Pneumatic tire

Abstract

To provide a pneumatic tire that can improve heel-and-toe abrasion-resistance performance while maintaining traction performance on a road surface having snow accumulated thereon.SOLUTION: A transverse groove 30 has a tie-bar 50 whose groove bottom is raised so that a shoulder block 21a arranged in a tire circumferential direction is connected thereto. The tie-bar 50 has an upper surface 51 at a depth position P1 having a depth equal to 50% of a groove depth D11 from a groove bottom 11a of a first shoulder main groove 11 or at a position closer to outside in a tire radial direction than the depth position. A belt 5 includes a first belt ply 5a and a second belt ply, laminated on the outside in the tire radial direction of the first belt ply 5a, which is narrower than the first belt ply 5a. When viewed on a tire meridional cross section, an outer end 5bE in a tire axial direction of the second belt ply 5b is positioned in an area having a width of 10 mm with a normal line NL of an inner surface of the tire passing on an outer end 51Eo in the tire axial direction of an upper surface 51 of the tie-bar 50 as a center.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to pneumatic tires. [Background technology]

[0002] All-season tires and the like employ a tread pattern with rows of blocks to ensure traction performance on snowy roads. Among the rows of blocks, shoulder blocks located on the axially outer side of the tire are particularly prone to uneven wear (heel-and-toe wear), in which the trailing edge wears more than the leading edge. In order to improve heel-and-toe wear resistance, it is effective to increase the pitch length of the blocks to increase block rigidity, but this reduces the number of pitches and therefore the number of lateral grooves, which may cause a decrease in traction performance on snowy roads.

[0003] Patent Document 1 describes a tire in which the bottoms of the lateral grooves that define the shoulder blocks are locally raised, but does not suggest a solution to the problem caused by the trade-off between traction performance and heel-and-toe wear resistance on snowy roads as described above. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-1940 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a pneumatic tire that can improve heel-and-toe wear resistance while maintaining traction performance on snow-covered road surfaces. [Means for solving the problem]

[0006] The tire disclosed herein includes a tread rubber including a plurality of main grooves extending in a tire circumferential direction between a first tread edge and a second tread edge, and a first shoulder land formed adjacent to an axially outer side of a first shoulder main groove that is the closest to the first tread edge among the plurality of main grooves, and a belt disposed on a radially inner side of the tread rubber, the first shoulder land being partitioned into a plurality of shoulder blocks by lateral grooves extending in a direction intersecting with the tire circumferential direction, the lateral grooves being arranged so as to connect the shoulder blocks arranged in the tire circumferential direction. The tie bar has an upper surface at a depth position that is 50% of the groove depth from the groove bottom of the first shoulder main groove or further outward in the tire radial direction, the belt includes a first belt ply and a second belt ply that is laminated on the tire radial direction outer side of the first belt ply and is narrower than the first belt ply, and when viewed in a tire meridian section, an axially outer end of the second belt ply is located within a 10 mm wide region centered on a normal line of the tire inner surface that passes through the axially outer end of the upper surface of the tie bar. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a meridian cross-sectional view showing a tire according to an embodiment of the present invention. [Diagram 2] Development diagram showing the tread pattern [Diagram 3] A meridian cross section of a tire showing the main parts of the tire [Figure 4] FIG. 1 is a perspective view showing a lateral groove that divides a shoulder block. [Diagram 5] Table showing the results of the performance evaluation DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of the present disclosure will be described with reference to the drawings.

[0009] The pneumatic tire T of this embodiment shown in FIG. 1 is a radial tire for automobiles including a pair of beads 1, sidewalls 2 extending radially outward from each of the beads 1, and a tread 3 continuing to the radially outer ends of each of the sidewalls 2. An annular bead core 1a is embedded in the bead 1. The bead core 1a is formed by covering a bundle of steel wires or the like with rubber. A bead filler 1b is disposed on the radially outer side of the bead core 1a. The bead filler 1b is formed of rubber with a triangular cross section extending radially outward from the bead core 1a.

[0010] Here, the tire radial direction is the direction along the diameter of the tire T, and corresponds to the up-down direction in FIG. 1. In FIG. 1, the upper side is the outer side in the tire radial direction, and the lower side is the inner side in the tire radial direction. The tire axial direction is a direction parallel to the rotation axis of the tire T, and corresponds to the left-right direction in FIG. 1. The side closer to the tire equator TC is the inner side in the tire axial direction, and the side away from the tire equator TC is the outer side in the tire axial direction. The tire equator TC is located at the center of the tire T in the axial direction, and is a virtual line perpendicular to the tire rotation axis in a plan view of the tread. The tire circumferential direction is the direction around the rotation axis of the tire T.

