pneumatic tires

Abstract

To provide a pneumatic tire which can easily ride over ruts on snowy and icy roads and improves driving performance on snowy and icy roads. [Solution] The buttress block of the sidewall has a first circumferentially oblique groove (861) that extends from one of a pair of buttress slits that are adjacent in the circumferential direction of the tire, at an angle relative to the tire circumferential direction, and terminates within the buttress, and a second circumferentially oblique groove (865) that extends from the other of the pair of buttress slits that are adjacent in the circumferential direction of the tire, in the opposite direction to the first circumferentially oblique groove (861), and at an angle relative to the tire circumferential direction, and terminates within the buttress, the first circumferentially oblique groove (861) has a first bent groove (862) that bends and extends from the tip that is the terminal end of the first circumferentially oblique groove (861), and the second circumferentially oblique groove (865) has a second bent groove (866) that bends and extends from the tip that is the terminal end of the second circumferentially oblique groove (865).

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, pneumatic tires such as studless tires used on snowy and icy roads have sometimes adopted so-called square shoulders to ensure a large contact area (see Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-222158 Summary of the Invention [Problem to be solved by the invention]

[0004] When square-shoulder tires try to ride over ruts on icy and snowy roads, the sharp edges of the shoulders make near-point contact with the inner wall of the rut, making it difficult to ride over the rut, so there was room for improvement.

[0005] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic tire that can easily ride over ruts on snow and ice roads and improves driving performance on snow and ice roads. [Means for solving the problem]

[0006] The pneumatic tire of the present invention is a pneumatic tire comprising a tread that comes into contact with a road surface and a pair of sidewalls that constitute tire sidewall surfaces, wherein each of the pair of sidewalls has an annular buttress along the tire circumferential direction on the outer side in the tire radial direction, the buttress extending in a direction intersecting the tire circumferential direction and including a plurality of buttress slits that are spaced apart in the tire circumferential direction, and a plurality of buttress blocks that are partitioned in the tire circumferential direction by the plurality of buttress slits, and the buttress blocks are formed by partitioning the buttress blocks into one of the pair of buttress slits that are adjacent in the tire circumferential direction. a first circumferential oblique groove extending from a buttress slit while being inclined with respect to the tire circumferential direction and terminating within the buttress; and a second circumferential oblique groove extending from the other of a pair of buttress slits adjacent in the tire circumferential direction in the opposite direction to the first circumferential oblique groove while being inclined with respect to the tire circumferential direction and terminating within the buttress, wherein the first circumferential oblique groove is provided with a first bent groove extending and bending from a tip end which is a terminal end of the first circumferential oblique groove, and the second circumferential oblique groove is provided with a second bent groove extending and bending from a tip end which is a terminal end of the second circumferential oblique groove. [Effects of the Invention]

[0007] According to the present invention, a pneumatic tire can be provided that can easily ride over ruts on snow and ice roads and improves driving performance on snow and ice roads. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a tire (pneumatic tire) according to an embodiment, partially showing a portion in the tire circumferential direction. [Figure 2] 1 is a partially enlarged front view showing a tread surface of a tire according to an embodiment. [Figure 3] FIG. 3 is an enlarged view of a portion indicated by III in FIG. 2. [Figure 4] FIG. 3 is an enlarged view of a portion indicated by IV in FIG. 2. [Figure 5] FIG. 5 is a cross-sectional view of FIG. 4 . [Figure 6]6 is a cross-sectional view taken along the line VI-VI in FIG. 4. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 4. [Figure 8] FIG. 10 is a diagram showing a modified example of the buttress of the embodiment, and is a plan view showing a part of the buttress. [Figure 9] FIG. 10 is a diagram showing another modified example of the buttress of the embodiment, and is a plan view showing a part of the buttress. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. Fig. 1 is a perspective view partially showing a part in the tire circumferential direction of a tire 1 as a pneumatic tire according to the embodiment. The tire 1 according to the embodiment is, for example, a pneumatic tire for passenger cars. Note that the configuration of the tire 1 according to the embodiment can be adopted for various vehicles such as light trucks, trucks, buses, etc. in addition to passenger cars.

[0010] As shown in FIG. 1 , a tire 1 includes a tread 2, which includes the tire's outer peripheral surface and is the portion that comes into contact with the road surface; a pair of beads 3, which are portions that fit onto the rim of a tire wheel (not shown); a pair of sidewalls 4, which are disposed between the tread 2 and each bead 3 and form the tire's sidewall surface; and shoulders 5 between each sidewall 4 and the tread 2. The tread 2 includes a tread surface 2A that comes into contact with the road surface, and a tread pattern 2B is formed on the tread surface 2A by multiple types of grooves, lands, etc. In this embodiment, the tread pattern 2B is asymmetric in the tire axial direction. Each of the pair of sidewalls 4 has a buttress 8 on its radially outer side. The buttress 8 is the portion that transitions from the sidewall 4 to the shoulder 5 and is the outermost annular portion of the sidewall 4 in a side view of the tire. For example, when traveling on snow, this portion is likely to come into contact with the inner wall surface of a rut.

[0011] FIG. 2 is a partially enlarged front view of the tire 1, showing the tread surface 2A, a pair of sidewalls 4, a pair of shoulders 5, and a pair of buttresses 8. FIG. 3 is an enlarged view of the portion indicated by III in FIG. 2. FIGS. 2 and 3 show the tire axial direction X, the tire circumferential direction C, and the tire equator E. The tire equator E is an imaginary line extending through the tire axial center along the tire circumferential direction. In FIGS. 2 and 3, one side (the right side in FIGS. 2 and 3) of the tire axial direction X is indicated by an arrow X1, and the other side (the left side in FIGS. 2 and 3) is indicated by an arrow X2. In addition, in FIGS. 2 and 3, one side (the lower side in FIG. 1) of the tire circumferential direction C is indicated by an arrow C1, and the other side (the upper side in FIG. 1) is indicated by an arrow C2. Note that these symbols are the same in FIG. 4.

