pneumatic tires

Abstract

To provide a pneumatic tire capable of securing drainage performance of a major groove while rigidity of a block is improved and steering stability is improved.SOLUTION: A pneumatic tire includes in a tread a first block column 18B provided on one side in a width direction of a major groove 12C and a second block column 18C provided on the other side in the width direction of the major groove 12C. In the pneumatic tire, a plurality of first blocks 16B constituting the first block column 18B and a plurality of second blocks 16C composing the second block columns 18C are provided with: obtuse angle parts 16B2, 16C2 divided at an obtuse angle by the major groove 12C and lateral grooves 14C, 14D; acute angle parts 16B1, 16C1 divided at an acute angle by the major groove 12C and the lateral grooves 14C, 14D; and reinforcement projections 20, 22 which project from the acute angle part side of the side walls 16B3, 16C3 facing the major groove 12C to the major groove 12C provided to a groove bottom 12C1 of the major groove 12C. A reinforcement projection 20 provided for the first blocks 16B and a reinforcement projection 22 provided for the second blocks 16C are alternately arranged in a tire circumferential direction C.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Some pneumatic tires have treads with blocks formed by main grooves extending in the tire circumferential direction and lateral grooves extending in the tire width direction. In tires with such blocks, rigidity at the corners of the blocks is reduced, which tends to reduce steering stability.

[0003] In order to increase the rigidity of the block and improve steering stability, Patent Document 1 discloses that the block is reinforced by providing a protrusion that protrudes into the main groove on the side wall of the block facing the main groove.

[0004] By providing such protrusions over a wide area on the block or by making the protrusions protrude significantly from the side walls of the block, the rigidity of the block can be significantly improved, but the drainage performance can be easily impaired due to the reduction in groove volume of the main groove. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-40656 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a pneumatic tire that can improve the rigidity of the blocks to improve steering stability while ensuring the drainage performance of the main grooves. [Means for solving the problem]

[0007] The pneumatic tire of this embodiment has a tread including a main groove extending in the tire circumferential direction, a first block row provided on one widthwise side of the main groove, and a second block row provided on the other widthwise side of the main groove, wherein the first block row includes a plurality of first blocks separated in the tire circumferential direction by first lateral grooves extending at an angle with respect to the tire width direction, and the second block row includes a plurality of second blocks separated in the tire circumferential direction by second lateral grooves extending at an angle with respect to the tire width direction, and the first blocks and the second blocks include an obtuse angle portion defined by the main groove, and the first lateral groove and the second lateral groove, an acute angle portion defined by the main groove, and the first lateral groove and the second lateral groove, and a reinforcing protrusion provided on the first block and the reinforcing protrusion provided on the second block are arranged alternately in the tire circumferential direction. [Effects of the Invention]

[0008] In the present invention, by providing the above-mentioned features, it is possible to improve the rigidity of the blocks and improve the steering stability, while ensuring the groove volume of the main groove. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a development view showing a tread pattern of a pneumatic tire according to one embodiment. [Figure 2] FIG. 2 is an enlarged plan view of a main portion of the tread pattern of FIG. 1. [Figure 3] Cross-sectional view of line III-III in Figure 2. [Figure 4] 1 is an enlarged perspective view showing a main part of a pneumatic tire according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] A tire according to one embodiment is a pneumatic tire including a pair of left and right bead portions and sidewalls, and a tread provided between the left and right sidewalls to connect the radially outer ends of the left and right sidewalls. The internal structure of the tire is not particularly limited, and may include, for example, an annular bead core embedded in the bead, a carcass ply having a radial structure extending toroidally between the pair of beads, and a belt and tread rubber provided in the tread on the tire radially outer side of the carcass ply. In this embodiment, a typical tire structure can be adopted except for the tread pattern.

[0012] Unless otherwise specified, the shapes and dimensions in this specification are those of a tire mounted on a standard rim and inflated to standard internal pressure under normal no-load conditions. A standard rim is a "standard rim" in the JATMA standard, a "design rim" in the TRA standard, or a "measuring rim" in the ETRTO standard. Standard internal pressure is the "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, or the "inflation pressure" in the ETRTO standard.

