tire

Abstract

A tire including: on a tread surface, a center land portion that has a rib shape is defined between two tire circumferential direction grooves. The center land portion includes: a circumferential direction sipe that intersects with the tire equatorial plane; a first connecting sipe that connects the circumferential direction sipe to one of the two tire circumferential direction grooves; and a second connecting sipe that connects the circumferential direction sipe to the one of the tire circumferential direction grooves, and is shallower than each of the circumferential direction sipe and the first connecting sipe. The second connecting sipe includes: a first portion, both ends of which connect to the circumferential direction sipe, and which defines a block-shaped portion between the first portion and the circumferential direction sipe; and a second portion that connects the first portion to the one of the tire circumferential direction grooves.

Description

DESCRIPTIONTITLE TIRETECHNICAL FIELD

[0001] The present disclosure relates to tires.BACKGROUND

[0002] A tire is known in which a block-shaped land portion defined by two tire circumferential direction grooves and two tire width direction grooves is formed on a tread surface that comes into contact with a road surface. Patent Literature (PTL) 1 describes this type of tire.CITATION LISTPatent Literature

[0003] PTL 1 : JP 2024-151969 ASUMMARY(Technical Problem)

[0004] According to the tire described in PTL 1, by providing both a main groove as a tire circumferential direction groove and first and second axial grooves as tire width direction grooves, drainage performance can be improved. On the other hand, according to the tire described in PTL 1, the block-shaped land portion is easily deformed during road surface contact. Therefore, the tire described in PTL 1 tends to have high rolling resistance. To address this, a ribshaped land portion that is defined between two tire circumferential grooves and extends endlessly along the tire circumferential direction could be adopted. This configuration can reduce rolling resistance, but tends to degrade drainage performance.

[0005] It would be helpful to provide a tire capable of enhancing drainage performance while also suppressing an increase in rolling resistance.(Solution to Problem)

[0006] A first aspect of the present disclosure is a tire comprising:on a tread surface that comes into contact with a road surface, a center PO245278-PCT-ZZ ( 1 / 24)land portion that has a rib shape, is defined between two tire circumferential direction grooves that extend endlessly along the tire circumferential direction, and intersects with the tire equatorial plane, whereinthe center land portion comprises:a circumferential direction sipe that extends along the tire circumferential direction, intersects with the tire equatorial plane, and is narrower than each of the two tire circumferential direction grooves;a first connecting sipe that connects the circumferential direction sipe to one of the two tire circumferential direction grooves and is narrower than each of the two tire circumferential direction grooves; anda second connecting sipe that connects the circumferential direction sipe to the one of the tire circumferential direction grooves, is narrower than each of the two tire circumferential direction grooves, and is shallower than each of the circumferential direction sipe and the first connecting sipe, wherein the second connecting sipe comprises:a first portion, both ends of which connect to the circumferential direction sipe at different positions in the tire circumferential direction, and which defines a block-shaped portion between the first portion and the circumferential direction sipe; anda second portion that connects the first portion to the one of the tire circumferential direction grooves.(Advantageous Effect)

[0007] According to the present disclosure a tire can be provided that is capable of enhancing drainage performance while also suppressing an increase in rolling resistance.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the accompanying drawings:FIG. 1 is a perspective diagram of a tire as an embodiment of the present disclosure;FIG. 2 is a diagram illustrating a portion of a developed view of a tread surface of the tire illustrated in FIG. 1 ;FIG. 3 is a cross-section diagram of the tread surface at the position of line I-I in FIG. 2; andFIG. 4 is a diagram illustrating an enlargement of a portion of FIG. 2.PO245278-PCT-ZZ (2 / 24)- -DETAILED DESCRIPTION

[0009] The following describes an embodiment of the tire according to the present disclosure, with reference to the drawings. In each drawing, the same structure is indicated by the same reference sign.

[0010] Hereinafter, tire width direction refers to the direction parallel to the rotation axis of the tire. Tire radial direction refers to the radial direction perpendicular to the rotation axis of the tire and centered at the rotation axis of the tire. Tire circumferential direction refers to the direction in which the tire rotates around the rotation axis of the tire.

[0011] FIG. 1 is a perspective view diagram of a pneumatic tire 1 (hereinafter also referred to simply as "tire 1") as an embodiment of the tire according to the present disclosure. The tire 1 of the present embodiment is a heavy-duty tire used for trucks, buses, and the like, but may be a tire used for other vehicles, such as a passenger vehicle tire.

[0012] As illustrated in FIG. 1, the tire 1 includes a pair of bead portions 11 mounted on a rim, a pair of sidewall portions 12, and a tread portion 13. The sidewall portions 12 are connected to the bead portions 11 outside in the tire radial direction A. The tread portion 13 is connected to the pair of the sidewall portions 12. Both ends of the tread portion 13 in the tire width direction B connect to the sidewall portions 12.

[0013] An outside surface in the tire radial direction A of the tread portion 13 (hereinafter also referred to as "outer surface of the tread portion 13") comprises tread rubber. The outer surface of the tread portion 13 is a tread surface T that comes into contact with a road surface. A tread pattern is formed on the tread surface T.

[0014] T he tire 1 of the present embodiment includes a bead core and bead filler embedded in each of the pair of the bead portions 11. Further, the tire 1 of the present embodiment includes a carcass that spans between the pair of the bead cores embedded in the pair of the bead portions 11. The carcass extends across the pair of the bead portions 11. the pair of the sidewall portions 12. and the tread portion 13. Further, the tire 1 of the present embodiment includes a belt disposed outside of a crown portion of the carcass in the tire radial direction A. The tread rubber of the present embodiment is disposed outside of the belt in the tire radial direction A. However, the internal structure of the tire 1 is not limited to the structure described above.PO245278-PCT-ZZ (3 / 24)

[0015] FIG. 2 is a diagram illustrating a portion of a developed view of the tread surface T of the tread portion 13 of the tire 1 of the present embodiment, illustrated in FIG. 1 .

