder lug groove 45 and the other terminating in the shoulder land portion 23. That is, the shoulder narrow groove 55 arranged on one side of the tire equatorial plane CL in the tire width direction and the other shoulder narrow groove 55 arranged on the other side are oriented in opposite directions in the tire circumferential direction.

[0042] Furthermore, a plurality of sipes 60 extending in the tire width direction are arranged in each land portion 20. The sipes 60 arranged in the land portion 20 are formed and arranged in a zigzag shape by repeatedly bending and oscillating in the tire circumferential direction while extending in the tire width direction. The ends of each sipe 60 may terminate within the land portion 20, or may open into another groove. The pneumatic tire 1 according to this 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 60 in each land portion 20 in this way.

[0043] The sipes 60 referred to here are formed in the shape of narrow grooves on the tread contact surface 3, and when the pneumatic tire 1 is assembled to a specified rim and the internal pressure is set to a specified internal pressure, the wall surfaces constituting the narrow grooves do not come into contact with each other under no load, but when a load is applied vertically on a flat plate and the narrow grooves are located in 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 portion provided on the wall surface, come into contact with each other due to deformation of the land portion 20. In this embodiment, the sipes 60 have a groove width of 1.4 mm or less, and a maximum depth from the tread contact surface 3 within a range of 3.5 mm to 9.0 mm.

[0044] The specified rim here means the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure means the "maximum air pressure" specified by JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO.

[0045] The sipe 60 may be a so-called three-dimensional sipe or a two-dimensional sipe. The three-dimensional sipe here refers to a sipe 60 having a curved wall surface with an amplitude in the width direction of the sipe 60 in both a cross-sectional view (a cross-sectional view including the width direction and depth direction of the sipe 60) in which the length direction of the sipe 60 is the normal direction, and a cross-sectional view (a cross-sectional view including the width direction and length direction of the sipe 60) in which the depth direction of the sipe 60 is the normal direction. The two-dimensional sipe refers to a sipe 60 having a straight wall surface in any cross-sectional view (a cross-sectional view including the width direction and depth direction of the sipe 60) in which the length direction of the sipe 60 is the normal direction.

[0046] 3 is a detailed view of part B in FIG. 2. The bent lug groove 42 is disposed in the first second land portion 22a and is formed by bending at a plurality of points, and is a lug groove 40 having two or more bent portions 43 whose extending direction changes. In this embodiment, the bent lug groove 42 has two bent portions 43, and has a first bent portion 43a which is a bent portion 43 located on the outer circumferential groove 35 side of the bent lug groove 42, and a second bent portion 43b which is a bent portion 43 located on the end side that terminates in the first second land portion 22a of the bent lug groove 42. As a result, the bent lug groove 42 has a first extending portion 42a, a second extending portion 42b, and a third extending portion 42c, with the two bent portions 43 as boundaries.

[0047] Specifically, the first extending portion 42a is a portion located between the end of the bent lug groove 42 on the side that opens into the outer circumferential groove 35 and the first bent portion 43a. The second extending portion 42b is a portion between the first bent portion 43a and the second bent portion 43b of the bent lug groove 42. The third extending portion 42c is a portion between a terminal portion 42d, which is an end of the bent lug groove 42 on the side that terminates within the first second land portion 22a, and the second bent portion 43b.

[0048] Furthermore, the two bent portions 43 of the bent lug groove 42 are the first bent portion 43a and the second bent portion 43b, and the bending direction in the groove width direction of the bent lug groove 42 is the same. In other words, the two bent portions 43 of the bent lug groove 42 have groove walls on the same side in the groove width direction, the groove walls being located on the minor angle side of the bend.

[0049] Moreover, the bent portion 43 of the bent lug groove 42 has a bend angle of 90° or more. That is, in the bent lug groove 42, the angle θ1 of the first bent portion 43a is 90° or more, and the angle θ2 of the second bent portion 43b is also 90° or more. In this case, the bend angle of the bent portion 43 is an angle on the minor angle side of the bend. That is, the bent portion 43 of the bent lug groove 42 is formed with an obtuse angle. Moreover, the bend angle of the bent portion 43 is an angle at the center line of the groove width of the bent lug groove 42. The angle θ1 of the first bent portion 43a is preferably within the range of 90°≦θ1≦130°, and the angle θ2 of the second bent portion 43b is also preferably within the range of 90°≦θ2≦130°.

[0050] The bent lug groove 42 is bent at two bends 43 as described above to have a first extension 42a, a second extension 42b, and a third extension 42c, where the first extension 42a is formed extending at an angle close to the tire width direction, and the second extension 42b is formed extending at an angle close to the tire circumferential direction. For example, the first extension 42a is preferably inclined at an angle of 55° to 75° with respect to the tire circumferential direction. The second extension 42b is preferably inclined at an angle of 0° to 20° with respect to the tire circumferential direction. The third extension 42c is preferably inclined at an angle of 65° to 85° with respect to the tire circumferential direction.

