Tire

Abstract

In this tire (1), a first center main groove (22) has a zigzag shape in which long sections and short sections are alternately connected. The second center main groove (23) has a bent shape in which a first groove section having a circumferential length L31, a second groove section having a circumferential length L32, and a third groove section having a circumferential length L33 are connected. The circumferential lengths (L31 to L33) of the first to third groove sections satisfy the relationship L31 > L32 > = L33.

Description

Technical Field

[0001] The present invention relates to a tire, and more particularly, to a tire capable of improving the snow performance of the tire. Background Art

[0002] In recent all-weather tires used in snowy areas, in order to improve the snow performance of the tire, main grooves having a sawtooth shape are adopted. As a conventional tire adopting this structure, the technique described in Patent Document 1 is known.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-113066 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a tire capable of improving the snow performance of the tire.

[0008] Means for Solving the Problems

[0009] In order to achieve the above object, the tire of the present invention includes a plurality of main grooves extending in the circumferential direction of the tire and a plurality of land portions divided by the plurality of main grooves, and is characterized in that the plurality of main grooves include a first central main groove and a second central main groove adjacent to each other with the tire equatorial plane interposed therebetween, the plurality of land portions include a central land portion divided by the first central main groove and the second central main groove, the first central main groove has a sawtooth shape formed by alternately connecting long-sized portions and short-sized portions, the second central main groove has a bent shape formed by connecting a first groove portion having a circumferential length L31, a second groove portion having a circumferential length L32, and a third groove portion having a circumferential length L33, and the circumferential lengths L31 to L33 of the first groove portion to the third groove portion have a relationship of L31 > L32 ≥ L33.

[0010] Advantages of the Invention

[0011] In the tire of the present invention, (1) the first central main groove 22 has a serrated shape formed by alternately connecting long-sized portions and short-sized portions, and the second central main groove has a bent shape formed by a first groove portion to a third groove portion. Therefore, the edge component in the central region of the tread surface can be ensured, and the snow performance of the tire is improved. In addition, (2) when the first central main groove is located in the outer region in the vehicle width direction and the second central main groove is located in the inner region in the vehicle width direction in the vehicle-mounted state of the tire, by making the first central main groove have a serrated shape with fewer bending points, the uneven wear resistance performance of the tire can be ensured, and by making the second central main groove have a bent shape with more bending points, the snow performance of the tire is effectively improved. Thus, it has the advantage of taking into account both the snow performance and the uneven wear resistance performance of the tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a cross-sectional view in the tire meridian direction of the tire showing an embodiment of the present invention.

[0013] Figure 2 is a plan view showing Figure 1 the tread surface of the tire described above.

[0014] Figure 3 is a plan view showing Figure 2 an enlarged view of the outer region in the vehicle width direction of the tire described above.

[0015] Figure 4 is a plan view showing Figure 3 an enlarged view of the outer intermediate land portion described above.

[0016] Figure 5 is a plan view showing Figure 4 a perspective view of the chamfered portion of the outer intermediate land portion described above.

[0017] Figure 6 is a plan view showing Figure 2 an enlarged view of the central region of the tread surface of the tire described above.

[0018] Figure 7 is a plan view showing Figure 6 an enlarged view of the central land portion described above.

[0019] Figure 8 is a plan view showing Figure 7 a cross-sectional view in the groove length direction of the second central cross rib groove of the central land portion described above.

[0020] Figure 9 is a plan view showing Figure 7 a perspective view of the chamfered portion of the central land portion described above.

[0021] Figure 10 is a plan view showing Figure 2Enlarged view of the inner region in the vehicle width direction of the tire described.

[0022] Figure 11 It shows Figure 10 Enlarged view of the inner intermediate land portion described.

[0023] Figure 12 It shows Figure 11 Cross-sectional view of the notch portion of the inner intermediate transverse groove described.

[0024] Figure 13 It is a graph showing the results of the performance test of the tire of the embodiment of the present invention.

[0025] Figure 14 It is a graph showing the results of the performance test of the tire of the embodiment of the present invention. Detailed implementation mode

[0026] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In addition, the present invention is not limited to this embodiment. In addition, the constituent elements of this embodiment include constituent elements that can be replaced and whose replacement is obvious while maintaining the identity of the invention. In addition, a plurality of modification examples described in this embodiment can be arbitrarily combined within the range that is obvious to those skilled in the art.

[0027] [Tire]

[0028] Figure 1 It is a cross-sectional view in the tire meridian direction of the tire 1 of the embodiment of the present invention. This figure shows a cross-sectional view of a single-sided region in the tire radial direction. In addition, in this figure, as an example of a tire, a pneumatic radial tire for an SUV (Sports Utility Vehicle) is shown.

[0029] In this figure, the cross-section in the tire meridian direction is defined as the cross-section when the tire is cut by a plane including the tire rotation axis (not shown). In addition, the tire equatorial plane CL is defined as a plane passing through the midpoint of the measurement points of the tire cross-section width specified by JATMA and perpendicular to the tire rotation axis. In addition, the tire width direction is defined as the direction parallel to the tire rotation axis, and the tire radial direction is defined as the direction perpendicular to the tire rotation axis.

[0030] In addition, the inner side and the outer side in the vehicle width direction are defined as the orientations with respect to the vehicle width direction when the tire is mounted on the vehicle. Further, the left and right regions with the tire equatorial plane as the boundary are defined as the outer region and the inner region in the vehicle width direction, respectively. In addition, the tire has an installation direction display portion (not shown) indicating the tire installation direction with respect to the vehicle. The installation direction display portion is constituted by, for example, marks and unevenness added to the sidewall portion of the tire. For example, ECE R30 (Article 30 of the Economic Commission for Europe Regulations) stipulates that a display portion of the vehicle installation direction must be provided on the sidewall portion that becomes the outer side in the vehicle width direction in the vehicle-mounted state.

[0031] The tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass ply 13, a belt ply 14, tread rubber, a pair of sidewall rubbers 16, 16, and a pair of rim cushion rubbers 17, 17 (see Figure 1 ).

[0032] The pair of bead cores 11, 11 are formed by winding one or more bead wires made of steel in a ring shape and multiple layers, and are embedded in the bead portions to form the cores of the left and right bead portions. The pair of bead fillers 12, 12 are respectively disposed on the outer periphery in the tire radial direction of the pair of bead cores 11, 11 to strengthen the bead portions.

[0033] The carcass ply 13 has a single-layer structure formed by one carcass ply or a multi-layer structure formed by laminating multiple carcass plies, and is erected in a ring shape between the left and right bead cores 11, 11 to form the skeleton of the tire. In addition, both end portions of the carcass ply 13 are folded back to the outside in the tire width direction so as to wrap the bead core 11 and the bead filler 12 and are fixed. The carcass ply of the carcass ply 13 is formed by covering multiple carcass cords made of steel or organic fiber materials (for example, aramid, nylon, polyester, rayon, etc.) with cover rubber and performing calendering, and has a cord angle of 80° or more and 100° or less (defined as the inclination angle of the length direction of the carcass cord with respect to the tire circumferential direction).

[0034] The belt ply 14 is formed by laminating multiple belt plies 141 to 144, and is wound around the outer periphery of the carcass ply 13. The belt plies 141 to 144 include a pair of crossed belts 141, 142 and multiple belt cover layers 143, 144.

[0035] A pair of crossed belt plies 141, 142 are formed by covering a plurality of belt cords made of steel or organic fiber material with cover rubber and performing calendering, and have a cord angle with an absolute value of 15° or more and 55° or less. In addition, the pair of crossed belt plies 141, 142 have cord angles with different signs (defined as the inclination angle of the length direction of the belt cord with respect to the tire circumferential direction), and the length directions of the belt cords are laminated so as to cross each other (so-called cross ply structure). In addition, the pair of crossed belt plies 141, 142 are laminated and disposed on the radially outer side of the carcass ply 13 of the tire.

[0036] The belt cover layers 143, 144 are formed by covering belt cover cords made of steel or organic fiber material with cover rubber, and have a cord angle with an absolute value of 0° or more and 10° or less. In addition, the belt cover layers 143, 144 are, for example, strips formed by covering one or more belt cover cords with cover rubber, and are formed by winding the strips around the outer peripheral surface of the crossed belt plies 141, 142 in a spiral shape a plurality of times in the tire circumferential direction. In addition, the plurality of belt cover layers 143, 144 are disposed so as to cover the entire area of the crossed belt plies 141, 142.

[0037] The tread rubber is disposed on the radially outer periphery of the carcass ply 13 and the belt ply 14 to form the tread portion of the tire. A pair of sidewall rubbers 16, 16 are respectively disposed on the outer sides in the tire width direction of the carcass ply 13 to form the left and right sidewall portions. A pair of rim cushion rubbers 17, 17 extend from the radially inner sides of the left and right bead cores 11, 11 and the folded-back portions of the carcass ply 13 to the outer sides in the tire width direction to form the rim fitting surfaces of the bead portions.

[0038] [Tread Pattern]

[0039] Figure 2 is a plan view showing Figure 1 the tread surface of the tire described. This figure shows the tread surface of an all-weather tire. In this figure, the tire circumferential direction means the direction around the tire rotation axis. In addition, the reference numeral T is the tire ground contact end, and the dimension mark TW is the tire ground contact width.

[0040] As Figure 2 shown, the tire 1 has four main grooves 21 to 24 on the tread surface, and five land portions 31 to 35 divided by these main grooves 21 to 24.

[0041] The main grooves 21 to 24 are composed of the outer and inner shoulder main grooves 21 and 24 and the outer and inner central main grooves 22 and 23. These main grooves 21 to 24 have an annular structure that extends continuously over the entire circumference of the tire in the circumferential direction. The shoulder main grooves 21 and 24 are the main grooves located on the outermost sides in the tire width direction and are defined by the respective left and right regions with the tire equatorial plane CL as the boundary. In addition, the outer shoulder main groove 21 and the outer central main groove 22 are located in the outer region in the vehicle width direction with the tire equatorial plane CL as the boundary, and the inner central main groove 23 and the inner shoulder main groove 24 are located in the inner region in the vehicle width direction.

[0042] The main grooves 21 to 24 are grooves with an obligation to display wear indicators specified by JATMA. In addition, the long-sized portions with a serrated shape described later in the main grooves 21, 22, and 24 and the first groove portion with a bent shape in the main groove 23 have a groove width of 2.5 [mm] or more and 15.0 [mm] or less and a groove depth of 8.0 [mm] or more and 12.0 [mm] or less.

[0043] The groove width is measured as the distance between the opposing groove walls at the groove opening in a non-loaded state where the tire is mounted on a specified rim and filled with a specified internal pressure. In a configuration where there is a notch or chamfer at the groove opening, the groove width is measured at the intersection of the extension line of the tread surface of the tread in a cross-section parallel to the groove width direction and the groove depth direction and the extension line of the groove wall.

[0044] The groove depth is measured as the distance from the tread surface to the groove bottom in a non-loaded state where the tire is mounted on a specified rim and filled with a specified internal pressure. In addition, in a configuration where there are local uneven portions or sipes at the groove bottom, they are excluded when measuring the groove depth.