[0013] (1) Basic structure of Tread 10 Figure 1 is a partial development view of a tire tread 10 according to one embodiment. In the drawing, the symbol CL indicates the tire equatorial plane, which corresponds to the tire widthwise center. The symbol W indicates the tire width direction (also referred to as the tire axial direction), with the inner side in the tire width direction W referring to the direction approaching the tire equatorial plane CL and the outer side in the tire width direction W referring to the direction away from the tire equatorial plane CL. The symbol C indicates the tire circumferential direction, which is the direction on the circumference centered on the tire rotation axis.

[0014] The tire shown in Fig. 1 is a tire that has a designated front and back when mounted on a vehicle, that is, the side that is mounted on the outside and the side that is mounted on the inside when mounted on a vehicle are designated. Therefore, a marking for designating the mounting orientation on a vehicle is provided on, for example, the sidewall surface of the tire. In Fig. 1, the tire is mounted on a vehicle so that the side indicated by the symbol OUT faces outward (outside of the vehicle) when mounted on the vehicle, and the side indicated by the symbol IN faces inward (inside of the vehicle) when mounted on the vehicle.

[0015] As shown in FIG. 1, the surface of the tread 10 is provided with main grooves 12A, 12B, 12C, and 12D extending in the tire circumferential direction C, lateral grooves 14A, 14B, 14C, 14D, 14E, 14F, 14G, and 14H extending in the tire width direction W, and blocks 16A, 16B, 16C, 16D, and 16E.

[0016] In detail, the tread 10 has four grooves: a pair of central main grooves 12A, 12B arranged on both sides of the tire equatorial plane CL, and a pair of shoulder main grooves 12C, 12D arranged respectively on the outer side of the pair of central main grooves 12A, 12B in the tire width direction.

[0017] In this embodiment, the inner central main groove 12A on the vehicle inner side IN, the inner shoulder main groove 12C on the vehicle inner side IN, and the outer shoulder main groove 12D on the vehicle outer side OUT extend in an approximately straight line in the tire circumferential direction C, and the outer central main groove 12B on the vehicle outer side OUT extends in the tire circumferential direction C in a zigzag manner while bending.

[0018] The inboard center main groove 12A, inboard shoulder main groove 12C, and outboard shoulder main groove 12D may be zigzag main grooves, and the outboard center main groove 12B may be a straight main groove. That is, as long as the main grooves 12A, 12B, 12C, and 12D extend in the tire circumferential direction C, they do not necessarily have to be parallel to the tire circumferential direction C, and may extend in the tire circumferential direction C at an angle.

[0019] A central block row 18A is provided between the inner central main groove 12A and the outer central main groove 12B. The central block row 18A includes a plurality of central blocks 16A separated in the tire circumferential direction C by first central lateral grooves 14A. The central lateral grooves 14A extend at an angle with respect to the tire width direction W and open to the inner central main groove 12A and the outer central main groove 12B.

[0020] The central block 16A is provided with second central lateral grooves 14B that are inclined in the opposite direction to the first central lateral grooves 14A. One end of the second central lateral groove 14B opens into the inner central main groove 12A and the other end terminates within the central block 16A. The first central lateral grooves 14A and the second central lateral grooves 14B are provided alternately in the tire circumferential direction C. Note that the first central lateral grooves 14A and the second central lateral grooves 14B may be straight, curved, or have bent portions, as long as they extend at an angle with respect to the tire width direction W.

[0021] An inner intermediate block row 18B is provided between the inner center main groove 12A and the inner shoulder main groove 12C. The inner intermediate block row 18B includes a plurality of inner intermediate blocks 16B separated in the tire circumferential direction C by inner intermediate lateral grooves 14C.

[0022] The inner intermediate lateral grooves 14C extend at an angle with respect to the tire width direction W and open to the inner central main groove 12A and the inner shoulder main groove 12C. The inner intermediate lateral grooves 14C are arranged alternately in the tire circumferential direction C. The inner intermediate lateral grooves 14C are straight grooves. Note that the inner intermediate lateral grooves 14C may be straight, curved, or have a bent portion, as long as they extend at an angle with respect to the tire width direction W.

[0023] Because the inner intermediate lateral grooves 14C extend at an angle relative to the tire width direction W, the inner intermediate blocks 16B have acute angle portions 16B1 and obtuse angle portions 16B2. The acute angle portions 16B1 are corners formed when the inner intermediate lateral grooves 14C intersect with the inner shoulder main grooves 12C at an acute angle. The obtuse angle portions 16B2 are corners formed when the inner intermediate lateral grooves 14C intersect with the inner shoulder main grooves 12C at an obtuse angle. The acute angle portions 16B1 and the obtuse angle portions 16B2 are alternately provided in the tire circumferential direction C.