[0051] In this embodiment, the two bent portions 43 of the bent lug groove 42 are bent in the same direction, so that the bent lug groove 42 that opens into the outer circumferential groove 35 and extends in the tire width direction is formed in a shape that turns back toward the outer circumferential groove 35 when viewed as a whole of the bent lug groove 42. That is, the bent lug groove 42 is formed such that the third extension portion 42c approaches the outer circumferential groove 35 where the first extension portion 42a opens as it moves from the second extension portion 42b side toward the terminal end portion 42d side.

[0052] In addition, the first extension portion 42a, the second extension portion 42b, and the third extension portion 42c of the bent lug groove 42 are formed to have different lengths. Specifically, in the bent lug groove 42, the first extension portion 42a is the longest, the second extension portion 42b is the next longest, and the third extension portion 42c is the shortest. That is, the lengths of the first extension portion 42a, the second extension portion 42b, and the third extension portion 42c of the bent lug groove 42 satisfy the relationship of the length of the first extension portion 42a > the length of the second extension portion 42b > the length of the third extension portion 42c.

[0053] The bent lug groove 42 has a plurality of bent portions 43, and the plurality of bent portions 43 of the bent lug groove 42 are arranged within a range of 40% of the maximum width in the tire width direction of the land portion 20, centered on the center in the tire width direction of the land portion 20 in which the bent lug groove 42 is arranged. In other words, both of the two bent portions 43 of the bent lug groove 42 are arranged within an arrangement region AP1 that is a range of 40% of the maximum width WB1 in the tire width direction of the first second land portion 22a, centered on the center CB1 in the tire width direction of the first second land portion 22a in which the bent lug groove 42 is arranged.

[0054] The arrangement area AP1 here is, in other words, an area that is 20% of the maximum width WB1 of the first second land portion 22a on both sides in the tire width direction of the center CB1 in the tire width direction of the first second land portion 22a. In other words, the arrangement area AP1 is an area that is between a 30% position and a 70% position of both ends in the tire width direction of the portion of the first second land portion 22a that has the maximum width WB1 in the tire width direction, where the position of one end side is 0% and the position of the other end side is 100%.

[0055] Further, the terminal end 42d of the bent lug groove 42 within the first second land portion 22a is also located in the arrangement region AP1. Therefore, the second extension portion 42b and the third extension portion 42c of the bent lug groove 42 are also located in the arrangement region AP1.

[0056] A plurality of bent lug grooves 42 are arranged in the first second land portion 22a, and the plurality of bent lug grooves 42 are arranged side by side in the tire circumferential direction with the same shape. In this manner, the plurality of bent lug grooves 42 arranged in the first second land portion 22a are preferably formed such that the total length L in the tire circumferential direction satisfies the relationship of 0.6≦(L / P)≦0.8 with respect to the pitch P between the bent lug grooves 42 adjacent in the tire circumferential direction.

[0057] Furthermore, the bent lug groove 42 has a groove width that increases from the end side terminating in the land portion 20 toward the end side opening into the circumferential groove 30, and a groove depth that increases from the end side terminating in the land portion 20 toward the end side opening into the circumferential groove 30. In detail, the bent lug groove 42 has a groove width that increases from the end portion 42d of the bent lug groove 42 in the first second land portion 22a toward the end side of the bent lug groove 42 opening into the outer circumferential groove 35, with the bent portion 43 as a boundary, and the groove depth also increases.

[0058] The bent lug groove 42 has different groove widths at the boundary of the bent portion 43, and therefore the groove widths of the bent lug groove 42 are different between the first extending portion 42a, the second extending portion 42b, and the third extending portion 42c. Specifically, the groove widths of the bent lug groove 42 satisfy the relationship Wg1>Wg2>Wg3 among the groove width Wg1 of the first extending portion 42a, the groove width Wg2 of the second extending portion 42b, and the groove width Wg3 of the third extending portion 42c.

[0059] Fig. 4 is a schematic diagram of a cross section along the extension direction of the bent lug groove 42 shown in Fig. 3. The bent lug groove 42 has different groove depths at the boundary of the position of the bent portion 43, so that the groove depths of the bent lug groove 42 are different between the first extension portion 42a, the second extension portion 42b, and the third extension portion 42c. Specifically, the groove depths of the bent lug groove 42 satisfy the relationship Dg1 of the first extension portion 42a, the groove depth Dg2 of the second extension portion 42b, and the groove depth Dg3 of the third extension portion 42c, Dg1>Dg2>Dg3.