[0045] The prescribed rim refers to the "standard rim" prescribed by JATMA, the "Design Rim" prescribed by TRA, or the "Measuring Rim" prescribed by ETRTO. In addition, the prescribed internal pressure refers to the "maximum air pressure" prescribed by JATMA, the maximum value of the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" prescribed by TRA, or the "INFLATION PRESSURES" prescribed by ETRTO. In addition, the prescribed load refers to the "maximum load capacity" prescribed by JATMA, the maximum value of the "TIRE LOAD LIMITS AT VARIOUSCOLD INFLATION PRESSURES" prescribed by TRA, or the "LOAD CAPACITY" prescribed by ETRTO. However, in JATMA, in the case of a tire for a passenger car, the prescribed internal pressure is an air pressure of 180 [kPa], and the prescribed load is 88 [%] of the maximum load capacity under the prescribed internal pressure.

[0046] The land portions 31 to 35 are composed of outer and inner shoulder land portions 31, 35, outer and inner middle land portions 32, 34, and a row of central land portions 33. These land portions 31 to 35 are divided by the main grooves 21 to 24, and constitute an annular tread extending over the entire circumference of the tire. The shoulder land portions 31, 35 are defined as the land portions on the outer side in the tire width direction divided by the shoulder main grooves 21, 24. The middle land portions 32, 34 are defined as the land portions on the inner side in the tire width direction divided by the shoulder main grooves 21, 24. In addition, the outer shoulder land portion 31 and the outer middle land portion 32 are located in the outer area in the vehicle width direction with the tire equatorial plane CL as the boundary. In addition, the central land portion 33 is located on the tire equatorial plane CL. In addition, the inner middle land portion 34 and the inner shoulder land portion 35 are located in the inner area in the vehicle width direction.

[0047] In addition, Figure 2 In the embodiment, the maximum contact widths Wb1 and Wb5 of the outer and inner shoulder land portions 31 and 35 are in the range of 20% or more and 60% or less, preferably in the range of 35% or more and 45% or less, relative to the tire contact width TW. In addition, the maximum contact widths Wb2 and Wb4 of the outer and inner middle land portions 32 and 34 are in the range of 20% or more and 50% or less, relative to the tire contact width TW. In addition, the maximum contact width Wb3 of the center land portion 33 is in the range of 30% or more and 40% or less, relative to the tire contact width TW.

[0048] The ground contact width of the land portion is measured as the linear distance in the tire axial direction at the contact surface between the land portion and the flat plate when the tire is mounted on a specified rim, a specified internal pressure is applied, and the tire is placed vertically with respect to the flat plate in a stationary state and a load corresponding to the specified load is applied.

[0049] The tire ground contact width TW is measured as the linear distance in the tire axial direction at the contact surface between the tire and the flat plate when the tire is mounted on a specified rim, a specified internal pressure is applied, and the tire is placed vertically with respect to the flat plate in a stationary state and a load corresponding to the specified load is applied.

[0050] The tire ground contact end T is defined as the position of the maximum width in the tire axial direction at the contact surface between the tire and the flat plate when the tire is mounted on a specified rim, a specified internal pressure is applied, and the tire is placed vertically with respect to the flat plate in a stationary state and a load corresponding to the specified load is applied.

[0051] [Outer shoulder main groove and outer center main groove]

[0052] Figure 3 is a magnified view of the outer region in the vehicle width direction of the tire 1 Figure 2 described. This figure shows the ground contact region on the outer side in the vehicle width direction with the tire equatorial plane CL as the boundary.

[0053] As Figure 3 shown, the outer shoulder main groove 21 has a sawtooth shape formed by alternately connecting long-sized portions and short-sized portions. In addition, the circumferential length L1 of the long-sized portion of the outer shoulder main groove 21 is in the range of 0.70 ≤ L1 / P1 ≤ 0.95 with respect to the pitch length P1 of the sawtooth shape of the outer shoulder main groove 21, preferably in the range of 0.80 ≤ L1 / P1 ≤ 0.90. By the above lower limit, the effect of improving snow evacuation on the snow road surface due to the long-sized portion of the sawtooth shape can be ensured, and by the above upper limit, the length of the short-sized portion can be ensured and the snow traction of the tire can be ensured. In addition, the number of pitches N1 of the sawtooth shape of the outer shoulder main groove 21 is in the range of 60 ≤ N1 ≤ 100.

[0054] The sawtooth shape of the main groove is defined as the shape of the groove center line of the main groove when observing the tread surface in a plan view.

[0055] The groove center line is defined as an imaginary line obtained by connecting the midpoints of the end points of the groove width. In addition, local uneven portions (for example, transverse grooves, openings of sipes, chamfered portions of the land portion, notches, etc.) formed at the opening of the main groove in the tread surface are excluded to define the groove center line of the main groove.

[0056] The circumferential length of the groove portion is measured as the length in the tire circumferential direction with the bending points of the groove center line of the main groove as the end points.

[0057] In addition, in Figure 3 , the amplitude A1 of the serrated shape of the outer shoulder main groove 21 is in the range of 0.15 ≤ A1 / Wg1 ≤ 0.50 with respect to the groove width Wg1 of the outer shoulder main groove 21, and preferably in the range of 0.25 ≤ A1 / Wg1 ≤ 0.35. By the above lower limit, the improvement effect of the snow traction performance brought by the serrated shape can be ensured, and by the above upper limit, the generation of uneven wear caused by excessive amplitude can be suppressed. In addition, the groove width Wg1 of the outer shoulder main groove 21 is in the range of 8.5 [mm] ≤ Wg1 ≤ 16.0 [mm], and the groove depth Hg1 (refer to Figure 5 described later) is in the range of 8.0 [mm] ≤ H1 ≤ 12.0 [mm].

[0058] In addition, in Figure 3 's configuration, the outer shoulder main groove 21 has a see-through structure in the tire circumferential direction. That is, the groove width Wg1 and the amplitude A1 of the outer shoulder main groove 21 are ensured in such a way that the edge portions of the left and right land portions 31, 32 divided by the outer shoulder main groove 21 do not overlap each other when observed in the tire circumferential direction. Thereby, while ensuring the improvement effect of the snow traction performance, the snow discharge property on the snow road surface can be improved.

[0059] As Figure 3 shown, the outer center main groove 22 has a serrated shape formed by alternately connecting long-sized portions and short-sized portions. In addition, the long-sized portion of the outer center main groove 22 is inclined in the opposite direction to the long-sized portion of the outer shoulder main groove 21 in the tire circumferential direction. Specifically, in Figure 3 's configuration, the long-sized portion of the outer shoulder main groove 21 is inclined toward the tire ground contact end T side downward in the figure, and the long-sized portion of the outer center main groove 22 is inclined toward the tire equatorial plane CL side downward in the figure.

[0060] In the above configuration, (1) the outer shoulder main groove 21 and the outer center main groove 22 have a serrated shape formed by alternately connecting long-sized portions and short-sized portions. Therefore, compared with a configuration (not shown) in which the main groove has a serrated shape formed by connecting groove portions of the same length, the snow discharge property on the snow road surface is improved, and the snow performance of the tire is improved. In addition, (2) the long-sized portions of the serrated shapes of the adjacent main grooves 21, 22 are inclined in opposite directions to each other with respect to the tire circumferential direction. Therefore, compared with a configuration (not shown) in which the two are inclined in the same direction with respect to the tire circumferential direction, the improvement effect of the snow traction performance brought by having a serrated shape can be ensured.

[0061] In addition, in Figure 3In this case, the circumferential length L2 of the long dimension portion of the outer central main groove 22 is in the range of 0.60 ≤ L2 / P2 ≤ 1.00 with respect to the pitch length P2 of the serrated shape of the outer central main groove 22, and preferably in the range of 0.80 ≤ L2 / P2 ≤ 0.95. By the above lower limit, the snow removal effect on the snow-covered road surface due to the long dimension portion of the serrated shape can be ensured, and by the above upper limit, the length of the short dimension portion can be ensured, and thus the snow traction performance of the tire can be ensured. In addition, when L2 / P2 = 1.00, the groove center line of the short dimension portion of the outer central main groove 22 is parallel to the tire axis.

[0062] In addition, in Figure 3 this case, the pitch length P2 of the serrated shape of the outer central main groove 22 is in the range of 1.50 ≤ P2 / P1 ≤ 3.00 with respect to the pitch length P1 of the serrated shape of the outer shoulder main groove 21, and preferably in the range of 2.00 ≤ P2 / P1 ≤ 2.50. Therefore, the pitch length P2 of the outer central main groove 22 is longer and the pitch length P1 of the outer shoulder main groove 21 is shorter. Thereby, the rigidity of the central region of the tread surface can be ensured, uneven wear of the tire can be suppressed, and in addition, the edge component of the shoulder region of the tread surface can be ensured, and the snow traction performance of the tire can be ensured. In addition, the number of pitches N2 of the serrated shape of the outer central main groove 22 is in the range of 30 ≤ N2 ≤ 50. In addition, in Figure 3 this configuration, the number of pitches N2 of the outer central main groove 22 is set to N2 / N1 = 1 / 2 with respect to the number of pitches N1 of the outer shoulder main groove 21.

[0063] In addition, in Figure 3 this case, the amplitude A2 of the serrated shape of the outer central main groove 22 is in the range of 1.40 ≤ A2 / Wg2 ≤ 1.90 with respect to the groove width Wg2 of the outer central main groove 22, and preferably in the range of 1.60 ≤ A2 / Wg2 ≤ 1.70. By the above lower limit, the improvement effect of the snow traction performance due to the serrated shape can be ensured, and by the above upper limit, the generation of uneven wear caused by an excessive amplitude can be suppressed.

[0064] In addition, in Figure 3 this case, the amplitude A2 of the serrated shape of the outer central main groove 22 is in the range of 2.00 ≤ A2 / A1 ≤ 4.00 with respect to the amplitude A1 of the serrated shape of the outer shoulder main groove 21, and preferably in the range of 2.50 ≤ A2 / A1 ≤ 3.50. Therefore, the amplitude A2 of the outer central main groove 22 is larger than the amplitude A1 of the outer shoulder main groove 21. Thereby, compared with a configuration (not shown) in which both have substantially the same amplitude, the edge component of the central region of the tread surface can be ensured, the snow traction performance of the tire can be ensured, and in addition, the rigidity of the shoulder region of the tread surface can be ensured, and uneven wear of the tire can be suppressed.

[0065] In addition, in Figure 3 , the groove width Wg2 of the outer central main groove 22 is in the range of 5.0 [mm] ≤ Wg2 ≤ 10.0 [mm], and the groove depth Hg2 (refer to Figure 8 described later) is in the range of 8.0 [mm] ≤ Hg2 ≤ 12.0 [mm]. By the above lower limit, the groove volume of the outer central main groove 22 can be ensured, and the snow performance of the tire can be ensured. By the above upper limit, the rigidity of the central region of the tread surface can be ensured, and the uneven wear resistance performance of the tire can be ensured.