[0016] As illustrated in FIG. 2. the tire 1 includes, on the tread surface T. two tire circumferential direction grooves 21. 22 extending endlessly along the tire circumferential direction C, and a center land portion 31 that has a rib shape, is defined between the two tire circumferential direction grooves 21, 22, and intersects the tire equatorial plane CL.

[0017] As illustrated in FIG. 2, the tire 1 of the present embodiment further includes, on the tread surface T, shoulder land portions 32 that are respectively defined between the tire circumferential direction groove 21 and a tread edge on one side in the tire width direction B, and between the tire circumferential direction groove 22 and a tread edge on the other side in the tire width direction B. That is, the tread surface T of the present embodiment comprises the two tire circumferential direction grooves 21, 22, the center land portion 31. and the two shoulder land portions 32. However, the tread surface T of the tire 1 is not particularly limited in configuration as long as the tread surface T comprises the two tire circumferential direction grooves 21, 22 described above and the center land portion 31 described above. Accordingly, the tire 1 may be further configured so that the tread surface T includes, for example, other tire circumferential direction grooves having a similar groove width to the two tire circumferential direction grooves 21, 22. disposed outside each of the two tire circumferential direction grooves 21, 22 in the tire width direction B. "Outside in the tire width direction" means a side in the tire width direction B that is away from the tire equatorial plane CL.

[0018] FIG. 3 is a cross-section diagram of the tread surface T at the position of line I-I in FIG. 2. As illustrated in FIG. 2 and FIG. 3, the center land portion 31 includes a circumferential direction sipe 41, a first connecting sipe 42, and a second connecting sipe 43. The term "sipe" means a narrow groove narrower than the tire circumferential direction groove. A maximum groove width W1 at any position in the extension direction of each of the tire circumferential direction grooves 21. 22 is. for example. 8 mm or more. By setting the maximum groove width W1 of each of the tire circumferential direction grooves 21. 22 to 8 mm or more, the drainage performance of the tread surface T can be improved. In contrast, a maximum sipe width W2. which is the maximum groove width at any position in the extension direction of the PO245278-PCT-ZZ (4 / 24)circumferential direction sipe 41. a maximum sipe width W3. which is the maximum groove width at any position in the extension direction of the first connecting sipe 42. and a maximum sipe width W4. which is the maximum groove width at any position in the extension direction of the second connecting sipe 43. are all. for example. 2 mm or less. The circumferential direction sipe 41. the first connecting sipe 42, and the second connecting sipe 43 are provided in the center land portion 31 to enhance the drainage performance of the tread surface T. By setting the maximum sipe widths W2 to W4 to 2 mm or less, deformation of the center land portion 31 during road surface contact can be suppressed by having the sipe walls on both sides, which are the groove walls of the circumferential direction sipe 41, the first connecting sipe 42, and the second connecting sipe 43, respectively, contact and support each other. This can suppress an increase in rolling resistance of the tire 1 .

[0019] The circumferential direction sipe 41 extends along the tire circumferential direction C so as to intersect the tire equatorial plane CL. As described in detail later, and as illustrated in FIG. 2, the circumferential direction sipe 41 of the present embodiment extends in a zigzag shape along the tire circumferential direction C. As mentioned above, the circumferential direction sipe 41 is narrower than each of the two tire circumferential direction grooves 21. 22. More specifically, as illustrated in FIG. 2 and FIG. 3, the maximum sipe width W2 of the circumferential direction sipe 41 is smaller than the maximum groove width W1 of each of the tire circumferential direction grooves 21 , 22.

[0020] The first connecting sipe 42 connects the circumferential direction sipe 41 to one of the two tire circumferential grooves 21 , 22, the tire circumferential direction groove 21. As described in detail later, as illustrated in FIG. 2, the first connecting sipe 42 of the present embodiment is a single line. That is, the first connecting sipe 42 of the present embodiment does not have a branched portion branching into a plurality of branches. One end of the single line of the first connecting sipe 42 is connected to the circumferential direction sipe 41. The other end of the single line of the first connecting sipe 42 is connected to the tire circumferential direction groove 21. As mentioned above, the first connecting sipe 42 is narrower than each of the two tire circumferential direction grooves 21. 22. More specifically, as illustrated in FIG. 2 and FIG. 3. the maximum sipe width W3 of the first connecting sipe 42 is smaller than the PO245278-PCT-ZZ (5 / 24)maximum groove width W1 of each of the tire circumferential direction grooves 21 , 22. The maximum sipe width W2 of the circumferential direction sipe 41 of the present embodiment is approximately equal to the maximum sipe width W3 of the first connecting sipe 42. but is not limited to this configuration The maximum sipe width W2 of the circumferential direction sipe 41 and the maximum sipe width W3 of the first connecting sipe 42 may be different.

[0021] The second connecting sipe 43 connects the circumferential direction sipe 41 to the tire circumferential direction groove 21. As mentioned above, the second connecting sipe 43 is narrower than each of the two tire circumferential direction grooves 21, 22. More specifically, as illustrated in FIG. 2 and FIG. 3, the maximum sipe width W4 of the second connecting sipe 43 is smaller than the maximum groove width W1 of each of the tire circumferential direction grooves 21, 22.