[0012] The tread surface 2A has a contact width region in the tire axial direction, which is the region that actually comes into contact with the road surface. As shown in FIG. 2, the contact width region of the tread surface 2A is between contact edges 2C at both axial ends of the tire set on the tread surface 2A. Note that the contact width region here refers to the region in the tire axial direction that comes into contact with the road surface when the tire 1, mounted on a standard rim and inflated to the standard internal pressure, comes into contact with the road and is subjected to a standard load. Each of the pair of sidewalls 4 extends radially inward from the contact edges 2C.

[0013] Grooves forming the tread pattern 2B include circumferential grooves including main grooves and secondary grooves, slits, lug grooves, sipes, etc., as described below. Circumferential grooves are basically grooves that run along the tire circumferential direction, while slits, lug grooves, and sipes are basically grooves that extend in a direction intersecting the tire circumferential direction. The width of these grooves is the largest for the main grooves and the smallest for the sipes. In the embodiment, the width of each sipe is, for example, about 0.3 mm or more and less than 1.0 mm, and the depth is, for example, about 4 mm or more and 11 mm or less, but is not limited thereto. The widths of the secondary grooves, slits, and lug grooves are generally smaller than the main grooves and larger than the sipes, but they may have similar widths or may differ.

[0014] As shown in Fig. 2, the tread 2 includes a plurality of lands 6 aligned in the tire axial direction and a plurality of circumferential grooves 7 extending in the tire circumferential direction and separating the lands 6 in the tire axial direction. Each of the lands 6 extends in the tire circumferential direction. The buttresses 8 include a first buttress 8A on one axial side X1 of the tire and a second buttress 8B on the other axial side X2 of the tire.

[0015] The multiple lands 6 include a central land 100 arranged on the tire equator E and in the center of the tire axial direction, a first intermediate land 200 arranged on one side X1 of the central land 100 in the tire axial direction, a second intermediate land 300 arranged on the other side X2 of the central land 100 in the tire axial direction, a first shoulder land 400 arranged on one side X1 of the first intermediate land 200 in the tire axial direction, and a second shoulder land 500 arranged on the other side X2 of the second intermediate land 300 in the tire axial direction.

[0016] In the embodiment, the maximum widths of the first intermediate land 200 and the second intermediate land 300 are approximately the same and are larger than the maximum width of the central land 100. In the embodiment, the widths of the first shoulder land 400 and the second shoulder land 500 are approximately the same and are larger than the widths of the first intermediate land 200 and the second intermediate land 300. Note that the width of each land 6 is not limited to this and may be any width.

[0017] The multiple circumferential grooves 7 include a sub-groove 600 between the central land 100 and the first intermediate land 200, a first main groove 700 between the central land 100 and the second intermediate land 300, a second main groove 800 between the first intermediate land 200 and the first shoulder land 400, and a third main groove 900 between the second intermediate land 300 and the second shoulder land 500. The maximum width of each of the main grooves 700, 800, and 900 is, for example, about 4 mm to 8 mm, and the depth is, for example, but not limited to, about 8 mm to 11 mm. The maximum width and depth of the sub-groove 600 are smaller than those of each of the main grooves 700, 800, and 900, for example, but not limited to, a maximum width of about 2 to 5 mm, and a depth of about 4 mm to 9 mm.

[0018] The sub groove 600 of the embodiment has a zigzag shape overall. The first main groove 700 of the embodiment is a groove that is linear along the tire circumferential direction and has a substantially constant width. The second main groove 800 and the third main groove 900 of the embodiment have a zigzag shape. The groove shapes of these circumferential grooves 7 on the tread surface 2A are not limited and may be any shape.

[0019] As shown in FIG. 3, the central land 100 includes a plurality of first central sipes 110, a plurality of second central sipes 120, and a plurality of third central sipes .

[0020] The multiple first central sipes 110 are arranged in an approximately central region in the width direction of the central land 100. The multiple first central sipes 110 are arranged at intervals in the tire circumferential direction. The first central sipes 110 generally extend along the tire axial direction. The surface shape of the first central sipes 110 on the tread surface 2A can be called an approximately S-shape or crank shape. The first central sipes 110 do not communicate with either the sub-grooves 600 or the first main grooves 700 on both sides of the tire axial direction, and both ends of the first central sipes 110 terminate within the central land 100.

[0021] As shown in FIG. 3 , the second central sipes 120 are arranged on one axial side X1 and the other axial side X2 of the first central sipe 110. The second central sipes 120 are spaced apart in the tire circumferential direction. The second central sipes 120 have a corrugated surface shape on the tread surface 2A. The second central sipes 120 extend in an inclined manner toward the one axial side C1 of the tire as they extend from the end on the other axial side X2 toward the end on the one axial side X1 of the tire. The second central sipes 120 arranged on the one axial side X1 of the first central sipe 110 communicate with the sub-groove 600. The second central sipes 120 arranged on the other axial side X2 of the first central sipe 110 communicate with the first main groove 700.

[0022] The second central sipe 120 is preferably a 3D sipe. The 3D sipe referred to here refers to a sipe that is three-dimensionally bent like a wave shape in the extension direction of the second central sipe 120 (the length direction from one end to the other end) and also has a portion that is bent in the sipe depth direction.

[0023] The plurality of third central sipes 130 are arranged on one axial side X1 of the first central sipes 110. The third central sipes 130 have a wave-shaped portion as a surface shape on the tread surface 2A. The third central sipes 130 are arranged between a predetermined pair of second central sipes 120 adjacent in the tire circumferential direction, among the second central sipes 120 arranged on one axial side X1 of the first central sipes 110. The overall extension direction of the third central sipes 130 is approximately parallel to the second central sipes 120. The third central sipes 130 are adjacent to the sub-groove 600 but do not communicate with the sub-groove 600, and both ends thereof terminate within the central land 100.

[0024] In this embodiment, the width of the second central sipe 120 and the width of the third central sipe 130 are approximately the same, and the width of the first central sipe 110 is larger than the widths of the second central sipe 120 and the third central sipe 130, but is not limited to this.

[0025] As shown in Figures 2 and 3, the central land 100 includes a plurality of first central slits 140 and a plurality of second central slits 150 extending in a direction intersecting the tire circumferential direction. The first central slits 140 and the second central slits 150 are spaced apart in the tire circumferential direction. The widths of the first central slits 140 and the second central slits 150 are, for example, but not limited to, approximately 3 mm to 6 mm. The depths of the first slits 140 are, for example, approximately 7.0 mm to 8.5 mm, and the depths of the second slits 150 are, for example, but not limited to, approximately 4.0 mm to 5.5 mm.

