Pneumatic tire

Abstract

To provide a pneumatic tire that can achieve improvement in traction performance in a tire circumferential direction between two shoulder main grooves of a tread and suppression of deterioration in rigidity of a land.SOLUTION: A pneumatic tire 1 includes a tread which has at least two inner blocks 70 arranged side by side in a tire circumferential direction between two shoulder main grooves extending in a tire circumferential direction, and a connection rib 72 connecting the two inner blocks to each other and extending in the tire circumferential direction. The connection rib includes, at both ends in the tire circumferential direction, two rib ends 153 and 154 intruding into the insides of the inner blocks from side surfaces in the tire circumferential direction of the two inner blocks. A sipe 91 is provided, between each of the two rib ends and each of the two inner blocks, to surround each of the two rib ends. The sipe has a linear part formed along a tire axial direction or a direction inclined with respect to the tire axial direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a tread including at least two inner blocks aligned in the tire circumferential direction between two shoulder main grooves. [Background technology]

[0002] Patent Document 1 describes a pneumatic tire having a plurality of lands defined by a plurality of circumferential main grooves and extending in the tire circumferential direction. In this configuration, the lands include lands with open-ended grooves, which are grooves that open at one end to the circumferential main groove and terminate at the other end within the land, and lands with open-ended grooves and open-ended grooves, both of which open at both ends to the circumferential main grooves on both sides. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-107798 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, the rigidity of the tire can be ensured by the grooves having only one-end open grooves, and the one-end open grooves may also ensure drainage. However, this groove does not have multiple blocks with edges that are likely to come into contact with the road surface at the tire circumferential ends near both axial ends of the tire, so the edge effect is low and there is room for improvement in terms of improving traction performance in the tire circumferential direction.

[0005] On the other hand, when a land is formed with open-ended grooves, the rigidity of the land divided in the tire circumferential direction by the open-ended grooves is reduced, similar to a configuration with multiple blocks spaced apart in the tire circumferential direction. This makes the divided land more susceptible to partial premature wear. In addition, in this configuration, it is also possible to connect two circumferentially adjacent blocks with a connecting portion whose axial width is smaller than that of the block. However, in this configuration, the edge component is reduced by the width of the connecting portion, leaving room for improvement in terms of improving tire circumferential traction performance.

[0006] In particular, with the recent trend toward the widespread use of electric vehicles, tires are increasingly required to have traction performance that can withstand high loads and high torque. In this case, insufficient rigidity in the land area of ​​the tire tread can easily lead to premature wear, and insufficient edge components can easily lead to reduced edge effect. In such circumstances, it is important to improve the rigidity of the land area and the traction performance in the tire circumferential direction.

[0007] An object of the present invention is to provide a pneumatic tire that can improve the traction performance in the tire circumferential direction between two shoulder main grooves of the tread and suppress a decrease in rigidity on land. [Means for solving the problem]

[0008] The pneumatic tire of the present invention is a pneumatic tire having a tread including two shoulder main grooves extending circumferentially on both axial sides of the tire, at least two inner blocks lined up circumferentially between the two shoulder main grooves, and a connecting rib connecting the two inner blocks and extending circumferentially, wherein the connecting rib includes two rib ends at both circumferential ends of the tire that extend from the circumferential side surfaces of the two inner blocks into the inner blocks, and sipes are provided between each of the two rib ends and each of the two inner blocks so as to surround each of the two rib ends, and the sipes have straight portions that extend in the axial direction of the tire or in a direction inclined relative to the axial direction of the tire. [Effects of the Invention]

[0009] The pneumatic tire according to the present invention can suppress a decrease in rigidity of the land area and can easily provide edges at the circumferential ends of each inner block that easily grip the road surface. This increases the edge effect and improves traction performance in the circumferential direction of the tire. Furthermore, the sipes surrounding the rib ends can further increase the edge effect in the circumferential direction of the tire, thereby further improving traction performance in the circumferential direction of the tire. This improves traction performance in the circumferential direction of the tire between the two shoulder main grooves of the tread and suppresses a decrease in rigidity of the land area. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a portion in the tire circumferential direction of a pneumatic tire that is an example of an embodiment. [Figure 2] FIG. 2 is a plan view of the pneumatic tire shown in FIG. 1, showing a part of the tread in the circumferential direction. [Figure 3] FIG. 3 is an enlarged perspective view of part A in FIG. 2. [Figure 4] FIG. 3 is an enlarged view of part B in FIG. 2. [Figure 5] 5 is a cross-sectional view taken along CC in FIG. 4. [Figure 6] FIG. 5 is a cross-sectional view taken along the line DD in FIG. 4. [Figure 7] FIG. 5 is a view corresponding to FIG. 4 in a first example of another embodiment. [Figure 8] FIG. 5 is a view corresponding to FIG. 4 in a second example of another embodiment. [Figure 9] FIG. 5 is a diagram corresponding to FIG. 4 in a first example of a comparative example. [Figure 10] FIG. 5 is a diagram corresponding to FIG. 4 in a second example of the comparative example. [Figure 11] FIG. 10 is a perspective view of a portion in the tire circumferential direction of a pneumatic tire according to a third example of another embodiment. [Figure 12] FIG. 12 is a plan view of the pneumatic tire shown in FIG. 11, showing a part of the tread in the circumferential direction. [Figure 13]13 is a cross-sectional view of FIG. 12 taken along the line N-N. [Figure 14] 13 is a cross-sectional view of FIG. 12 taken along a plane P-P line. [Figure 15] FIG. 10 is a schematic diagram showing some blocks of the first inner land and the second inner land in a tire according to a fourth example of another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an example of an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment. Furthermore, the present invention includes selective combinations of the components of the multiple embodiments and modified examples described below.

[0012] [Overall tire configuration] FIG. 1 is a perspective view of a portion of a pneumatic tire 1 in the circumferential direction of the tire, which is an example of an embodiment. FIG. 2 is a plan view of the pneumatic tire 1 shown in FIG. 1, showing a portion of a tread 10 in the circumferential direction. FIG. 3 is an enlarged perspective view of portion A in FIG. 2. As shown in FIGS. 1 to 3, the pneumatic tire 1 has a tread 10, which is the portion that comes into contact with the road surface. Hereinafter, the "pneumatic tire 1" will be referred to as the "tire 1." The tread 10 has a tread pattern including a plurality of lands spaced apart in the tire axial direction and a plurality of grooves spaced apart in the tire axial direction, and is formed in an annular shape along the tire circumferential direction (the up-and-down direction in FIGS. 1 and 2). In FIGS. 1 to 3, the tire circumferential direction is indicated by arrow X, the tire axial direction is indicated by arrow Y, and the tire radial direction is indicated by Z.