[0011] The tire T includes a carcass 4 extending in a toroidal shape across a pair of beads 1. The carcass 4 is wound up from the inside to the outside in the tire axial direction so as to sandwich the bead cores 1a and the bead fillers 1b. The carcass 4 is formed of a carcass ply formed by rubber-coating carcass cords. The carcass cords are aligned in a direction intersecting the tire circumferential direction (for example, in a direction at an angle of 75 to 90 degrees with respect to the tire circumferential direction). Organic fibers such as polyester, rayon, nylon, and aramid are preferably used as the material for the carcass cords.

[0012] The tire T includes a belt 5 laminated on the outer side of the carcass 4 in the tire radial direction. The belt 5 is formed of a plurality of (two in this embodiment) belt plies 5a, 5b laminated on each other. The belt plies 5a, 5b are each formed by rubber-coating belt cords. The belt cords are aligned in a direction inclined with respect to the tire circumferential direction (for example, in a direction at an angle of 20 to 30 degrees with respect to the tire circumferential direction). Metal such as steel is preferably used as the material for the belt cords. The belt plies 5a, 5b are laminated such that the belt cords cross each other in opposite directions between them.

[0013] The tire T includes a belt reinforcement 6 laminated on the outer side of the belt 5 in the tire radial direction. The belt reinforcement 6 is formed of a belt reinforcement ply formed by rubber-coating belt reinforcement cords. The belt reinforcement cords are aligned substantially parallel to the tire circumferential direction. The belt reinforcement ply is formed, for example, by winding one or more rubber-coated belt reinforcement cords in a spiral shape along the tire circumferential direction. The above-mentioned organic fiber is preferably used as the material for the belt reinforcement cord. In this embodiment, the belt reinforcement 6 covers the entire belt 5, but it may have a structure in which it covers only both ends of the belt 5.

[0014] An inner liner rubber 7 that maintains the internal pressure of the tire T is provided on the inner surface of the tire. The inner liner rubber 7 is made of rubber with excellent air shielding properties, such as butyl rubber. A sidewall rubber 8 that forms the outer surface of the sidewall 2 is provided on the axially outer side of the carcass 4. A tread rubber 9 that forms the outer surface of the tread 3 is provided on the radially outer side of the belt 5 and the belt reinforcement 6. The belt reinforcement 6 may be omitted. In this embodiment, a square shoulder is adopted in which both ends of the tread 3 in the axial direction of the tire are angular.

[0015] In this embodiment, the tire T is a tire for a light truck, but is not limited to this and may be, for example, a tire for a passenger car, a tire for a heavy load, or a tire of another category.

[0016] In this embodiment, the tire T is an all-season tire, but is not limited thereto and may be, for example, a snow tire. Therefore, the tire T may have a 3PMSF (Three Peak Mountain Snow Flake) mark on the outer surface of at least one sidewall 2.

[0017] A tread pattern is formed on the tread surface 9f on the outer peripheral surface of the tread rubber 9 according to the required tire performance and usage conditions. As shown in Fig. 2, the tread pattern of this embodiment includes a plurality of main grooves 10 extending in the tire circumferential direction (corresponding to the up-down direction in Fig. 2) between the first tread edge TE1 and the second tread edge TE2, and a plurality of lands 20 partitioned by the main grooves 10. The first tread edge TE1 and the second tread edge TE2 are the outermost positions in the axial direction of the tire contact surface when a tire T mounted on a regular rim is inflated to a regular internal pressure, placed vertically on a flat road surface, and a regular load is applied.

[0018] The regular rim is a rim that is determined for each tire by each standard in the standard system including the standard on which the tire is based, for example, the standard rim for JATMA, and the "Measuring Rim" for TRA and ETRTO. The regular load is a load that is determined for each tire by each standard in the standard system including the standard on which the tire is based, for example, the "Maximum Load Capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "LOAD CAPACITY" for ETRTO. If the tire is for a passenger car, it is a load equivalent to 88% of the above load.

[0019] The normal internal pressure is the air pressure set for each tire by each standard in the standard system including the standard on which the tire is based. For truck and bus tires and light truck tires, it is the maximum air pressure for JATMA, the value corresponding to the Load Index listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. For passenger car tires, it is usually 180kPa, but for tires labeled "Extra Load" or "Reinforced", it is 220kPa.