[0022] As illustrated in FIG. 3, the second connecting sipe 43 is shallower than each of the circumferential direction sipe 41 and the first connecting sipe 42. More specifically, a sipe depth H4, which is the groove depth at any position in the extension direction of the second connecting sipe 43, is shallower than a sipe depth H2, which is the groove depth at any position in the extension direction of the circumferential direction sipe 41, and shallower than a sipe depth H3, which is the groove depth at any position in the extension direction of the first connecting sipe 42. Here, "groove depth" means the maximum depth in the tire radial direction A of the groove. The sipe depth H2 of the circumferential direction sipe 41 and the sipe depth H3 of the first connecting sipe 42 may each be 10 mm or more, for example. In contrast, the sipe depth H4 of the second connecting sipe 43 may be 5 mm or less, for example.

[0023] As illustrated in FIG. 3, according to the present embodiment, the sipe depths H2 to H4 described above and a groove depth Hl at any position in the extension direction of the tire circumferential direction grooves 21. 22 satisfy the relationships Hl > H2 > H4 and Hl > H3 > H4. According to the present embodiment, the sipe depth H3 of the first connecting sipe 42 is shallower than the sipe depth H2 of the circumferential direction sipe 41. but is not limited to this configuration. The sipe depth H3 of the first connecting sipe 42 may be equal to the sipe depth H2 of the circumferential direction sipe 41 . for example. Further, according to the present embodiment, the sipe depth H2 of circumferential direction sipe 41 is approximately equal to the groove depth PO245278-PCT-ZZ (6 / 24)Hl of the tire circumferential direction grooves 21, 22, but is not limited to this configuration. The sipe depth H2 of circumferential direction sipe 41 may be shallower than the groove depth Hl of the tire circumferential direction grooves 21 , 22.

[0024] As illustrated in FIG. 2, the second connecting sipe 43 includes a first portion 43a and a second portion 43b.

[0025] The first portion 43a is connected to the circumferential direction sipe 41 at ends 80a, 80b at different positions along the tire circumferential direction C. As illustrated in FIG. 2, the first portion 43a defines a blockshaped portion 50 between the first portion 43a and the circumferential direction sipe 41 . The first portion 43a is a single line. That is, the first portion 43a of the present embodiment does not have a branched portion branching into a plurality of branches. As described in detail below, the first portion 43a of the present embodiment includes a bent portion 62. The block-shaped portion 50 of the present embodiment has a parallelogram-shaped outline in the developed view of the tread surface T illustrated in FIG. 2 (hereinafter also referred to as the "tread developed view" ). More specifically, the block-shaped portion 50 of the present embodiment has a rhombic outline. However, the configuration of the first portion 43a is not particularly limited, as long as both the ends 80a. 80b are connected to the circumferential direction sipe 41 at different positions in the tire circumferential direction C and the first portion 43a with the circumferential direction sipe 41 defines the block-shaped portion 50.

[0026] The second portion 43b connects the first portion 43a with the tire circumferential direction groove 21. As described in detail below, the second portion 43b of the present embodiment is a single line. That is, the second portion 43b of the present embodiment does not have a branched portion branching into a plurality of branches. Further, as illustrated in FIG. 2, the second portion 43b of the present embodiment extends in a straight line. Further, as illustrated in FIG. 2. the second portion 43b of the present embodiment extends parallel to the first connecting sipe 42. However, the second portion 43b is not particularly limited in configuration, as long as the second portion 43b connects the first portion 43a to the tire circumferential direction groove 21.

[0027] As illustrated in FIG. 3. a maximum sipe width W4a at any position in the extension direction of the first portion 43a of the present embodiment is PO245278-PCT-ZZ (7 / 24)approximately equal to a maximum sipe width W4b at any position in the extension direction of the second portion 43b, but is not limited to this configuration. The maximum sipe width W4a of the first portion 43a and the maximum sipe width W4b of the second portion 43b may be different. Further, according to the present embodiment, the maximum sipe width W4a of the first portion 43a and the maximum sipe width W4b of the second portion 43b are both narrower than the maximum sipe width W2 of the circumferential direction sipe 41 and narrower than the maximum sipe width W3 of the first connecting sipe 42.

[0028] Further, as illustrated in FIG. 3, a sipe depth H4a at any position in the extension direction of the first portion 43a of the present embodiment is approximately equal to a sipe depth H4b at any position in the extension direction of the second portion 43b, but is not limited to this configuration. The sipe depth H4a of the first portion 43a and the sipe depth H4b of the second portion 43b may be different. However, the sipe depth H4a of the first portion 43a and the sipe depth H4b of the second portion 43b are both shallower than the sipe depth H2 of the circumferential direction sipe 41 and the sipe depth H3 of the first connecting sipe 42.

[0029] Thus, in addition to the circumferential direction sipe 41 and the first connecting sipe 42, the center land portion 31 includes the second connecting sipe 43 that includes the first portion 43a and the second portion 43b. This allows the drainage performance of the tread surface T to be enhanced compared to a configuration with only the circumferential direction sipe 41 and the first connecting sipe 42. Further, the second connecting sipe 43 is shallower than the circumferential direction sipe 41 and the first connecting sipe 42. Therefore, compared to a configuration with a second connecting sipe that is deeper than the circumferential direction sipe 41 and the first connecting sipe 42, for example, an increase in rolling resistance due to the second connecting sipe 43 can be suppressed.

[0030] As described above, in the tire 1. the center land portion 31 that has a rib shape includes the circumferential direction sipe 41. the first connecting sipe 42. and the second connecting sipe 43 to improve drainage performance and to suppress an increase in rolling resistance.