[0013] In the embodiment, for ease of understanding, in Fig. 1, the IN side and the OUT side are specified as an example of a case where the tire 1 is mounted on a vehicle so that the left side is the outer side (OUT side) in the width direction of the vehicle and the right side is the inner side (IN side) in the width direction of the vehicle. However, in reality, the mounting direction of the front and back of the tire 1 on the vehicle is not specified.

[0014] The tread 10 has multiple main grooves 20, 21, 22 arranged axially around the entire tire. The multiple main grooves 20, 21, 22 include two shoulder main grooves 20, 21 arranged closest to the axially opposite ground-contact edges of the tire, and one center main groove 22 arranged axially between the two shoulder main grooves 20, 21. The tread 10 has four lands 41, 42, 43, 44 separated by the three main grooves 20, 21, 22. The two shoulder main grooves 20, 21 extend annularly in the tire circumferential direction while bending slightly axially on both axial sides. The center main groove 22 extends annularly in the tire circumferential direction while bending in a zigzag pattern. The center main groove 22 corresponds to an intermediate main groove.

[0015] The four lands 41, 42, 43, and 44 are protrusions that protrude radially outward from the reference plane of the tread 10. The "reference plane" is an imaginary plane that follows the bottom surfaces of the deepest main grooves 20, 21, and 22, and refers to the outer peripheral surface of the tread 10 when the lands 41, 42, 43, and 44 do not exist. The shoulder main grooves 20 and 21 and the center main groove 22 have approximately the same maximum radial depth.

[0016] The four lands 41, 42, 43, and 44 include a shoulder land 41 located axially outward of the outboard shoulder main groove 20, a first inner land 42 located between the shoulder main groove 20 and the center main groove 22, a second inner land 43 located between the center main groove 22 and the inboard shoulder main groove 21, and a shoulder land 44 located axially outward of the shoulder main groove 21. Thus, the tread 10 has two shoulder lands 41 and 44 located at both axial ends of the tire, and two inner lands 42 and 43 located between the two shoulder lands 41 and 44 and axially adjacent to each other with the center main groove 22 interposed therebetween. Each inner land 42 and 43 is located between the two shoulder lands 41 and 44, with a pair of shoulder main grooves 20 and 21 interposed between them. The center main groove 22 and each inner land 42 and 43 are located axially across the tire equator, i.e., the axial center CL (FIG. 2). Each of the inner lands 42 and 43 corresponds to an inner block group.

[0017] Each shoulder land 41, 44 is divided by lug grooves 50, 51 extending axially at multiple positions around the tire and includes multiple shoulder blocks 60, 61, 62, 63 arranged in the tire circumferential direction. Each shoulder block 60, 61, 62, 63 is located at a position that includes the ground contact edges T1, T2. Each inner land 42, 43 has multiple inner blocks 70, 71 connected in the tire circumferential direction by multiple connecting ribs 72, 73 extending in the tire circumferential direction, forming a connecting rib shape that continues around the entire tire circumferential direction. As a result, in each inner land 42, 43, two circumferentially adjacent inner blocks 70, 71 are connected by the connecting ribs 72, 73 extending in the tire circumferential direction.

[0018] The tire 1 includes a sidewall 12 that is provided axially outward of the tread 10 and bulges outward most axially, and a bead 14 that is fixed to the rim of a wheel. The sidewall 12 and the bead 14 are formed in an annular shape along the circumferential direction of the tire and form a tire side surface 13. The sidewall 12 extends radially inward from both axial ends of the tread 10.

[0019] The tire 1 is a pneumatic tire that is filled with air at a predetermined pressure. The tread 10 and the sidewall 12 are made of, for example, different types of rubber.

[0020] The shoulder lands 41, 44 disposed at both axial ends of the tread 10 include contact edges T1, T2 which are the axially outer ends of the contact surface.

[0021] The axial end of each shoulder land 41, 44 extends axially outward from the ground contact edges T1, T2 and curves gently radially inward so that the outer peripheral surface is convex outward. The portions of each shoulder land 41, 44 extending axially outward from the ground contact edges T1, T2 are called buttresses.

[0022] "Touching edges T1, T2" refer to both axial ends of the area of ​​the tire that comes into contact with a flat road surface when an unused tire 1 is mounted on a standard rim, inflated to the standard internal pressure, and subjected to a load of 70% of the standard load at the standard internal pressure.

[0023] Here, a "regular rim" is a rim specified by the tire standard, and is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO. "Regular internal pressure" is the "maximum air pressure" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "INFLATION PRESSURE" for ETRTO. "Regular load" is the "maximum load capacity" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "LOAD CAPACITY" for ETRTO.

[0024] A shoulder shallow groove 106 is provided at both circumferential ends of the contact surface of each shoulder land 41, 44 on the shoulder main groove 20, 21 side. The shoulder shallow groove 106 is provided in a substantially U-shape along the periphery of the contact surface of each shoulder block 60, 61, 62, 63 on the shoulder main groove 20, 21 side. Two shallow grooves 109 are formed side by side in the tire circumferential direction in the axial middle of the contact surface of each shoulder block 60, 61, 62, 63. The two shallow grooves 109 are aligned substantially axially.

[0025] The tire 1 includes a carcass, a belt, and an inner liner. The carcass is a cord layer coated with rubber and forms the framework of the tire 1, which can withstand loads, impacts, air pressure, etc. The belt is a reinforcing band placed between the carcass and the rubber that makes up the tread 10. The belt tightly fastens the carcass, increasing the rigidity of the tire 1. The inner liner is a rubber layer provided on the inner surface of the carcass, and maintains the air pressure of the tire 1. The bead 14 includes a bead core and a bead filler.

[0026] [Configuration of tread features] 2, in the present embodiment, the first inner land 42 has two first protrusions 80 that are spaced apart in the tire circumferential direction when viewed from the outside in the tire radial direction, protruding toward the center main groove 22 in the tire axial direction and having a V-shaped edge on the contact patch facing the center main groove 22. Meanwhile, the second inner land 43 has a second protrusion 83 that protrudes toward the center main groove 22 in the tire axial direction when viewed from the outside in the tire radial direction, having a V-shaped edge on the contact patch facing the center main groove 22, and that is inserted into a first groove 81 that is a circumferential part of the V-shape of the center main groove 22 between the two first protrusions 80. The center main groove 22 is formed by connecting multiple V-shaped first grooves 81 that are oriented differently in the tire axial direction, alternately in the tire circumferential direction.