[0066] In addition, in Figure 3 , the groove width of the short dimension part of the serrated shape of the outer central main groove 22 (the dimension mark in the figure is omitted) is narrower than that of the long dimension part. In addition, the groove width of the short dimension part is in the range of 30 [%] or more and 70 [%] or less with respect to the groove width of the long dimension part, and preferably in the range of 45 [%] or more and 55 [%] or less. In this configuration, particularly in a configuration such as Figure 3 where the inclination angle of the short dimension part with respect to the tire circumferential direction is large, it is preferable in terms of ensuring the rigidity of the land parts 32 and 33 and ensuring the uneven wear resistance performance of the tire. However, not limited thereto, the short dimension part and the long dimension part of the outer central main groove 22 may have a uniform groove width (omitted from the illustration).

[0067] In addition, in Figure 3 , the groove width Wg2 of the outer central main groove 22 is in the range of 0.50 ≤ Wg2 / Wg1 ≤ 0.80 with respect to the groove width Wg1 of the outer shoulder main groove 21, and preferably in the range of 0.60 ≤ Wg2 / Wg1 ≤ 0.70. Therefore, the groove width Wg2 of the outer central main groove 22 is narrower than the groove width Wg1 of the outer shoulder main groove 21. Thereby, compared with a configuration (omitted from the illustration) in which both have substantially the same groove width, the snow performance of the tire is improved.

[0068] In addition, in Figure 3 , the outer central main groove 22 has a see throughless structure in the tire circumferential direction. That is, the groove width Wg2 and the amplitude A2 of the outer central main groove 22 are set such that the edge parts of the left and right land parts 32 and 33 divided by the outer central main groove 22 overlap each other when observed in the tire circumferential direction.

[0069] [Outer shoulder land part]

[0070] As Figure 3 shows, the outer shoulder land part 31 includes an outer shoulder cross-groove 311 and an outer shoulder block 312.

[0071] The outer shoulder transverse groove 311 has a linear shape or a gentle arc shape, penetrates the outer shoulder land portion 31 in the tire width direction, and is connected to the tire ground contact end T and the outer shoulder main groove 21. In addition, the outer shoulder transverse groove 311 is connected to the end of the long dimension portion of the serrated shape of the outer shoulder main groove 21, and is also connected to the maximum amplitude position on the tire ground contact end T side of the serrated shape. In addition, the outer shoulder main groove 21 has a bottom elevation portion (the reference numeral in the figure is omitted) at the opening on the outer shoulder main groove 21 side. In addition, a plurality of outer shoulder transverse grooves 311 are arranged at a predetermined interval in the tire circumferential direction. In addition, the groove width Wg11 (the dimension mark in the figure is omitted) of the outer shoulder transverse groove 311 is in the range of 5.0 [mm] or more and 10.0 [mm] or less, and the groove depth Hg11 is in the range of 6.0 [mm] or more and 11.0 [mm] or less.

[0072] The outer shoulder block 312 is divided by a plurality of outer shoulder transverse grooves 311. In addition, the edge portion on the outer shoulder main groove 21 side of the outer shoulder block 312 is divided by a set of long dimension portion and short dimension portion of the outer shoulder main groove 21 and has a V-shaped that protrudes toward the tire equatorial plane CL side. Thereby, the rigidity of the block can be ensured, and uneven wear of the tire can be suppressed.

[0073] In addition, as Figure 3 shown, the outer shoulder block 312 has a plurality of sipes (the reference numeral in the figure is omitted). Thereby, the snow performance of the tire is improved.

[0074] [Outer intermediate land portion]

[0075] Figure 4 is a magnified view showing Figure 3 the outer intermediate land portion 32 described in

[0076] As Figure 3 shown, the outer intermediate land portion 32 includes first and second outer intermediate transverse grooves 321A, 321B and first and second outer intermediate blocks 322A, 322B.

[0077] The first and second outer intermediate transverse grooves 321A, 321B have a linear shape or a gentle arc shape, penetrate the outer intermediate land portion 32 in the tire width direction, and are connected to the outer shoulder main groove 21 and the outer central main groove 22. In addition, the first and second outer intermediate transverse grooves 321A, 321B are inclined in the same direction with respect to the tire circumferential direction.

[0078] Further, one end of one of the first and second outer intermediate transverse grooves 321A and 321B is separated from the maximum amplitude position of the serrated shape of the outer shoulder main groove 21 and is connected to the central portion of the long dimension portion of the serrated shape. Further, the other end of the first outer intermediate transverse groove 321A is connected to the end of the long dimension portion of the serrated shape of the outer central main groove 22, and is also connected to the maximum amplitude position on the tire ground contact end T side of the serrated shape. On the other hand, the other end of the second intermediate transverse groove 321B is separated from the maximum amplitude position of the serrated shape of the outer central main groove 22 and is connected to the central portion of the long dimension portion of the serrated shape.

[0079] Further, in Figure 3 , the groove widths Wg21 (Wg21A, Wg21B; refer to Figure 4 ) of the first and second outer intermediate transverse grooves 321A and 321B are in the range of 0.40 ≤ Wg21 / Wg2 ≤ 0.80 with respect to the groove width Wg2 of the long dimension portion of the outer central main groove 22, and preferably in the range of 0.50 ≤ Wg21 / Wg2 ≤ 0.70. Further, the groove width Wg21 of the outer intermediate transverse grooves 321A and 321B is in the range of 2.0 [mm] ≤ Wg21 ≤ 5.0 [mm].

[0080] Further, as Figure 3 shown, the first and second outer intermediate transverse grooves 321A and 321B are inclined in the same direction in the tire circumferential direction with respect to the long dimension portion of the serrated shape of the outer shoulder main groove 21. Further, in Figure 4 , the inclination angles θ21 (θ21A, θ21B) of the first and second outer intermediate transverse grooves 321A and 321B are in the range of 60 [deg] ≤ θ21 ≤ 90 [deg].

[0081] Further, in the structure of Figure 3 , the first outer intermediate transverse groove 321A extends in a manner that extends the short dimension portion of the serrated shape of the outer central main groove 22 in the tire width direction. Specifically, as Figure 4 shown, one side (the upper side in the figure) of the groove wall of the first outer intermediate transverse groove 321A on the outer central main groove 22 side is connected coplanarly to the groove wall of the short dimension portion of the outer central main groove 22. Thereby, the snow discharging performance of the outer central main groove 22 and the first outer intermediate transverse groove 321A is improved.

[0082] Further, as Figure 3As shown, the connecting portions of the outer intermediate cross-grooves 321A and 321B connected to the outer shoulder main groove 21 are arranged offset in the tire circumferential direction with respect to the connecting portion of the outer shoulder cross-groove 311 connected to the outer shoulder main groove 21. Specifically, the circumferential distance D1 of the tire from the intersection of the extension line of the groove center line of the outer intermediate cross-grooves 321A and 321B and the groove center line of the outer shoulder main groove 21 to the intersection of the extension line of the groove center line of the outer shoulder cross-groove 311 and the groove center line of the outer shoulder main groove 21 is in the range of 0.15 ≤ D1 / P1 ≤ 0.50 with respect to the pitch length P1 of the sawtooth shape of the outer shoulder main groove 21, and preferably in the range of 0.20 ≤ D1 / P1 ≤ 0.50. Thereby, the passing noise of the tire is reduced.

[0083] The outer intermediate blocks 322A and 322B are divided by the outer intermediate cross-grooves 321A and 321B. In addition, the edge portions on the outer central main groove 22 side of the first and second outer intermediate blocks 322A and 322B have a linear shape divided by the long-sized portions of the sawtooth shape of the outer central main groove 22. In addition, the circumferential edge portions of the first and second outer intermediate blocks 322A and 322B, that is, the edge portions divided by the first and second outer intermediate cross-grooves 321A and 321B, have a linear shape or a gentle arc shape. Thereby, uneven wear of the blocks in the central region of the tread surface can be suppressed.

[0084] In addition, as Figure 4 shown, the edge portions on the outer shoulder main groove 21 side of the first and second outer intermediate blocks 322A and 322B have a sawtooth shape including two bending points. Therefore, the first and second outer intermediate blocks 322A and 322B have a concave hexagon with a concave portion in the edge portion on the outer shoulder main groove 21 side. Thereby, the snow traction performance of the tire is improved. In addition, the contact area ratio of the first and second outer intermediate blocks 322A and 322B is in the range of 0.55 or more and 1.10 or less, and preferably in the range of 0.70 or more and 1.05 or less. Thereby, the contact area of the outer intermediate blocks 322A and 322B is made uniform.

[0085] In addition, as Figure 4 shown, the outer intermediate blocks 322A and 322B have a plurality of sipes (the reference numerals in the figure are omitted). Thereby, the snow performance of the tire is improved.

[0086] Figure 5 is a perspective view showing the chamfered portions 323A and 323B of the outer intermediate land portion 32 described in Figure 4 .

[0087] As Figure 4 and Figure 5As shown, the outer intermediate land portion 32 has chamfered portions 323A and 323B at the edge portion on the side of the outer shoulder main groove 21. These chamfered portions 323A and 323B open at the short dimension portion of the sawtooth shape of the outer shoulder main groove 21 when observing the tread in a plan view. In addition, in Figure 4 and Figure 5 configuration, the chamfered portions 323A and 323B have a triangular pyramid shape with the short dimension portion of the outer shoulder main groove 21 as one side, connecting adjacent long dimension portions. Through these chamfered portions 323A and 323B, the snow discharge property of discharging snow from the outer shoulder main groove 21 on a snow road surface is improved. In addition, in Figure 5 , the maximum depth H23 of the chamfered portions 323A and 323B is in the range of 0.10 ≤ H23 / Hg1 ≤ 0.40 with respect to the groove depth Hg1 of the outer shoulder main groove 21, and preferably in the range of 0.20 ≤ H23 / Hg1 ≤ 0.30. Through the above lower limit, the snow discharge effect brought by the chamfered portions 323A and 323B can be ensured, and through the above upper limit, the rigidity of the land portion can be ensured.

[0088] In addition, as Figure 3 shown, the edge portion of the outer intermediate land portion 32 on the side of the outer shoulder main groove 21 has a sawtooth shape formed by alternately connecting long dimension portions and short dimension portions. In addition, in Figure 4 , the circumferential length L1' of the long dimension portion of the sawtooth shape of the edge portion on the side of the outer shoulder main groove 21 is in the range of 0.70 ≤ L1' / P1' ≤ 0.95 with respect to the pitch length P1' of the sawtooth shape. In addition, the ratio L1' / P1' is equal to the ratio L1 / P1 of the sawtooth shape of the outer shoulder main groove 21.