[0024] An inner shoulder block row 18C is provided on the outer side of the inner shoulder main groove 12C in the tire width direction (i.e., between the inner shoulder main groove 12C and the ground contact edge). The inner shoulder block row 18C includes a plurality of inner shoulder blocks 16C separated in the tire circumferential direction C by inner shoulder lateral grooves 14D.

[0025] The inner shoulder lateral grooves 14D extend at an angle relative to the tire width direction W and open to the inner shoulder main groove 12C and the tread edge. The openings of the inner shoulder lateral grooves 14D that open to the inner shoulder main groove 12C are formed on an extension of the inner intermediate lateral grooves 14C. The inner shoulder lateral grooves 14D are grooves that have a bent portion. Note that the inner shoulder lateral grooves 14D may be straight, curved, or have a bent portion, as long as they extend at an angle relative to the tire width direction W.

[0026] Because the inner shoulder lateral groove 14D extends at an angle relative to the tire width direction W, the inner shoulder block 16C has an acute-angle portion 16C1 and an obtuse-angle portion 16C2. The acute-angle portion 16C1 is a corner formed when the inner shoulder lateral groove 14D intersects with the inner shoulder main groove 12C at an acute angle. The obtuse-angle portion 16C2 is a corner formed when the inner shoulder lateral groove 14D intersects with the inner shoulder main groove 12C at an obtuse angle.

[0027] Like the acute angle portions 16B1 and obtuse angle portions 16B2 of the inner intermediate blocks 16B, the acute angle portions 16C1 and obtuse angle portions 16C2 of the inner shoulder blocks 16C are alternately arranged in the tire circumferential direction C. The acute angle portions 16C1 of the inner shoulder blocks 16C face the obtuse angle portions 16B2 of the inner intermediate blocks 16B in the extension direction of the inner intermediate lateral grooves 14C. The obtuse angle portions 16C2 of the inner shoulder blocks 16C face the acute angle portions 16B1 of the inner intermediate blocks 16B in the extension direction of the inner intermediate lateral grooves 14C.

[0028] An outer intermediate block row 18D is provided between the outer center main groove 12B and the outer shoulder main groove 12D. The outer intermediate block row 18D includes a plurality of outer intermediate blocks 16D separated in the tire circumferential direction C by first outer intermediate lateral grooves 14E. The first outer intermediate lateral grooves 14E extend obliquely with respect to the tire width direction W and open to the outer center main groove 12B and the outer shoulder main grooves 12D.

[0029] The outer intermediate block 16D is provided with a second outer intermediate lateral groove 14F that is inclined in the opposite direction to the first outer intermediate lateral groove 14E. One end of the second outer intermediate lateral groove 14F opens into the outer shoulder main groove 12D and the other end terminates within the outer intermediate block 16D. The first outer intermediate lateral groove 14E and the second outer intermediate lateral groove 14F are alternately provided in the tire circumferential direction C. Note that the first outer intermediate lateral groove 14E and the second outer intermediate lateral groove 14F may be straight, curved, or have a bent portion as long as they extend at an angle with respect to the tire width direction W. Alternatively, the second outer intermediate lateral groove 14F may have one end that opens into the outer shoulder main groove 12D and the other end that opens into the outer central main groove 12B.

[0030] An outer shoulder block row 18E is provided on the outer side of the outer shoulder main groove 12D in the tire width direction (i.e., between the outer shoulder main groove 12D and the ground contact edge). The outer shoulder block row 18E includes a plurality of outer shoulder blocks 16E separated in the tire circumferential direction C by first outer shoulder lateral grooves 14G. The first outer shoulder lateral grooves 14G extend at an angle with respect to the tire width direction W and open to the outer shoulder main groove 12D and the ground contact edge.

[0031] The outer shoulder block 16E is provided with a second outer shoulder lateral groove 14H extending parallel to the first outer shoulder lateral groove 14G. The second outer shoulder lateral groove 14H is a groove that opens at one end to the ground contact edge and terminates at the other end within the outer shoulder block 16E. The first outer shoulder lateral groove 14G and the second outer shoulder lateral groove 14H are provided alternately in the tire circumferential direction C. Note that the first outer shoulder lateral groove 14G and the second outer shoulder lateral groove 14H may be straight, curved, or have a bent portion, as long as they extend at an angle with respect to the tire width direction W.