[0027] As shown in FIGS. 3 and 5 , the tread 10 is formed with a first rib 74 that protrudes radially outward from the tire and has dimples 75 recessed from the contact surface S1 on its radially outer surface so as to connect to the inside of the corners of the center main groove 22. A second rib 76 that protrudes radially outward from the tire and has dimples 77 recessed from the contact surface S2 on its radially outer surface so as to connect to the inside of the corners of the second projections 83. Each dimple 75, 77 corresponds to a shallow groove. This increases the rigidity near each corner, thereby improving the tire's circumferential traction performance. Furthermore, since the dimples 75, 77 are formed on each rib 74, 76, the concentration of surface pressure near the edges of each corner when the tire contacts the ground on a dry road surface can be suppressed, thereby suppressing localized early wear. Furthermore, although the recessed shape from the contact surfaces S1, S2 tends to reduce rigidity, this reduction in rigidity can be compensated for by the reinforcement provided by each rib 74, 76. This makes it possible to suppress large changes in the vicinity of the contact surfaces S1 and S2 when the tire comes into contact with the ground. By increasing the rigidity near each corner in this way, early partial wear can also be suppressed.

[0028] Specifically, the inner block 70 constituting the first inner land 42 is formed into a shape including an inverted S-shape by alternately connecting a plurality of inclined portions U1, U3, and U5 inclined with respect to the tire circumferential direction and a plurality of circumferential portions U2, U4, and U6 extending in the tire circumferential direction. The inverted S-shape is the shape of an S when viewed from the back. The plurality of circumferential portions U2, U4, and U6 also have an end circumferential portion U6 provided at one end of the inner block 70 in the tire circumferential direction. The end circumferential portion U6 is disposed between both axial ends of the inner block 70 in the tire axial direction.

[0029] In this example, the first inner land 42 and the second inner land 43 are arranged in a state where their shapes, which are opposite to each other in the tire axial direction and the tire circumferential direction, are shifted by half a pitch in the tire circumferential direction and interdigitate with each other when viewed from the outside in the tire radial direction. Each inner land 42, 43 is formed by repeating a part of the shape in the tire circumferential direction multiple times around the entire tire.

[0030] Therefore, the inner block 71 constituting the second inner land 43 is formed into an inverted S-shape by connecting a plurality of inclined portions V1, V3, V5 inclined with respect to the tire circumferential direction and a plurality of circumferential portions V2, V4, V6 extending in the tire circumferential direction alternately one by one in the reverse order in the tire circumferential direction of the inner block 70. The plurality of circumferential portions V2, V4, V6 also have an end circumferential portion V6 provided at the other end of the inner block 71 in the tire circumferential direction. The end circumferential portion V6 is arranged between both axial ends of the inner block 71 in the tire axial direction.

[0031] At the ends of the ground contact surfaces of the inclined portions U1, U3, U5, V1, V3, and V5, the connecting portions with the wall surface on the side of the center main groove 22 are not chamfered but are angular. On the other hand, at the ends of the ground contact surfaces of the circumferential portions U2, U6, V2, and V6, the connecting portions with the wall surface on the side of the center main groove 22 are chamfered to have an arc-shaped cross section.

[0032] The corner where the first rib 74 is provided is substantially V-shaped when viewed from the outside in the tire radial direction, and the first rib 74 is provided at the back of the corner. As a result, the portion of the center main groove 22 provided inside the corner has a U-shape that widens toward the side away from the first rib 74, and is configured to include inclined portions U3 and U5 that are inclined in opposite directions around the tire circumferential direction, and a circumferential portion U4 that connects one end of the inclined portions U3 and U5 and extends around the tire circumferential direction.

[0033] As shown in FIG. 3, the first rib 74 has a contact surface S1, which is the top surface, that is approximately U-shaped, and has a wall surface on the inside that includes an approximately U-shaped inclined surface, and a bottom surface connected to the bottom side of the wall surface, and a dimple 75 is formed that is recessed radially inward in the tire.

[0034] 3 and 5, in the first inner land 42, sipes 85, which are thin lines having a substantially U-shape when viewed from the outside in the tire radial direction, are formed between the U-shaped contact surface S1 of the first rib 74 and the edge of the contact surface S3 at the corner of the first inner land 42 on the side of the center main groove 22. Both ends of the sipe 85 open into the center main groove 22.

[0035] Meanwhile, the second rib 76 is provided on the inner block 71 of the second inner land 43, inside the corner of the second protrusion 83. When viewed from the outer side in the tire radial direction, the second protrusion 83 is generally J-shaped, widening toward the IN side, which is one side in the tire axial direction, and including inclined portions V1 and V3 inclined in opposite directions around the tire circumferential direction, and a circumferential portion V2 that connects one ends of the inclined portions V1 and V3 and extends around the tire circumferential direction.

[0036] As shown in Fig. 3, one longitudinal end of each inner block 70 on one circumferential side (the lower side in Fig. 3) of the tire faces the longitudinal end of the adjacent inner block 70 on that side in the tire circumferential direction, via a circumferential portion 86a of a V-shaped lug groove 86 extending in the tire circumferential direction. One end of the circumferential portion 86a is connected to the center main groove 22, and the other end is connected to an inclined portion 86b of the lug groove 86 that is inclined with respect to the tire circumferential direction. The inclined portion 86b faces a linear lug groove 87 that is inclined axially opposite the tire circumferential direction, via a circumferentially intermediate portion of the connecting rib 72.

[0037] The inner block 71 is circumferentially opposite to the inner block 70, with one longitudinal end on the other circumferential side (upper side in FIG. 3 ) of the tire facing the longitudinal end of the adjacent inner block 71 on the other circumferential side of the tire, via a circumferential portion 88a extending in the tire circumferential direction of a V-shaped lug groove 88. One end of the circumferential portion 88a is connected to the center main groove 22, and the other end is connected to an inclined portion 88b of the lug groove 88 that is inclined with respect to the tire circumferential direction. The inclined portion 88b faces a linear lug groove 89 inclined toward the opposite side in the tire circumferential direction in the tire axial direction, via a circumferentially intermediate portion of the connecting rib 73.