[0089] In addition, as Figure 3 shown, the edge portion of the outer intermediate land portion 32 on the side of the outer central main groove 22 has a sawtooth shape formed by alternately connecting long dimension portions and short dimension portions. In addition, in Figure 4 , the circumferential length L2' of the long dimension portion of the sawtooth shape of the edge portion on the side of the outer central main groove 22 is in the range of 0.60 ≤ L2' / P2' ≤ 1.00 with respect to the pitch length P2' of the sawtooth shape. In addition, the ratio L2' / P2' is equal to the ratio L2 / P2 of the sawtooth shape of the outer central main groove 22. In addition, the pitch length P2' of the edge portion on the side of the outer central main groove 22 is in the range of 0.40 ≤ P2' / P1' ≤ 0.50 with respect to the pitch length P1' of the edge portion on the side of the outer shoulder main groove 21.

[0090] In addition, as Figure 3 shown, the long dimension portion of the edge portion of the outer intermediate land portion 32 on the side of the outer central main groove 22 is inclined in the opposite direction in the tire circumferential direction with respect to the long dimension portion of the edge portion on the side of the outer shoulder main groove 21. Specifically, as Figure 4As shown, the long dimension portion of the edge portion on the side of the outer shoulder main groove 21 inclines downward in the drawing toward the tire ground contact end T side, and the long dimension portion of the edge portion on the side of the outer center main groove 22 inclines downward in the drawing toward the tire equatorial plane CL side. Therefore, the ground contact width of the outer intermediate land portion 32 periodically increases and decreases in the tire circumferential direction.

[0091] In addition, in Figure 4 , the minimum ground contact width Wb2’ of the outer intermediate land portion 32 is in the range of 0.30 ≤ Wb2’ / Wb2 ≤ 0.70 with respect to the maximum ground contact width Wb2 of the outer intermediate land portion 32, and preferably in the range of 0.45 ≤ Wb2’ / Wb2 ≤ 0.55. Thereby, the rigidity of the land portion in the tire circumferential direction is homogenized.

[0092] [Inner center main groove]

[0093] Figure 6 is an enlarged view of the central region of the tread surface of the tire 1 described in Figure 2 . This figure particularly shows the outer and inner center main grooves 22, 23 and the central land portion 33.

[0094] As Figure 6 shown, the inner center main groove 23 has a bent shape formed by connecting a first groove portion having a circumferential length L31, a second groove portion having a circumferential length L32, and a third groove portion (reference numeral in the drawing is omitted) having a circumferential length L33. In addition, the circumferential lengths L31 to L33 of the first to third groove portions have a relationship of L31 > L32 ≥ L33. Therefore, the first groove portion is defined as the groove portion having the longest circumferential length L31. In addition, the second and third groove portions may have the same circumferential lengths L32, L33. In addition, the inner center main groove 23 can have a short dimension connecting portion (reference numeral in the drawing is omitted) that connects the first to third groove portions. For example, in the configuration of Figure 6 , the first and second groove portions are connected by a short dimension connecting portion having a circumferential length shorter than that of the third groove portion.

[0095] The bent shape of the main groove is defined as the shape of the groove center line of the main groove when observing the tread surface in a plan view.

[0096] In addition, as Figure 6 shown, the longest first groove portion inclines in the opposite direction in the tire circumferential direction with respect to the other second and third groove portions. Specifically, in Figure 6In the structure, the first groove portion inclines downward in the drawing and in a direction away from the tire equatorial plane CL, and the second and third groove portions incline downward in the drawing and toward the tire equatorial plane CL side. Further, the second and third groove portions incline in the same direction with respect to the tire circumferential direction. Further, the inclination angle (omitting the dimension mark in the drawing) of the long-sized second groove portion with respect to the tire circumferential direction is smaller than the inclination angle of the short-sized third groove portion. Further, the longest first groove portion of the inner central main groove 23 inclines in the same direction in the tire circumferential direction with respect to the long-sized portion of the outer central main groove 22.

[0097] In the above structure, (1) the outer central main groove 22 has a sawtooth shape formed by alternately connecting long-sized portions and short-sized portions, and the inner central main groove 23 has a bent shape formed by the first to third groove portions. Therefore, the edge components in the central region of the tread surface can be ensured, and the snow performance of the tire is improved. Further, (2) the inner central main groove 23 located in the inner region in the vehicle width direction with a high contribution to the snow performance has a bent shape including more bending points, whereby the snow structure of the tire is effectively improved. At the same time, the outer central main groove 22 located in the outer region in the vehicle width direction where uneven wear is likely to occur has a sawtooth shape including fewer bending points, whereby the uneven wear resistance of the tire can be ensured. Moreover, (3) the longest first groove portion of the inner central main groove 23 inclines in the same direction in the tire circumferential direction with respect to the long-sized portion of the outer central main groove 22, whereby the rigidity of the central land portion 33 is made uniform in the tire circumferential direction, and uneven wear of the central land portion 33 can be suppressed.

[0098] In addition, in Figure 6 the circumferential length L31 of the first groove portion of the inner central main groove 23 is in the range of 0.35 ≤ L31 / P3 ≤ 0.75 with respect to the pitch length P3 of the bent shape of the inner central main groove 23, and preferably in the range of 0.50 ≤ L31 / P3 ≤ 0.60. By the above lower limit, the circumferential length L31 of the long-sized first groove portion can be ensured, and the effect of improving the snow removal performance on the snow road surface can be ensured. By the above upper limit, the edge components of the short-sized second and third groove portions can be ensured, and the snow traction of the tire can be ensured.

[0099] In addition, in Figure 6 the circumferential length L32 of the second groove portion of the inner central main groove 23 is in the range of 0.20 ≤ L32 / P3 ≤ 0.45 with respect to the pitch length P3 of the bent shape of the inner central main groove 23, and preferably in the range of 0.30 ≤ L32 / P3 ≤ 0.40. Thereby, the circumferential length L32 of the short-sized second groove portion is optimized.

[0100] In addition, in Figure 6In this case, the circumferential length L33 of the third groove portion of the inner central main groove 23 is in the range of 0.05 ≤ L33 / P3 with respect to the spacing length P3 of the bent shape of the inner central main groove 23, and preferably in the range of 0.08 ≤ L33 / P3. In addition, the inclination angle of the third groove portion with respect to the tire circumferential direction is greater than the inclination angles of the first and second groove portions with respect to the tire circumferential direction, and is in the range of 40° or more and 90° or less. In addition, preferably, the inclination angle of the third groove portion with respect to the tire circumferential direction is 30° or more greater than the inclination angle of the second groove portion. Thereby, the edge component of the short-sized third groove portion can be ensured, and the snow traction of the tire can be ensured. The upper limit of L33 / P3 is not particularly limited, but is restricted due to the relationship L31 > L32 ≥ L33 of the circumferential lengths L31 to L33 of the first to third groove portions.

[0101] In addition, in Figure 6 the configuration, the third groove portion of the inner central main groove 23 is arranged offset in the tire circumferential direction with respect to the short-sized portion of the outer central main groove 22. Specifically, as Figure 6 shown, the third groove portion of the inner central main groove 23 is inclined in the same direction in the tire circumferential direction with respect to the short-sized portion of the outer central main groove 22, and in addition, the two are arranged in a staggered manner in the tire circumferential direction. In addition, the phase of the third groove portion of the inner central main groove 23 and the short-sized portion of the outer central main groove 22, that is, the circumferential distance D2, is in the range of 0.30 ≤ D2 / P2 ≤ 0.70 with respect to the spacing length P2 of the serrated shape of the outer central main groove 22, and preferably in the range of 0.40 ≤ D2 / P2 ≤ 0.60. Thereby, uneven wear in the central region of the tread surface can be suppressed.

[0102] In addition, in Figure 6 the configuration, the groove width (omitting the dimension mark in the figure) of the second groove portion of the inner central main groove 23 is wider than the groove widths of the other first and third groove portions. Specifically, the groove width of the second groove portion is in the range of 65% or more and 95% or less with respect to the groove width of the third groove portion, and preferably in the range of 75% or more and 85% or less. In this configuration, it is preferable in terms of improving the snow discharge property of discharging snow from the third groove portion with the shortest size on a snow road surface. Specifically, but not limited thereto, the first to third groove portions may also have the same groove width (omitting the illustration).

[0103] In addition, in Figure 6Among them, the spacing length P3 of the bent shape of the inner central main groove 23 is in the range of 0.80 ≤ P3 / P2 ≤ 1.20 with respect to the spacing length P2 of the serrated shape of the outer central main groove 22, and preferably in the range of 0.95 ≤ P3 / P2 ≤ 1.05. The ratio P3 / P2 represents the range of the non-uniformity of the spacing lengths P2 and P3 of the respective spacings. Therefore, the spacing length P3 of the inner central main groove 23 is set to be substantially the same as the spacing length P2 of the outer central main groove 22. Thereby, the rigidity of the central region of the tread surface is homogenized, and uneven wear of the tire is suppressed. In addition, the number of spacings N3 of the bent shape of the inner central main groove 23 is in the range of 30 ≤ N3 ≤ 50. In addition, in Figure 6 In the structure of, the number of spacings N3 of the inner central main groove 23 is set to N3 / N2 = 1 with respect to the number of spacings N2 of the outer central main groove 22.

[0104] In addition, in Figure 6 Among them, the amplitude A3 of the bent shape of the inner central main groove 23 is in the range of 0.55 ≤ A3 / Wg3 ≤ 0.95 with respect to the groove width Wg3 of the inner central main groove 23, and preferably in the range of 0.70 ≤ A3 / Wg3 ≤ 0.90. By the above lower limit, the improvement effect of the snow traction performance brought by the bent shape can be ensured, and by the above upper limit, the generation of uneven wear caused by excessive amplitude can be suppressed.

[0105] In addition, in Figure 6 Among them, the amplitude A3 of the bent shape of the inner central main groove 23 is in the range of 0.80 ≤ A3 / A2 ≤ 1.20 with respect to the amplitude A2 of the serrated shape of the outer central main groove 22, and preferably in the range of 0.95 ≤ A3 / A2 ≤ 1.05. Therefore, the amplitude A3 of the inner central main groove 23 is substantially the same as the amplitude A2 of the outer central main groove 22. Thereby, the rigidity of the central region of the tread surface is homogenized, and the uneven wear resistance of the tire is improved.

[0106] In addition, in Figure 6 Among them, the groove width Wg3 of the inner central main groove 23 is in the range of 4.0 [mm] ≤ Wg3 ≤ 12.0 [mm], and the groove depth Hg3 (refer to Figure 8 described later) is in the range of 8.0 [mm] ≤ Hg3 ≤ 12.0 [mm]. By the above lower limit, the groove volume of the inner central main groove 23 can be ensured, and the snow performance of the tire can be ensured. By the above upper limit, the rigidity of the central region of the tread surface can be ensured, and the uneven wear resistance performance of the tire can be ensured.

[0107] In addition, in Figure 6In this case, the groove width Wg3 of the inner central main groove 23 is in the range of 0.80 ≤ Wg3 / Wg2 ≤ 1.20, preferably in the range of 0.95 ≤ Wg3 / Wg2 ≤ 1.05, with respect to the groove width Wg2 of the outer central main groove 22. Therefore, the groove width Wg3 of the inner central main groove 23 is substantially the same as the groove width Wg2 of the outer central main groove 22. Thereby, the rigidity of the central region of the tread surface is homogenized, and the uneven wear resistance of the tire is improved.