[0032] (2) Inner intermediate block 16B and inner shoulder block 16C Next, the inner intermediate block 16B and the inner shoulder block 16C will be described. As shown in Figures 1 and 2, the inner intermediate block 16B and the inner shoulder block 16C are provided with reinforcing protrusions 20, 22, respectively.

[0033] The reinforcing projection 20 protrudes from the acute angle side of the sidewall 16B3 of the inner intermediate block 16B facing the shoulder main groove 12C toward the center of the shoulder main groove 12C (toward the sidewall 16B3 of the inner shoulder block 16C facing the sidewall 16B3). As shown in Fig. 3, the reinforcing projection 20 is provided from the tread surface 16B4 of the inner intermediate block 16B to the groove bottom 12C1 of the shoulder main groove 12C.

[0034] As shown in Figure 3, the reinforcing protrusion 20 has a tread side inclined surface 20a that is connected to the tread surface 16B4 of the inner intermediate block 16B and extends toward the groove bottom 12C1 side, and a groove bottom side inclined surface 20b that is connected to the tread side inclined surface 20a and further extends toward the groove bottom 12C1 side.

[0035] The tread-side inclined surface 20a is inclined relative to the tire radial direction. The groove-bottom-side inclined surface 20b is provided substantially parallel to the tire radial direction. That is, the inclination angle θ1 of the tread-side inclined surface 20a relative to the tire radial direction is larger than the inclination angle of the groove-bottom-side inclined surface 20b relative to the tire radial direction. θ1 is, for example, 25° or more and 65° or less.

[0036] In addition, the groove bottom side inclined surface 20b may be inclined with respect to the tire radial direction as long as the inclination angle with respect to the tire radial direction is smaller than the inclination angle θ1 of the tread side inclined surface 20a. For example, the inclination angle of the groove bottom side inclined surface 20b with respect to the tire radial direction can be 10° or less.

[0037] A curved surface that smoothly connects the groove bottom side inclined surface 20b and the groove bottom 12C1 is provided on the groove bottom 12C1 side of the groove bottom side inclined surface 20b.

[0038] The reinforcing protrusions 22 protrude from the acute angle side of the sidewall 16C3 of the inner shoulder block 16C facing the shoulder main groove 12C toward the center of the inner shoulder main groove 12C (toward the sidewall 16B3 of the inner intermediate block 16B). The reinforcing protrusions 22 are provided from the tread surface 16C4 of the inner shoulder block 16C to the groove bottom 12C1 of the shoulder main groove 12C. These reinforcing protrusions 22 and the reinforcing protrusions 20 provided on the inner shoulder block 16C are arranged alternately in the tire circumferential direction C (see FIGS. 1 and 2).

[0039] The reinforcing protrusion 22 has a tread side inclined surface 22a that is connected to the tread surface 16C4 of the inner shoulder block 16C and extends toward the groove bottom 12C1 side, and a groove bottom side inclined surface 22b that is connected to the tread side inclined surface 22a and further extends toward the groove bottom 12C1 side.

[0040] The tread-side inclined surface 22a is inclined relative to the tire radial direction. The groove-bottom-side inclined surface 22b is provided substantially parallel to the tire radial direction. That is, the inclination angle θ2 of the tread-side inclined surface 22a relative to the tire radial direction is larger than the inclination angle of the groove-bottom-side inclined surface 22b relative to the tire radial direction. θ2 is, for example, 25° or more and 65° or less.

[0041] In addition, the groove bottom side inclined surface 22b may be inclined with respect to the tire radial direction as long as the inclination angle with respect to the tire radial direction is smaller than the inclination angle θ2 of the tread side inclined surface 22a. For example, the inclination angle of the groove bottom side inclined surface 22b with respect to the tire radial direction can be 10° or less.

[0042] A curved surface that smoothly connects the groove bottom side inclined surface 22b and the groove bottom 12C1 is provided on the groove bottom 12C1 side of the groove bottom side inclined surface 22b.