[0038] As shown in Fig. 3, the second rib 76 has a shape with a dimple 77 on its top surface that is recessed radially inward from the contact patch S2, which is the top surface of the corner of the second protrusion 83. When viewed from the outside in the tire radial direction, the dimple 77 has a shape in which a portion near one corner of a triangle has been removed. The periphery of the bottom surface of the dimple 77 and the contact patch S2 of the second protrusion 83 are connected by a wall surface that includes an inclined surface along the periphery of the bottom surface of the dimple.

[0039] [Configuration of connecting ribs and sipes surrounding the ends of the connecting ribs] As shown in FIG. 4 , the connecting rib 72 connecting the inner blocks 70 protrudes radially outward so as to extend in the tire circumferential direction. When viewed from the outside in the tire radial direction, the connecting rib 72 has a trapezoidal shape in which the axially outer side is longer than the axially inner side, and the height of the contact surface S5, which is the top surface, is approximately the same as the height of the contact surface S3 of each inner block 70. Two rib ends 153, 154 are formed at both ends in the tire circumferential direction of the connecting rib 72, respectively, extending from the tire circumferential side surfaces of two circumferentially adjacent inner blocks 70 toward the inner side, i.e., the rear side, of the inner blocks 70 in the tire circumferential direction. In this state, the rib ends 153, 154 are connected to the two inner blocks 70. In this manner, the circumferentially adjacent inner blocks 70 are connected by the connecting rib 72, which can suppress a decrease in the rigidity of the inner land 42, as described below. In addition, since both side surfaces of the connecting rib 72 in the tire circumferential middle portion face the tire axial ends of each lug groove 86, 87, the edge effect against lateral slippage when the vehicle corners can be increased, and the tire axial grip force can be increased.

[0040] Furthermore, a dimple 90 is provided on the inside of the contact surface S5 of the connecting rib 72, extending in the tire circumferential direction and recessed radially inward from the contact surface S5. The wall surface 90a of the dimple 90 has an oval shape extending in the tire circumferential direction when viewed from the outside in the tire radial direction, and both ends in the tire axial direction are aligned with the tire circumferential direction. Furthermore, a dimple chamfer 90b with an arc-shaped cross section is formed at the top of the inclined surface that is inclined all around the dimple 90 relative to the contact surface S5 of the connecting rib 72. As described above, the dimple 90 extending in the tire circumferential direction is formed on the connecting rib 72, which enhances the edge effect against lateral slip during cornering, thereby increasing the tire's axial grip. Furthermore, the dimple 90 extending in the tire circumferential direction improves drainage at the tire's contact patch.

[0041] The above describes the connecting rib 72 that connects adjacent inner blocks 70, but the connecting rib 73 (Figures 2 and 3) that connects adjacent inner blocks 71 is similar to the connecting rib 72, except that its shape when viewed from the outside in the tire radial direction is opposite in the tire circumferential direction and tire axial direction.

[0042] FIG. 5 is a cross-sectional view taken along the line CC in FIG. 4. FIG. 6 is a cross-sectional view taken along the line DD in FIG. 4. As shown in FIGS. 3 to 6, sipes 91 are formed in the contact surfaces of the inner lands 42, 43 in portions surrounding the contact surfaces of the rib ends 153, 154 of the connecting ribs 72, 73. Specifically, in the contact surfaces of the inner lands 42, 43, the sipes 91, which are thin lines having a substantially U-shape when viewed from the outside in the tire radial direction, are formed between the contact surfaces S5 of the rib ends 153, 154 of the connecting ribs 72, 73 and the contact surfaces S3, S2 of the inner blocks 70, 71. As a result, the sipes 91 are provided between each of the two rib ends 153, 154 and each of the two inner blocks 70, 71 so as to surround each of the rib ends 153, 154. Both ends of the sipes 91 open into the inclined portions 86b, 88b of the V-shaped lug grooves 86, 88 and the lug grooves 87, 89. The depth of the sipe 91 is shallowest at the connection with the lug grooves 86, 87, 88, and 89, gradually deepens toward the inner ends of the inner blocks 70 and 71, and is deepest at an inclined portion 91a that is linearly inclined relative to the tire axial direction at the inner ends of the inner blocks 70 and 71. The maximum depth of the inclined portion 91a is 40% or more of the maximum depth of each main groove 20, 21, and 22. The inclined portion 91a corresponds to a straight portion.

[0043] FIG. 5 is a cross-sectional view taken along the CC line in FIG. 4 . FIG. 6 is a cross-sectional view taken along the DD line in FIG. 4 . Dimples 90 recessed from the ground contact surface S5 are provided on the sides of the connecting ribs 72, 73 away from the sipe 91. The depth of the dimples 90 is smaller than the maximum depth of each main groove 20, 21, 22. The apex of the wall surface of the dimple 90 is formed with a dimple chamfer 90b having an arc-shaped cross section. This prevents the inner blocks 70, 71 from collapsing between the separated portions on both sides of the U-shape by the connecting ribs 72, 73 on the inside of the U-shape. Conversely, the collapsing of the connecting ribs 72, 73 is prevented by the inner blocks 70, 71. This increases the rigidity of the inner blocks 70, 71 and the connecting rib 72. Furthermore, the dimple chamfer 90b distributes the contact pressure of the ground contact surface of each connecting rib 72, 73, thereby suppressing initial uneven wear.

[0044] The dimple edges can be angular rather than chamfered at the top of the wall surfaces of the dimples 90 on the connecting ribs 72, 73. This configuration allows the dimples to have a greater edge effect when the vehicle is cornering, thereby increasing the tire's axial grip.

[0045] [Composition and effects of the inner land block shape] Furthermore, according to this embodiment, each inner land 42, 43 includes a plurality of inner blocks 70, 71 arranged side by side in the tire circumferential direction, with one or the other axial end of the inner block 70, 71 adjacent to one shoulder main groove 20 or the other shoulder main groove 21. Each inner block 70, 71 is formed into a shape including an inverted S-shape by alternatingly connecting a plurality of inclined portions U1, U3, U5, V1, V3, V5 inclined with respect to the tire circumferential direction with a plurality of circumferential portions U2, U4, U6, V2, V4, V6 extending in the tire circumferential direction. As a result, in each inner block 70, 71, a plurality of inclined portions U1, U3, U5, V1, V3, V5 inclined in opposite directions with respect to the tire circumferential direction are alternately arranged. In this way, a zigzag-shaped center main groove 22 is formed between the two inner land 42, 43, thereby achieving both improved drainage in the ground contact patch and improved traction performance in the tire circumferential direction.