[0031] Further details of the center land portion 31 of the present embodiment are described below with reference to FIG. 2 to FIG. 4. FIG. 4 is a diagram illustrating an enlargement of a portion of FIG. 2.PO245278-PCT-ZZ (8 / 24)

[0032] As illustrated in FIG. 2. the center land portion 31 that has a rib shape of the present embodiment is divided into two rib-shaped portions 31a, 31b in the tire width direction B by the circumferential direction sipe 41 that intersects the tire equatorial plane CL. For convenience of explanation, the ribshaped portion 31a adjacent to the tire circumferential direction groove 21 is hereinafter also referred to as "first rib-shaped portion 31a". Further, the ribshaped portion 31b adjacent to the tire circumferential direction groove 22 is referred to as "second rib-shaped portion 31b".

[0033] The first connecting sipe 42 and the second connecting sipe 43 described above are provided in the first rib-shaped portion 31a and in the second rib-shaped portion 31b. That is, the center land portion 31 of the present embodiment includes both the first connecting sipe 42 and the second connecting sipe 43 that connect the circumferential direction sipe 41 to the tire circumferential direction groove 21 and the first connecting sipe 42 and the second connecting sipe 43 that connect the circumferential direction sipe 41 to the tire circumferential direction groove 22. The first connecting sipe 42 and the second connecting sipe 43 on the first rib-shaped portion 31a and the first connecting sipe 42 and the second connecting sipe 43 on the second rib-shaped portion 31b have line symmetry with respect to a center line where the tire equatorial plane CL intersects on the tread surface T.

[0034] As illustrated in FIG. 4, the center land portion 31 that has a rib shape of the present embodiment comprises a plurality of unit elements arranged over the entire area in the tire circumferential direction C, where each unit element consists of a first block-shaped group 70a having a hexagonal parallelogon shape in the first rib-shaped portion 31a and a second block-shaped group 70b having a hexagonal parallelogon shape in the second rib-shaped portion 31b. The first block-shaped group 70a of the present embodiment is defined by the circumferential direction sipe 41 , two of the second connecting sipes 42 that are adjacent in the tire circumferential direction C in the first rib-shaped portion 31 a. and the tire circumferential direction groove 21 . The second blockshaped group 70b of the present embodiment is defined by the circumferential direction sipe 41. two of the second connecting sipes 42 that are adjacent in the tire circumferential direction C in the second rib-shaped portion 31b. and the tire circumferential direction groove 22.

[0035] Features of the first rib-shaped portion 31a according to the present embodiment are exemplified and described below. The second rib-shaped PO245278-PCT-ZZ (9'24)portion 31b has the same features as the first rib-shaped portion 31a described below. Therefore, description of the features of the second rib-shaped portion 31b is omitted in the present embodiment.

[0036] As illustrated in FIG. 2. the circumferential direction sipe 41 of the present embodiment extends in a zigzag shape along the tire circumferential direction C. More specifically, the circumferential direction sipe 41 of the present embodiment includes a first inclined portion 41a that extends in a straight line in the tread developed view illustrated in FIG. 2 and FIG. 4, and a second inclined portion 41b that extends in a straight line in the tread developed view illustrated in FIG. 2 and FIG. 4. The first inclined portion 41a is inclined to one side with respect to the tire circumferential direction C. The second inclined portion 41b is inclined to the other side with respect to the tire circumferential direction C. Specifically, the first inclined portion 41a of the present embodiment is inclined with respect to the tire circumferential direction C so that, in FIG. 2 and FIG. 4. the first inclined portion 41a extends from an upper left side to a lower right side. In contrast, the second inclined portion 41 b of the present embodiment is inclined with respect to the tire circumferential direction C so that, in FIG. 2 and FIG. 4, the second inclined portion 41b extends from an upper right side to a lower left side. In the circumferential direction sipe 41 of the present embodiment, the first inclined portion 41a and the second inclined portion 41b are continuous in the tire circumferential direction C. More specifically, the circumferential direction sipe 41 of the present embodiment includes a plurality of the first inclined portion 41 a and a plurality of the second inclined portion 41b. The first inclined portions 41a and the second inclined portions 41b are arranged alternately in the tire circumferential direction C. That is, separate instances of the second inclined portion 41b are connected to each side in the tire circumferential direction C of the first inclined portion 41a. Further, separate instances of the first inclined portion 41a are connected to each side in the tire circumferential direction C of the second inclined portion 41b. The first inclined portions 41a and the second inclined portions 41b each extend across the tire equatorial plane CL in the tire width direction B. Further, the circumferential direction sipe 41 of the present embodiment is an endless sipe extending endlessly in the tire circumferential direction C. consisting of a plurality of the first inclined portions 41a and a plurality of the second inclined portions 41b described above.PO245278-PCT-ZZ ( 10 / 24)

[0037] The circumferential direction sipe 41 of the present embodiment extends in a zigzag shape along the tire circumferential direction C. as described above, but is not limited to this configuration. The circumferential direction sipe 41 may. for example, extend in a wavy shape along the tire circumferential direction C. That is. the circumferential direction sipe 41 may include, for example, a plurality of first inclined portions and second inclined portions extending in a curved shape in the tread developed view illustrated in FIG. 2 and FIG. 4. Such circumferential direction sipe 41 may, for example, extend in a sinusoidal pattern along the tire circumferential direction C.