[0043] The groove-bottom-side inclined surfaces 20b, 22b of the reinforcing projections 20, 22 preferably have a height H from the groove bottom 12C1 of the inner shoulder main groove 12C that is 50% or more of the depth D0 of the inner shoulder main groove 12C. In other words, the tread-side inclined surfaces 20a, 22a are preferably provided closer to the tread than a position that is 50% of the depth D0 of the inner shoulder main groove 12C. For example, the depth D0 of the inner shoulder main groove 12C may be 5 to 10 cm, the height H of the groove-bottom-side inclined surfaces 20b, 22b may be 5 to 8.5 cm, and the height (length in the tire radial direction) of the tread-side inclined surfaces 20a, 22a may be 1 to 3 cm.

[0044] Sipes may also be provided in the inner intermediate block 16B and the inner shoulder block 16C. In this embodiment, three sipes 24a, 24b, and 24c are provided in the inner intermediate block 16B, and three sipes 24d, 24e, and 24f are provided in the inner shoulder block 16C.

[0045] Here, a sipe refers to a cut formed in a block, and has a minute groove width. The groove width of the sipe is not particularly limited, and may be, for example, 0.1 to 1.5 mm, 0.2 to 1.0 mm, or 0.3 to 0.8 mm. Note that the sipe does not necessarily have to be parallel to the tire width direction W as long as it is a narrow groove extending in the tire width direction W, and may be a narrow groove extending in the tire width direction W while being inclined. Furthermore, the sipe may be straight, curved, or have a bent portion.

[0046] As shown in FIGS. 2 and 4, three sipes 24a, 24b, 24c provided in the inner intermediate block 16B extend obliquely with respect to the tire width direction W and open into the inner shoulder main groove 12C.

[0047] Specifically, the sipes 24a are acute-angle-side sipes that open to the reinforcing projections 20. As shown in FIG. 3, the depth D1 of the acute-angle-side sipes 24a may be the same as or shallower than the depth D0 of the inboard shoulder main groove 12C. The depth D1 of the acute-angle-side sipes 24a may be constant in the direction of extension or may vary in the direction of extension. For example, the depth D1 may be shallower at the end of the opening to the inboard shoulder main groove 12C and deeper at the center in the direction of extension.

[0048] The depth D11 at the opening end may be shallower than the lower end position of the tread-side inclined surface 20a (the upper end position of the groove bottom-side inclined surface 20b), and may be, for example, 10% to 90% of the depth D0 of the inboard shoulder main groove 12C. Also, the acute-angle-side sipe 24a may open to the tread-side inclined surface 20a without opening to the groove bottom-side inclined surface 20b.

[0049] The depth D1 of the acute-angle side sipe 24a at the center in the extension direction may be deeper than the lower end position of the tread-side inclined surface 20a, for example, 50% to 90% of the depth D0 of the inner shoulder main groove 12C.

[0050] The sipe 24b is an intermediate sipe 24b provided in the center of the inner intermediate block 16B in the tire circumferential direction C, and is an intermediate sipe 24b that opens at the boundary between the side wall 16B3 of the inner intermediate block 16B and the reinforcing projection 20. In other words, the intermediate sipe 24b is disposed between the acute angle side sipe 24a and the obtuse angle side sipe 24c, and opens at the base of the reinforcing projection 20.

[0051] The sipes 24c are obtuse-angle side sipes 24c that open on the obtuse-angle side of the sidewall 16B3 of the inner intermediate block 16B (that is, at positions facing the reinforcing projections 22 of the inner shoulder blocks 16C in the tire width direction W).

[0052] The acute angle side sipes 24a, intermediate sipes 24b, and obtuse angle side sipes 24c are arranged parallel to the inner intermediate lateral groove 14C, but may be grooves extending at an angle relative to the inner intermediate lateral groove 14C. The acute angle side sipes 24a and obtuse angle side sipes 24c also open into the inner central main groove 12A and are arranged so as to completely cross the inner intermediate block 16B, but this is not necessarily the case. The intermediate sipe 24b does not have to completely cross the inner intermediate block 16B as in the illustrated example, but it may also completely cross it.

[0053] As shown in FIG. 2, three sipes 24d, 24e, 24f provided in the inner shoulder block 16C extend obliquely with respect to the tire width direction W and open into the inner shoulder main groove 12C.