[0046] The multiple circumferential portions U2, U4, U6, V2, V4, V6 each have an end circumferential portion U6, V6 provided at one circumferential end or the other circumferential end of the inner blocks 70, 71. Furthermore, the end circumferential portions U6, V6 are disposed between both axial ends of the inner blocks 70, 71 in the tire axial direction.

[0047] This allows the axial extent of the continuous portion of the ground contact patch to be expanded compared to a configuration in which three or more inner lands are provided between a pair of shoulder main grooves in the tread, separated in the axial direction by two or more circumferential main grooves along the tire circumferential direction. This improves the rigidity of the inner lands 42, 43 located between the pair of shoulder main grooves 20, 21. Furthermore, the inclined portions U1, U3, U5, V1, V3, V5 of the inner blocks 70, 71 improve circumferential traction performance. Furthermore, circumferential portions 86a, 88a can be formed adjacent to the end circumferential portions U6, V6, which can be located near the tire's axial center. This prevents a decrease in drainage performance due to a reduction in the number of circumferential main grooves along the tire circumferential direction between the pair of shoulder main grooves 20, 21 in the tread 10. This makes it possible to more significantly improve the rigidity of the inner land grooves 42, 43 disposed between the pair of shoulder main grooves 20, 21, improve the traction performance in the tire circumferential direction, and suppress the deterioration of drainage.

[0048] The tread 10 also includes a first inner land 42 and a second inner land 43, which are two inner block groups arranged to intermesh with each other when viewed from the outside in the tire radial direction. This makes it possible to suppress collapse of the inner land 42, 43 at the contact portion of the tread 10 even if the inner land 42, 43 tends to collapse during running, thereby increasing the rigidity of the inner land 42, 43.

[0049] When a predetermined range in the tire circumferential direction of a set block group 130 consisting of two inner lands 42, 43 is viewed from the tire radially outer side, the set includes inclined portions 86b, 88b and lug grooves 87, 89 of lug grooves 86, 88, which are inclined grooves connected to at least one of the shoulder main grooves 20, 21 and the center main groove 22 and inclined relative to the tire circumferential direction, and circumferential portions 86a, 88a of the lug grooves 86, 88, which are circumferential grooves connected to the center main groove 22 and extending in the tire circumferential direction. In this case, the total area of ​​the inclined portions 86b, 88b and the circumferential portions 86a, 88a as inclined grooves connected to the center main groove 22 and not connected to either of the pair of shoulder main grooves 20, 21 is greater than the total area of ​​the lug grooves 87, 89 as inclined grooves connected to one or the other of the shoulder main grooves 20, 21. For example, in the length range of the tire circumferential direction block group 130 indicated by arrow G1 in Fig. 2, if the total area of ​​the lug grooves 87, 89 is S1a and the total area of ​​the inclined portions 86b, 88b and the circumferential portions 86a, 88a is S2a, then S2a > S1a. This increases the total area of ​​the inclined portions 86b, 88b, which are inclined grooves, and the circumferential portions 86a, 88a, which are circumferential grooves, in the axial central region of the tire where drainage performance is particularly required, thereby efficiently suppressing a decrease in drainage performance.

[0050] The multiple circumferential portions U2, U4, U6, V2, V4, V6 of the inner blocks 70, 71 are provided at the other end or one end of the inner blocks 70, 71 in the tire axial direction, which is the end that protrudes most in the tire axial direction, and include circumferential portions U2, V2 as protrusion-side circumferential portions that form protrusions that are convex on the other end or one end of the tire axial direction.

[0051] The ratio L1 / L2, which is the ratio of the second axial length L2 (FIG. 2) from the axial end of the inner blocks 70, 71 opposite the circumferential portions U2, V2 to the end of the end circumferential portions U6, V6 on the circumferential portions U2, V2 side, to the first axial length L1 (FIG. 2), which is the maximum axial length of the inner blocks 70, 71, is 1.9 or greater and 2.1 or less. This allows the axial lengths of the inclined portions U1, U3, U5, V1, V3, V5 of the inner blocks 70, 71 to be increased while improving drainage in the axial center region. This improves circumferential traction performance.

[0052] In addition, in the inner blocks 70 and 71, the angle formed by the extensions of the edges forming the center main groove 22 at the contact patch of at least two adjacent inclined portions U1, U3, U5, V1, V3, V5 among the multiple inclined portions U1, U3, U5, V1, V3, V5 is an acute angle. For example, the angle formed by the edges H1 and H2 in FIG. 2 is an acute angle. As a result, the inclined portions U1, U3, U5, V1, V3, V5 are arranged in a direction approaching the tire axial direction, thereby further improving the traction performance in the tire circumferential direction.

[0053] The tire 1 described above includes a tread 10 including connecting ribs 72, 73 that connect two circumferentially aligned inner blocks 70, 71 and extend in the tire circumferential direction. The connecting ribs 72, 73 also include two rib ends 153, 154 at both circumferential ends of the tire, extending from the circumferential side surfaces of the two inner blocks 70, 71 toward the inside of the inner blocks 70, 71. Sipes 91 are provided between each of the two rib ends 153, 154 and each of the two inner blocks 70, 71, surrounding each rib end 153, 154. The sipes 91 have inclined portions 91a that are inclined relative to the tire axial direction. This configuration suppresses a decrease in the rigidity of the inner lands 42, 43 and facilitates the provision of edges at the circumferential ends of each inner block 70, 71 that easily engage the road surface. This configuration enhances the edge effect and improves traction performance in the tire circumferential direction. Furthermore, the inclined portions 91a provided at the tire circumferential ends of the sipes 91 surrounding the rib ends 153, 154 enhance the edge effect in the tire circumferential direction, thereby further improving the tire circumferential traction performance. Therefore, the tire circumferential traction performance between the two shoulder main grooves 20, 21 of the tread 10 can be improved, and a decrease in the rigidity of each of the inner lands 42, 43 can be suppressed.

[0054] In this embodiment, an inclined portion 91a that is inclined linearly relative to the tire axial direction is provided at the circumferential end of the sipe 91. However, a straight portion that is inclined linearly relative to the tire axial direction may be provided at the circumferential end of the sipe 91 instead of the inclined portion 91a. Even in this configuration, the sipes that surround the rib end can further increase the edge effect in the tire circumferential direction, thereby further improving traction performance in the tire circumferential direction.

[0055] When the sipe 91 is viewed from the outside in the tire radial direction, both ends of the sipe 91 reach the circumferential side surfaces of the inner blocks 70, 71. This increases the edge component of the sipe 91 that prevents lateral slip of the tire, thereby increasing the axial grip of the tire. Furthermore, drainage at the tire's contact area can be further improved.