[0026] The end of the first central slit 140 on one axial side X1 of the tire is connected to the secondary groove 600. The first central slit 140 extends from one end connected to the secondary groove 600 to the other axial side X2 of the tire and terminates just before reaching the first main groove 700. The first central slit 140 is inclined with respect to the tire axial direction so as to extend toward the other circumferential side C2 of the tire as it moves from its end connected to the secondary groove 600 toward the other axial side X2 of the tire. The end portion of the first central slit 140 on the other axial side X2 of the tire has a hook-shaped portion 141 that extends toward the one circumferential side C1 of the tire as it moves toward the other axial side X2 of the tire. It is preferable that the direction of extension of the hook-shaped portion 141 on the one circumferential side C1 of the tire, i.e., the direction from the end of the first central slit 140 toward its tip, is a direction from the tire leading side (leading side) toward the tire trailing side (trailing side) and is inclined with respect to the tire circumferential direction. The first central slit 140 extends across the tire equator E. That is, the first central slit 140 extends in a direction intersecting the tire equator E. In the first central slit 140 of the embodiment, the tire equator E passes near the starting end of the hook-shaped portion 141.

[0027] The end of the second central slit 150 on the other axial side X2 of the tire is connected to the first main groove 700. The second central slit 150 extends from one end connected to the first main groove 700 toward one axial side X1 of the tire and terminates just before reaching the secondary groove 600. The second central slit 150 is inclined with respect to the tire axial direction so as to extend toward one circumferential side C1 of the tire as it moves from its end connected to the first main groove 700 toward one axial side X1 of the tire. The second central slit 150 extends across the tire equator E. That is, the second central slit 150 extends in a direction intersecting with the tire equator E.

[0028] The first central slits 140 and the second central slits 150 are alternately arranged in the tire circumferential direction. A predetermined number of first central sipes 110, second central sipes 120, and third central sipes 130 are arranged between adjacent first central slits 140 and second central slits 150 in the tire circumferential direction. None of the central sipes 110, 120, and 130 and none of the central slits 140 and 150 cross the central land 100 and are not connected to both the sub-groove 600 and the first main groove 700. Therefore, the central land 100 has a rib shape that extends continuously in an annular shape in the tire circumferential direction.

[0029] 2 and 3, the first intermediate land 200 includes a plurality of first intermediate blocks 210 arranged in the tire circumferential direction and a plurality of first intermediate slits 220 extending in a direction intersecting the tire circumferential direction. The plurality of first intermediate slits 220 are arranged at intervals in the tire circumferential direction. The first intermediate slits 220 cross the first intermediate land 200 and communicate with the sub-groove 600 and the second main groove 800.

[0030] As shown in FIG. 3 , the first intermediate slit 220 has a first bent portion 221 that protrudes toward one side C1 in the tire circumferential direction. The first bent portion 221 is formed in the first intermediate slit 220 at a position closer to one side X1 in the tire axial direction. The first intermediate slit 220 has a first inclined portion 222 that extends from the first bent portion 221 to the second main groove 800 and a second inclined portion 223 that extends from the first bent portion 221 to the secondary groove 600. When viewed from the first bent portion 221 as a starting point, the first inclined portion 222 and the second inclined portion 223 are inclined with respect to the tire axial direction so as to extend toward the other side C2 in the tire circumferential direction as they extend in a direction away from the first bent portion 221 in the tire axial direction. The first intermediate slit 220 has a first protruding recess 224 that protrudes toward one side X1 in the tire axial direction on one side C1 in the tire circumferential direction of the first bent portion 221.

[0031] As described above, the width of the secondary groove 600 and the second main groove 800 as the circumferential groove 7 is larger for the second main groove 800 and smaller for the secondary groove 600. Furthermore, the widths of the first inclined portion 222 and the second inclined portion 223 of the first intermediate slit 220 are smaller for the first inclined portion 222 than for the second inclined portion 223. In the first intermediate slit 220, the first inclined portion 222 on the smaller groove width side communicates with the second main groove 800 on the larger groove width side of the circumferential groove 7, and the second inclined portion 223 on the larger groove width side communicates with the secondary groove 600 with the smaller groove width in the circumferential groove 7. In other words, the groove width of the first inclined portion 222 communicating with the second main groove 800 is smaller than the groove width of the second inclined portion 223 communicating with the secondary groove 600. The width of the first inclined portion 222 is, for example, about 2.5 mm to 4.5 mm, and the depth is, for example, but not limited to, about 3.0 mm to 9.0 mm. The width of the second inclined portion 223, which is larger than the first inclined portion 222, is, for example, about 3.0 mm to 5.0 mm, and the depth is, for example, but not limited to, about 7.0 mm to 9.0 mm.

[0032] Each of the multiple first intermediate blocks 210 is defined in a substantially rectangular shape by a secondary groove 600, a second main groove 800, and a pair of circumferentially adjacent first intermediate slits 220. The first central slit 140 of the central land 100 extends on the extension of the first intermediate slit 220, sandwiching the secondary groove 600 therebetween.

[0033] 3, the sub-groove 600 is configured by a plurality of dividing grooves 610 formed in each first intermediate block 210 and divided in the tire circumferential direction, which are continuous in the tire circumferential direction via first intermediate slits 220. Each dividing groove 610 is inclined with respect to the tire circumferential direction so as to extend toward one tire axial side X1 as it moves from the other tire circumferential side C2 toward one tire circumferential side C1. As a result, the edge of the central land 100 extending in the tire circumferential direction on one tire axial side X1 has a zigzag shape.

[0034] 3, the first intermediate block 210 has a pair of first and second notches 211 and 212 at approximately the center in the tire circumferential direction and at positions that are approximately opposite to each other in the tire axial direction. The first notch 211 is formed in an edge of the first intermediate block 210 on one side X1 in the tire axial direction, and communicates with the second main groove 800. The second notch 212 is formed in an edge of the first intermediate block 210 on the other side X2 in the tire axial direction, and communicates with the sub-groove 600.