[0060] In addition, in the first second land portion 22a, which is the land portion 20 in which the bent lug groove 42 is arranged, a communicating sipe 61 is arranged, which opens into the bent lug groove 42 and the circumferential groove 30 different from the circumferential groove 30 on the side where the bent lug groove 42 opens. That is, the communicating sipe 61 opens at one end into the first inner circumferential groove 31a, which is the circumferential groove 30 different from the circumferential groove 30 on the side where the bent lug groove 42 opens, among the two circumferential grooves 30 that divide the first second land portion 22a, and opens at the other end into the bent lug groove 42. In detail, the communicating sipe 61 opens into the bent lug groove 42 at the position of the first bent portion 43a of the bent lug groove 42, and is formed along the extension line of the first extension portion 42a from the position of the first bent portion 43a toward the first inner circumferential groove 31a side, and the end opens into the first inner circumferential groove 31a. The communicating sipe 61 formed across between the bent lug groove 42 and the first inner circumferential groove 31a is formed as a straight sipe 60.

[0061] In addition, the sipes 60 arranged in the first second land portion 22a are inclined in the tire circumferential direction with respect to the tire width direction, in other words, the sipes 60 arranged in the first second land portion 22a are inclined in the tire width direction with respect to the tire circumferential direction. Specifically, the sipes 60 arranged in the first second land portion 22a are inclined with respect to the tire circumferential direction in the same direction as the inclination direction of the first extension portion 42a formed with the longest length in the bent lug groove 42 in the tire width direction with respect to the tire circumferential direction.

[0062] 5 is a detailed view of part C in FIG. 2. The circumferential narrow groove 50 arranged in the second second land portion 22b, which is a block-shaped land portion 20, has one or more bent portions 51 whose extension direction changes within the second second land portion 22b, and thus has a long portion 50a and a short portion 50b whose lengths are relatively different. In this case, the long portion 50a is longer than the short portion 50b. In this embodiment, the circumferential narrow groove 50 has two bent portions 51, that is, the circumferential narrow groove 50 is bent at two points. The two bent portions 51 are bent in opposite directions in the groove width direction of the circumferential narrow groove 50, and therefore the circumferential narrow groove 50 is formed in a crank-like shape by extending in the tire circumferential direction and bending at two points.

[0063] At least one of the bent portions 51 of the circumferential narrow groove 50 has a bending angle θb of 90° or more. In this embodiment, the bending angles θb of the two bent portions 51 of the circumferential narrow groove 50 are both 90° or more. In this case, the bending angle θb of the bent portion 51 is an angle on the minor angle side of the bending. That is, the bending angle of the bent portion 51 of the circumferential narrow groove 50 is formed at an obtuse angle. The bending angle of the bent portion 51 is an angle at the center line of the groove width of the circumferential narrow groove 50. The angle θ of the bent portion 51 of the circumferential narrow groove 50 is preferably within the range of 90°≦θb≦140°.

[0064] In the circumferential narrow groove 50 formed in a crank-like shape, the portion between two bent portions 51 is a short portion 50b, and the portion between each bent portion 51 and the end of the circumferential narrow groove 50 that opens into the communicating lug groove 44 is a long portion 50a. That is, the circumferential narrow groove 50 has two long portions 50a that open into the communicating lug grooves 44 adjacent to each other in the tire circumferential direction, and a short portion 50b that is disposed between the ends of the two long portions 50a on the opposite side to the ends that open into the communicating lug groove 44. The length of each of the two long portions 50a is longer than the length of the short portion 50b, and the lengths of the long portions 50a are approximately the same.

[0065] In addition, the total length of the long portions 50a of each circumferential narrow groove 50 is within a range of 60% to 90% of the total length of each circumferential narrow groove 50. In other words, when the length of one of the two long portions 50a of the circumferential narrow groove 50 is L1, the length of the other long portion 50a is L2, and the length of the short portion 50b is L3, the total length (L1+L2) of the long portions 50a is within a range of 60% to 90% of the total length (L1+L2+L3) of each circumferential narrow groove 50. In other words, the lengths of the circumferential narrow grooves 50 satisfy the relationship 0.6≦(L1+L2) / (L1+L2+L3)≦0.9.

[0066] The two long portions 50a of the circumferential narrow groove 50 are both inclined toward the tire width direction with respect to the tire circumferential direction, and the inclination angle with respect to the tire circumferential direction is approximately the same for the two long portions 50a. The inclination θn of the long portions 50a of the circumferential narrow groove 50 toward the tire width direction with respect to the tire circumferential direction is within a range of 5° to 45°.