[0056] Furthermore, the sipe depth of the sipe 91 at a position where it reaches the tire circumferential side surface of the inner blocks 70, 71 is smaller than the sipe depth of the inclined portions 91a of the sipe 91 that are located circumferentially adjacent to the tire circumferential ends of the connecting ribs 72, 73. This makes it difficult for the rib ends 153, 154 of the connecting ribs 72, 73 to move, thereby increasing the rigidity of the connecting ribs 72, 73, while increasing the grip force in the tire axial direction by maintaining an edge component against lateral slip of the tire.

[0057] In the configuration of this example, the sipes 91 only need to be provided so as to surround the rib ends 153, 154 of the connecting ribs 72, 73, and both ends of the sipes may not open to the tire circumferential side surfaces of the inner blocks 70, 71. In this case as well, the tire circumferential ends of the sipes surrounding the rib ends 153, 154 of the connecting ribs 72, 73 can enhance the edge effect in the tire circumferential direction, thereby improving traction performance in the tire circumferential direction and increasing grip in the tire axial direction compared to a case where there are no sipes.

[0058] [First and second examples of another embodiment] FIG. 7 is a view corresponding to FIG. 4 of a first example of another embodiment. In the configuration of this example, the axial length of the connecting rib 72a provided on the inner land 42a is shorter than in the configuration of FIGS. 1 to 6. As in the configuration of FIGS. 1 to 6, the connecting rib 72a also has a dimple 155 formed thereon that is recessed from the contact surface of the connecting rib 72a and extends in the tire circumferential direction. When viewed from the outside in the tire radial direction, the dimple 155 has an elongated rectangular shape. No chamfering is formed on the top of the wall surface of the dimple 155. In this example, the other configurations and functions are the same as those of the configuration of FIGS. 1 to 6.

[0059] Figure 8 is a view corresponding to Figure 4 of a second example of another embodiment. In the configuration of this example, the axial length of the connecting rib 72b provided on the inner land 42b is longer than in the configuration of Figures 1 to 6. The connecting rib 72b also has a dimple 156 recessed from the contact patch and extending in the circumferential direction of the tire. The axial length of the dimple 156 is longer than that of the dimple 90 in the configuration of Figures 1 to 6. In this example, the other configurations and functions are the same as those of the configuration of Figures 1 to 6.

[0060] [Preferred ratio of rib width and dimple width] In each of the above embodiments, the first ratio ((W2 / W1) × 100), which is the ratio of the rib width W2 ( FIG. 4 ), which is the width of the connecting rib 72, 73 in the tire axial direction, to the contact width W1 ( FIG. 2 ), which is the width between the two axially opposite contact ends T1, T2 of the tread 10, is preferably 2% or more and 20% or less. With this preferred configuration, the rib width W2 is not excessively large in relation to the contact width W1, so the axial length of the portion of the circumferential side surface of the inner block 70, 71 that does not axially overlap with the connecting rib 72, 73 can be increased. Furthermore, because the rib width W2 is not too small, the connecting ribs 72, 73 can effectively improve the rigidity of the inner block 70, 71. This makes it possible to more significantly improve the tire circumferential traction performance while suppressing a decrease in the rigidity of the inner land 42, 43.

[0061] In addition, in order to more significantly achieve both improved traction performance in the tire circumferential direction and suppression of a decrease in rigidity of the inner lands 42, 43, it is more preferable that the first ratio of the rib width W2 to the contact width W1 be 4% or more and 10% or less.

[0062] Table 1 below shows the contact patch width W1, rib width W2, and the first ratio ((W2 / W1)×100) of tires of Examples 1 to 3, which are examples of the embodiment shown in Figures 1 to 4, 7, and 8. Example 1 is formed so that the first ratio is the minimum value in the preferred range (2% or more and 20% or less). Example 3 is formed so that the first ratio is the maximum value in the preferred range (2% or more and 20% or less). Example 2 is formed so that the first ratio is an intermediate value between Examples 1 and 3, and falls within a more preferred range (4% or more and 10% or less).

[0063] [Table 1]

[0064] Furthermore, in each of the above embodiments, the second ratio ((W3 / W2) × 100), which is the ratio of the axial dimple width W3 of the bottom of the dimple 90 to the axial rib width W2 of the connecting ribs 72, 73, is preferably 20% or greater and 70% or less. With this preferred configuration, the dimple width W3 is not excessively large in relation to the rib width W2, thereby preventing a decrease in the rigidity of the connecting ribs 72, 73 due to the dimple 90. Furthermore, since the dimple width W3 is not too small, it is possible to prevent a decrease in drainage performance and prevent excessive concentration of surface pressure on the edges of the contact surfaces of the connecting ribs 72, 73, thereby reducing uneven wear on the contact surfaces of the connecting ribs 72, 73. This more significantly achieves both a reduction in the rigidity of the connecting ribs 72, 73 and a reduction in drainage performance and uneven wear of the connecting ribs 72, 73.

[0065] Table 2 below shows the rib width W2, dimple width W3, and second ratio ((W3 / W2) x 100) of tires according to Examples 1 to 3, which are examples of the embodiment shown in Figures 1 to 4, 7, and 8. Example 1 is formed so that the second ratio is the minimum value within the preferred range (20% to 70%). Example 3 is formed so that the second ratio is the maximum value within the preferred range (20% to 70%). Example 2 is formed so that the second ratio is an intermediate value between Examples 1 and 3.

[0066] [Table 2]

[0067] In each of the above embodiments, the depth of the dimples 90 is preferably 0.5 mm or greater and 5 mm or less. This brings the dimple depth into a more optimal range, making it possible to more significantly improve the edge effect during cornering and increase the rigidity of the connecting ribs 72, 73 at the same time.

[0068] Furthermore, in order to more significantly increase the edge effect when the vehicle is cornering and increase the rigidity of the connecting ribs 72, 73 at the same time, it is more preferable that the depth of the dimples 90 be 2 mm or more and 3 mm or less.

[0069] Table 3 below shows the dimple depths of Examples 1 to 3, which are examples of the embodiment shown in Figures 1 to 4, 7, and 8. Example 1 is formed so that the dimple depth is the minimum value in the preferred range (0.5 mm or more and 5 mm or less). Example 3 is formed so that the dimple depth is the maximum value in the preferred range (0.5 mm or more and 5 mm or less). Example 2 is formed so that the dimple depth is intermediate between Examples 1 and 3, and falls within a more preferred range (2 mm or more and 3 mm or less).