[0035] The first intermediate block 210 includes a plurality of first intermediate sipes 213 extending in a direction intersecting the tire circumferential direction. The first intermediate sipes 213 have a portion whose surface shape on the tread surface 2A is wavy. The first intermediate sipes 213 are generally curved so as to be convex toward one tire circumferential side C1, but the proportion of the portion inclined with respect to the tire axial direction on the other tire axial side X2 is long.

[0036] The first intermediate sipes 213 include those whose ends on one axial side X1 of the tire communicate with the first notch 211, extend from their communicating end toward the secondary groove 600, and terminate just before reaching the secondary groove 600, those whose ends on the other axial side X2 of the tire communicate with the second notch 212, extend from their communicating end toward the second main groove 800, and terminate just before reaching the second main groove 800, and those that communicate with the secondary groove 600 and the second main groove 800. However, the sipe pattern formed by the shapes, arrangements, etc. of these multiple first intermediate sipes 213 is common to each first intermediate block 210.

[0037] The region of the central land 100 between a pair of first central slits 140 adjacent in the tire circumferential direction corresponds to the region of the two first intermediate blocks 210 between a pair of first intermediate slits 220 of the first intermediate land 200 that are continuous with the first central slit 140 and adjacent in the tire circumferential direction. Therefore, the central land 100 and the first intermediate land 200 in these regions form a pair of one configuration, that is, a "two-piece set" configuration.

[0038] 2 and 3, the second intermediate land 300 includes a plurality of second intermediate blocks 310 arranged in the tire circumferential direction, a plurality of second intermediate slits 320 extending in a direction intersecting the tire circumferential direction, a plurality of third intermediate slits 330, and a plurality of fourth intermediate slits 340. The width of each of the slits 320, 330, and 340 is, for example, but not limited to, approximately 2.5 mm to 5.0 mm. The depth of the slit 320 is, for example, approximately 7.0 mm to 8.5 mm, and the depth of the slits 330 and 340 is, for example, but not limited to, approximately 4.0 mm to 5.5 mm.

[0039] The second intermediate slits 320 are arranged at intervals in the tire circumferential direction. The second intermediate slits 320 traverse the second intermediate land 300 and communicate with the first main groove 700 and the third main groove 900.

[0040] As shown in Fig. 3, the second intermediate slit 320 has a second bent portion 321 and a third bent portion 322 at each end in the tire axial direction. The second bent portion 321 is formed at the end on one axial side X1 of the tire and protrudes toward the other circumferential side C2 of the tire. The third bent portion 322 is formed at the end on the other axial side X2 of the tire and protrudes toward the one circumferential side C1 of the tire. The second intermediate slit 320 has a third inclined portion 323 extending from the second bent portion 321 to the first main groove 700, a fourth inclined portion 324 extending from the third bent portion 322 to the third main groove 900, and a fifth inclined portion 325 connecting the second bent portion 321 and the third bent portion 322.

[0041] The fifth inclined portion 325 is a main portion of the second intermediate slit 320 and is longer than the third inclined portion 323 and the fourth inclined portion 324. The fifth inclined portion 325 is inclined with respect to the tire axial direction so as to extend toward one side C1 in the tire circumferential direction as it moves from the second bent portion 321 toward the third bent portion 322. The third inclined portion 323 and the fourth inclined portion 324 have approximately the same length and are inclined in the opposite direction to the fifth inclined portion 325.

[0042] The second intermediate slit 320 has a second protruding recess 326 that protrudes toward the other tire axial side X2 on the other tire circumferential side C2 of the second bent portion 321, and has a third protruding recess 327 that protrudes toward the one tire axial side X1 on one tire circumferential side C1 of the third bent portion 322.

[0043] Each of the plurality of second intermediate blocks 310 is defined in a substantially rectangular shape by the first main groove 700, the third main groove 900, and a pair of second intermediate slits 320 adjacent to each other in the tire circumferential direction.

[0044] As shown in FIG. 2, the second intermediate blocks 310 having the third intermediate slits 330 and the second intermediate blocks 310 having the fourth intermediate slits 340 are arranged alternately in the tire circumferential direction.

[0045] As shown in FIG. 3 , the third intermediate slit 330 is formed on the edge of the second intermediate block 310 on one side X1 in the tire axial direction. The third intermediate slit 330 is bent in a hook shape. The third intermediate slit 330 communicates with the first main groove 700, and the end opposite the communicating end is tapered and terminates within the second intermediate block 310. The fourth intermediate slit 340 is formed on the edge of the second intermediate block 310 on the other side X2 in the tire axial direction. The fourth intermediate slit 340 has the same shape as the third intermediate slit 330 and is bent in a hook shape, but the bending direction is opposite to that of the third intermediate slit 330. The fourth intermediate slit 340 communicates with the third main groove 900, and the end opposite the communicating end is tapered and terminates within the second intermediate block 310. The second central slit 150 of the central land 100 extends in an extension of the third intermediate slit 330 with the first main groove 700 interposed therebetween.

[0046] The second intermediate block 310 includes a plurality of second intermediate sipes 311 extending in a direction intersecting the tire circumferential direction. The second intermediate sipes 311 have a wavy surface shape on the tread surface 2A. There are multiple types of second intermediate sipes 311, each differing in length, extension direction, position, and the like, and by the number of communicating grooves and slits. For example, the second intermediate sipes 311 may extend in a substantially linear or curved direction. Some second intermediate sipes 311 communicate only with the first main groove 700 or only with the third main groove 900, thereby terminating at one end within the second intermediate block 310. Some second intermediate sipes 311 communicate with either the first main groove 700 or the third main groove 900 and the second intermediate slit 320. However, the sipe pattern formed by the shapes, arrangements, etc. of the plurality of second intermediate sipes 311 is common to each second intermediate block 310.

[0047] The region of the central land 100 between a pair of first central slits 140 adjacent in the tire circumferential direction corresponds to the region of two second intermediate blocks 310 adjacent in the tire circumferential direction of the second intermediate land 300, that is, the second intermediate block 310 having the third intermediate slit 330 and the second intermediate block 310 not having the third intermediate slit 330. Therefore, the central land 100 and the second intermediate land 300 in these regions form a pair, that is, a "pair" configuration.