[0067] The lengths L1 and L2 of the long portions 50a of the circumferential narrow grooves 50, the length L3 of the short portions 50b, and the inclination θn of the long portions 50a are the lengths and inclinations of the circumferential narrow grooves 50 at the center line of the groove width.

[0068] The short portion 50b of the circumferential narrow groove 50 has an inclination direction in the tire width direction opposite to the tire circumferential direction. Since the inclination directions in the tire width direction are opposite to each other in the long portion 50a and the short portion 50b, the circumferential narrow groove 50 is formed in a zigzag shape that extends in the tire circumferential direction and oscillates in the tire width direction.

[0069] The sipes 60 arranged in the second second land portion 22b are inclined in the tire circumferential direction with respect to the tire width direction, in other words, the sipes 60 arranged in the second second land portion 22b are inclined in the tire width direction with respect to the tire circumferential direction. Specifically, the sipes 60 arranged in the second second land portion 22b are inclined with respect to the tire circumferential direction in the opposite direction to the inclination direction of the long portion 50a of the circumferential narrow groove 50 in the tire width direction with respect to the tire circumferential direction.

[0070] The circumferential narrow grooves 50 have their ends opening into the communicating lug grooves 44, but the circumferential narrow grooves 50 that open from opposite sides in the groove width direction of the communicating lug groove 44 open to the same communicating lug groove 44 at positions close to each other in the tire width direction relative to the communicating lug groove 44, or have portions that open at the same position in the tire width direction.

[0071] Of the two circumferential grooves 30 that define both sides in the tire width direction of the second second land portion 22b in which the circumferential narrow groove 50 is arranged, the second inner circumferential groove 31b that defines the inner side in the tire width direction is formed in a zigzag shape by extending in the tire circumferential direction and oscillating in the tire width direction. The second inner circumferential groove 31b is formed in a zigzag shape having a long portion 32 and a short portion 33 that are relatively different in length, and the long portion 32 and the short portion 33 are alternately arranged with the zigzag bending position as a boundary. In this case, the long portion 32 is relatively longer than the short portion 33.

[0072] In this way, the second inner circumferential groove 31b formed in a zigzag shape having the long portion 32 and the short portion 33 has a zigzag period in the tire circumferential direction that is the same as the pitch in the tire circumferential direction between adjacent communicating lug grooves 44. Therefore, the long portion 32 and the short portion 33 of the second inner circumferential groove 31b are located in the portion of the second inner circumferential groove 31b that is located between the communicating lug grooves 44 adjacent in the tire circumferential direction. As a result, the long portion 32 and the short portion 33 are located in the portion of the second inner circumferential groove 31b that defines one second second land portion 22b. In other words, the portion formed by the second inner circumferential groove 31b in one second second land portion 22b is defined by a pair of the long portion 32 and the short portion 33 of the second inner circumferential groove 31b.

[0073] Since the second inner circumferential groove 31b is formed to extend in the tire circumferential direction and oscillate in the tire width direction, the long portion 32 and the short portion 33 are inclined in the tire width direction with respect to the tire circumferential direction, and the inclination directions in the tire width direction are opposite to each other. The circumferential narrow groove 50 arranged in the second second land portion 22b has a long portion 50a inclined in the tire width direction with respect to the tire circumferential direction in the opposite direction to the long portion 32 of the second inner circumferential groove 31b inclined in this way with respect to the tire circumferential direction. That is, the circumferential narrow groove 50 has two long portions 50a, each of which has an inclination direction in the tire width direction with respect to the tire circumferential direction opposite to the inclination direction in the tire width direction with respect to the tire circumferential direction with respect to the long portion 32 of the second inner circumferential groove 31b.

[0074] The inclination θc of the long portion 32 of the second inner circumferential groove 31b in the tire width direction relative to the tire circumferential direction is within a range of 5° to 30°. In this case, the inclination θc of the long portion 32 of the second inner circumferential groove 31b is the inclination of the center line of the groove width of the second inner circumferential groove 31b. It is preferable that the inclination θn of the long portion 50a of the circumferential narrow groove 50 in the tire width direction relative to the tire circumferential direction is larger than the inclination θc of the long portion 32 of the second inner circumferential groove 31b.

[0075] Moreover, the bent portion 51 of the circumferential narrow groove 50 is disposed within a range of 40% of the maximum width in the tire width direction of the land portion 20, centered on the center in the tire width direction of the land portion 20 in which the circumferential narrow groove 50 is disposed. In other words, both of the two bent portions 51 of the circumferential narrow groove 50 are disposed within an arrangement region AP2 that is a range of 40% of the maximum width WB2 in the tire width direction of the second second land portion 22b, centered on the center CB2 in the tire width direction of the second second land portion 22b in which the circumferential narrow groove 50 is disposed.

