Motorcycle tires for rough terrain

Abstract

The present invention provides a motorcycle tire for running on uneven terrain, which can exhibit excellent traction performance and cornering performance on soft roads. The motorcycle tire for running on uneven terrain has a tread portion (2). The tread portion (2) includes a base surface (8) and a plurality of pattern blocks (10). The pattern blocks (10) include a crown pattern block (11) on the tire equator (C) side, and a shoulder pattern block (13) on the tread end (Te) side. The height hs of the shoulder pattern block (13) from the base surface (8) is greater than the height hc of the crown pattern block (11) from the base surface (8). The shoulder pattern block (13) is provided with a base portion (20) on the base surface (8) side, which is locally enlarged along the cross section of the base surface (8).

Description

Technical Field

[0001] The invention relates to a tire for a motorcycle used for running on uneven ground. Background Art

[0002] Patent Document 1 listed below proposes a motorcycle tire for running on rough terrain, which improves the traction performance on rough terrain and the transient characteristics when turning by improving the arrangement of the crown blocks and the middle blocks.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-060347

[0004] In recent years, there has been a demand for motorcycle tires for driving on uneven surfaces that can provide superior performance on various road surfaces. In particular, there is a demand for improved traction and cornering performance on soft roads where even the shoulder blocks of the tread portion touch the ground when the vehicle is traveling straight (hereinafter, such roads are referred to as "soft roads").

[0005] The inventors have repeatedly conducted various studies on this point and have found that the traction performance and cornering performance on soft roads can be improved by improving the crown blocks and shoulder blocks, thereby completing the present invention. Summary of the invention

[0006] The present invention has been made in view of the above-mentioned actual situation, and a main object of the present invention is to provide a motorcycle tire for running on rough terrain that can exhibit excellent traction performance and cornering performance on soft roads.

[0007] The present invention relates to a motorcycle tire for running on uneven terrain having a tread portion, the tread portion comprising a base surface and a plurality of pattern blocks protruding from the base surface toward the radially outer side of the tire, the pattern blocks comprising a crown pattern block on the equatorial side of the tire and a shoulder pattern block on the tread end side, a height hs of the shoulder pattern block from the base surface being greater than a height hc of the crown pattern block from the base surface, and the shoulder pattern block being provided with a base portion locally enlarged along a cross section of the base surface on the side of the base surface.

[0008] In the motorcycle tire for running on rough terrain of the present invention, it is preferable that the height hs is 105% to 150% of the height hc.

[0009] In the motorcycle tire for running on uneven terrain of the present invention, it is preferred that the above-mentioned pattern blocks include intermediate pattern blocks arranged between the above-mentioned crown pattern blocks and the above-mentioned shoulder pattern blocks, and the above-mentioned tread portion includes shoulder tie bars formed by the above-mentioned base surface protrusions and connecting the above-mentioned shoulder pattern blocks and the above-mentioned intermediate pattern blocks.

[0010] In the motorcycle tire for running on rough terrain of the present invention, it is preferable that the shoulder reinforcement bar is connected to the base portion.

[0011] In the motorcycle tire for running on rough terrain of the present invention, it is preferable that the height of the shoulder reinforcement bar is smaller than the height of the base portion.

[0012] In the motorcycle tire for running on rough terrain of the present invention, it is preferred that only one shoulder reinforcement bar is connected to the shoulder block.

[0013] In the motorcycle tire for running on rough terrain of the present invention, the blocks preferably include middle blocks arranged between the shoulder blocks and the crown blocks, and a height hm of the middle blocks from the base surface is smaller than the height hs.

[0014] In the motorcycle tire for running on uneven terrain of the present invention, it is preferred that the above-mentioned pattern blocks include middle pattern blocks arranged between the above-mentioned shoulder pattern blocks and the above-mentioned crown pattern blocks, and the above-mentioned tread portion includes shoulder reinforcements formed by the above-mentioned base surface protrusions and connecting the above-mentioned shoulder pattern blocks and the above-mentioned middle pattern blocks, and crown reinforcements formed by the above-mentioned base surface protrusions and connecting the above-mentioned crown pattern blocks and the above-mentioned middle pattern blocks.