[0108] In addition, in Figure 6 the configuration, the groove width (omitting the dimension mark in the figure) of the second groove portion having the circumferential length L32 is wider than the groove widths of the other first and third groove portions. In this configuration, it is preferable in terms of achieving both snow removal performance and uneven wear resistance. However, not limited thereto, the first to third groove portions of the inner central main groove 23 may also have a uniform groove width (omitting the illustration).

[0109] In addition, in Figure 6 the configuration, the inner central main groove 23 has a non-perspective structure in the tire circumferential direction. That is, the groove width Wg3 and the amplitude A3 of the inner central main groove 23 are set such that the edge portions of the left and right land portions 33, 34 divided by the inner central main groove 23 overlap each other when observed in the tire circumferential direction.

[0110] [Central land portion]

[0111] Figure 7 is an enlarged view showing the Figure 6 central land portion 33 described in Figure 8 is a cross-sectional view showing the groove length direction of the second central cross-groove 331B of the Figure 7 central land portion 33 described in

[0112] As Figure 6 shown, the central land portion 33 includes first and second central cross-grooves 331A, 331B and first and second central blocks 332A, 332B.

[0113] The first and second central cross-grooves 331A, 331B have a straight shape or a gentle arc shape, penetrate the central land portion 33 in the tire width direction, and are connected to the outer central main groove 22 and the inner central main groove 23. In addition, the first and second central cross-grooves 331A, 331B are inclined in opposite directions with respect to the tire circumferential direction. Thereby, the snow traction performance in the central land portion 33 is improved. In addition, the short-sized first central cross-groove 331A is inclined in the opposite direction to the above-described outer intermediate cross-grooves 321A, 321B and the inner intermediate cross-grooves 341A, 341B described later in the tire circumferential direction, and the long-sized second central cross-groove 331B is inclined in the same direction as the outer intermediate cross-grooves 321A, 321B and the inner intermediate cross-grooves 341A, 341B in the tire circumferential direction.

[0114] However, without being limited thereto, it is also possible that the short first central cross-groove 331A is inclined in the same direction in the tire circumferential direction with respect to the outer intermediate cross-grooves 321A, 321B and the inner intermediate cross-grooves 341A, 341B, and the long second central cross-groove 331B is inclined in the opposite direction in the tire circumferential direction with respect to the outer intermediate cross-grooves 321A, 321B and the inner intermediate cross-grooves 341A, 341B (the illustration is omitted).

[0115] In addition, in Figure 6 the above-described outer central main groove 22 and the inner central main groove 23 to be described later have mutually asymmetric sawtooth shapes and bent shapes, whereby the contact width of the central land portion 33 periodically increases and decreases in the tire circumferential direction. In addition, the first central cross-groove 331A is disposed in a region where the contact width of the central land portion 33 decreases, and the second central cross-groove 331B is disposed in a region where the contact width of the central land portion 33 increases. Thus, the first central cross-groove 331A is shorter than the second central cross-groove 331B.

[0116] Specifically, one end of one of the first and second central cross-grooves 331A, 331B is separated from the maximum amplitude position of the sawtooth shape of the outer central main groove 22 and is connected to the center portion of the long dimension portion of the sawtooth shape. In addition, the other end of the first central cross-groove 331A is connected to the maximum amplitude position of the bent shape of the inner central main groove 23 on the tire equatorial plane CL side. On the other hand, the other end of the second central cross-groove 331B is separated from the maximum amplitude position of the bent shape of the inner central main groove 23 and is connected to the center portion of the long dimension portion of the sawtooth shape.

[0117] In addition, in Figure 6 the groove width Wg31 (Wg31A, Wg31B; refer to Figure 7 ) of one of the first and second central cross-grooves 331A, 331B is in the range of 0.30 ≤ Wg31 / Wg2 ≤ 0.90 with respect to the groove width Wg2 of the long dimension portion of the outer central main groove 22, and preferably in the range of 0.55 ≤ Wg31 / Wg2 ≤ 0.85. In addition, the groove width Wg31 of the central cross-grooves 331A, 331B is in the range of 2.0 [mm] ≤ Wg31 ≤ 7.0 [mm]. In addition, in Figure 7 the inclination angle θ31 (θ31A, θ31B) of the first and second central cross-grooves 331A, 331B is in the range of 50 [deg] ≤ θ31 ≤ 90 [deg].

[0118] In addition, in Figure 6In the structure, the first central transverse groove 331A extends in such a way as to extend the groove wall connecting the first groove portion and the second groove portion of the inner central main groove 23 in the tire width direction. Specifically, as Figure 7 shown, the groove wall on one side (the lower side in the figure) of the first central transverse groove 331A on the inner central main groove 23 side is connected coplanarly to the groove wall of the connecting portion of the first groove portion and the second groove portion of the inner central main groove 23. Thus, the corner portion of the first central block 332A described later has an obtuse-angled V shape divided by the first central transverse groove 331A and the long dimension portion of the inner central main groove 23.

[0119] In addition, as Figure 7 shown, the first central transverse groove 331A has a widened portion (the reference numeral in the figure is omitted) at the connecting portion connecting to the outer central main groove 22 and the inner central main groove 23. In addition, the second central transverse groove 331B has a chamfered portion (the reference numeral in the figure is omitted) at the connecting portion connecting to the outer central main groove 22 and the inner central main groove 23. Thus, the snow evacuation performance of the first central transverse groove 331A, the outer central main groove 22, and the inner central main groove 23 is improved.

[0120] In addition, as Figure 8 shown, the second central transverse groove 331B has a bottom elevation portion 3311 at the central portion of the central land portion 33. Thus, the rigidity of the central land portion 33 can be ensured. In addition, the depth H311 from the tread surface of the central land portion 33 to the top surface of the bottom elevation portion 3311 is in the range of 0.60 ≤ H311 / H31 ≤ 0.90 with respect to the maximum groove depth H31 of the second central transverse groove 331B. In addition, the maximum groove depth H31 of the second central transverse groove 331B is in the range of 65[%] or more and 95[%] or less with respect to the maximum groove depths Hg2 and Hg3 of the outer central main groove 22 and the inner central main groove 23.

[0121] The central blocks 332A and 332B are divided by the central transverse grooves 331A and 331B. In addition, the edge portion of the first central block 332A on the side of the outer central main groove 22 has a serrated shape including two bending points, and the edge portion of the inner central main groove 23 has an obtuse V-shaped formed by the long dimension portion of the first central transverse groove 331A and the inner central main groove 23 as described above. In addition, the edge portion of the second central block 332B on the side of the outer central main groove 22 has a linear shape, and the edge portion of the inner central main groove 23 has a serrated shape including two bending points. Therefore, the first and second central blocks 332A and 332B as a whole have a concave hexagon with a concave portion at the edge portion on the side of the outer central main groove 22 or the inner central main groove 23. Thereby, the snow traction performance of the tire is improved. In addition, the grounding area ratio of the first and second central blocks 332A and 332B is in the range of 0.80 or more and 1.20 or less, preferably in the range of 0.85 or more and 1.15 or less. Thereby, the grounding area of the central blocks 332A and 332B is made uniform.

[0122] In addition, as Figure 7 shown, the central blocks 332A and 332B have a plurality of sipes (the reference numerals in the figure are omitted). Thereby, the snow performance of the tire is improved.

[0123] Figure 9 is a perspective view showing Figure 7 the chamfered portion 333 of the central land portion 33 described in

[0124] As Figure 7 shown, the central land portion 33 has a chamfered portion 333 at the edge portion on the side of the outer central main groove 22. As Figure 7 and Figure 9 shown, these chamfered portions 333 have a triangular pyramid shape with the short dimension portion of the serrated shape on the side of the outer central main groove 22 as one side when observing the tread surface in a plan view, and connect the adjacent long dimension portions. Through these chamfered portions 333, the snow discharging property of discharging snow from the outer central main groove 22 on the snow road surface is improved. In addition, in Figure 9 , the maximum depth H33 of the chamfered portion 333 is in the range of 0.10 ≤ H33 / Hg2 ≤ 0.40 with respect to the groove depth Hg2 of the outer central main groove 22, preferably in the range of 0.20 ≤ H33 / Hg2 ≤ 0.30. Through the above lower limit, the snow discharging effect brought by the chamfered portion 333 can be ensured, and through the above upper limit, the rigidity of the land portion can be ensured.

[0125] In addition, as Figure 6 shown, the edge portion of the central land portion 33 on the side of the outer central main groove 22 has a serrated shape formed by alternately connecting long dimension portions and short dimension portions. In addition, in Figure 7In the case of the outer central main groove 22, the circumferential length L2’ of the long-sized portion of the serrated shape at the edge portion on the side of the outer central main groove 22 is in the range of 0.60 ≤ L2’ / P2’ ≤ 1.00 with respect to the pitch length P2’ of the serrated shape. In addition, the ratio L2’ / P2’ is equal to the ratio L2 / P2 of the serrated shape of the outer central main groove 22.

[0126] In addition, as Figure 6 shown, the edge portion on the side of the inner central main groove 23 of the central land portion 33 has a bent shape formed by connecting the first to third groove portions. In addition, in Figure 7 the circumferential length L31’ of the edge portion divided by the first groove portion is in the range of 0.30 ≤ L31’ / P3’ ≤ 0.80 with respect to the pitch length P3’ of the bent shape. In addition, the ratio L31’ / P3’ is equal to the ratio L31 / P3 of the bent shape of the inner central main groove 23. In addition, the pitch length P3’ of the edge portion on the side of the inner central main groove 23 is in the range of 0.80 ≤ P3’ / P2’ ≤ 1.20 with respect to the pitch length P2’ of the edge portion on the side of the outer central main groove 22.

[0127] In addition, as Figure 6 shown, the longest edge portion (the edge portion divided by the first groove portion of the inner central main groove 23) on the side of the inner central main groove 23 of the central land portion 33 is inclined in the same direction in the tire circumferential direction with respect to the long-sized portion of the edge portion on the side of the outer central main groove 22. On the other hand, by making the outer central main groove 22 and the inner central main groove 23 have mutually asymmetric serrated shapes and bent shapes, the ground contact width of the central land portion 33 periodically increases and decreases in the tire circumferential direction as Figure 7 shown.

[0128] In addition, in Figure 7 the minimum ground contact width Wb3’ of the central land portion 33 is in the range of 0.20 ≤ Wb3’ / Wb3 ≤ 0.50 with respect to the maximum ground contact width Wb3 of the central land portion 33, and preferably in the range of 0.25 ≤ Wb3’ / Wb3 ≤ 0.35. Thereby, the rigidity of the land portion in the tire circumferential direction is made uniform.

[0129] [Inner shoulder main groove]

[0130] Figure 10 is an enlarged view of the inner region in the vehicle width direction of the tire 1 described in Figure 2 . This figure shows the ground contact region on the inner side in the vehicle width direction with the tire equatorial plane CL as the boundary.