[0076] The arrangement area AP2 here is, in other words, an area that is 20% of the maximum width WB2 of the second second land portion 22b on both sides in the tire width direction of the center CB2 in the tire width direction of the second second land portion 22b. In other words, the arrangement area AP2 is an area that is between a 30% position and a 70% position of both ends in the tire width direction of the portion of the second second land portion 22b that has the maximum width WB2 in the tire width direction, where the position of one end side is 0% and the position of the other end side is 100%.

[0077] 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.

[0078] Furthermore, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters grooves such as the circumferential grooves 30 and the lug grooves 40, and the sipes 60, and these grooves drain the water between the tread surface 3 and the road surface 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 enables the vehicle to travel.

[0079] 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 the circumferential grooves 30 and the lug grooves 40, compacting the snow 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, and snow traction can be ensured. This enables the vehicle to travel on a snowy road surface.

[0080] In addition, when traveling on a snowy road surface or an icy road surface, the edge effect of the circumferential groove 30, the lug groove 40, and the sipe 60 is also used to travel. In other words, when traveling on a snowy road surface or an icy road surface, the edge of the circumferential groove 30, the edge of the lug groove 40, and the edge of the sipe 60 are caught on the snowy or icy road surface, and the tire also uses the resistance caused by the edges of the circumferential groove 30, the edges of the lug groove 40, and the edges of the sipe 60 catching on the snowy or icy road surface. In addition, when traveling on an icy road surface, the sipe 60 absorbs 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, making it easier for the icy road surface and the tread contact surface 3 to 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 running performance of the vehicle equipped with the pneumatic tire 1 can be ensured.

[0081] The circumferential grooves 30, lug grooves 40, and sipes 60 formed in the tread portion 2 contribute to ensuring running performance when running on wet road surfaces, snowy road surfaces, and icy road surfaces, so that in order to improve wet performance, which is running performance on wet road surfaces, for example, it is effective to increase the groove area of ​​the tread portion 2. In other words, when the groove area, which is the area of ​​the grooves such as the circumferential grooves 30 and the lug grooves 40, 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.

[0082] In addition, 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 inserted into the circumferential grooves 30 and the lug grooves 40 during driving on snowy roads can be increased, and the snow column shear force acting on the snow that has entered the grooves can be increased. This improves snow traction during driving on snowy roads, and improves snow performance.

[0083] Here, when the groove area of ​​the tread portion 2 is increased, the volume of the land portion 20 defined by the circumferential groove 30 and the lug groove 40 decreases with the increase in the groove area. When the volume of the land portion 20 is reduced, the rigidity of the land portion 20 decreases, and when the rigidity of the land portion 20 is reduced, 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 is reduced, and it may become difficult to ensure driving performance.

[0084] 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 contacting the icy road surface is also important. However, if the rigidity of the land portion 20 is reduced by increasing the groove area of ​​the tread portion 2, the land portion 20 is likely to collapse when a load is applied, so the contact area is likely to be reduced, and there is a concern that it may be 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, so the contact area is likely to be reduced, and there is a concern that the braking performance on the icy road surface may be easily reduced.

[0085] In contrast, in the pneumatic tire 1 according to the present embodiment, the first second land portion 22a, which is the land portion 20 defined by the circumferential groove 30 on both sides in the tire width direction, is provided with a bent lug groove 42 having two or more bent portions 43 whose extension direction changes, one end of which opens into the circumferential groove 30 and the other end of which terminates within the land portion 20. This makes it possible to increase the groove area of ​​the tread portion 2 while suppressing a decrease in the rigidity of the land portion 20. That is, the bent lug groove 42 has an end opposite to the end of the end that opens into the circumferential groove 30, among both ends in the length direction, which terminates within the land portion 20, thereby making it possible to suppress the land portion 20 from being divided in the tire circumferential direction by the bent lug groove 42. In other words, the land portion 20 in which the bent lug groove 42 is provided can be formed in a shape that is continuous in the tire circumferential direction, thereby ensuring the rigidity of the land portion 20 and suppressing the collapse of the land portion 20 when a load is applied to the land portion 20. Therefore, it is possible to prevent the land portion 20 from collapsing and thereby reducing the contact area, and therefore it is possible to ensure the performance on ice, that is, the driving performance on icy road surfaces, including the braking performance when driving on icy road surfaces.

[0086] In addition, the bent lug groove 42 has two or more bent portions 43, i.e., is bent at two or more places, so that the length and groove area can be secured. This allows a lot of snow to enter the bent lug groove 42 when traveling on a snowy road surface, and a snow column shear force can be secured, so that snow traction can be improved and performance on snow can be improved.