[0015] The motorcycle tire for running on rough terrain of the present invention can exhibit excellent traction performance and cornering performance on soft roads due to the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a transverse cross-sectional view showing one embodiment of the tire for motorcycles for running on rough terrain according to the present invention.

[0017] Figure 2 It is shown Figure 1 An expanded view of the tread pattern of the tread portion.

[0018] Figure 3 yes Figure 2 An enlarged stereoscopic view of the shoulder tread block.

[0019] Figure 4 yes Figure 2 An enlarged top view of the shoulder, crown and center tread blocks.

[0020] Figure 5 yes Figure 4 BB line cross-sectional view.

[0021] Figure 6 It is a development view of the tread portion of a motorcycle tire for running on rough terrain according to a comparative example.

[0022] Description of reference numerals:

[0023] 2...tread portion; 8...base surface; 10...pattern block; 11...crown pattern block; 13...shoulder pattern block; 20...base portion; hs...height of shoulder pattern block; hc...height of crown pattern block. DETAILED DESCRIPTION

[0024] Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0025] exist Figure 1 1 is a transverse cross-sectional view of a motorcycle tire for running on rough terrain (hereinafter, sometimes simply referred to as a “tire”) 1 in a normal state, which represents one embodiment of the present invention. Figure 2 It is a development view showing a tread pattern of the tread portion 2 of the tire 1 . Figure 1 yes Figure 2 The A-A line sectional view is a meridian sectional view including the tire rotation axis.

[0026] "Normal state" refers to an unloaded state in which the tire is assembled on a regular rim and filled with a regular internal pressure when various specifications of tires are specified. In the case where various specifications of tires are not specified, the above-mentioned normal state refers to an unloaded state as a standard usage state corresponding to the intended use of the tire. In this specification, unless otherwise specified, the dimensions of each part are values ​​measured under the above-mentioned normal state. In addition, for the dimensions of each part of the tire, in the case of slight differences depending on the measurement position, unless otherwise specified, the dimensions shown in this specification refer to the central value between the minimum value and the maximum value. In addition, each structure described in this specification allows for normal errors contained in rubber molded products.

[0027] “Regular rims” refer to rims whose specifications are prescribed for each tire in a standard system including the standards to which the tire conforms, such as “standard rims” in JATMA, “design rims” in TRA, and “measuring rims” in ETRTO.

[0028] "Normal internal pressure" refers to the air pressure specified for each tire in the specification system including the specifications to which the tire complies. If it is JATMA, it is the "maximum air pressure". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "INFLATION PRESSURE".

[0029] like Figure 1 As shown, the tire 1 of the present invention can be suitably used as a tire for off-road motorcycle competition, for example. The tire of this embodiment can be suitably used as a tire for the rear wheel of an off-road motorcycle vehicle, for example. However, it is not limited to such a form. The tread portion 2 of the tire 1 of this embodiment has an outer surface curved into an arc shape convex toward the outer side of the tire radial direction in a cross section.

[0030] The tire 1 of the present embodiment includes, for example, a carcass 6 and a tread reinforcing layer 7. These can appropriately adopt known structures.

[0031] like Figure 2 As shown, the tread portion 2 has, for example, a directional pattern in which the rotation direction R is specified. The rotation direction R is indicated on the side wall portion 3 ( Figure 1 However, the present invention is not limited to such a form. In addition, in several drawings of this specification, the rotation direction R is shown by arrows.

[0032] The tread portion 2 is divided into, for example, a crown region Cr, a middle region Mi, and a shoulder region Sh.

[0033] The crown region Cr is a region having a width of 1 / 3 of the tread development width TWe centered at the tire equator C. The shoulder region Sh is a region having a width of 1 / 6 of the tread development width TWe from each tread end Te toward the tire equator C. The middle region Mi is a region between the crown region Cr and the shoulder region Sh.

[0034] The developed tread width TWe is the distance between the tread ends Te and Te in the tire axial direction when the tread portion 2 is developed into a plane. The tread end Te refers to the axially outer edge of the block included in the axially outermost block row among the blocks arranged on the tread portion 2.