[0048] 2, the first shoulder land 400 includes a plurality of first shoulder blocks 410 aligned in the tire circumferential direction and a plurality of first lug grooves 420 extending in a direction intersecting the tire circumferential direction. The width of the first lug groove 420 is, for example, about 3.5 mm to 6.0 mm, and the depth is, for example, about 6.5 mm to 8.5 mm, but is not limited to these.

[0049] The first shoulder land 400 of the embodiment is a land in the region between the second main groove 800 and the ground contact edge 2C on one axial side X1 of the tire in the tire axial direction. A first buttress 8A is provided so as to be continuous with the first shoulder land 400 on one axial side X1 of the tire than the ground contact edge 2C.

[0050] The multiple first lug grooves 420 are arranged at intervals in the tire circumferential direction. The first lug grooves 420 communicate with the second main grooves 800 and are continuous with first buttress slits 820, which will be described later. Most of the first lug grooves 420 on the side communicating with the second main grooves 800 are slightly inclined with respect to the tire axial direction.

[0051] The plurality of first shoulder blocks 410 are defined between a pair of first lug grooves 420 adjacent in the tire circumferential direction in a substantially rectangular shape in a plan view, and are lined up in the tire circumferential direction.

[0052] The first shoulder block 410 includes a first shoulder slit 411 and a plurality of first shoulder sipes 412. The first shoulder slit 411 and the first shoulder sipes 412 both extend in a direction intersecting the tire circumferential direction.

[0053] The first shoulder slit 411 has a shape that is bent in a substantially Z-shape. The first shoulder slit 411 does not communicate with any grooves except the sipes and terminates inside the first shoulder block 410. The width of the first shoulder slit 411 is, for example, about 0.5 mm or more and 2.0 mm or less, and the depth is, for example, about 0.5 mm or more and 2.0 mm or less, but is not limited to these.

[0054] The multiple first shoulder sipes 412 are aligned at intervals in the tire circumferential direction. Each first shoulder sipe 412 has a wave-shaped portion. Each first shoulder sipe 412 communicates with the second main groove 800, extends from the communicating end toward the shoulder 5, and communicates with a dimple 414 (a depression) provided in the shoulder 5.

[0055] 2, the configuration of the second shoulder land 500 and the second buttress 8B on the other axial side X2 of the third main groove 900 is substantially point-symmetrical to the configuration of the first shoulder land 400 and the first buttress 8A on one axial side X1 of the second main groove 800, and they have the same configuration as described below. Note that the widths and depths of corresponding slits and grooves that are point-symmetrical are substantially the same.

[0056] The second shoulder land 500 includes a plurality of second shoulder blocks 510 aligned in the tire circumferential direction and a plurality of second lug grooves 520 extending in a direction intersecting the tire circumferential direction. In this embodiment, the second shoulder land 500 is a land in the region between the third main groove 900 and the ground contact edge 2C on the other axial side X2 of the tire in the tire axial direction. A second buttress 8B is provided on the other axial side X2 of the tire beyond the ground contact edge 2C in a manner continuous with the second shoulder land 500.

[0057] The multiple second lug grooves 520 are arranged at intervals in the tire circumferential direction. The second lug grooves 520 communicate with the third main groove 900 and also communicate with second buttress slits 920, which will be described later. Most of the second lug grooves 520 on the side communicating with the third main groove 900 are slightly inclined with respect to the tire axial direction.

[0058] The second shoulder blocks 510 are partitioned into a substantially rectangular shape in plan view by a pair of second lug grooves 520 adjacent to each other in the tire circumferential direction, and are arranged in the tire circumferential direction.

[0059] The second shoulder block 510 includes a second shoulder slit 511 and a plurality of second shoulder sipes 512. The second shoulder slit 511 and the second shoulder sipes 512 both extend in a direction intersecting the tire circumferential direction.

[0060] The second shoulder slit 511 has a shape that is bent in a substantially Z-shape. The second shoulder slit 511 does not communicate with any grooves except for the sipes, and terminates within the second shoulder block 510.

[0061] The multiple second shoulder sipes 512 are aligned at intervals in the tire circumferential direction. Each second shoulder sipe 512 has a wave-shaped portion. Each second shoulder sipe 512 communicates with the third main groove 900, extends from the communicating end toward the shoulder 5, and communicates with a dimple 514 (a depression) provided in the shoulder 5.

[0062] As shown in FIG. 2, the first buttress 8A includes first buttress blocks 810 as multiple buttress blocks lined up in the tire circumferential direction, and first buttress slits 820 as multiple buttress slits extending in the tire axial direction and tire radial direction, in a direction intersecting the tire circumferential direction.

[0063] The other axial side X2 of each first buttress slit 820 communicates with a first lug groove 420 of the first shoulder land 400 near the ground contact edge 2C, and the one axial side X1 of each first buttress slit 820 communicates with the first annular groove 9A. The first annular groove 9A is an annular groove that extends along the tire circumferential direction and is formed on the tire radially inward side of the first buttress 8A. A continuous slit is formed by the first lug grooves 420 and the first buttress slits 820. The multiple first buttress blocks 810 are partitioned into approximately rectangular shapes between adjacent first buttress slits 820 in the tire circumferential direction and are lined up in the tire circumferential direction.

[0064] The first buttress block 810 includes a pair of first hooked grooves 81 and second hooked grooves 82 that face each other in the tire axial direction. The second hooked groove 82 is arranged on the other axial side X2 of the first hooked groove 81. The first buttress block 810 also has a first groove 830 and a second groove 840.

[0065] As shown in FIG. 2, the second buttress 8B includes second buttress blocks 910 as multiple buttress blocks lined up in the tire circumferential direction, and second buttress slits 920 as multiple buttress slits extending in the tire axial direction and tire radial direction, in a direction intersecting the tire circumferential direction.