[0038] As illustrated in FIG. 2, the first portion 43a of the second connecting sipe 43 of the present embodiment is a bent sipe portion that defines the block shaped portion 50 having a parallelogram shape between the first portion 43a and the first inclined portion 41a and the second inclined portion 41b of the circumferential direction sipe 41. That is, the first portion 43a of the second connecting sipe 43 of the present embodiment includes a first inclined portion 43al that extends parallel to the first inclined portion 41a of the circumferential direction sipe 41 and a second inclined portion 43a2 that extends parallel to the second inclined portion 41b of the circumferential direction sipe 41. The first inclined portion 43al and the second inclined portion 43a2 are continuous in the tire circumferential direction C. Of both ends of the first inclined portion 43al , an end opposite the end continuous with the second inclined portion 43a2 (the end 80a of the first portion 43a in the present embodiment) connects to the circumferential direction sipe 41. More specifically, the end of the first inclined portion 43al of the present embodiment is connected to the circumferential direction sipe 41 at a connection 61 where the first inclined portion 41a and the second inclined portion 41b of the circumferential direction sipe 41 are connected. Further, of both ends of the second inclined portion 43a2, an end opposite the end continuous with the first inclined portion 43al (the end 80b of the first portion 43a in the present embodiment) connects to the circumferential direction sipe 41 . More specifically, the end of the second inclined portion 43a2 of the present embodiment is connected to the circumferential direction sipe 41 at the connection 61 where the first inclined portion 41a and the second inclined portion 41b of the circumferential direction sipe 41 are connected. The blockshaped portion 50 having a parallelogram shape is defined by the first inclined portion 41 a and the second inclined portion 41 b of the circumferential direction PO245278-PCT-ZZ ( 11 24)sipe 41 and the first inclined portion 43al and the second inclined portion 43a2 of the first portion 43a of the second connecting sipe 43.

[0039] Thus, the block-shaped portion 50 having a parallelogram shape that has no sides parallel to the tire width direction B is defined between the first portion 43a of the second connecting sipe 43 and the first inclined portion 41a and the second inclined portion 41b of the circumferential direction sipe 41, thereby suppressing wear of edge portions at positions of the four sides of the block-shaped portion 50 having a parallelogram shape.

[0040] Further, in the tread developed view illustrated in FIG. 2 and FIG. 4, the acute angle of an inclination angle with respect to the tire circumferential direction C of each of the first inclined portion 41a and the second inclined portion 41 b of the present embodiment is less than 45 degrees. That is, as illustrated in FIG. 4, the acute angle of the inclination angle 01 with respect to the tire circumferential direction C of the first inclined portion 41a of the present embodiment is less than 45 degrees. Further, the acute angle of the inclination angle 02 with respect to the tire circumferential direction C of the second inclined portion 41b of the present embodiment is less than 45 degrees. In this way, the length of the block-shaped portion 50 in the tire circumferential direction C is longer than the length of the block-shaped portion 50 in the tire width direction B, compared to a configuration where the inclination angles 01.02 are each 45 degrees or greater. This can suppress wear (heel-and-toe wear) at the edges of the block-shaped portion 50 having a parallelogram shape on both sides of the tire circumferential direction C.

[0041] Further, as illustrated in FIG. 2 and FIG. 4, the block-shaped portion 50 of the present embodiment is rhombic in shape. In this way, variations in the amount of edge wear can be suppressed at the four edge portions of the block-shaped portion 50 having a rhombic shape. That is, uneven wear occurring locally at a portion of an edge of the block-shaped portion 50 can be suppressed. The block-shaped portion 50 having a rhombic shape of the present embodiment is formed so that the two diagonals are parallel to the tire width direction B and parallel to the tire circumferential direction C.

[0042] As in the present embodiment, the inclination angle 01 of the first inclined portion 41a and the inclination angle 02 of the second inclined portion 41b are preferably approximately equal. In this way. variation in the amount of edge wear at the four edge portions of the block-shaped portion 50 having a rhombic shape can be better suppressed.PO245278-PCT-ZZ (12 / 24)

[0043] As illustrated in FIG. 2. the connection where the first connecting sipe 42 is connected to the circumferential direction sipe 41 of the present embodiment is the connection 61 where the first inclined portion 41a and the second inclined portion 41b of the circumferential direction sipe 41 are connected. That is. the first connecting sipe 42 of the present embodiment and the first portion 43a of the second connecting sipe 43 are connected to the circumferential direction sipe 41 at the position of the connection 61 of the circumferential direction sipe 41. In other words, the first portion 43a of the second connecting sipe 43 of the present embodiment is connected to the circumferential direction sipe 41 at a position of the connection where the first connecting sipe 42 is connected to the circumferential direction sipe 41 (the connection 61 in the present embodiment).

[0044] Further, as illustrated in FIG. 2 and FIG. 4, the second portion 43b of the second connecting sipe 43 of the present embodiment is connected to the first portion 43a of the second connecting sipe 43 at the bent portion 62 where the first portion 43a of the second connecting sipe 43 bends. As mentioned above, the first portion 43a of the present embodiment includes the first inclined portion 43al and the second inclined portion 43a2. The bent portion 62 of the present embodiment is formed at the connection where the first inclined portion 43al and the second inclined portion 43a2 are connected.

[0045] The first connecting sipe 42 of the present embodiment and the second portion 43b of the second connecting sipe 43 are each a single line, as described above. More specifically, the first connecting sipe 42 of the present embodiment and the second portion 43b of the second connecting sipe 43 each extends in a straight line in the tread developed view illustrated in FIG. 2 and FIG. 4. The single line of the first connecting sipe 42 connects the circumferential direction sipe 41 to the tire circumferential direction groove 21. Further, the single line of the second portion 43b of the second connecting sipe 43 connects the first portion 43a of the second connecting sipe 43 to the tire circumferential direction groove 21.