[0035] The tread portion 2 includes a base surface 8 and a plurality of pattern blocks 10 that protrude from the base surface 8 toward the outer side in the tire radial direction. The pattern blocks 10 of the present embodiment include a plurality of crown pattern blocks 11 on the tire equator C side, a plurality of shoulder pattern blocks 13 on the tread end Te side, and a plurality of middle pattern blocks 12 arranged therebetween. The centroid of the tread of the crown pattern block 11 is located in the crown region Cr. In a preferred embodiment, the crown pattern block 11 is disposed on the tire equator C. The centroid of the tread of the middle pattern block 12 is located in the middle region Mi. In addition, the middle pattern block 12 is adjacent to the crown pattern block 11. The centroid of the tread of the shoulder pattern block 13 is located in the shoulder region Sh. In addition, the shoulder pattern block 13 is adjacent to the middle pattern block 12.

[0036] The axial width of the crown block 11 is, for example, 20% to 30% of the tread development width TWe. The axial width of the middle block 12 is, for example, 10% to 20% of the tread development width TWe. The axial width of the shoulder block 13 is, for example, 8% to 15% of the tread development width TWe. However, the present invention is not limited to such a form.

[0037] like Figure 1 As shown in FIG. 1 , the height hs of the shoulder block 13 from the base surface 8 is greater than the height hc of the crown block 11 from the base surface 8. The height hs and the height hc correspond to the minimum distance from the height reference plane 17 to the centroid of the tread of the block 10. The height reference plane 17 is a surface that serves as a reference when measuring the height of the block 10, and is composed of the base surface 8 and an imaginary surface obtained by extending the base surface 8 at the root portion of the block 10. The imaginary surface is an imaginary surface that is surrounded by the boundary edge between the block 10 and the base surface 8 and is smoothly continuous with the surrounding base surface 8.

[0038] exist Figure 3 FIG. 1 shows an enlarged stereoscopic view of the shoulder pattern block 13. Figure 3 As shown, the shoulder block 13 has a base portion 20 on the base surface 8, and the cross section of the base portion 20 along the base surface 8 is locally enlarged. In order to facilitate understanding of the base portion 20, the base portion 20 is colored in the diagram of the block viewed from above in this specification.

[0039] The tire 1 of the present invention can exhibit excellent traction performance and cornering performance on soft roads by adopting the above-mentioned structure. The following mechanism is presumed as the reason for this.

[0040] Generally speaking, on a soft road surface, there is a tendency for the entire tread portion 2 to be buried in the road surface. Therefore, when a motorcycle tire for running on uneven ground is running straight on a soft road surface, not only the crown block 11 but also the shoulder block 13 is in contact with the road surface. On the other hand, in the tire 1 of the present invention, the height hs of the shoulder block 13 is greater than the height hc of the crown block 11. Therefore, the shoulder block 13 pushes away soil and mud even when running straight on a soft road surface to provide a reaction force, thereby exerting excellent traction performance.

[0041] In addition, the shoulder pattern block 13 of the present invention is provided with the above-mentioned base portion 20, so the root portion of the pattern block has high rigidity and can exert greater reaction force. In addition, such shoulder pattern block 13 also exerts high reaction force in the tire axial direction, which also contributes to the improvement of cornering performance.

[0042] The following describes a more detailed structure of the present embodiment. In addition, the structure described below shows a specific form of the present embodiment. Therefore, it goes without saying that the present invention can achieve the above-mentioned effect even without the structure described below. In addition, even if any one of the structures described below is applied alone to the tire of the present invention having the above-mentioned characteristics, it is expected that the performance corresponding to each structure will be improved. Moreover, in the case where several of the structures described below are applied in combination, it is expected that the performance corresponding to the combination of each structure will be improved.

[0043] like Figure 1 As shown, the height hs of the shoulder block 13 is 103% or more, more preferably 105% or more, preferably 150% or less, more preferably 120% or less, and further preferably 110% or less of the height hc of the crown block 11. Such a shoulder block 13 has moderate rigidity, and improves the traction performance and cornering performance on soft roads in a balanced manner.

[0044] exist Figure 4 FIG. 1 shows an enlarged top view of the shoulder pattern block 13, the crown pattern block 11 and the middle pattern block 12. Figure 4 As shown in the figure, the tread of the shoulder pattern block 13 of the present embodiment is, for example, rectangular, preferably trapezoidal. The tread of the shoulder pattern block 13 of the present embodiment includes two edges extending parallel to the tire circumferential direction. The length of the shoulder pattern block 13 in the tire circumferential direction increases as it approaches the tread end Te side. Such a shoulder pattern block 13 has a larger rigidity as it approaches the tread end Te side, so that the responsiveness when the camber angle of the vehicle body is increased can be made linear.