[0020] In this embodiment, four lands 20 are defined by three main grooves 10. The three main grooves 10 include a first shoulder main groove 11 closest to the first tread edge TE1, a second shoulder main groove 12 closest to the second tread edge TE2, and a center main groove 13 located between them. The four lands 20 include a first shoulder land 21 formed adjacent to the axially outer side of the first shoulder main groove 11, a second shoulder land 22 formed adjacent to the axially outer side of the second shoulder main groove 12, and a pair of center lands 23, 24 formed adjacent to the axially inner side of the pair of shoulder main grooves 11, 12. The main grooves 10 extend in a zigzag pattern along the tire circumferential direction, but are not limited thereto, and may extend in a straight line, for example.

[0021] The tread surface 9f further includes lateral grooves 30 extending in a direction intersecting the tire circumferential direction, and cut-like sipes 40. The lateral grooves 30 have a groove width of, for example, more than 1.5 mm, and preferably have a groove width of 1.8 mm or more. The lateral grooves 30 have a groove depth of, for example, 3.0 mm or more, and preferably have a groove depth of 4.0 mm or more. The maximum groove depth of the lateral grooves 30 is set to be equal to the groove depth of the main grooves 10, but is not limited thereto. The sipes 40 have a width of, for example, 1.5 mm or less. The sipes 40 have a depth of, for example, 2.0 mm or more, and preferably have a depth of 3.0 mm or more.

[0022] The first shoulder land 21 is divided into a plurality of shoulder blocks 21a. The lateral grooves 30 dividing the shoulder blocks 21a extend from the first shoulder main groove 11 axially outward to the first tread edge TE1. The center land 23 is divided into a plurality of center blocks 23a. The lateral grooves 30 dividing the center blocks 23a extend from the first shoulder main groove 11 axially inward to the center main groove 13. The tread pattern of this embodiment is point-symmetric with respect to any point on the tire equator TC, and the second shoulder land 22 and the center land 24 are also divided into a plurality of blocks in the same manner as above.

[0023] The shoulder block 21a has a vertical side portion 61 facing the first shoulder main groove 11, a vertical side portion 62 facing the first tread edge TE1 (forming a part of the first tread edge TE1), a lateral side portion 63 facing the lateral groove 30 on one side in the tire circumferential direction (lower side in FIG. 2), and a lateral side portion 64 facing the lateral groove 30 on the other side in the tire circumferential direction (upper side in FIG. 2). The vertical side portion 61 is bent so as to be convex toward the inside in the tire axial direction, and intersects with the lateral side portions 63, 64 at an obtuse angle. The lateral side portions 63, 64 extend parallel to each other and inclined with respect to the tire axial direction. In this embodiment, the shoulder block 21a is formed in a substantially pentagonal shape in a tread plan view.

[0024] As described above, the tire T of this embodiment includes a tread rubber 9 including a plurality of main grooves 10 extending in the tire circumferential direction between the first tread edge TE1 and the second tread edge TE2, and a first shoulder land 21 formed adjacent to the axially outer side of a first shoulder main groove 11 that is the closest to the first tread edge TE1 among the plurality of main grooves 10, and a belt 5 disposed on the radially inner side of the tread rubber 9. The first shoulder land 21 is divided into a plurality of shoulder blocks 21a by lateral grooves 30 extending in a direction intersecting with the tire circumferential direction.

[0025] Fig. 3 is a meridian cross-sectional view of the tire crossing the lateral groove 30 that defines the shoulder block 21a. Fig. 4 is a perspective view showing the lateral groove 30. As shown in Figs. 3 and 4, the lateral groove 30 has a tie bar 50 (not shown in Figs. 1 and 2) whose groove bottom is raised so as to connect the shoulder blocks 21a arranged in the tire circumferential direction. The tie bar 50 has an upper surface 51 at a point where the raised height is maximum. The upper surface 51 extends substantially parallel to the contour line (profile line) of the tread surface 9f, and the groove depth D30 of the lateral groove 30 at the upper surface 51 is constant. The upper surface 51 is formed by a smooth surface that is not provided with serrations.