[0131] As Figure 10As shown, the inner shoulder main groove 24 has a serrated shape formed by alternately connecting long-sized portions and short-sized portions. In addition, the long-sized portion of the inner shoulder main groove 24 is inclined in the circumferential direction of the tire in the opposite direction with respect to the first groove portion (the groove portion having the circumferential length L31) of the longest dimension of the inner central main groove 23. Specifically, in Figure 10 's configuration, the long-sized portion of the inner shoulder main groove 24 is inclined toward the tire equatorial plane CL side downward in the figure, and the first groove portion of the inner central main groove 23 is inclined toward the tire ground contact end T side downward in the figure.

[0132] In the above configuration, (1) the inner shoulder main groove 24 and the inner central main groove 23 have a serrated shape or a bent shape having a long-sized portion or a long-sized groove portion. Therefore, compared with a configuration (not shown) in which the main groove has a serrated shape formed by connecting groove portions of the same length, the snow evacuation property on the snow road surface is improved, and the snow performance of the tire is improved. In addition, (2) the long-sized portion of the inner shoulder main groove 24 and the long-sized first groove portion of the inner central main groove 23 are inclined in opposite directions with respect to the tire circumferential direction. Therefore, compared with a configuration (not shown) in which the two are inclined in the same direction with respect to the tire circumferential direction, the edge component increases and the snow traction performance of the tire is ensured.

[0133] In addition, in Figure 10 , the circumferential length L4 of the long-sized portion of the inner shoulder main groove 24 is in the range of 0.70 ≤ L4 / P4 ≤ 0.95 with respect to the pitch length P4 of the serrated shape of the inner shoulder main groove 24, and preferably in the range of 0.80 ≤ L4 / P4 ≤ 0.90. By the above lower limit, the improvement effect of the snow evacuation property on the snow road surface due to the long-sized portion of the serrated shape can be ensured, and by the above upper limit, the length of the short-sized portion can be ensured and the snow traction of the tire can be ensured.

[0134] In addition, in Figure 10 , the pitch length P4 of the serrated shape of the inner shoulder main groove 24 has a relationship of 0.35 ≤ P3 / P4 ≤ 0.65 with respect to the pitch length P3 of the bent shape of the inner central main groove 23, and preferably has a relationship of 0.40 ≤ P3 / P4 ≤ 0.50. Therefore, the pitch length P3 of the inner central main groove 23 is longer, and the pitch length P4 of the inner shoulder main groove 24 is shorter. Thereby, the rigidity of the central region of the tread surface can be ensured, uneven wear of the tire can be suppressed, and in addition, the edge component of the shoulder region of the tread surface can be ensured, and the snow traction performance of the tire can be ensured. In addition, the number of pitches N4 of the serrated shape of the inner shoulder main groove 24 is in the range of 30 ≤ N4 ≤ 50. In addition, in Figure 10 's configuration, the number of pitches N4 of the inner shoulder main groove 24 has a relationship of N3 / N4 = 1 / 2 with respect to the number of pitches N3 of the inner central main groove 23.

[0135] In addition, in Figure 10 , the amplitude A4 of the sawtooth shape of the inner shoulder main groove 24 is in the range of 0.20 ≤ A4 / Wg4 ≤ 0.50 with respect to the groove width Wg4 of the inner shoulder main groove 24, preferably in the range of 0.30 ≤ A4 / Wg4 ≤ 0.40. By the above lower limit, the improvement effect of the snow traction performance brought by the sawtooth shape can be ensured, and by the above upper limit, the generation of uneven wear caused by excessive amplitude can be suppressed.

[0136] In addition, in Figure 10 , the amplitude A4 of the sawtooth shape of the inner shoulder main groove 24 has a relationship of 0.30 ≤ A3 / A4 ≤ 0.60 with respect to the amplitude A3 of the bent shape of the inner central main groove 23, preferably having a relationship of 0.40 ≤ A3 / A4 ≤ 0.50. Therefore, the amplitude A3 of the inner central main groove 23 is larger than the amplitude A4 of the inner shoulder main groove 24. Thus, compared with the configuration (not shown) in which both have substantially the same amplitude, the edge component is increased and the snow traction of the tire is ensured.

[0137] In addition, in Figure 10 , the groove width Wg4 of the inner shoulder main groove 24 is in the range of 8.0 [mm] ≤ Wg4 ≤ 15.0 [mm], and the groove depth Hg4 (refer to Figure 12 described later) is in the range of 8.0 [mm] ≤ H4 ≤ 12.0 [mm].

[0138] In addition, in Figure 10 , the groove width Wg4 of the inner shoulder main groove 24 has a relationship of 0.50 ≤ Wg3 / Wg4 ≤ 0.90 with respect to the groove width Wg3 of the inner central main groove 23, preferably having a relationship of 0.60 ≤ Wg3 / Wg4 ≤ 0.80. Therefore, the groove width Wg3 of the inner central main groove 23 is narrower than the groove width Wg4 of the inner shoulder main groove 24. Thus, compared with the configuration (not shown) in which both have substantially the same groove width, the snow performance of the tire is improved.

[0139] In addition, in Figure 10 , the inner shoulder main groove 24 has a perspective structure in the tire circumferential direction. That is, the groove width Wg4 and the amplitude A4 of the inner shoulder main groove 24 are ensured in such a manner that the edge portions of the left and right land portions 34, 35 divided by the inner shoulder main groove 24 do not overlap each other when observed in the tire circumferential direction.

[0140] In addition, as Figure 2 shown, the long dimension portion of the inner shoulder main groove 24 is inclined in the same direction as the long dimension portion of the outer shoulder main groove 21 in the tire circumferential direction. In addition, the inner shoulder main groove 24 has a point-symmetrical structure with respect to the outer shoulder main groove 21.

[0141] In addition, inFigure 2 In, the pitch length P4 of the serrated shape of the inner shoulder main groove 24 (see Figure 10 ) is in the range of 0.80 ≤ P4 / P1 ≤ 1.20 with respect to the pitch length P1 of the serrated shape of the outer shoulder main groove 21 (see Figure 3 ), preferably in the range of 0.95 ≤ P4 / P1 ≤ 1.05. Therefore, the pitch length P3 of the inner shoulder main groove 24 is set to be substantially the same as the pitch length P1 of the outer shoulder main groove 21. In addition, in Figure 10 's configuration, the number of pitches N4 of the inner shoulder main groove 24 is equal to the number of pitches N1 of the outer shoulder main groove 21, N4 / N1 = 1.0.

[0142] In addition, in Figure 2 In, the amplitude A4 of the serrated shape of the inner shoulder main groove 24 (see Figure 10 ) has a relationship of 0.80 ≤ A4 / A1 ≤ 1.20 with respect to the amplitude A1 of the serrated shape of the outer shoulder main groove 21 (see Figure 3 ), preferably having a relationship of 0.95 ≤ A4 / A1 ≤ 1.05. Therefore, the amplitude A4 of the inner shoulder main groove 24 is substantially the same as the amplitude A1 of the outer shoulder main groove 21. Thus, the rigidity of the left and right shoulder regions is homogenized.

[0143] In addition, in Figure 2 In, the groove width Wg4 of the inner shoulder main groove 24 (see Figure 10 ) has a relationship of 0.80 ≤ Wg4 / Wg1 ≤ 1.20 with respect to the groove width Wg1 of the outer shoulder main groove 21 (see Figure 3 ), preferably having a relationship of 0.95 ≤ Wg4 / Wg1 ≤ 1.05. Therefore, the groove width Wg4 of the inner shoulder main groove 24 is substantially the same as the groove width Wg1 of the outer shoulder main groove 21. Thus, the rigidity of the left and right shoulder regions is homogenized.

[0144] [Inner intermediate land portion]

[0145] Figure 11 is an enlarged view showing the inner intermediate land portion 34 described in Figure 10 .

[0146] As Figure 10 shown, the inner intermediate land portion 34 includes first and second inner intermediate transverse grooves 341A, 341B and first and second inner intermediate blocks 342A, 342B.

[0147] The first and second inner intermediate cross-grooves 341A and 341B have a linear shape or a gentle arc shape, penetrate the inner intermediate land portion 34 in the tire width direction, and are connected to the inner central main groove 23 and the inner shoulder main groove 24. In addition, the first and second inner intermediate cross-grooves 341A and 341B are inclined in the same direction relative to each other in the tire circumferential direction. In addition, the first and second inner intermediate cross-grooves 341A and 341B are inclined in the same direction as the first and second outer intermediate cross-grooves 321A and 321B in the tire circumferential direction.

[0148] In addition, the first inner intermediate cross-groove 341A is connected to the maximum amplitude position of the bent shape of the inner central main groove 23 toward the tire ground contact end T at one end, and is connected to the maximum amplitude position of the serrated shape of the inner shoulder main groove 24 toward the tire equatorial plane CL at the other end. In addition, the second inner intermediate cross-groove 341B is connected to a position separated from the maximum amplitude position of the bent shape of the inner central main groove 23 at one end, and is connected to the maximum amplitude position of the serrated shape of the inner shoulder main groove 24 toward the tire equatorial plane CL at the other end. In addition, the first and second inner intermediate cross-grooves 341A and 341B are connected to the first groove portion with a long dimension of the bent shape of the inner central main groove 23 at one end, and are connected to the short dimension portion of the serrated shape of the inner shoulder main groove 24 at the other end.

[0149] In addition, in Figure 10 the groove width Wg41 (Wg41A, Wg41B; refer to Figure 11 ) of the first and second inner intermediate cross-grooves 341A and 341B is in the range of 0.40 ≤ Wg41 / Wg3 ≤ 0.80 with respect to the groove width Wg3 of the inner central main groove 23, and preferably in the range of 0.55 ≤ Wg41 / Wg3 ≤ 0.65. In addition, the groove width Wg41 of the inner intermediate cross-grooves 341A and 341B is in the range of 2.0 [mm] ≤ Wg41 ≤ 6.0 [mm].

[0150] In addition, as Figure 10 shown, the first and second inner intermediate cross-grooves 341A and 341B are inclined in the same direction as the long dimension portion of the serrated shape of the inner shoulder main groove 24 in the tire circumferential direction. In addition, in Figure 11 the inclination angle θ41 (θ41A, θ41B) of the first and second inner intermediate cross-grooves 341A and 341B is in the range of 40 [deg] ≤ θ41 ≤ 70 [deg].

[0151] In addition, in Figure 10 the structure, the first inner intermediate cross-groove 341A extends in a manner that extends the short dimension third groove portion of the bent shape of the inner central main groove 23 in the tire width direction. Specifically, asFigure 11 As shown, the groove wall on one side (the lower side in the figure) of the inner central main groove 23 side of the first inner intermediate transverse groove 341A is connected coplanarly with the groove wall of the third groove portion of the inner central main groove 23. Thereby, the snow discharging property of the inner central main groove 23 and the first inner intermediate transverse groove 341A is improved.