[0045] The shoulder block 13 of this embodiment is not provided with the base portion 20 on the side surface on the tread end Te side, but is provided with the base portion 20 in the area outside the shoulder block 13. Such shoulder block 13 is easy to bend appropriately toward the tread end Te side, so the driver can easily understand the movement of the vehicle body during the process of turning at a near maximum camber angle.

[0046] exist Figure 5 Shown in Figure 4 In addition, Figure 5 8 is a diagram showing a cross section of the base portion 20 perpendicular to the base surface 8. Figure 5 As shown, the base portion 20 has a stepped profile in the cross section. The profile of the base portion 20 is preferably a step of three or less steps, and the profile of the base portion 20 in this embodiment is a step of one step.

[0047] The raised height h1 of the base portion 20 is 5% to 50%, preferably 5% to 15% of the height hs of the shoulder block 13. Such a base portion 20 can improve the rigidity of the shoulder block 13 while maintaining the ease with which the shoulder block 13 penetrates the road surface.

[0048] The protruding width W2 of the base portion 20 from the shoulder block 13 along the base surface 8 is, for example, the width W1 of the shoulder block 13 in the tire axial direction ( Figure 4 The base portion 20 can increase the rigidity of the shoulder block 13 without excessively impairing the amount of penetration of the shoulder block 13 into the road surface.

[0049] The base portion 20 includes an outer side surface 20a extending along the base surface 8. The intersection angle θ1 between the side surface of the shoulder block 13 and the outer side surface 20a is, for example, 90 to 130 degrees. This makes it easier for the shoulder block 13 to penetrate the road surface, improving traction and cornering performance.

[0050] like Figure 4 As shown, the tread portion 2 preferably includes a shoulder reinforcement 21 formed by protruding from the base surface 8 and connecting the shoulder pattern block 13 and the above-mentioned middle pattern block 12. Such shoulder reinforcement 21 suppresses deformation near the root of the shoulder pattern block 13 and the middle pattern block 12. In addition, the shoulder reinforcement 21 also exerts an effect of pushing away mud, thereby also contributing to the improvement of traction performance.

[0051] The shoulder bars 21 are preferably connected to the base 20. The height of the shoulder bars is smaller than that of the base 20. Specifically, the height of the shoulder bars 21 is 50% to 90% of the height of the base 20. This can prevent mud from adhering to and retaining it around the shoulder blocks 13.

[0052] The shoulder bars 21 have a width that decreases, for example, from the shoulder blocks 13 toward the middle blocks 12. Such shoulder bars 21 contribute to making the responsiveness linear when the tire is tilted at a near maximum camber angle.

[0053] It is preferred that only one shoulder bar 21 is connected to the shoulder block 13. Thus, soil and mud pushed away by one shoulder bar 21 are easily discharged, and excellent traction performance and cornering performance are continuously exhibited.

[0054] For example, the crown block 11 of this embodiment has a circumferential length L2 that is smaller than the axial length L1 of the tire. Specifically, the circumferential length L2 of the crown block 11 is preferably 40% to 90% of the length L1. Such a crown block 11 helps improve traction performance.

[0055] For the crown block 11, the side surface 23 facing the first contact side (hereinafter referred to as the "first contact side") in the rotation direction R is preferably recessed toward the rear contact side (hereinafter referred to as the "rear contact side") in the rotation direction R. For example, two planes 23a inclined in opposite directions relative to the tire axial direction are connected via a ridge to form the above-mentioned side surface 23 of the present embodiment. The angle of the above-mentioned plane 23a relative to the tire axial direction is, for example, 5 to 25 degrees. Such the above-mentioned side surface 23 exerts a large reaction force when pushing away mud and soil when driving on uneven ground.

[0056] The crown block 11 of the present embodiment includes a block body 24 and at least one convex piece 25 extending in the tire circumferential direction with a smaller width in the tire axial direction than the block body. The convex piece 25 is provided, for example, on the rear ground contact side of the block body 24. Such a convex piece 25 effectively prevents the block from tilting toward the rear ground contact side, thereby exerting excellent traction performance.