[0054] Specifically, the sipes 24d are acute-angle side sipes that open to the reinforcing projections 22. As shown in FIG. 2, the acute-angle side sipes 24d may be provided on an extension of the obtuse-angle side sipes 24c provided in the inner central block 16B.

[0055] The depth D2 of the acute-angle-side sipe 24d, like the acute-angle-side sipe 24a provided in the inner intermediate block 16B, may be the same as the depth D0 of the inner shoulder main groove 12C, or may be shallower. The depth D2 of the acute-angle-side sipe 24d may be constant in the extension direction, or may vary in the extension direction. For example, the depth D2 may be shallower at the opening end to the inner shoulder main groove 12C and deeper at the center in the extension direction.

[0056] The depth D21 at the opening end may be shallower than the lower end position of the tread-side inclined surface 22a (the upper end position of the groove bottom-side inclined surface 22b), and may be, for example, 10% to 90% of the depth D0 of the inner shoulder main groove 12C. Also, the acute-angle side sipe 24d may open to the tread-side inclined surface 22a without opening to the groove bottom-side inclined surface 22b.

[0057] The depth D2 of the acute-angle side sipe 24d at the center in the extension direction may be deeper than the lower end position of the tread-side inclined surface 22a, for example, 50% to 90% of the depth D0 of the inner shoulder main groove 12C.

[0058] The sipe 24e is an intermediate sipe 24e provided in the center of the inner shoulder block 16C in the tire circumferential direction C, and opens at the boundary between the sidewall 16C3 of the inner shoulder block 16C and the reinforcing projection 22. In other words, the intermediate sipe 24e is disposed between the acute angle side sipe 24d and the obtuse angle side sipe 24f, and opens at the base of the reinforcing projection 22. As shown in FIG. 2, the intermediate sipe 24e may be provided on an extension of the intermediate sipe 24b provided in the inner intermediate block 16B.

[0059] The sipes 24f are obtuse-angle side sipes 24f that open on the obtuse-angle side of the sidewall 16C3 of the inner shoulder block 16C (i.e., at positions facing the reinforcing projections 20 of the inner intermediate block 16B in the tire width direction W). The acute-angle side sipes 24d may be provided on an extension of the obtuse-angle side sipes 24c provided in the inner intermediate block 16B, as shown in FIG.

[0060] Although the acute angle side sipes 24d, the intermediate sipes 24e, and the obtuse angle side sipes 24f are provided parallel to the inner shoulder lateral groove 14D, they may be grooves that extend at an angle relative to the inner shoulder lateral groove 14D.

[0061] (3) Effects In the pneumatic tire of the present embodiment as described above, a reinforcing protrusion 20 is provided on the side wall 16B3 on the acute angle portion 16B1 side of the inner intermediate block 16B, and a reinforcing protrusion 22 is provided on the side wall 16C3 of the acute angle portion 16C1 of the inner shoulder block 16C. This improves the block rigidity of the inner intermediate block 16B and the inner shoulder block 16C while reducing the rigidity difference between the acute angle portions 16B1, 16C1 and the obtuse angle portions 16B2, 16C2, thereby improving steering stability and suppressing uneven wear.

[0062] Additionally, the reinforcing protrusions 20 provided on the inner intermediate block 16B and the reinforcing protrusions 22 provided on the inner shoulder block 16C are arranged alternately in the tire circumferential direction C within the inner shoulder main groove 12C. This prevents the reinforcing protrusions 20, 22 from locally narrowing the groove cross-sectional area, ensuring good drainage even when the reinforcing protrusions 20, 22 protrude into the inner shoulder main groove 12C.

[0063] In this embodiment, since the reinforcing protrusions 20, 22 do not face each other in the tire width direction W, a distance can be secured between the inner intermediate block 16B and the inner shoulder block 16C on the groove bottom side of the inner shoulder main groove 12C, thereby suppressing the occurrence of cracks at the groove bottom 12C1.

[0064] In this embodiment, the reinforcing projections 20, 22 can slow down the flow velocity of air passing through the inner shoulder main groove 12C during running, thereby suppressing noise caused by air columnar resonance.

[0065] In this embodiment, since the reinforcing protrusions 20, 22 are provided with the tread-side inclined surfaces 20a, 22a as described above, the inner intermediate block 16B and the inner shoulder block 16C deform during cornering, causing the tread-side inclined surfaces 20a, 22a to come into contact with the ground, thereby securing a contact area and improving handling stability.