[0087] In addition, the bent lug grooves 42 are bent at two or more points to ensure a sufficient groove area, allowing a large amount of water to enter the bent lug grooves 42 when traveling on a wet road surface. In addition, one end of the bent lug grooves 42 opens to the circumferential grooves 30, allowing a large amount of water that has entered the bent lug grooves 42 to flow into the circumferential grooves 30. This improves the drainage performance when water between the tread contact surface 3 and the road surface is drained by the bent lug grooves 42, improving wet performance. As a result, it is possible to ensure performance on snow and wet performance while suppressing a decrease in performance on ice.

[0088] In addition, the bent portion 43 of the bent lug groove 42 has bending angles θ1 and θ2 of 90° or more, so that the rigidity of the land portion 20 can be more reliably ensured and the ease of water flow in the bent lug groove 42 can be ensured. In other words, if the bending angles θ1 and θ2 of the bent portion 43 are less than 90°, that is, if the bent portion 43 is formed at an acute angle, it may be difficult to ensure the rigidity of the portion of the land portion 20 located on the minor angle side of the bent portion 43. In this case, it may be difficult to effectively suppress the collapse of the land portion 20 when a load is applied to the land portion 20. In addition, if the bending angles θ1 and θ2 of the bent portion 43 are less than 90°, the flow of water in the bent lug groove 42 may be poor when water enters the bent lug groove 42. In this case, it may be difficult to effectively ensure the drainage performance of the bent lug groove 42.

[0089] In contrast, when the bending angles θ1, θ2 of the bend portion 43 are 90° or more, the rigidity of the portion of the land portion 20 located on the minor angle side of the bend portion 43 is ensured, the collapse of the land portion 20 is effectively suppressed, and the ease of water flow in the bent lug groove 42 is ensured. Therefore, it is possible to more reliably suppress a reduction in the contact area due to the collapse of the land portion 20, and to more reliably ensure drainage in the bent lug groove 42. As a result, it is possible to more reliably achieve both on-ice performance and wet performance.

[0090] In addition, the bent portion 43 of the bent lug groove 42 is arranged within a range of 40% of the maximum width WB1 of the first second land portion 22a, which is the land portion 20 in which the bent lug groove 42 is arranged, centered on the center CB1 in the tire width direction of the first second land portion 22a, so that the rigidity of the first second land portion 22a can be more reliably ensured and the snow column shear force can be ensured when traveling on a snowy road surface. In other words, if the arrangement position of the bent portion 43 is outside the range of 40% of the maximum width WB1 of the first second land portion 22a, it may be difficult to ensure performance on snow or on ice. For example, if the arrangement position of the bent portion 43 is near the outer circumferential groove 35, which is the circumferential groove 30 on the side where the bent lug groove 42 opens, and is outside the range of 40% of the maximum width WB1 of the first second land portion 22a, the length of the bent lug groove 42 may be too short. In this case, it is difficult to ensure the groove area of ​​the bent lug groove 42, and it may be difficult to effectively ensure the snow column shear force. In addition, if the arrangement position of the bent portion 43 is near the first inner circumferential groove 31a, which is the circumferential groove 30 on the side where the bent lug groove 42 is not open, and is outside the range of 40% of the maximum width WB1 of the first second land portion 22a, it may be difficult to ensure the rigidity of the portion between the bent portion 43 and the first inner circumferential groove 31a in the first second land portion 22a. In this case, it may be difficult to suppress the collapse of the first second land portion 22a when a load is applied to the first second land portion 22a, and it may be difficult to effectively suppress the reduction in the contact area when a load is applied.

[0091] On the other hand, when the position of the bent portion 43 of the bent lug groove 42 is within 40% of the maximum width WB1 of the first second land portion 22a, the length of the bent lug groove 42 can be prevented from becoming too short while ensuring the rigidity of the first second land portion 22a. This more reliably prevents the first second land portion 22a from collapsing and thus reducing the contact area, and ensures the amount of snow that can be accommodated in the bent lug groove 42, thereby ensuring the shear force of the snow column when traveling on a snowy road surface. As a result, it is possible to more reliably achieve both on-ice performance and on-snow performance.

[0092] In addition, the first second land portion 22a in which the bent lug groove 42 is arranged has a communicating sipe 61 that opens into the first inner circumferential groove 31a and the bent lug groove 42, so that the rigidity of the first second land portion 22a can be prevented from being locally high in the vicinity of the bent lug groove 42. In other words, the rigidity of the portion of the first second land portion 22a in which the bent lug groove 42 is arranged is lowered by the bent lug groove 42, so that the portion of the first second land portion 22a between the first inner circumferential groove 31a and the bent lug groove 42 has a relatively high rigidity locally compared to the portion with a low rigidity. For this reason, there is a risk that uneven wear due to a rigidity difference is likely to occur in the vicinity of the portion of the first second land portion 22a in which the bent lug groove 42 is arranged.