[0026] The tie bar 50 has an upper surface 51 at a depth position P1 that is 50% of the groove depth D11 from the groove bottom 11a of the first shoulder main groove 11 or further outward in the tire radial direction. Therefore, the groove depth D30 at the upper surface 51 is 50% or less of the groove depth D11. By providing such a tie bar 50 with a large protruding height, in combination with the structure of the belt 5 described later, the rigidity of the shoulder block 21a can be sufficiently increased. In this embodiment, an example is shown in which the upper surface 51 of the tie bar 50 is at the depth position P1 and the groove depth D30 at the upper surface 51 is 50% of the groove depth D11.

[0027] As described above, the belt 5 includes the belt ply 5a (corresponding to the first belt ply) and the belt ply 5b (corresponding to the second belt ply) laminated on the tire radially outer side of the belt ply 5a. The belt ply 5b is formed narrower than the belt ply 5a. The belt ply 5b is the belt ply located on the tire radially outermost side among the multiple belt plies constituting the belt 5. The tire axially outer end 5bE (hereinafter simply referred to as the "outer end 5bE") of the belt ply 5b is located axially inner than the tire axially outer end 5aE of the belt ply 5a, and the step length SL, which is the distance therebetween, is preferably 4 mm or more. The step length SL is set to, for example, 10 mm or less.

[0028] As shown in FIG. 3, in the tire T, the outer end 5bE of the belt ply 5b is located within a 10 mm wide region X centered on a normal line NL of the tire inner surface passing through an axially outer end 51Eo (hereinafter simply referred to as the "outer end 51Eo") of the upper surface 51 of the tie bar 50, in the tire meridian section (section cut along a plane including the center axis of the tire T). The region X extends in a strip shape within a range of 5 mm on either side in a direction perpendicular to the normal line NL. The normal line NL is determined in a no-load state in which the tire T is mounted on a regular rim and inflated to a regular internal pressure, and various dimensions described in this specification are similar to this. Both the outer end 5bE and the outer end 51Eo are located axially inward of the first tread end TE1.

[0029] By positioning the outer end 5bE in the region X, the belt plies 5b and 5a are disposed on the tire radially inner side of the tie bar 50, and together with the increased raised height of the tie bar 50 as described above, the rigidity of the shoulder block 21a can be sufficiently increased. In order to achieve this effect, it is preferable that the outer end 5bE is positioned on the normal line NL or further outward in the tire axial direction. If the outer end 5bE is positioned further outward in the tire axial direction than the region X, the belt 5 will have a shape that hangs down significantly toward the tire radially inner side toward the tire axially outer side, and distortion will be easily concentrated at the outer ends 5aE, 5bE, which may cause a deterioration in high-speed durability.

[0030] In this tire T, the rigidity of the shoulder block 21a is sufficiently increased as described above, so that heel-and-toe wear can be effectively suppressed. In addition, there is no need to increase the pitch length to increase the block rigidity, and therefore the number of lateral grooves is not affected, so that traction performance on snowy road surfaces can be maintained. As a result, heel-and-toe wear resistance can be improved while maintaining traction performance on snowy road surfaces. In addition, the tire T of this embodiment is a tire for light trucks, and is expected to be driven under slower speeds and higher loads than tires for passenger cars, so there is little concern that the provision of the tie bars 50 with a larger protrusion height will result in a decrease in hydroplaning resistance.

[0031] Elements that contribute to traction performance on snowy road surfaces include the edge effect at the block edges and the snow column shear effect in the lateral grooves 30, but this tire T focuses on the edge effect. Therefore, this tire T deliberately employs tie bars 50 with a large protrusion height, which is considered to be disadvantageous to the snow column shear effect, in order to reduce the volume of the lateral grooves 30. As confirmed by the test results described later, this tire T is able to maintain traction performance on snowy road surfaces even with the tie bars 50 with a large protrusion height, and this is thought to be because the increased block rigidity by the tie bars 50 and belts 5 works to improve the edge effect.

[0032] The tie bar 50 has an upper surface 51, an outer side surface 52 extending from an outer end 51Eo of the upper surface 51 in the tire radial direction inward to the groove bottom of the lateral groove 30, and an inner side surface 53 extending from an axially inner end 51Ei of the upper surface 51 (hereinafter simply referred to as the "inner end 51Ei") in the tire radial direction inward to the groove bottom of the lateral groove 30. The outer end 51Eo is a position where the upper surface 51 and the outer side surface 52 intersect at a corner, and when the corner is formed in a chamfered shape, it is a position where their imaginary extension lines intersect. Similarly, the inner end 51Ei is a position where the upper surface 51 and the inner side surface 53 intersect, and when the corner is formed in a chamfered shape, it is a position where their imaginary extension lines intersect. The axial separation distance between the outer end 51Eo and the inner end 51Ei is, for example, 7 mm or more, and preferably 12 mm or more.