[0152] In addition, as Figure 10 shown, the connecting portions of the inner intermediate transverse grooves 341A and 341B connected to the inner shoulder main groove 24 are arranged at substantially the same positions in the tire circumferential direction with respect to the connecting portions of the inner shoulder transverse groove 351 (described later) connected to the inner shoulder main groove 24. Specifically, the circumferential distance D4 of the tire from the intersection of the extension line of the groove center line of the inner intermediate transverse grooves 341A and 341B and the groove center line of the inner shoulder main groove 24 to the intersection of the extension line of the groove center line of the inner shoulder transverse groove 351 and the groove center line of the inner shoulder main groove 24 is in the range of 0 ≤ D4 / P4 < 0.15 with respect to the pitch length P4 of the serrated shape of the inner shoulder main groove 24, and preferably in the range of 0 ≤ D4 / P4 < 0.10. Thereby, the snow discharging property on the snow road surface is improved.

[0153] The inner intermediate blocks 342A and 342B are divided by the inner intermediate transverse grooves 341A and 341B. In addition, the grounding area ratio of the first and second inner intermediate blocks 342A and 342B is in the range of 0.80 or more and 1.20 or less, and preferably in the range of 0.85 or more and 1.15 or less. Thereby, the grounding area of the inner intermediate blocks 342A and 342B is homogenized.

[0154] In addition, as Figure 11 shown, the inner intermediate blocks 342A and 342B have a plurality of sipes (the reference numerals in the figure are omitted). Thereby, the snow performance of the tire is improved.

[0155] Figure 12 is a cross-sectional view showing the notch portions 3411 of the inner intermediate transverse grooves 341A and 341B described in Figure 11 . This figure shows a cross-sectional view in the groove width direction of the inner intermediate transverse grooves 341A and 341B.

[0156] As Figure 11 shown, the inner intermediate transverse grooves 341A and 341B have notch portions 3411 at the connecting portions on the inner shoulder main groove 24 side. As Figure 11As shown, these notch portions 3411 extend in the groove length direction of the inner intermediate transverse grooves 341A and 341B when observing the tread in a plane view and open at the edge portion on the inner shoulder main groove 24 side of the inner intermediate land portion 34. In addition, the extension length of the notch portion 3411 (omitting the dimension mark in the figure) is in the range of 0.40 [%] or more and 0.80 [%] or less with respect to the groove length of the inner intermediate transverse grooves 341A and 341B. Thereby, the groove volume of the inner intermediate transverse grooves 341A and 341B is enlarged, and the snow discharge property of discharging snow from the inner intermediate transverse grooves 341A and 341B on a snow-covered road surface is improved.

[0157] In addition, as Figure 12 shown, the width W411 of the notch portion 3411 is in the range of 0.50 ≤ W411 / W41 ≤ 0.80 with respect to the groove width Wg41 of the inner intermediate transverse grooves 341A and 341B, and preferably in the range of 0.60 ≤ W411 / W41 ≤ 0.70. In addition, the maximum depth H411 of the notch portion 3411 is in the range of 0.50 ≤ H411 / H41 ≤ 0.90 with respect to the groove depth H41 of the inner intermediate transverse grooves 341A and 341B, and preferably in the range of 0.70 ≤ H411 / H41 ≤ 0.80. By the above lower limit, the snow discharge effect brought by the notch portion 3411 can be ensured, and by the above upper limit, the rigidity of the land portion can be ensured.

[0158] In addition, as Figure 11 shown, the edge portion on the inner central main groove 23 side of the inner intermediate land portion 34 has a bent shape formed by connecting the first to third straight portions. In addition, in Figure 4 , the circumferential length L3' of the straight portion of the longest dimension of the edge portion on the inner central main groove 23 side is in the range of 0.35 ≤ L3' / P3' ≤ 0.60 with respect to the pitch length P3' of the bent shape. In addition, the ratio L3' / P3' is equal to the ratio L3 / P3 of the bent shape of the inner central main groove 23.

[0159] In addition, as Figure 11 shown, the edge portion on the inner shoulder main groove 24 side of the inner intermediate land portion 34 has a serrated shape formed by alternately connecting long dimension portions and short dimension portions. In addition, in Figure 11 , the circumferential length L4' of the long dimension portion of the serrated shape of the edge portion on the inner shoulder main groove 24 side is in the range of 0.80 ≤ L4' / P4' ≤ 0.90 with respect to the pitch length P4' of the serrated shape. In addition, the ratio L4' / P4' is equal to the ratio L4 / P4 of the serrated shape of the inner shoulder main groove 24. In addition, the pitch length P4' of the edge portion on the inner shoulder main groove 24 side has a relationship of 0.35 ≤ P3' / P4' ≤ 0.65 with respect to the pitch length P3' of the edge portion on the inner central main groove 23 side.

[0160] In addition, as Figure 11 shown, the straight portion of the longest dimension of the edge portion on the inner center main groove 23 side of the inner center land portion 34 is inclined in the opposite direction in the tire circumferential direction with respect to the long dimension portion of the edge portion on the inner shoulder main groove 24 side. Specifically, as Figure 10 shown, the straight portion of the longest dimension of the edge portion on the inner center main groove 23 side is inclined downward in the drawing toward the tire ground contact end T side, and the long dimension portion of the edge portion on the inner shoulder main groove 24 side is inclined downward in the drawing toward the tire equatorial plane CL side. Therefore, the ground contact width of the inner center land portion 34 periodically increases and decreases in the tire circumferential direction.

[0161] In addition, in Figure 11 , the minimum ground contact width Wb4' of the inner center land portion 34 is in the range of 0.30 ≤ Wb4' / Wb4 ≤ 0.70 with respect to the maximum ground contact width Wb4 of the inner center land portion 34, and preferably in the range of 0.45 ≤ Wb4' / Wb4 ≤ 0.55. Thereby, the rigidity of the land portion in the tire circumferential direction is made uniform.

[0162] [Inner shoulder land portion]

[0163] As Figure 10 shown, the inner shoulder land portion 35 includes an inner shoulder cross-groove 351 and an inner shoulder block 352.

[0164] The inner shoulder cross-groove 351 has a straight shape or a gentle arc shape, penetrates the inner shoulder land portion 35 in the tire width direction, and is connected to the tire ground contact end T and the inner shoulder main groove 24. In addition, the inner shoulder cross-groove 351 is connected to the end portion of the long dimension portion of the serrated shape of the inner shoulder main groove 24, and is also connected to the maximum amplitude position on the tire ground contact end T side of the serrated shape. In addition, the inner shoulder main groove 24 has a bottom elevation portion (omitted from the reference numeral in the drawing) at the opening portion on the inner shoulder main groove 24 side. In addition, a plurality of inner shoulder cross-grooves 351 are arranged at a predetermined interval in the tire circumferential direction. In addition, the groove width Wg51 (omitted from the dimension mark in the drawing) of the inner shoulder cross-groove 351 is in the range of 5.0 [mm] or more and 10.0 [mm] or less, and the groove depth Hg51 is in the range of 6.0 [mm] or more and 11.0 [mm] or less.

[0165] The inner shoulder block 352 is divided by a plurality of inner shoulder blocks 352. In addition, the edge portion on the inner shoulder main groove 24 side of the inner shoulder block 352 is divided by a set of long dimension portion and short dimension portion of the inner shoulder main groove 24 and has a V shape protruding toward the tire equatorial plane CL side. Thereby, the rigidity of the block can be ensured, and uneven wear of the tire can be suppressed.

[0166] In addition, as Figure 10As shown, the inner shoulder block 352 has a plurality of sipes (reference numerals are omitted in the figure). Thus, the snow performance of the tire is improved.

[0167] [Effect]

[0168] As described above, [1] the tire 1 includes a plurality of main grooves 21 to 24 extending in the tire circumferential direction and a plurality of land portions 31 to 35 defined by the plurality of main grooves 21 to 24 (see Figure 2 ). In addition, the plurality of main grooves 21 to 24 include first and second central main grooves 23 and 24 adjacent to each other in a manner sandwiching the tire equatorial plane CL. In addition, the plurality of land portions 31 to 35 include a central land portion 33 divided by the first and second central main grooves 23 and 24. In addition, the first central main groove (outer central main groove) 22 has a zigzag shape formed by alternately connecting long-dimension portions and short-dimension portions (see Figure 6 ). In addition, the second central main groove (inner central main groove) 23 has a bent shape formed by connecting a first groove portion having a circumferential length L31, a second groove portion having a circumferential length L32, and a third groove portion having a circumferential length L33. In addition, the circumferential lengths L31 to L33 of the first to third groove portions have a relationship of L31>L32≥L33.

[0169] In the above-mentioned structure, (1) the first central main groove 22 has a sawtooth shape formed by alternately connecting the long dimension part and the short dimension part, and the second central main groove 23 has a bent shape formed by the first to third groove parts, so that the edge component of the central area of ​​the tread portion can be ensured, and the snow performance of the tire is improved. In addition, (2) when the first central main groove 22 is located in the outer area in the vehicle width direction and the second central main groove 23 is located in the inner area in the vehicle width direction when the tire is installed on the vehicle, the first central main groove 22 is made to have a sawtooth shape with fewer bending points, so that the tire's resistance to uneven wear can be ensured, and the second central main groove 23 is made to have a bent shape with more bending points. The snow performance of the tire is effectively improved. As a result, it has the advantages of taking into account both the snow performance and the uneven wear resistance of the tire.

[0170] [2] In the tire 1, based on the tire 1 described in [1], the circumferential length L2 of the long portion of the first central main groove 22 is in the range of 0.60≤L2 / P2≤1.00 relative to the pitch length P2 of the zigzag shape of the first central main groove 22 (see Figure 6 By using the above lower limit, the effect of improving the snow removal performance on the snowy road surface brought about by the long dimension portion of the sawtooth shape can be ensured, and by using the above upper limit, there is an advantage that the length of the short dimension portion can be ensured to ensure the snow traction performance of the tire.

[0171] In addition, [3] in the tire 1, based on the tire 1 described in [1] or [2] above, the amplitude A2 of the sawtooth shape of the first central main groove 22 is in the range of 1.40 ≤ A2 / Wg2 ≤ 1.90 with respect to the groove width Wg2 of the first central main groove 22 (refer to Figure 6 ). By the above lower limit, the improvement effect of the snow traction performance brought by the sawtooth shape can be ensured, and by the above upper limit, there is an advantage of being able to suppress the generation of uneven wear caused by excessive amplitude.

[0172] In addition, [4] in the tire 1, based on the tire 1 described in any one of [1] to [3] above, the first groove portion of the second central main groove 23 and the second and third groove portions are inclined in opposite directions to each other in the tire circumferential direction (refer to Figure 6 ). Thus, there is an advantage that the bent shape of the second central main groove 23 is optimized.

[0173] In addition, [5] in the tire 1, based on the tire 1 described in any one of [1] to [4] above, the first groove portion of the second central main groove 23 is inclined in the same direction as the long dimension portion of the first central main groove 22 in the tire circumferential direction (refer to Figure 6 ). Thus, there are advantages that the rigidity of the central land portion 33 is homogenized in the tire circumferential direction and the uneven wear of the central land portion 33 is suppressed.