[0046] As illustrated in FIG. 2. the first rib-shaped portion 31a of the center land portion 31 of the present embodiment includes a plurality of the first connecting sipe 42 disposed at different positions in the tire circumferential direction C. Further, the first rib-shaped portion 31a of the center land portion 31 of the present embodiment includes a plurality of the second connecting sipe 43 disposed at different positions in the tire circumferential direction C.PO245278-PCT-ZZ ( 13 / 24)As illustrated in FIG. 2. the first connecting sipes 42 and the second connecting sipes 43 are arranged alternately in the tire circumferential direction C. As illustrated in FIG. 2. the first rib-shaped portion 31 a of the center land portion 31 includes a block-shaped portion 51 that is defined between the first connecting sipe 42. the first inclined portion 43al of the first portion 43a of the second connecting sipe 43, the second portion 43b of the second connecting sipe 43, and the tire circumferential direction groove 21. Further, the first ribshaped portion 31a of the center land portion 31 includes a block-shaped portion 52 that is defined between the first connecting sipe 42. the second inclined portion 43a2 of the first portion 43a of the second connecting sipe 43, the second portion 43b of the second connecting sipe 43, and the tire circumferential direction groove 21. Hereafter, for convenience of explanation, the block-shaped portions 50 to 52 are distinguished and described as "first block-shaped portion 50", "second block-shaped portion 51", and "third blockshaped portion 52".

[0047] As illustrated in FIG. 2, the first rib-shaped portion 31a of the center land portion 31 of the present embodiment includes a plurality of the first block-shaped portion 50. Further, the first rib-shaped portion 31a of the center land portion 31 of the present embodiment includes a plurality of the second block-shaped portion 51 and a plurality of the third block-shaped portion 52. As illustrated in FIG. 2, in the first rib-shaped portion 31 a of the center land portion 31 , the second block-shaped portions 51 and the third block-shaped portions 52 are arranged alternately in the tire circumferential direction C.

[0048] As illustrated in FIG. 2, in the present embodiment, a difference in inclination angles with respect to the tire circumferential direction C of the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 is less than 10 degrees. More specifically, the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 of the present embodiment extend parallel to each other. That is. according to the present embodiment, the difference in inclination angles with respect to the tire circumferential direction C of the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 is zero. Thus, by making the difference in the inclination angles with respect to the tire circumferential direction C of the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 less than 10 degrees, shape uniformity of the second block-shaped portion 51 and the third block-shaped portion 52 can be improved.PO245278-PCT-ZZ (14 / 24)This allows for suppression of rigidity variation in the tire circumferential direction C.

[0049] Further, in the present embodiment, the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 each extend at an incline with respect to the tire width direction B. In this way. wear of edges on both sides of the tire circumferential direction C of the second block-shaped portion 51 and the third block-shaped portion 52 can be suppressed compared to a configuration in which the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 each extend parallel to the tire width direction B. Further, pattern noise can be suppressed at the position of the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43.

[0050] Further, according to the present embodiment, the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 each extend at an incline with respect to the tire circumferential direction C. The acute angle of the inclination angle with respect to the tire circumferential direction C of each of the first connecting sipe 42 and the second portion 43b of the second connecting sipe 43 is greater than the inclination angles 91, 02 of the circumferential direction sipe 41 described above. That is, as illustrated in FIG.4, the acute angle of the inclination angle 03 with respect to the tire circumferential direction C of the first connecting sipe 42 of the present embodiment is greater than the inclination angles 01 , 02 of the circumferential direction sipe 41 described above. Further, the acute angle of the inclination angle 04 with respect to the tire circumferential direction C of the second portion 43b of the second connecting sipe 43 is greater than the inclination angles 01 , 02 of the circumferential direction sipe 41 described above. More specifically, the inclination angles 03, 04 of the present embodiment are each greater than 45 degrees.

[0051] As illustrated in FIG. 2 and FIG. 4. the two tire circumferential grooves 21. 22 of the present embodiment each extend in a zigzag shape along the tire circumferential direction C. Further, the two tire circumferential direction grooves 21. 22 of the present embodiment each extend in a zigzag shape so that the second block-shaped portion 51 and the third block-shaped portion 52 are each parallelogram-shaped in the tread developed view illustrated in FIG. 2 and FIG. 4.

[0052] Specifically, the tire circumferential direction groove 21 of the present PO245278-PCT-ZZ ( 15 / 24)embodiment includes a first inclined portion 21a that extends in a straight line in the tread developed view illustrated in FIG. 2 and FIG. 4. and a second inclined portion 21b that extends in a straight line in the tread developed view illustrated in FIG. 2. The first inclined portion 21a is inclined to one side with respect to the tire circumferential direction C. The second inclined portion 21b is inclined to the other side with respect to the tire circumferential direction C. Specifically, the first inclined portion 21a of the present embodiment is inclined with respect to the tire circumferential direction C so that, in FIG. 2 and FIG. 4, the first inclined portion 21a extends from the upper left side to the lower right side. In contrast, the second inclined portion 21b of the present embodiment is inclined with respect to the tire circumferential direction C so that, in FIG. 2 and FIG. 4, the second inclined portion 21b extends from the upper right side to the lower left side. In the tire circumferential direction groove 21 of the present embodiment, the first inclined portion 21a and the second inclined portion 21b are continuous in the tire circumferential direction C. More specifically, the tire circumferential direction groove 21 of the present embodiment includes a plurality of the first inclined portion 21a and a plurality of the second inclined portion 21b. Further, the first inclined portions 21a and the second inclined portions 21b are arranged alternately in the tire circumferential direction C. That is, separate instances of the second inclined portion 21b are connected to each side in the tire circumferential direction C of the first inclined portion 21a. Further, separate instances of the first inclined portion 21a are connected to each side in the tire circumferential direction C of the second inclined portion 21b. The first inclined portion 21a extends parallel to the first inclined portion 41a of the circumferential direction sipe 41. Further, the second inclined portion 21b extends parallel to the second inclined portion 41b of the circumferential direction sipe 41.