[0066] One axial side X1 of each second buttress slit 920 communicates with a second lug groove 520 of the second shoulder land 500 near the contact edge 2C, and the other axial side X2 of the tire communicates with the second annular groove 9B. The second annular groove 9B is an annular groove that runs along the tire circumferential direction and is formed on the tire radially inward side of the second buttress 8B. The second lug grooves 520 and the second buttress slits 920 form a continuous slit. The multiple second buttress blocks 910 are partitioned into approximately rectangular shapes between circumferentially adjacent second buttress slits 920 and are lined up in the tire circumferential direction.

[0067] The second buttress block 910 includes a pair of first hooked grooves 83 and second hooked grooves 84 that face each other in the tire axial direction. The second hooked groove 84 is arranged on one side X1 in the tire axial direction of the first hooked groove 83. The second buttress block 910 also has a first groove 930 and a second groove 940.

[0068] The first buttress 8A will be described in detail below. As mentioned above, the first buttress 8A and the second buttress 8B are nearly point-symmetric and have the same configuration, so by describing the first buttress 8A, a description of the second buttress 8B will be omitted.

[0069] Figure 4 is an enlarged view of the area indicated by IV in Figure 2, showing a part of the first buttress 8A. As described above, the first buttress 8A has a first buttress block 810 provided between each of a plurality of first buttress slits 820 that are aligned in the tire circumferential direction. Note that the first buttress blocks 810 and the first buttress slits 820 correspond to the second buttress blocks 910 and the second buttress slits 920, respectively, in the second buttress 8B.

[0070] The first hook groove 81 and the second hook groove 82 included in the first buttress block 810 have the same shape. The width of the first hook groove 81 and the second hook groove 82 is, for example, not less than 1.0 mm and not more than 3.5 mm, and the depth is, for example, not less than 0.5 mm and not more than 1.5 mm, but is not limited to these. The first hook groove 81 and the second hook groove 82 correspond to the first hook groove 83 and the second hook groove 84, respectively, in the second buttress 8B.

[0071] The first hook-shaped groove 81 includes a first circumferentially inclined groove 861 and a first bent groove 862. The base end of the first circumferentially inclined groove 861 communicates with one of a pair of first buttress slits 820 adjacent in the tire circumferential direction (the lower side in FIG. 4 ) and the first annular groove 9A, and extends from the first buttress slit 820 and the first annular groove 9A toward the other tire circumferential side C2 while inclining relative to the tire circumferential direction, and terminates inside the first buttress block 810 without reaching the first buttress slit 820 in the extending direction. Note that the first annular groove 9A corresponds to the second annular groove 9B on the second buttress 8B side. The first circumferentially inclined groove 861 is inclined so as to extend axially inward as it approaches the other tire circumferential side C2. The first bent groove 862 is bent at an acute angle from a tip 861a, which is the end of the first circumferentially oblique groove 861, toward the inside in the tire axial direction and toward one side C1 in the tire circumferential direction.

[0072] The second hook-shaped groove 82 includes a second circumferentially inclined groove 865 and a second bent groove 866. The base end of the second circumferentially inclined groove 865 is connected to the other (upper in FIG. 4 ) of a pair of first buttress slits 820 adjacent in the tire circumferential direction, and extends from that first buttress slit 820 toward one tire circumferential side C1 in the opposite direction to the first circumferentially inclined groove 861 while inclining with respect to the tire circumferential direction, and terminates inside the first buttress block 810 without reaching the first buttress slit 820 in the extending direction. The second circumferentially inclined groove 865 is inclined so as to extend axially outward as it approaches the tire circumferentially one side C1. The second bent groove 866 is bent at an acute angle from a tip 865a, which is the terminal end of the second circumferentially inclined groove 865, toward the tire axially outward and toward the tire circumferentially other side C2.

[0073] The first hooked groove 81 and the second hooked groove 82 are arranged in opposite directions in the tire circumferential direction, with the circumferentially inclined grooves 861, 865 parallel to each other and the bent grooves 862, 866 engaging with each other. The inclination angle θ of each of the circumferentially inclined grooves 861, 865 extending at an angle to the tire circumferential direction is preferably 5° or more and 22° or less.

[0074] Fig. 5 is a cross-sectional view taken along line VV in Fig. 4. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 4. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 4.

[0075] FIG. 5 shows a cross-sectional shape of the second circumferentially inclined groove 865 of the second hooked groove 82, and FIG. 6 shows a cross-sectional shape of a tip 865a of the second circumferentially inclined groove 865. As shown in FIGS. 5 and 6, a bottom 870 of the second circumferentially inclined groove 865 has, over its entire length, an arc portion 871 and an inclined surface 872 inclined from the arc portion 871 to one side in the groove width direction. The inclined surface 872 is disposed on the side of the second bent groove 866. FIG. 7 shows a cross-sectional shape of a tip portion of the second bent groove 866 of the second hooked groove 82. As shown in FIG. 7, a bottom 880 of the second bent groove 866 has, over its entire length, an arc portion 881 and an inclined surface 882 inclined from the arc portion 881 to one side in the groove width direction. The inclined surface 882 is disposed on the side of the second bent groove 866. The arc portion 871 of the second circumferential inclined groove 865 is continuous with the arc portion 881 of the second bent groove 866, and the inclined surface 872 of the second circumferential inclined groove 865 is continuous with the inclined surface 882 of the second bent groove 866. The first hooked groove 81 has a cross-sectional shape similar to that of the second hooked groove 82.

[0076] 4 shows the above-mentioned dimple 414. A plurality of dimples 414 are arranged at intervals in the tire circumferential direction on the ground-contact edge 2C of the tread 2 in the shoulder 5 portion extending from the tread 2 to the buttress 8. Similar to the dimples 414, a plurality of dimples 514 are also arranged at intervals in the tire circumferential direction on the ground-contact edge 2C on the second buttress 8B side. In a plan view of the tire, the dimples 414, 415 have a generally rectangular shape with their length extending in the tire axial direction.

[0077] 4, the first buttress block 810 has the above-mentioned first groove 830 and second groove 840. The first groove 830 and second groove 840 correspond to the first groove 930 and second groove 940, respectively, in the second buttress 8B.