[0174] In addition, [6] in the tire 1, based on the tire 1 described in any one of [1] to [5] above, the circumferential length L31 of the first groove portion of the second central main groove 23 is in the range of 0.35 ≤ L31 / P3 ≤ 0.75 with respect to the pitch length P3 of the bent shape of the second central main groove 23 (refer to Figure 6 ). By the above lower limit, the circumferential length L31 of the long-sized first groove portion can be ensured, and the improvement effect of the snow evacuation performance on the snow road surface can be ensured. By the above upper limit, there is an advantage that the edge components of the short-sized second and third groove portions can be ensured, and the snow traction of the tire can be ensured.

[0175] In addition, [7] in the tire 1, based on the tire 1 described in any one of [1] to [6] above, the circumferential length L32 of the second groove portion of the second central main groove 23 is in the range of 0.20 ≤ L32 / P3 ≤ 0.45 with respect to the pitch length P3 of the bent shape of the inner central main groove 23 (refer to Figure 6 ). Thus, there is an advantage that the circumferential length L32 of the short-sized second groove portion is optimized.

[0176] In addition, [8] in the tire 1, based on the tire 1 described in any one of the above [1] to [7], the circumferential length L33 of the third groove portion of the second central main groove 23 is in the range of 0.05 ≤ L33 / P3 with respect to the pitch length P3 of the bent shape of the second central main groove 23 (see Figure 6 ). Thus, it has the advantage of ensuring the edge component of the short-sized third groove portion and ensuring the snow traction of the tire.

[0177] In addition, [9] in the tire 1, based on the tire 1 described in any one of the above [1] to [8], the pitch length P3 of the bent shape of the second central main groove 23 is in the range of 0.80 ≤ P3 / P2 ≤ 1.20 with respect to the pitch length P2 of the serrated shape of the first central main groove 22 (see Figure 6 ). Thus, it has the advantages of uniformizing the rigidity of the central region of the tread surface and suppressing the uneven wear of the tire.

[0178] In addition,

[10] in the tire 1, based on the tire 1 described in any one of the above [1] to [9], the amplitude A3 of the bent shape of the second central main groove 23 is in the range of 0.55 ≤ A3 / Wg3 ≤ 0.95 with respect to the groove width Wg3 of the second central main groove 23 (see Figure 6 ). By the above lower limit, the improvement effect of the snow traction performance brought by the bent shape can be ensured, and by the above upper limit, it has the advantage of being able to suppress the generation of uneven wear caused by excessive amplitude.

[0179] In addition,

[11] in the tire 1, based on the tire 1 described in any one of the above [1] to

[10] , the amplitude A3 of the bent shape of the second central main groove 23 is in the range of 0.80 ≤ A3 / A2 ≤ 1.20 with respect to the amplitude A2 of the serrated shape of the first central main groove 22 (see Figure 6 ). Thus, it has the advantages of uniformizing the rigidity of the central region of the tread surface and improving the uneven wear resistance of the tire.

[0180] In addition,

[12] in the tire 1, based on the tire 1 described in any one of the above [1] to

[11] , the central land portion 33 is provided with first and second central cross grooves 331A, 331B that penetrate the central land portion 33 in the tire width direction and are respectively connected to the first and second central main grooves 22, 23 (see Figure 6 ). In addition, the first and second central cross grooves 331A, 331B are inclined in opposite directions to each other with respect to the tire circumferential direction. Thus, it has the advantage of improving the snow traction at the central land portion 33.

[0181] [Applicable object]

[0182] In this embodiment, as an example of a tire, a pneumatic tire has been described. However, the present invention is not limited thereto, and the configurations described in the present embodiment can be arbitrarily applied to other tires within the scope obvious to those skilled in the art. Examples of other tires include non-pneumatic tires, solid tires, and the like.

[0183] Example

[0184] Figures 13 - 14 It is a graph showing the results of performance tests of the tires of the embodiments of the present invention.

[0185] In this performance test, various test tires were evaluated in terms of (1) snow performance and (2) abrasion resistance performance. In addition, a test tire with a tire size of 225 / 65R17 102H was assembled on a rim with a rim size of 17×6.5J, and an internal pressure of 230 [kPa] and a specified load of JATMA were applied to this test tire. In addition, the test tires were installed on all the wheels of a 4WD vehicle of an SUV (Sports Utility Vehicle) as a test vehicle.

[0186] In the evaluation related to (1) snow performance, the test vehicle traveled at a speed of 40 [km / h] on a predetermined handling course as a snow road, and a sensory evaluation related to handling stability was performed by a test driver. This evaluation was carried out by an index evaluation with a comparative example as a reference (100), and the larger the value, the more preferable.

[0187] In the evaluation related to (2) abrasion resistance performance, after the test vehicle traveled 8000 [km] on a predetermined off-road route, the difference in wear amount between the shoulder land portion 31 and the center land portion 33 was measured for evaluation. This evaluation was carried out by an index evaluation with a comparative example as a reference (100), and the larger the value, the smaller the difference in the above wear amount, and the more preferable.

[0188] The test tire of the example includes Figure 1 and Figure 2 The four main grooves 21 to 24 have a sawtooth shape or a bent shape with an amplitude in the tire width direction. In addition, in Figure 2 the tire contact width TW is 172 [mm], and the maximum contact widths of the respective land portions 31 to 35 are Wb1 = 33.5 [mm], Wb2 = 33.5 [mm], Wb3 = 33.8 [mm], Wb4 = 29.5 [mm], Wb5 = 33.5 [mm]. In addition, in Figure 3 and Figure 10Among them, the groove widths of the long-sized portions with a sawtooth shape in the main grooves 21, 22, and 24 are Wg1 = 8.0 [mm], Wg2 = 5.2 [mm], and Wg4 = 8.0 [mm]. In addition, the groove width of the first groove portion with a bent shape in the inner central main groove 23 is Wg3 = 5.2 [mm].

[0189] The test tire of the comparative example is such that in the test tire of Example 1, the shoulder main grooves 21 and 24 on the outer and inner sides have a sawtooth shape formed by alternately connecting long-sized portions and short-sized portions, and the central main grooves on the outer and inner sides have a sawtooth shape formed by alternately connecting groove portions of the same length. In addition, the number of pitches P1 and P4 of the sawtooth shape of the shoulder main grooves 21 and 24 on the outer and inner sides is 1 / 2 with respect to the number of pitches P2 and P3 of the central main grooves on the outer and inner sides.

[0190] As shown in the test results, it can be seen that in the test tire of the embodiment, the snow performance and wear resistance performance of the tire are taken into account.

[0191] Description of Reference Numerals

[0192] 1 Tire; 11 Bead Core; 12 Bead Filler; 13 Carcass Ply; 14 Belt Ply; 141, 142 Cross Belt Plys; 143, 144 Belt Cover Layers; 16 Sidewall Rubber; 17 Rim Cushion Rubber; 21 Outer Shoulder Main Groove; 22 Outer Central Main Groove; 23 Inner Central Main Groove; 24 Inner Shoulder Main Groove; 31 Outer Shoulder Land; 311 Outer Shoulder Transverse Groove; 312 Outer Shoulder Block; 32 Outer Intermediate Land; 321A, 321B Outer Intermediate Transverse Grooves; 322A Outer Intermediate Block; 323A, 323B Chamfered Portions; 33 Central Land; 331A, 331B Central Transverse Grooves; 3311 Bottom Elevation Portion; 332A, 332B Central Blocks; 333 Chamfered Portion; 34 Inner Intermediate Land; 341A, 341B Inner Intermediate Transverse Grooves; 3411 Notch Portion; 342A, 342B Inner Intermediate Blocks; 35 Inner Shoulder Land; 351 Inner Shoulder Transverse Groove; 352 Inner Shoulder Block

Claims

1. A tire having a plurality of main grooves extending in the circumferential direction of the tire and a plurality of land portions defined by the plurality of main grooves, characterized in that The plurality of main grooves include a first central main groove and a second central main groove adjacent to each other in a manner sandwiching the tire equatorial plane. The plurality of land portions include a central land portion divided by the first central main groove and the second central main groove. The first central main groove has a sawtooth shape formed by alternately connecting long-sized portions and short-sized portions. The second central main groove has a bent shape formed by connecting a first groove portion having a circumferential length L31, a second groove portion having a circumferential length L32, and a third groove portion having a circumferential length L33, and the circumferential lengths L31 to L33 of the first groove portion to the third groove portion have a relationship of L31 > L32 ≥ L33.

2. The tire according to claim 1, The circumferential length L2 of the long dimension portion of the first central main groove is in the range of 0.60 ≤ L2 / P2 ≤ 1.00 with respect to the pitch length P2 of the serrated shape of the first central main groove.

3. The tire according to claim 1 or 2, The amplitude A2 of the serrated shape of the first central main groove is in the range of 1.40 ≤ A2 / Wg2 ≤ 1.90 with respect to the groove width Wg2 of the first central main groove.

4. The tire according to any one of claims 1 to 3, The first groove portion of the second central main groove is inclined in opposite directions in the circumferential direction of the tire with respect to the second groove portion and the third groove portion.

5. The tire according to any one of claims 1 to 4, The first groove portion of the second central main groove is inclined in the same direction in the circumferential direction of the tire with respect to the long dimension portion of the first central main groove.

6. The tire according to any one of claims 1 to 5, The circumferential length L31 of the first groove portion of the second central main groove is in the range of 0.35 ≤ L31 / P3 ≤ 0.75 with respect to the pitch length P3 of the bent shape of the second central main groove.

7. The tire according to any one of claims 1 to 6, The circumferential length L32 of the second groove portion of the second central main groove is in the range of 0.20 ≤ L32 / P3 ≤ 0.45 with respect to the pitch length P3 of the bent shape of the second central main groove.

8. The tire according to any one of claims 1 to 7, The circumferential length L33 of the third groove portion of the second central main groove is in the range of 0.05 ≤ L33 / P3 with respect to the pitch length P3 of the bent shape of the second central main groove.

9. The tire according to any one of claims 1 to 8, The spacing length P3 of the bent shape of the second central main groove is in the range of 0.80 ≤ P3 / P2 ≤ 1.20 with respect to the spacing length P2 of the serrated shape of the first central main groove.

10. The tire according to any one of claims 1 to 9, The amplitude A3 of the bent shape of the second central main groove is in the range of 0.55 ≤ A3 / Wg3 ≤ 0.95 with respect to the groove width Wg3 of the second central main groove.

11. The tire according to any one of claims 1 to 10, The amplitude A3 of the bent shape of the second central main groove is in the range of 0.80 ≤ A3 / A2 ≤ 1.20 with respect to the amplitude A2 of the serrated shape of the first central main groove.

12. The tire according to any one of claims 1 to 11, The central land portion has a first central cross-groove and a second central cross-groove that penetrate the central land portion in the tire width direction and are respectively connected to the first central main groove and the second central main groove, and the first central cross-groove and the second central cross-groove are inclined in opposite directions with respect to the tire circumferential direction.

Images