[0093] In contrast, when the communicating sipes 61 that open to the first inner circumferential groove 31a and the bent lug groove 42 are disposed in the first second land portion 22a, the portion between the first inner circumferential groove 31a and the bent lug groove 42 can be prevented from becoming too rigid compared to other portions. This can prevent uneven wear caused by the difference in stiffness. As a result, uneven wear resistance can be ensured.

[0094] In addition, the bent lug groove 42 has a groove depth that is deeper from the end portion 42d that terminates in the land portion 20 toward the end portion that opens into the circumferential groove 30, so that when driving on a wet road surface, water that has entered the bent lug groove 42 can be easily drained toward the circumferential groove 30 where the bent lug groove 42 opens. In addition, the bent lug groove 42 has a groove width that is wider from the end portion 42d that terminates in the land portion 20 toward the end portion that opens into the circumferential groove 30, so that water that has entered the bent lug groove 42 can be easily drained toward the circumferential groove 30. This makes it possible to more reliably ensure the drainage performance of the bent lug groove 42. As a result, it is possible to more reliably improve wet performance.

[0095] In addition, since the land portion 20 is provided with a plurality of sipes 60 extending in the tire width direction, the edge component can be increased, and the edge effect can improve the performance on ice when driving on an icy road surface. Furthermore, by providing a plurality of sipes 60 on the land portion 20, the sipes 60 can absorb water on the road surface when driving on a wet road surface, improving the drainage. As a result, the performance on ice and wet conditions can be improved more reliably.

[0096] [Variations] In the above embodiment, the bent lug groove 42 has two bent portions 43, but one bent lug groove 42 may have three or more bent portions 43. In the above embodiment, the bent portions 43 of the two bent lug grooves 42 have the same bent direction in the groove width direction of the bent lug groove 42, but the bent directions of the multiple bent portions 43 of one bent lug groove 42 may be different from each other. Regardless of the number and bending directions of the bent portions 43, the bent lug groove 42 has multiple bent portions 43, and thereby can secure a groove area while suppressing a decrease in the rigidity of the land portion 20 in which the bent lug groove 42 is arranged.

[0097] In the above-described embodiment, the two bent portions 43 of the bent lug groove 42 each have a bend angle of 90° or more, but the bend angles of all the bent portions 43 do not have to be 90° or more. It is sufficient that at least one of the bent portions 43 among the multiple bent portions 43 of one bent lug groove 42 has a bend angle of 90° or more. The bent lug groove 42 is formed so that at least one of the bent portions 43 has a bend angle of 90° or more, thereby making it possible to ensure the ease of flow of water in the bent lug groove 42 while suppressing a decrease in the rigidity of the land portion 20 in which the bent lug groove 42 is arranged.

[0098] In addition, in the above-described embodiment, the bent lug groove 42 opens into the circumferential groove 30 that defines the outer side of the land portion 20 in the tire width direction, among the circumferential grooves 30 that define both sides of the bent lug groove 42 in the tire width direction, but the circumferential groove 30 into which the bent lug groove 42 opens may be the circumferential groove 30 that defines the inner side of the land portion 20 in the tire width direction.

[0099] In the above-described embodiment, the bent lug groove 42 is disposed in the first second land portion 22a among the multiple land portions 20 arranged side by side in the tire width direction, but the land portion 20 in which the bent lug groove 42 is disposed may be a land portion 20 other than the first second land portion 22a. The bent lug groove 42 may be disposed in multiple land portions 20 that are different from each other in positions in the tire width direction.

[0100] In the above-described embodiment, the number of circumferential grooves 30 arranged in the tread portion 2 is four, but the number of circumferential grooves 30 may be other than four. The above-described embodiments and modified examples may be appropriately combined. In the above-described embodiment, the pneumatic tire 1 is used as an example of a tire according to the present invention, but the tire according to the present invention may be other than the pneumatic tire 1. The tire according to the present invention may be, for example, a so-called airless tire that can be used without filling with gas.

[0101] [Example] 6 is a table showing the results of a performance evaluation test of a pneumatic tire. Below, a performance evaluation test conducted on a conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and a comparative pneumatic tire compared to the pneumatic tire 1 according to the present invention will be described. The performance evaluation test was conducted on braking performance on a snowy road surface, braking performance on an icy road surface, and braking performance on a wet road surface.

[0102] 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 250 kPa for the front wheels and 240 kPa for the rear wheels, and running the evaluation vehicle.