[0066] In this embodiment, the acute-angle side sipes 24a, 24d that open to the reinforcing projections 20, 22 increase the snow pillar shear force against the snow pillars that form in the inboard shoulder main groove 12C when driving on icy and snowy roads, improving traction performance. Furthermore, in this embodiment, the reinforcing projections 20, 22 capture the snow pillars that form in the inboard shoulder main groove 12C when driving on icy and snowy roads. The intermediate sipes 24b, 24e are provided at the boundary between the sidewall 16B3 of the inboard intermediate block 16B and the reinforcing projection 20, and at the boundary between the sidewall 16C3 of the inboard shoulder block 16C and the reinforcing projection 22. The openings of the intermediate sipes 24b, 24e make the blocks 16B, 16C more flexible, allowing the snow pillars to be used more effectively, improving braking and acceleration performance on icy and snowy roads.

[0067] The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0068] 10...tread, 12A...inner central main groove, 12B...outer central main groove, 12C...inner shoulder main groove, 12C1...groove bottom, 12D...outer shoulder main groove, 14A...first central lateral groove, 14B...second central lateral groove, 14C...inner intermediate lateral groove, 14D...inner shoulder lateral groove, 14E...first outer intermediate lateral groove, 14F...second outer intermediate lateral groove, 14G...first outer shoulder lateral groove, 14H...second outer shoulder lateral groove, 16A...center block, 16B...inner intermediate block, 16B1...acute angle portion, 16B2...obtuse angle portion, 16B3...side wall, 16B4...tread surface, 16C...inner shoulder block, 16C 1...acute angle portion, 16C2...obtuse angle portion, 16C3...side wall, 16D...outer intermediate block, 16E...outer shoulder block, 18A...center block row, 18B...inner intermediate block row, 18C...inner shoulder block row, 18D...outer intermediate block row, 18E...outer shoulder block row, 20...reinforcing protrusion, 20a...tread side inclined surface, 20b...groove bottom side inclined surface, 22...reinforcing protrusion, 22a...tread side inclined surface, 22b...groove bottom side inclined surface, 24a...acute angle side sipe, 24b...intermediate sipe, 24c...obtuse angle side sipe, 24d...acute angle side sipe, 24e...intermediate sipe, 24f...obtuse angle side sipe

Claims

1. A pneumatic tire having a tread including a main groove extending in the tire circumferential direction, a first block row provided on one side of the main groove in the width direction, and a second block row provided on the other side of the main groove in the width direction, the first block row includes a plurality of first blocks separated in the tire circumferential direction by first lateral grooves extending obliquely with respect to the tire width direction, the second block row includes a plurality of second blocks extending obliquely with respect to the tire width direction and separated in the tire circumferential direction by second lateral grooves, the first block and the second block each include an obtuse-angle portion defined by the main groove, the first lateral groove, and the second lateral groove at an obtuse angle; an acute-angle portion defined by the main groove, the first lateral groove, and the second lateral groove at an acute angle; and a reinforcing protrusion provided on a sidewall facing the main groove from the acute-angle portion side to a groove bottom of the main groove and protruding into the main groove, the reinforcing protrusions provided on the first blocks and the reinforcing protrusions provided on the second blocks are alternately arranged in the tire circumferential direction, The reinforcing protrusions are a tread-side inclined surface connected to the tread surfaces of the first block and the second block, the height of the reinforcing projection from the groove bottom decreasing toward the tip end in the protruding direction of the reinforcing projection; a groove bottom side inclined surface connected to the groove bottom side of the tread side inclined surface and inclined so that its angle with respect to the tire radial direction is smaller than that of the tread side inclined surface; Equipped with the first block and the second block each have a first sipe that opens onto the tread side inclined surface without opening onto the groove bottom side inclined surface.

2. The pneumatic tire according to claim 1 , wherein the first block and the second block each include a second sipe that opens at a boundary between the first block and the reinforcing projection on a sidewall facing the main groove.

3. 3. The pneumatic tire according to claim 1, wherein the main groove is a shoulder main groove provided at a position closest to the tread edge.

4. The pneumatic tire according to any one of claims 1 to 3, wherein the tread-side inclined surface is provided on the tread side of a position that is 50% of the groove depth of the main groove.

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