[0078] The first groove 830 is disposed on the inner side of the first buttress block 810 in the tire axial direction (toward the tire equator E, left side in FIG. 4). The base end of the first groove 830 communicates with one side (lower side in FIG. 4) of a pair of first buttress slits 820 adjacent in the tire circumferential direction, and extends from the first buttress slit 820 along the tire circumferential direction to the other tire circumferential side C2. The first groove 830 is adjacent to the second circumferentially oblique groove 865 of the second hook-shaped groove 82. The width of the first groove 830 is, for example, about 1.0 mm or more and 3.0 mm or less, and the depth is, for example, about 0.5 mm or more and 1.5 mm or less, but is not limited to these values.

[0079] The second groove 840 is disposed on the outer side of the first buttress block 810 in the tire axial direction (the side away from the tire equator E, the right side in FIG. 4). The second groove 840 is formed in a notch shape so as to communicate with the other side (the upper side in FIG. 4) of a pair of first buttress slits 820 adjacent in the tire circumferential direction and the first annular groove 9A. The second groove 840 is adjacent to the first circumferentially inclined groove 861 of the first hook-shaped groove 81. The width of the second groove 840 is, for example, a maximum of approximately 0.5 mm or more and 2.0 mm or less, and the depth is, for example, a maximum of approximately 0.5 mm or more and 1.5 mm or less, but is not limited to these values.

[0080] 2, on one axial side X1 of the tread surface 2A, four slits and grooves, namely, the first buttress slit 820 of the first buttress 8A, the first lug groove 420 of the first shoulder land 400, the first intermediate slit 220 of the first intermediate land 200, and the first central slit 140 of the central land 100, extend continuously in a direction intersecting the tire circumferential direction. Here, these four slits are referred to as a single continuous slit and are referred to as a first continuous slit 10.

[0081] 2, on the other axial side X2 of the tread surface 2A, three slits and grooves, namely, the second buttress slit 920 of the second buttress 8B, the second lug groove 520 of the second shoulder land 500, and the second intermediate slit 320 of the second intermediate land 300, extend continuously in a direction intersecting the tire circumferential direction. Here, these three slits are referred to as a single continuous slit and are referred to as a second continuous slit 20.

[0082] The slit lengths are different between the first continuous slit 10 and the second continuous slit 20. The slit length here refers to the total length tracing the shape of the slit on the tire surface.

[0083] Of the slits and grooves that make up the first continuous slit 10, the first buttress slit 820, the first lug groove 420, and the first intermediate slit 220 cross the first buttress 8A, the first shoulder land 400, and the first intermediate land 200, respectively, in the tire axial direction, but the first central slit 140 intersects with the tire equator E and terminates within the central land 100. In other words, the first continuous slit 10 terminates within one land 6.

[0084] On the other hand, the second buttress slit 920, the second lug groove 520, and the second intermediate slit 320 constituting the second continuous slit 20 cross the second buttress 8B, the second shoulder land 500, and the second intermediate land 300, respectively, in the tire axial direction and do not terminate within each land. In other words, the second continuous slit 20 crosses multiple lands 6 in the tire axial direction and does not terminate within the land 6.

[0085] The second central slit 150 of the central land 100 extends in the opposite direction to the first continuous slit 10, that is, from the other axial side X2 of the tire, and terminates within the central land 100.

[0086] The first intermediate slit 220 constituting the first continuous slit 10 has a first bent portion 221 that bends within the first intermediate land 200. That is, the first continuous slit 10 has the first bent portion 221 that bends within the first intermediate land 200. Furthermore, the first continuous slit 10 has a first protruding recess 224 that protrudes from the first bent portion 221.

[0087] The second intermediate slit 320 constituting the second continuous slit 20 has a second bent portion 321 and a third bent portion 322 that bend within the second intermediate land 300. That is, the second continuous slit 20 has the second bent portion 321 and the third bent portion 322 that bend within the second intermediate land 300. Furthermore, the second continuous slit 20 has a second protruding recess 326 that protrudes from the second bent portion 321 and a third protruding recess 327 that protrudes from the third bent portion 322.

[0088] The tire 1 according to the embodiment described above provides the following effects.

[0089] (1) A tire 1 according to an embodiment is a pneumatic tire including a tread 2 that comes into contact with a road surface and a pair of sidewalls 4 that form tire sidewall surfaces, and each of the pair of sidewalls 4 has an annular buttress 8 along the tire circumferential direction on the outer side in the tire radial direction, and the buttress 8 extends in a direction intersecting the tire circumferential direction and includes first buttress slits 820 and second buttress slits 920 as a plurality of buttress slits that are spaced apart in the tire circumferential direction, and first buttress blocks 810 and second buttress blocks 910 as a plurality of buttress blocks that are partitioned in the tire circumferential direction by the plurality of buttress slits, and the buttress blocks are adjacent to each other in the tire circumferential direction. The tire has a first circumferentially inclined groove 861 that extends from one of a pair of adjacent buttress slits, at an angle relative to the tire circumferential direction, and terminates within the buttress 8, and a second circumferentially inclined groove 865 that extends from the other of the pair of buttress slits that is adjacent in the tire circumferential direction, in the opposite direction to the first circumferentially inclined groove 861, and at an angle relative to the tire circumferential direction, and terminates within the buttress 8, the first circumferentially inclined groove 861 has a first bent groove 862 that extends and bends from a tip 861a that is a terminal end of the first circumferentially inclined groove 861, and the second circumferentially inclined groove 865 has a second bent groove 866 that extends and bends from a tip 865a that is a terminal end of the second circumferentially inclined groove 865.

[0090] With the tire 1 of this embodiment, when attempting to ride over ruts while traveling on snowy and icy roads, the two circumferentially inclined grooves of the buttress 8, the first circumferentially inclined groove 861 and the second circumferentially inclined groove 865, dig into the inner wall of the rut, effectively generating traction due to the edge effect. Because the two circumferentially inclined grooves 861, 865 each extend from different first buttress slits 820 that are adjacent in the tire circumferential direction, the buttress blocks are more likely to flex uniformly, making it easier to obtain the edge effect. As a result, it becomes easier to ride over ruts on snowy and icy roads, improving driving performance on snowy and icy roads.

[0091] (2) In the tire 1 according to the embodiment (1), the first circumferential oblique grooves 861 and the second circumferential oblique grooves 865 are preferably inclined at an angle of 5° to 22° relative to the tire circumferential direction.