[0070] [Table 3]

[0071] [Configuration of Comparative Example] FIG. 9 is a diagram corresponding to FIG. 4 of a first comparative example. In the comparative example of FIG. 9, in the inner land 42c, circumferentially adjacent inner blocks 70c are not connected by a connecting rib. In this configuration, the inner land 42c does not have a connecting rib, so the axial length of the circumferential side surface of each inner block 70c is increased. While this may improve circumferential traction performance, it significantly reduces the rigidity of the inner land 42c.

[0072] FIG. 10 is a diagram corresponding to FIG. 4 of a second comparative example. In the comparative example of FIG. 10, the inner land 42d does not include multiple inner blocks separated in the tire circumferential direction. The inner land 42d is connected in an annular shape in the tire circumferential direction, and the axial length of the inner land 42d is large throughout the tire circumferential direction, and no grooves extending from both sides in the tire circumferential direction are formed. With this configuration, the rigidity of the inner land 42d is increased, but the traction performance in the tire circumferential direction is significantly reduced.

[0073] According to each of the embodiments shown in Figures 1 to 8 above, unlike the comparative examples shown in Figures 9 and 10, it is possible to improve the traction performance in the tire circumferential direction and suppress a decrease in rigidity on the inner land.

[0074] [Third example of another embodiment] Fig. 11 is a perspective view of a portion in the tire circumferential direction of a tire 1a according to a third example of another embodiment. Fig. 12 is a plan view of the tire 1a, showing a portion in the circumferential direction of a tread 10a. Fig. 13 is a cross-sectional view taken along line NN of Fig. 12. Fig. 14 is a cross-sectional view taken along line PP of Fig. 12.

[0075] In the configuration of this example, in the tread 10a, the connecting ribs 140, 141 provided on the first inner land 42f and the second inner land 43f include two rib ends 142 at both ends in the tire circumferential direction, which extend from the tire circumferential side surfaces of the two inner blocks 70f, 71f to the inside of the inner blocks 70f, 71f. The top surfaces of the intermediate portions 143 of the connecting ribs 140, 141, which are located between the two rib ends 142 and the tire circumferential side surfaces of the two inner blocks 70f, 71f, are lower than the top surfaces of the rib ends 142.

[0076] 11 and 14, the top surface of the intermediate portion 143 is recessed in the shape of a valley with a generally V-shaped cross section so as to become deeper toward the tire circumferential center of the intermediate portion 143. Furthermore, a sipe 144 extending in the tire circumferential direction is formed in the tire axial center of the connecting ribs 140, 141.

[0077] Furthermore, shallow grooves 152 recessed in a triangular shape as viewed from the outside in the tire radial direction are formed on the top surfaces of the inner blocks 70f, 71f of the inner lands 42f, 43f at the ends of the shoulder main grooves 20, 21 in the circumferentially intermediate portions of the tire. The circumferential width of the shallow grooves 152 narrows toward the shoulder main grooves 20, 21 connected to the shallow grooves 152.

[0078] On the top surface of each inner block 70f, 71f, shallow grooves 145 are formed at the tips of the first protrusions 80a and second protrusions 83a in the circumferentially intermediate portion of the tire, forming triangular recesses as viewed from the radially outer side of the tire. The circumferential width of the shallow grooves 145 narrows toward the center main groove 22. The top of the wall surface of each shallow groove 145 is not chamfered to have an arc-shaped cross section, but forms an edge that is inclined with respect to the circumferential direction of the tire or that runs along the circumferential direction of the tire. This improves traction performance in the circumferential direction of the tire and enhances the edge effect when the vehicle is cornering.

[0079] Furthermore, a sipe 146 that is approximately U-shaped when viewed from the outside in the tire radial direction is formed on the contact surfaces of the shoulder blocks 60, 61, 62, and 63 of each shoulder land 41a and 44a. The sipe 146 is connected to both axial ends of the two shallow grooves 109a, and one axial end of the sipe 146 opens into the shoulder main grooves 20 and 21.

[0080] Sipes 147, 148, and 149 inclined relative to the tire circumferential direction are also formed on the contact surfaces of the inner lands 42f and 43f. Some of the sipes 148 and 149 are connected to the shallow groove 145, and one end of the sipe 149 opens near the axial center of the center main groove 22.

[0081] In the configuration of this example, the top surface of an intermediate portion 143 of each connecting rib 140, 141, which is located between two rib ends 142 and between the circumferential side surfaces of the two inner blocks 70f, 71f, is lower than the top surface of the rib end 142. This improves drainage near the intermediate portion 143. The minimum height from the bottom surfaces of the lug grooves 86, 87, 88, 89, which coincide with the bottom surfaces of the main grooves 20, 21, 22, to the top surface of the intermediate portion 143 can be, for example, 20% to 50% of the depth of the main grooves 20, 21, 22. In this example, the other configurations and functions are the same as those of the configurations in FIGS. 1 to 6.

[0082] [Fourth example of another embodiment] FIG. 15 is a schematic diagram illustrating some blocks of the first inner land 42g and the second inner land 43g in a tire according to a fourth example of another embodiment. In the above-described embodiment, the inner blocks constituting each inner land have a shape that includes an inverted S-shape. In the configuration of this example, however, each inner block 70g, 71g is formed to have a shape that includes an S-shape. Specifically, in each inner block 70g, 71g, the tire circumferential arrangement of the multiple circumferential portions U2, U4, U6 and the multiple inclined portions U1, U3, U5 of each inner block 70, 71 in the configurations shown in FIGS. 1 to 6 is reversed. Furthermore, the multiple blocks 70g, 71g constituting the two inner land 42g, 43g are arranged axially opposite each other, thereby forming a center main groove 22 between the two inner land 42g, 43g. In each of the inner land portions 42g, 43g, a plurality of inner blocks 70g, 71g adjacent to each other in the tire circumferential direction are connected to each other by connecting ribs (not shown in FIG. 15) that extend in the tire circumferential direction.

[0083] Even when the inner blocks 70g and 71g having the above-described shapes are used, similarly to the above examples, it is possible to simultaneously achieve improved rigidity of the inner lands 42g and 43g disposed between the pair of shoulder main grooves in the tread, improved traction performance in the tire circumferential direction, and suppressed deterioration of drainage. In this example, the other configurations and functions are the same as those in Figures 1 to 6.