[0103] The evaluation method for each test item was as follows: for braking on snow, a test vehicle fitted with test tires was used to conduct braking tests on a test course with a snowy road surface, and the reciprocal of the braking distance was evaluated by expressing it as an index, with the conventional example described below being set at 100. For braking on snow, a higher index indicates a shorter braking distance on snowy roads, and better performance in terms of braking on snow.

[0104] Braking on ice was evaluated by conducting braking tests on an icy test course using an evaluation vehicle fitted with the test tires, and expressing the reciprocal of the braking distance as an index, with the conventional example (described below) set at 100. A higher index indicates a shorter braking distance on icy roads, and better performance in terms of braking on ice.

[0105] For wet braking, a braking test was conducted on a test course with a wet road surface using an evaluation vehicle fitted with the test tires, and the reciprocal of the braking distance was expressed as an index, with the conventional example described below being set at 100. For wet braking, a higher index indicates a shorter braking distance on a wet road surface, and thus better wet braking performance.

[0106] The performance evaluation test was carried out using a conventional pneumatic tire, which is an example of a conventional pneumatic tire, and Examples 1 to 3, which are pneumatic tires 1 according to the present invention. 4 7, Comparative Examples which are pneumatic tires compared to the pneumatic tire 1 according to the present invention, and Reference Examples 5、 The test was carried out on nine types of pneumatic tires, tyres 1 and 2. Among them, in the conventional example, both ends of the bent lug groove having a bent portion are open to the circumferential groove, while in the comparative example, the bent lug groove has one bent portion.

[0107] In contrast, Examples 1 to 4, which are examples of the pneumatic tire 1 according to the present invention, 4 In Examples 1 to 7, one end of each of the bent lug grooves 42 is open to the circumferential groove 30, and the other end is closed by terminating within the land portion 20, and the bent lug grooves 42 have two or more bent portions 43. 4 ,7,and,Reference Example 5、 The pneumatic tires 1 of the sixth embodiment differ in the bending angle of the bent portion 43, whether the position of the bent portion 43 is within a range of 40% of the maximum width of the land portion 20, the presence or absence of a communicating sipe 61, the relative relationship of the groove depth between the end side on the opening side and the end side on the non-opening side of the bent lug groove 42, and the relative relationship of the groove width between the end side on the opening side and the end side on the non-opening side of the bent lug groove 42.

[0108] A performance evaluation test was carried out using these pneumatic tires 1. As a result, as shown in FIG. 4 It was found that the pneumatic tire 1 according to the seventh embodiment can improve the performance in all of braking on snow, braking on ice, and braking on wet surfaces, compared to the conventional example. 4 The pneumatic tire 1 according to the seventh and seventh embodiments can ensure the performance on snow and the performance on wet ground while suppressing the deterioration of the performance on ice. [Explanation of symbols]

[0109] 1. Pneumatic tires 2 Tread section 3 Tread contact surface 5 Shoulder section 8 Sidewall 10 Bead section 13 Carcass layer 14 Belt layer 20 Land 21 Center Land Section 22 Second Land Division 22a 1st Second Land Section 22b 2nd Land Section 23 Shoulder Land Section 30 Circumferential groove 31 Inner circumferential groove 31a 1st inner circumferential groove 31b 2nd inner circumferential groove 32 Long section 33 Short section 35 Outer circumferential groove 40 Lug groove 41 Center lug groove 42 Flexed lug groove 43 Bend 44 Connecting lug groove 45 Shoulder lug groove 50 Circumferential thin groove 50a long section 50b Short section 51 Bend 55 Shoulder narrow groove 60 sipes 61 Interconnected sipes

Claims

1. A plurality of circumferential grooves extending in a tire circumferential direction; A plurality of land portions defined by the circumferential groove; A lug groove is disposed in the land portion, both sides of which in the tire width direction are partitioned by the circumferential groove, one end of which opens into the circumferential groove and the other end of which terminates within the land portion, and which has two or more bent portions whose extending direction changes; Equipped with The lug groove has a groove depth that increases from an end side that terminates within the land portion toward an end side that opens into the circumferential groove, A tire characterized in that a communicating sipe that opens into the lug groove and the circumferential groove that is different from the circumferential groove on the side where the lug groove opens is arranged in the land portion in which the lug groove is arranged.

2. The tire according to claim 1 , wherein at least one of the plurality of bent portions in one lug groove has a bend angle of 90° or more.

3. The tire according to claim 1 or 2, wherein the bent portion is disposed within a range of 40% of a maximum width of the land portion in the tire width direction, centered on a center in the tire width direction of the land portion.

4. The tire according to any one of claims 1 to 3, wherein the lug groove has a groove width that increases from an end side terminating within the land portion toward an end side opening into the circumferential groove.

5. The tire according to any one of claims 1 to 4, wherein a plurality of sipes extending in the tire width direction are arranged in the land portion.

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