[0053] As illustrated in FIG. 2 and FIG. 4, the second block-shaped portion 51 having a parallelogram shape is defined between the first connecting sipe 42. the first inclined portion 43al of the first portion 43a of the second connecting sipe 43. the second portion 43b of the second connecting sipe 43. and the first inclined portion 21a of the tire circumferential direction groove 21. Further, the third block-shaped portion 52 having a parallelogram shape is defined between the first connecting sipe 42. the second inclined portion 43a2 of the first portion 43a of the second connecting sipe 43. the second portion 43b of the second connecting sipe 43. and the second inclined portion 21b of the tire PO245278-PCT-ZZ ( 16 / 24)circumferential direction groove 21.

[0054] Thus, shape uniformity of the second block-shaped portion 51 and the third block-shaped portion 52 can be further enhanced by the second blockshaped portion 51 and the third block-shaped portion 52 both being parallelogram-shaped in the tread developed view illustrated in FIG. 2 and FIG.4.

[0055] Further, as illustrated in FIG. 4, in the first rib-shaped portion 31a of the center land portion 31, the first block-shaped group 70a, comprising one of the first block-shaped portions 50 and, adjacent to the one of the first blockshaped portions 50, one of the second block-shaped portions 51 and one of the third block-shaped portions 52, has a hexagonal parallelogon shape. The first block-shaped group 70a of the present embodiment is defined by the first inclined portion 41a and the second inclined portion 41b of the circumferential direction sipe 41, two of the second connecting sipes 42 that are adjacent in the tire circumferential direction C, and the first inclined portion 21a and the second inclined portion 21b of the tire circumferential direction groove 21.

[0056] Thus, the tire circumferential direction groove 21 of the present embodiment extends in a zigzag shape along the tire circumferential direction C so that the first block-shaped group 70a has a hexagonal parallelogon shape. More specifically, according to the present embodiment, the tire circumferential direction groove 21 and the circumferential direction sipe 41 are arranged with phases shifted in the tire circumferential direction C so that the first block-shaped group 70a has a hexagonal parallelogon shape. In this way, rigidity of the first block-shaped group 70a against external force input from various directions can be increased compared to a configuration in which the tire circumferential direction groove 21 extends parallel to the tire circumferential direction C, and shape stability of the first block-shaped group 70a can be improved.

[0057] Further, as illustrated in FIG. 2. in the first rib-shaped portion 31a of the center land portion 31 of the present embodiment, the first block-shaped groups 70a each having a hexagonal parallelogon shape are arranged along the tire circumferential direction C. Accordingly, variation in rigidity depending on position along the tire circumferential direction C of the center land portion 31 can be suppressed, and uneven wear can be suppressed.

[0058] As mentioned above, the second block-shaped group 70b of the second rib-shaped portion 31b (see FIG. 4) also has the same characteristics as the PO245278-PCT-ZZ ( 17 / 24)first block-shaped group 70a of the first rib-shaped portion 31 a described above. Therefore, variation in rigidity depending on position along the tire circumferential direction C of the center land portion 31 can be further suppressed. Further, variation in rigidity depending on position along the tire width direction B of the center land portion 31 can also be suppressed. This allows for further suppression of uneven wear on the center land portion 31.

[0059] The tire according to the present disclosure is not limited to the specific configurations illustrated by the embodiments described above, and various variations, changes, and combinations are possible as long as they do not depart from the scope of the claims.

[0060] In the tire 1 of the embodiment described above, all of the first inclined portions 41 a of the circumferential direction sipe 41 are used to define the first block-shaped portions 50 of the first rib-shaped portion 31 a and the first blockshaped portions 50 of the second rib-shaped portion 31b, but this configuration is not limiting. Further, in the tire 1 of the embodiment described above, all of the second inclined portions 41b of the circumferential direction sipe 41 are used to define the first block-shaped portions 50 of the first rib-shaped portion 31a and the first block-shaped portions 50 of the second rib-shaped portion 31b, but this configuration is not limiting. That is, in the tire 1 of the embodiment described above, the second connecting sipe 43 is provided between any two adjacent instances of the first connecting sipe 42 in the tire circumferential direction C in the first rib-shaped portion 1a of the center land portion 31. but this configuration is not limiting. The first rib-shaped portion 31a may be configured to include two adjacent instances of the first connecting sipe 42 in the tire circumferential direction C without the second connecting sipe 43 therebetween. The same is true for the second rib-shaped portion 31b of the center land portion 31. In the tire 1 of the embodiment described above, the second connecting sipe 43 is provided between any two adjacent instances of the first connecting sipe 42 in the tire circumferential direction C in the second rib-shaped portion 31b of the center land portion 31. but this configuration is not limiting. The second rib-shaped portion 31b may be configured to include two adjacent instances of the first connecting sipe 42 in the tire circumferential direction C without the second connecting sipe 43 therebetween. However, from the viewpoint of suppressing variation in rigidity of the center land portion 31 in the tire width direction B and the tire circumferential direction C. in the first rib-shaped portion 31a and the second rib-shaped portion 31b of PO245278-PCT-ZZ ( I 8 / 24)the center land portion 31. the second connecting sipe 43 is preferably provided between any two adjacent instances of the first connecting sipe 42 in the tire circumferential direction C. as in the present embodiment.REFERENCE SIGNS LIST