[0033] The tie bar 50 rises in a stepped manner from the bottom of the lateral groove 30. This configuration makes it possible to suppress the concentration of strain by making the angle of rise from the bottom of the lateral groove 30 gentle, which is advantageous in preventing the occurrence of groove cracks. In this embodiment, the outer side surface 52 and the inner side surface 53 are formed in a stepped shape, and each has middle surfaces 52m, 53m that are substantially parallel to the top surface 51. The middle surfaces 52m, 53m are located radially inward of the top surface 51 and radially outward of the bottom of the lateral groove 30 (and the groove bottom 11a of the first shoulder main groove 11).

[0034] It is preferable that the tie bar 50 is provided in each of the multiple lateral grooves 30 that define the shoulder block 21a. With this configuration, the multiple shoulder blocks 21a that constitute the first shoulder land 21 are connected in series in the tire circumferential direction via the tie bar 50, so that the block rigidity is more effectively increased. As described above, in this embodiment, the second shoulder land 22 is point-symmetrical to the first shoulder land 21, and a tie bar is provided on the second shoulder land 22 as well as the first shoulder land 21, but this is not limited to this. It is also possible to provide such tie bars with a large raised height on the center lands 23, 24.

[0035] The tread rubber 9 includes a cap rubber layer 9a that forms a tread surface 9f, and a base rubber layer 9b disposed radially inward of the cap rubber layer 9a. An interface BF between the cap rubber layer 9a and the base rubber layer 9b extends in the tire axial direction along the outer peripheral surface of the belt 5, and extends radially inward from the vicinity of the outer end of the belt 5 toward the outer side of the tire axial direction, reaching the bottom surface of the tread rubber 9, not the side surface. The interface BF is connected to the sidewall rubber 8 at the bottom surface of the tread rubber 9. The interface BF is not exposed to the bottom of the lateral groove 30, which is advantageous in preventing the occurrence of groove cracks.

[0036] The base rubber layer 9b is made of a rubber having excellent low heat generation properties. The base rubber layer 9b is made of a rubber having a smaller loss tangent tanδ than the cap rubber layer 9a. In this embodiment, the loss tangent tanδ of the base rubber layer 9b is 54 when the loss tangent tanδ of the cap rubber layer 9a is 100.

[0037] In this embodiment, the thickness T9b of the base rubber layer 9b is maximum on the inner side in the tire radial direction of the tie bar 50. This makes it possible to appropriately suppress heat generation that is caused by increasing the rubber volume by providing a tie bar 50 with a large protruding height. The thickness T9b may be maximum on the inner side in the tire radial direction of the middle surface 52m or the middle surface 53m of the tie bar 50, but is preferably maximum on the inner side in the tire radial direction of the top surface 51 of the tie bar 50. The thickness T9b is a value measured along the normal direction of the inner surface of the tire.

[0038] If the raised height of the tie bar 50 is excessively large, the upper surface 51 is likely to be exposed as the tread surface 9f wears, and the block edges may decrease at a relatively early stage, resulting in a decrease in the edge effect. From this perspective, the upper surface 51 of the tie bar 50 is preferably located at a depth position P2 that is 75% of the groove depth D11 from the groove bottom 11a of the first shoulder main groove 11 or further inward in the tire radial direction, and more preferably at a depth position (not shown) that is 65% of the groove depth D11 from the groove bottom 11a or further inward in the tire radial direction.

[0039] The tie bar 50 is preferably eccentric toward the outside in the tire axial direction with respect to the shoulder block 21a. That is, the center position of the tie bar 50 in the tire axial direction is preferably located axially outside the center position of the shoulder block 21a (the lateral side portion 63, 64). In this embodiment, as shown in FIG. 4, in the plan view of the tread, a distance D1 from the axially inner end of the lateral side portion 63 on the tread surface 9f to the upper surface 51 and a distance D2 from the axially outer end (first tread edge TE1) of the lateral side portion 63 on the tread surface 9f to the upper surface 51 satisfy the relationship D1>D2, and the same is true for the lateral side portion 64. From the viewpoint of ensuring a groove volume near the first tread edge TE1, the distance D2 is preferably greater than 0 mm, and is set to, for example, 8 mm or more.