[0057] The crown block 11 of the present embodiment includes, for example, three fins 25. Specifically, the crown block 11 includes a first fin 26 on one side in the tire axial direction, a second fin 27 on the other side in the tire axial direction, and a third fin 28 provided therebetween.

[0058] The first fin portion 26 is connected to one axial side surface of the block body 24. The second fin portion 27 is connected to the other axial side surface of the block body 24. The first fin portion 26 and the second fin portion 27 are configured in substantially the same shape.

[0059] The third fin portion 28 is connected to the central portion of the tread block main body 24 in the tire axial direction. In the present embodiment, the crown block 11 is arranged at the tire equator C, and the third fin portion 28 included in the crown block 11 is arranged on the tire equator C. In a further preferred embodiment, the centroid of the tread surface of the tread block is located in a region extending the third fin portion 28 toward the first contact side parallel to the tire circumferential direction. Thus, the third fin portion 28 effectively suppresses the tilting of the tread block main body 24, and exhibits excellent traction performance.

[0060] To more reliably exert the above-mentioned effect, the third fin 28 has a tire circumferential length greater than, for example, the first and second fins 26 and 27. The third fin 28 protrudes further toward the rear than the first and second fins 26 and 27.

[0061] The width W4 of the third fin portion 28 in the tire axial direction is, for example, greater than the widths of the first fin portion 26 and the second fin portion 27 in the tire axial direction. Specifically, the width W4 of the third fin portion 28 is, for example, 130% to 200% of the width W3 of the first fin portion 26. Thus, the third fin portion 28 can suppress the tilting of the block body 24, and prevent mud and dirt from being retained around the finned block by appropriately deforming the first fin portion 26 and the second fin portion 27.

[0062] like Figure 1 As shown, the height hm of the middle block 12 from the base surface 8 is preferably smaller than the height hs of the shoulder block 13. The height hm is 90% to 95% of the height hs. This makes the responsiveness when the vehicle body tilts linear, thereby improving the turning performance.

[0063] like Figure 4 As shown, the middle block 12 of the present embodiment includes a block body 29 and at least one convex piece 30 extending in the tire circumferential direction with a smaller width in the tire axial direction than the block body 29. The convex piece 30 is provided, for example, on the rear ground contact side of the block body 29. Such a convex piece 30 effectively prevents the middle block 12 from tilting toward the rear ground contact side, and contributes to the excellent traction performance.

[0064] The middle block 12 includes, for example, a first fin portion 31 on one side in the tire axial direction and a second fin portion 32 on the other side in the tire axial direction. On the other hand, the middle block 12 does not include a third fin portion like the crown block 11. Such a middle block 12 is easier to deform than the crown block 11, and can prevent mud and dirt from being retained around it.

[0065] The lengths of the first fins 31 and the second fins 32 of the middle block 12 in the tire circumferential direction are smaller than the length of the third fins 28 of the crown block 11 in the tire circumferential direction. The lengths of the first fins 31 and the second fins 32 of the middle block 12 in the tire circumferential direction are the same as the lengths of the first fins 26 and the second fins 27 of the crown block 11 in the tire circumferential direction. Thus, the traction force changes linearly when traveling straight and when turning.

[0066] The side surface of the middle block 12 facing the first contact side in the rotation direction R is inclined toward the first contact side, for example, as it moves from the tire equator C side toward the tread end Te side. In addition, the centroid of the tread surface of the middle block 12 is located closer to the first contact side than the centroid of the tread surface of the crown block 11. As a result, the crown block 11 can further push away the mud and soil pushed away by the middle block 12 toward the tire equator C side, thereby achieving better traction performance.

[0067] The axial length L3 of the middle block 12 is preferably smaller than the axial length L1 of the crown block 11. Specifically, the length L3 of the middle block 12 is 50% to 80% of the length L1 of the crown block 11.

[0068] The tread portion 2 of the present embodiment includes, for example, a crown bar 22 in addition to the shoulder bars 21 described above. The crown bar 22 is formed by protruding from the base surface 8 and connects the crown block 11 and the middle block 12. Such a crown bar 22 exerts an effect of pushing away soil and mud, and contributes to improving traction performance.