[0061] 1 : tire11 : bead portion12: sidewall portion13: tread portion21 , 22: tire circumferential direction groove21a: first inclined portion of tire circumferential direction groove 21b: second inclined portion of tire circumferential direction groove 31 : center land portion31a: first rib-shaped portion31b: second rib-shaped portion32: shoulder land portion41 : circumferential direction sipe41a: first inclined portion of circumferential direction sipe 41b: second inclined portion of circumferential direction sipe 42: first connecting sipe43: second connecting sipe43a: first portion of second connecting sipe43al : first inclined portion of first portion of second connecting sipe 43a2: second inclined portion of first portion of second connecting sipe43b: second portion of second connecting sipe50: first block-shaped portion51 : second block-shaped portion52: third block-shaped portion61 : connection62: bent portion70a: first block-shaped group of first rib-shaped portion70b: second block-shaped group of second rib-shaped portion 80a. 80b: end of first portion of second connecting sipeA: tire radial directionB: tire width directionPO245278-PCT-ZZ ( 19 / 24)C: tire circumferential directionT: tread surfaceCL: tire equatorial planeHl : groove depth of tire circumferential direction grooveH2: sipe depth of circumferential direction sipeH3: sipe depth of first connecting sipeH4: sipe depth of second connecting sipeH4a: sipe depth of first portion of second connecting sipe H4b: sipe depth of second portion of second connecting sipe W1 : maximum groove width of tire circumferential direction groove W2: maximum sipe width of circumferential direction sipe W3: maximum sipe width of first connecting sipeW4: maximum sipe width of second connecting sipeW4a: maximum sipe width of first portion of second connecting sipe W4b: maximum sipe width of second portion of second connecting sipe91 : inclination angle of first inclined portion of circumferential direction sipe02: inclination angle of second inclined portion of circumferential direction sipe03: inclination angle of first connecting sipe04: inclination angle of second portion of second connecting sipePO245278-PCT-ZZ (20 / 24)

Claims

CLAIMS

1. A tire comprising:on a tread surface that comes into contact with a road surface, a center land portion that has a rib shape, is defined between two tire circumferential direction grooves that extend endlessly along the tire circumferential direction, and intersects with the tire equatorial plane, whereinthe center land portion comprises:a circumferential direction sipe that extends along the tire circumferential direction, intersects with the tire equatorial plane, and is narrower than each of the two tire circumferential direction grooves;a first connecting sipe that connects the circumferential direction sipe to one of the two tire circumferential direction grooves and is narrower than each of the two tire circumferential direction grooves; anda second connecting sipe that connects the circumferential direction sipe to the one of the tire circumferential direction grooves, is narrower than each of the two tire circumferential direction grooves, and is shallower than each of the circumferential direction sipe and the first connecting sipe, wherein the second connecting sipe comprises:a first portion, both ends of which connect to the circumferential direction sipe at different positions in the tire circumferential direction, and which defines a block-shaped portion between the first portion and the circumferential direction sipe; anda second portion that connects the first portion to the one of the tire circumferential direction grooves.

2. The tire according to claim 1, wherein the circumferential direction sipe extends in a wavy shape or a zigzag shape along the tire circumferential direction.

3. The tire according to claim 2. whereinthe circumferential direction sipe has a zigzag shape, andin the circumferential direction sipe. a first inclined portion extending in a straight line and inclined to one side with respect to the tire circumferential direction and a second inclined portion extending in a straight line and inclined to the other side with respect to the tire circumferential direction are PO245278-PCT-ZZ (21 / 24)continuous in the tire circumferential direction.

4. The tire according to claim 3. wherein the first portion of the second connecting sipe is a bent sipe portion that defines the block-shaped portion as having a parallelogram shape between the first portion of the second connecting sipe and the first inclined portion and the second inclined portion of the circumferential direction sipe.

5. The tire according to claim 4, wherein an acute angle of an inclination angle with respect to the tire circumferential direction of each of the first inclined portion and the second inclined portion of the circumferential direction sipe is less than 45 degrees.

6. The tire according to claim 5, wherein the block-shaped portion has a rhombic shape.

7. The tire according to any one of claims 4 to 6, wherein the second portion of the second connecting sipe is connected to the first portion of the second connecting sipe at a bent portion where the first portion of the second connecting sipe bends.

8. The tire according to any one of claims 1 to 7, wherein the first portion of the second connecting sipe is connected to the circumferential direction sipe at a position of a connection where the first connecting sipe is connected.

9. The tire according to any one of claims 1 to 8, wherein the first connecting sipe and the second portion of the second connecting sipe are each a single line.

10. The tire according to claim 9. wherein the first connecting sipe and the second portion of the second connecting sipe each extend in a straight line.

11. The tire according to claim 10. wherein a difference in inclination angles with respect to the tire circumferential direction of the first PO245278-PCT-ZZ (22 / 24)connecting sipe and the second portion of the second connecting sipe is less than 10 degrees.

12. The tire according to any one of claims 1 to 11 , wherein the first connecting sipe and the second portion of the second connecting sipe each extend at an inclined angle with respect to the tire circumferential direction.

13. The tire according to any one of claims 1 to 12, wherein the one tire circumferential direction groove extends in a zigzag shape along the tire circumferential direction.PO245278-PCT-ZZ (23 / 24)

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