[0040] When a lateral force acts on the tire T, the frictional energy at the axially outer portion of the shoulder block 21a tends to be relatively large (and thus the amount of uneven wear tends to be large). Therefore, by arranging the tie bar 50 eccentrically on the axially outer side as described above, it is possible to effectively improve uneven wear resistance performance in the case where the axially outer portion of the shoulder land 21 wears out earlier than the axially inner portion. It is preferable that the tie bar 50 (upper surface 51) is located in the axial center of the lateral side surface portions 63, 64 while being eccentrically on the axially outer side as described above, which effectively increases the rigidity of the shoulder block 21a.

[0041] Figure 5 is a table showing the results of evaluation of heel-and-toe wear resistance and traction performance on snowy roads. Each performance evaluation was carried out as follows.

[0042] (1) Heel and toe abrasion resistance The tires were mounted on a light truck and driven a specified distance on a test course, after which the difference in wear between the leading edge and leading edge of the shoulder block (uneven wear) was measured. The smaller the value, the better the heel-and-toe wear resistance.

[0043] (2) Traction performance on snowy roads The tires were mounted on a light truck and a spin traction test was carried out based on UN / ECE Regulation No. 117 Anenex 7 to determine the Snow Grip Index, with the result of Reference Example 1 being taken as 100. A higher value indicates better traction performance on snowy roads.

[0044] 1 to 4, the tire was prepared as an example, with the upper surface 51 of the tie bar 50 positioned at a depth P1 that was 50% of the groove depth D11 from the groove bottom 11a of the first shoulder main groove 11. Reference Example 1 was prepared as a tire having the same structure as the example, except that the upper surface 51 of the tie bar 50 was positioned at a depth that was 14% of the groove depth D11 from the groove bottom 11a of the first shoulder main groove 11. Reference Example 2 was prepared as a tire having the same structure as Reference Example 1, except that the shoulder blocks were increased in size to increase the pitch length.

[0045] As shown in Fig. 5, the uneven wear amount in the Examples was reduced by half compared to Reference Example 1, and heel-and-toe wear resistance was improved. Moreover, the snow grip index of the Examples was comparable to that of Reference Example 1, and traction performance on snowy roads was maintained. Although Reference Example 2 is expected to have better heel-and-toe wear resistance than Reference Example 1 (however, performance evaluation has not been performed), it was confirmed that traction performance on snowy roads is reduced.

[0046] The tire T of this embodiment is equivalent to a normal pneumatic tire, except that the shoulder land and the belt are configured as described above, and any conventionally known material, shape, structure, etc. can be adopted. The tread pattern is not particularly limited as long as it includes a shoulder land divided into a plurality of shoulder blocks, and for example, the number of main grooves 10 may be two, four, five or more. In addition, in this embodiment, an example in which the tread pattern is a point symmetric pattern is shown, but it is not limited thereto, and for example, it may be a line symmetric pattern or an asymmetric pattern.

[0047] [1] As described above, the pneumatic tire T of this embodiment includes a tread rubber 9 including a plurality of main grooves 10 extending in the tire circumferential direction between the first tread edge TE1 and the second tread edge TE2, a first shoulder land 21 formed adjacent to the tire axially outer side of the first shoulder main groove 11 that is the closest to the first tread edge TE1 among the plurality of main grooves 10, and a belt 5 disposed on the tire radially inner side of the tread rubber 9. The first shoulder land 21 is divided into a plurality of shoulder blocks 21a by lateral grooves 30 extending in a direction intersecting the tire circumferential direction. The lateral groove 30 has a tie bar 50 whose groove bottom is raised so as to connect the shoulder blocks 21a arranged in the tire circumferential direction. The tie bar 50 has an upper surface 51 at a depth position P1 that is 50% of the groove depth D11 from the groove bottom 11a of the first shoulder main groove 11 or further outward in the tire radial direction. The belt 5 includes a first belt ply 5a and a second belt ply 5b that is laminated on the tire radially outer side of the first belt ply 5a and is narrower than the first belt ply 5a. When viewed in a tire meridian section, an axially outer end 5bE of the second belt ply 5b is located within a 10 mm-wide region X centered on a normal line NL of the tire inner surface that passes through an axially outer end 51Eo of the upper surface 51 of the tie bar 50. This configuration can improve heel-and-toe wear resistance while maintaining traction performance on snow-covered road surfaces.