[0092] This improves traction on ruts on snowy and icy roads.

[0093] (3) In the tire 1 according to the above embodiments (1) and (2), the first bent groove 862 extends from the tip 861a of the first circumferentially inclined groove 861, bending at an acute angle, and the second bent groove 866 extends from the tip 865a of the second circumferentially inclined groove 865, bending at an acute angle.

[0094] This enhances the edge effect of the portion bending from the first circumferential inclined groove 861 to the first bent groove 862 and the portion bending from the second circumferential inclined groove 865 to the second bent groove 866, improving traction on ruts on snowy and icy roads.

[0095] (4) In the tire 1 according to the above embodiments (1) to (3), the bottom portion 870 of each of the first circumferential inclined groove 861 and the second circumferential inclined groove 865 has an inclined surface 872 that is inclined to one side in the groove width direction.

[0096] As a result, when the buttress 8 is deflected and stress is applied to the first circumferential inclined groove 861 and the second circumferential inclined groove 865, partial stress concentration on the bottom portion 870 can be suppressed, thereby suppressing the occurrence of cracks in the bottom portion 870.

[0097] (5) In the tire 1 according to the above embodiments (1) to (4), a plurality of dimples 414, 514 as recesses are arranged at intervals around the tire on the contact edge 2C located in the region from the tread 2 to the buttress 8.

[0098] The dimples 414, 514 relieve the ground contact pressure applied to the ground contact edge 2C, thereby equalizing the ground contact pressure of the tread 2 and buttress 8, and as a result, uneven wear of the tread 2 and buttress 8 is suppressed.

[0099] (6) In the tire 1 according to the above embodiments (1) to (5), the buttress block has first grooves 830, 930 extending circumferentially from one buttress slit and adjacent to the second circumferentially oblique groove 865, and second grooves 840, 940 extending circumferentially from the other buttress slit and adjacent to the first circumferentially oblique groove 861.

[0100] This makes it easier to equalize the amount of deflection of the pair of buttresses 8, thereby suppressing the occurrence of cracks in the buttresses 8 due to unevenness in the amount of deflection.

[0101] The present invention is not limited to the above-described embodiment, and any modifications and improvements made within the scope of the present invention are included within the scope of the present invention.

[0102] 8 and 9 are figures corresponding to FIG. 4, including the reference numerals, and show an example in which the tire aspect ratio is different from that of tire 1 of the above embodiment, and the tire radial length of the first buttress 8A is accordingly different.

[0103] In Figure 8, the tire aspect ratio is smaller than that of tire 1 of the above embodiment, so the radial length of the first buttress 8A is larger, and accordingly, the dimensions of the dimple 414, as well as the first hook groove 81, the second hook groove 82, the first groove 830, and the second groove 840, have been significantly changed in terms of radial and axial lengths.

[0104] In Figure 9, the tire aspect ratio is larger than that of tire 1 of the above embodiment, so the radial length of the first buttress 8A is smaller, and accordingly, the dimensions of the first hook groove 81, the second hook groove 82, the first groove 830, and the second groove 840, as well as the dimple 414, have been changed so that their radial and axial lengths are smaller. [Explanation of symbols]

[0105] 1. Tires (pneumatic tires) 2 Tread 2C ground end 4 Sidewall 8 Buttress 8A First Buttress 8B First Buttress 414, 514 dimples (dents) 810 First Buttress Block (Buttress Block) 820 First Buttress Slit (Buttress Slit) 861 1st circumferential inclined groove 861a Tip of the first circumferential inclined groove 862 1st bend groove 865 2nd circumferential inclined groove 865a Tip of second circumferential inclined groove 866 2nd bend groove 870 Bottom 872 Slope 910 Second Buttress Block (Buttress Block) 920 Second Buttress Slit (Buttress Slit) E Tire Equator C Circumferential direction of tire X Tire Axial Direction

Claims

1. A pneumatic tire having a tread that comes into contact with a road surface and a pair of sidewalls that form tire sidewall surfaces, Each of the pair of sidewalls has an annular buttress along the tire circumferential direction on an outer side in the tire radial direction, The buttress is a plurality of buttress slits extending in a direction intersecting the tire circumferential direction and arranged at intervals in the tire circumferential direction; a plurality of buttress blocks partitioned in the tire circumferential direction by the plurality of buttress slits, The buttress block is a first circumferentially oblique groove extending from one of the pair of buttress slits adjacent in the tire circumferential direction while obliquely extending with respect to the tire circumferential direction and terminating within the buttress; a second circumferentially oblique groove extending from the other of the pair of buttress slits adjacent in the tire circumferential direction in a direction opposite to the first circumferentially oblique groove and at an incline with respect to the tire circumferential direction, and terminating within the buttress, The first circumferentially inclined groove is provided with a first bent groove that extends in a bent manner from a tip end that is an end of the first circumferentially inclined groove, The pneumatic tire is configured such that the second circumferentially oblique groove is provided with a second bent groove that extends in a bent manner from a tip that is an end of the second circumferentially oblique groove.

2. The pneumatic tire according to claim 1 , wherein the first circumferential oblique groove and the second circumferential oblique groove are inclined at an angle of 5° to 22° with respect to the tire circumferential direction.

3. the first bent groove extends from the tip of the first circumferentially oblique groove while bending at an acute angle, The pneumatic tire according to claim 1 or 2, wherein the second bent groove extends from the tip of the second circumferential oblique groove while bending at an acute angle.

4. The pneumatic tire according to claim 1 , wherein a bottom portion of each of the first circumferential oblique groove and the second circumferential oblique groove has an inclined surface that is inclined to one side in the groove width direction.

5. The pneumatic tire according to claim 1 or 2, wherein a plurality of recesses are arranged at intervals in the tire circumferential direction on a ground contact edge that is arranged in a region extending from the tread to the buttress.

6. The buttress block is a first groove extending from the one buttress slit in the tire circumferential direction and adjacent to the second circumferential oblique groove; The pneumatic tire according to claim 1 or 2, further comprising: a second groove extending in the tire circumferential direction from the other buttress slit and located adjacent to the first circumferential oblique groove.

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