[0084] The present disclosure is further illustrated by the following embodiments. Configuration 1: Two shoulder main grooves extending in the tire circumferential direction on both sides of the tire axial direction; At least two inner blocks arranged in the tire circumferential direction between the two shoulder main grooves; a connecting rib connecting the two inner blocks and extending in the tire circumferential direction, the connecting rib includes, at both ends in the tire circumferential direction, two rib ends extending from side surfaces of the two inner blocks in the tire circumferential direction toward the inside of the inner blocks, A sipe is provided between each of the two rib ends and each of the two inner blocks so as to surround each of the two rib ends, The sipe has a straight portion along the tire axial direction or a direction inclined with respect to the tire axial direction. Pneumatic tires. Configuration 2: a dimple recessed from the ground contact surface of the connecting rib and extending in the tire circumferential direction; 10. The pneumatic tire according to claim 1. Configuration 3: The ratio of the rib width, which is the width of the connecting rib in the tire axial direction, to the contact width, which is the width between two contact ends on both sides of the tire axial direction in the tread, is 2% or more and 20% or less. 3. The pneumatic tire according to claim 1 or 2. Configuration 4: a ratio of the dimple width of the bottom of the dimple in the tire axial direction to a rib width, which is the width of the connecting rib in the tire axial direction, of 20% or more and 70% or less; 3. The pneumatic tire according to claim 2. Configuration 5: The depth of the dimples is 0.5 mm or more and 5 mm or less. 3. The pneumatic tire according to claim 2. Configuration 6: a pair of inner block groups arranged adjacent to each other in the tire axial direction between the two shoulder main grooves, with a zigzag intermediate main groove arranged between them; Each of the pair of inner block groups includes a plurality of inner blocks arranged side by side in the tire circumferential direction, the inner blocks adjacent to each other in the tire circumferential direction being connected by the connecting rib, and each of the inner blocks has a shape including an S-shape or an inverted S-shape in which a plurality of inclined portions inclined in opposite directions with respect to the tire circumferential direction are alternately arranged. 6. The pneumatic tire of any one of configurations 1 to 5. Configuration 7: When the sipe is viewed from the outer side in the tire radial direction, both ends of the sipe reach the side surfaces of the inner blocks in the tire circumferential direction. 7. The pneumatic tire of any one of claims 1 to 6. Configuration 8: In the sipe, a sipe depth at a position where the sipe reaches a side surface in the tire circumferential direction of the inner block is smaller than a sipe depth of the straight portion in the sipe that is located at a position adjacent in the tire circumferential direction to one end of the connecting rib in the tire circumferential direction. 8. The pneumatic tire according to claim 7. Configuration 9: a top surface of a portion of the connecting rib that is disposed between the two rib ends and between the tire circumferential direction side surfaces of the two inner blocks is lower than the top surfaces of the rib ends; 9. The pneumatic tire of any one of configurations 1 to 8. [Explanation of symbols]

[0085] 1,1a pneumatic tire (tire), 10,10a tread, 12 sidewall, 13 tire side, 14 bead, 20,21 shoulder main groove, 22 center main groove, 41 shoulder land, 42,42a,42b,42c,42d,42f,42g first inner land, 43,43f,43g second inner land, 44 shoulder land, 50,51 lug groove, 60,61,62,63 shoulder block, 70,71,70f,71f,70g,71g inner block, 72,73 connecting rib, 74 first rib, 75 dimple, 76 second rib, 77 dimple, 80,80a first protrusion, 81 first groove, 83,83a second protrusion, 85 sipe, 86,87,88,89 lug groove, 90 Dimples, 91 Sipes, 106 Shoulder shallow grooves, 109, 109a Shallow grooves, 114, 115 Concave, 130 Block groups, 140, 141 Connecting ribs, 142 Rib ends, 143 Middle section, 144 Sipes, 145 Shallow grooves, 146 Sipes, 147, 148, 149 Sipes, 152 Shallow grooves, 153, 154 Rib ends, 155, 156 Dimples.

Claims

1. Two shoulder main grooves extending in the tire circumferential direction on both sides in the tire axial direction; At least two inner blocks arranged in the tire circumferential direction between the two shoulder main grooves; a connecting rib connecting the two inner blocks and extending in the tire circumferential direction, the connecting rib includes, at both ends in the tire circumferential direction, two rib ends extending from side surfaces of the two inner blocks in the tire circumferential direction toward the inside of the inner blocks, a sipe is provided between each of the two rib ends and each of the two inner blocks so as to surround each of the two rib ends; The sipe has a straight portion along the tire axial direction or a direction inclined with respect to the tire axial direction. Pneumatic tires.

2. a dimple recessed from the ground contact surface of the connecting rib and extending in the tire circumferential direction; The pneumatic tire according to claim 1 .

3. a ratio of a rib width, which is the width of the connecting rib in the tire axial direction, to a contact width, which is the width between two contact ends on both sides of the tire axial direction of the tread, is 2% or more and 20% or less; The pneumatic tire according to claim 1 .

4. a ratio of a dimple width of the bottom of the dimple in the tire axial direction to a rib width, which is the width of the connecting rib in the tire axial direction, is 20% or more and 70% or less; The pneumatic tire according to claim 2.

5. The depth of the dimples is 0.5 mm or more and 5 mm or less. The pneumatic tire according to claim 2.

6. a pair of inner block groups disposed adjacent to each other in the tire axial direction between the two shoulder main grooves, with a zigzag intermediate main groove disposed between them; Each of the pair of inner block groups includes a plurality of inner blocks arranged side by side in the tire circumferential direction, the inner blocks adjacent to each other in the tire circumferential direction being connected by the connecting rib, and each of the inner blocks has a shape including an S-shape or an inverted S-shape in which a plurality of inclined portions inclined in opposite directions with respect to the tire circumferential direction are alternately arranged. The pneumatic tire according to claim 1 .

7. When the sipe is viewed from the outer side in the tire radial direction, both ends of the sipe reach the side surfaces of the inner blocks in the tire circumferential direction. The pneumatic tire according to claim 1 .

8. In the sipe, a sipe depth at a position where the sipe reaches a side surface in the tire circumferential direction of the inner block is smaller than a sipe depth of the straight portion in the sipe that is located at a position adjacent in the tire circumferential direction to one end of the connecting rib in the tire circumferential direction. The pneumatic tire according to claim 7.

9. a top surface of a portion of the connecting rib that is disposed between the two rib ends and between the tire circumferential direction side surfaces of the two inner blocks is lower than the top surfaces of the rib ends; The pneumatic tire according to claim 1 .

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