[0048] [2] In the pneumatic tire T of [1] above, it is preferable that the tie bar 50 rises stepwise from the groove bottom of the lateral groove 30. This makes it possible to suppress the concentration of strain by making the rise angle from the groove bottom of the lateral groove 30 gentle, which is advantageous in preventing the occurrence of groove cracks.

[0049] [3] In the pneumatic tire T of [1] or [2] above, the tread rubber 9 includes a cap rubber layer 9a forming a tread surface 9f and a base rubber layer 9b disposed on the tire radially inner side of the cap rubber layer 9a, and it is preferable that the thickness T9b of the base rubber layer 9b is maximum on the tire radially inner side of the tie bar 50. This makes it possible to appropriately suppress heat generation that is caused by increasing the rubber volume by providing a tie bar 50 with a large protruding height.

[0050] [4] If the raised height of the tie bar 50 is excessively large, the upper surface 51 is likely to be exposed to the worn tread surface 9f, and the block edges may be reduced at a relatively early stage, resulting in a decrease in the edge effect. From this viewpoint, in the pneumatic tire T of any one of the above [1] to [3], the upper surface 51 of the tie bar 50 is preferably located at a depth position P2 that is 75% of the groove depth D11 from the groove bottom 11a of the first shoulder main groove 11 or further inward in the tire radial direction.

[0051] [5] In the pneumatic tire T of any one of the above [1] to [4], it is preferable that the tie bar 50 is eccentric toward the axially outer side with respect to the shoulder block 21a. This can satisfactorily improve uneven wear resistance performance with respect to uneven wear in which the axially outer portion of the shoulder block 21 wears earlier than the axially inner portion.

[0052] Although the embodiment of the present disclosure has been described based on the drawings, the specific configuration should not be considered to be limited to this embodiment. The scope of the present disclosure is indicated not only by the description of the above embodiment but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

[0053] The tire of the present disclosure is not limited to the above-mentioned embodiment, and is not limited to the above-mentioned action and effect. The tire of the present disclosure can be variously improved or modified without departing from the spirit of the tire. In addition, the configurations adopted in the above-mentioned embodiment can be adopted in any combination. [Explanation of symbols]

[0054] 5 Belt 5a 1st belt ply 5b 2nd belt ply 9 Tread rubber 9a Cap rubber layer 9b Base rubber layer 9f Tread surface 10 Main groove 11 First shoulder main groove 21 First Shoulder Land 21a Shoulder Block 30 Yokomizo 50 Tie Bar 51 Top side TE1 First tread edge TE2 Second tread edge

Claims

1. a tread rubber including a plurality of main grooves extending in a tire circumferential direction between a first tread edge and a second tread edge, and a first shoulder land formed adjacent to an axially outer side of a first shoulder main groove that is closest to the first tread edge among the plurality of main grooves; A belt is disposed on the radially inner side of the tread rubber, The first shoulder land is divided into a plurality of shoulder blocks by lateral grooves extending in a direction intersecting with the tire circumferential direction, The lateral groove has a tie bar having a raised groove bottom so as to connect the shoulder blocks arranged in the tire circumferential direction, the tie bar has an upper surface at a depth position that is 50% of a groove depth from a groove bottom of the first shoulder main groove or on the outer side in the tire radial direction, The belt includes a first belt ply and a second belt ply that is laminated on the outer side of the first belt ply in the tire radial direction and has a width narrower than that of the first belt ply, When viewed in a tire meridian section, a tire axially outer end of the second belt ply is located within a region having a width of 10 mm centered on a normal line of an inner surface of the tire that passes through the tire axially outer end of the upper surface of the tie bar.

2. The pneumatic tire according to claim 1 , wherein the tie bar rises stepwise from the groove bottom of the lateral groove.

3. The tread rubber includes a cap rubber layer that forms a tread surface, and a base rubber layer that is disposed radially inward of the cap rubber layer, The pneumatic tire according to claim 1 , wherein the thickness of the base rubber layer is greatest on an inner side in the tire radial direction of the tie bar.

4. The pneumatic tire according to claim 1 , wherein the upper surface of the tie bar is located at a depth position that is 75% of a groove depth from a groove bottom of the first shoulder main groove or further inward in the tire radial direction.

5. The pneumatic tire according to any one of claims 1 to 4, wherein the tie bar is eccentrically disposed axially outward with respect to the shoulder block.

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