[0069] The crown tie bar 22 extends, for example, with a constant width between the crown block 11 and the middle block 12. Such a crown tie bar 22 helps to suppress uneven wear of the crown block 11 and the middle block 12.

[0070] As mentioned above, the preferred embodiment of the motorcycle tire for running on rough terrain of the present invention has been described in detail, but the present invention is not limited to the above-mentioned specific embodiment, and can be implemented in various modified forms.

[0071] [Example]

[0072] Based on the specifications in Table 1, we have produced Figure 2 The rear tire of a motorcycle for running on uneven ground with a basic pattern of Figure 6 As shown in FIG. 1 , a tire without a base portion provided on the shoulder pattern block a was trial-produced. In addition, the height hs of the tire of Comparative Example 1 is the same as the height hm. The height hs of the tire of Comparative Example 2 is greater than the height hm. The tires of Comparative Examples 1 and 2 have the same characteristics as those of Comparative Example 1 and Comparative Example 2 except for the above-mentioned items. Figure 2 The tread patterns shown are substantially the same tread patterns. The traction performance and cornering performance of each test tire were tested. The common specifications and test methods of each test tire are as follows.

[0073] Vehicle used: 450cc off-road motorcycle racing vehicle

[0074] Tire size: 120 / 80-19

[0075] Rim size: 2.15WM

[0076] Internal pressure: 80kPa

[0077] The test method is as follows.

[0078] <Traction performance>

[0079] The traction performance of the test vehicle when traveling on a soft road surface was evaluated by the senses of the test riders. The results were expressed as a score with Comparative Example 1 being 100, and a larger value indicates a better traction performance.

[0080] <Cornering performance>

[0081] The turning performance of the test vehicle when traveling on a soft road surface was evaluated by the senses of the test riders. The results were expressed as a score with Comparative Example 1 being 100, and a larger value indicates a better turning performance.

[0082] The results of the test are shown in Table 1.

[0083]

Table 1

[0084]

[0085] As is clear from Table 1, it can be confirmed that the tires of the examples exhibit excellent traction performance and cornering performance.

Claims

1. A motorcycle tire for running on uneven ground, having a tread portion, characterized in that: The tread portion includes a base surface and a plurality of pattern blocks protruding from the base surface toward the outer side in the tire radial direction. The above-mentioned pattern blocks include crown pattern blocks on the tire equator side and shoulder pattern blocks on the tread end side. The height hs of the shoulder blocks from the base surface is greater than the height hc of the crown blocks from the base surface. The shoulder block is provided with a base portion having a stepped profile and locally enlarged along the cross section of the base surface on the base surface side. The base portion is provided in a region of the shoulder block excluding the side surface on the tread end side.

2. The motorcycle tire for running on uneven terrain according to claim 1, characterized in that: The height hs is 105% to 150% of the height hc.

3. The motorcycle tire for running on uneven terrain according to claim 1 or 2, characterized in that: The above-mentioned pattern blocks include middle pattern blocks arranged between the above-mentioned crown pattern blocks and the above-mentioned shoulder pattern blocks, The tread portion includes a shoulder reinforcement bar formed by protruding from the base surface and connecting the shoulder block and the middle block.

4. The motorcycle tire for running on uneven terrain according to claim 3, characterized in that: The shoulder reinforcement is connected to the base portion.

5. The tire for motorcycles for running on rough terrain according to claim 3, characterized in that: The height of the shoulder reinforcement is smaller than the height of the base portion.

6. The tire for motorcycles for running on rough terrain according to claim 3, characterized in that: The shoulder pattern block is connected to only one shoulder reinforcement.

7. The motorcycle tire for running on uneven terrain according to claim 1 or 2, characterized in that: The above-mentioned pattern blocks include middle pattern blocks arranged between the above-mentioned shoulder pattern blocks and the above-mentioned crown pattern blocks, A height hm of the middle block from the base surface is smaller than the height hs.

8. The motorcycle tire for running on uneven terrain according to claim 1 or 2, characterized in that: The above-mentioned pattern blocks include middle pattern blocks arranged between the above-mentioned shoulder pattern blocks and the above-mentioned crown pattern blocks, The tread portion includes: a shoulder reinforcement formed by the base surface rising up and connecting the shoulder block and the middle block; and a crown reinforcement formed by the base surface rising up and connecting the crown block and the middle block.

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