tire

Abstract

To provide a tire that can exert excellent anti-falling performance, while maintaining wear resistance performance of a shoulder block.SOLUTION: A tire comprises a tread part 2. The tread part 2 includes shoulder land parts 7. The shoulder land part 7 is provided with a plurality of shoulder lateral grooves 12 extending from a shoulder circumferential groove 5 to at least a first tread end T1. The shoulder land part 7 includes a plurality of shoulder blocks 10 sectioned by the plurality of shoulder lateral grooves 12. Widths in a tire axial direction of a tread of the shoulder blocks 10 are 35%-48% of a tread half-width TWh between a tire equator C and the first tread end T1. One or a plurality of shoulder sipes 15 extending in a tire circumferential direction is exclusively formed on treads of the shoulder blocks 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 below proposes a pneumatic tire with a specific shoulder block configuration to prevent the vehicle from rolling over during cornering. By adjusting the loss tangent and lateral rigidity of the shoulder blocks, the pneumatic tire reduces the cornering force of the shoulder blocks when the vehicle rolls significantly, thereby preventing the vehicle from rolling over. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-137015 Summary of the Invention [Problem to be solved by the invention]

[0004] As in the case of the pneumatic tire described above, when the cornering force of the shoulder blocks is reduced in order to improve the rollover resistance, the wear resistance of the shoulder blocks tends to be impaired.

[0005] The present disclosure has been devised in light of the above-described circumstances, and has as its main object to provide a tire that can exhibit excellent rollover resistance while maintaining the wear resistance of the shoulder blocks. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion, wherein the tread portion includes a first tread edge, a shoulder circumferential groove adjacent to the first tread edge and extending continuously in the tire circumferential direction, and a shoulder land portion including the first tread edge and divided into the shoulder circumferential groove, wherein the shoulder land portion is provided with a plurality of shoulder lateral grooves extending from the shoulder circumferential groove at least to the first tread edge, and the shoulder land portion includes a plurality of shoulder blocks divided into the plurality of shoulder lateral grooves, wherein the axial width of the tread surface of each shoulder block is 35% to 48% of the half tread width from the tire equator to the first tread edge, and wherein the tread surface of each shoulder block is provided with only one or more shoulder sipes extending in the tire circumferential direction. [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present disclosure can exhibit excellent rollover resistance while maintaining the wear resistance of the shoulder blocks. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a development view of a tread portion of a tire according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged view of a shoulder land portion and a middle land portion of FIG. [Figure 3] FIG. 3 is an enlarged view of the shoulder block and the shoulder lateral groove of FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 5] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. [Figure 6] FIG. 2 is an enlarged view of the crown land portion of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 showing an embodiment of the present disclosure. The tire 1 of this embodiment is suitably used, for example, as a pneumatic tire for passenger cars. However, the present disclosure is not limited to such an embodiment and may also be applied to pneumatic tires for heavy loads and non-pneumatic tires that are not filled with pressurized air inside the tire.

[0010] As shown in Fig. 1 , the tread portion 2 of the tire 1 includes a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction between a first tread edge T1 and a second tread edge T2, and a plurality of land portions 4 separated by these circumferential grooves 3. The tire 1 of this embodiment is a so-called five-rib tire in which the tread portion 2 is configured with four circumferential grooves 3 and five land portions 4. However, the present disclosure is not limited to this aspect. In another embodiment of the tire 1 of the present disclosure, for example, the tread portion 2 may be a so-called four-rib tire in which the tread portion 2 is configured with three circumferential grooves 3 and four land portions 4.

[0011] The mounting orientation of the tread portion 2 on a vehicle is not specified, and the rotation direction is not specified either. For convenience, in each drawing in this specification, the first tread edge T1 is shown as the tread edge on the left side of the tire equator C, and the second tread edge T2 is shown as the tread edge on the right side of the tire equator C, but this is not limited to this. It is desirable that the tread portion 2 has substantially the same configuration in the region between the first tread edge T1 and the tire equator C and the region between the second tread edge T2 and the tire equator C. Furthermore, as a more desirable aspect, the tread portion 2 of this embodiment has a so-called point-symmetric pattern.

[0012] The first tread edge T1 and the second tread edge T2 each correspond to the edge of the contact patch when a normal load is applied to the tire 1 in a normal state and the tread portion 2 is brought into contact with a flat surface at a camber angle of 0°.

[0013] "Normal condition" means, in the case of a pneumatic tire for which various standards are established, that the tire is mounted on a normal rim, inflated to the normal internal pressure, and is in an unloaded state. In the case of a tire for which various standards are not established or a non-pneumatic tire, the normal condition means a standard use state according to the intended use of the tire, in which the tire is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition.

[0014] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

[0015] "Normal internal pressure" is the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0016] For pneumatic tires for which various standards are established, "normal load" refers to the load specified for each tire in the standard system including the standard on which the tire is based. For JATMA, this is "maximum load capacity," for TRA, this is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, this is "LOAD CAPACITY." For tires for which various standards are not established, "normal load" refers to the maximum load that can be applied when using the tire in accordance with the above standards.

[0017] The circumferential grooves 3 include two shoulder circumferential grooves 5 and two crown circumferential grooves 6. The shoulder circumferential groove 5 is adjacent to the first tread edge T1 or the second tread edge T2. The two crown circumferential grooves 6 are arranged between the two shoulder circumferential grooves 5 so as to sandwich the tire equator C.

[0018] Each circumferential groove 3 of this embodiment extends, for example, linearly in parallel to the tire circumferential direction. Each circumferential groove 3 may extend, for example, in a wavy shape.

[0019] The groove width W1 of each circumferential groove 3 is preferably at least 3 mm or more. Also, the groove width W1 of each circumferential groove 3 is preferably 3.0% to 5.0% of the tread width TW. The tread width TW is the axial distance from the first tread edge T1 to the second tread edge T2 in the normal state.

[0020] The land portion 4 includes two shoulder land portions 7. The shoulder land portion 7 includes the first tread edge T1 or the second tread edge T2, and is located axially outward of the shoulder circumferential groove 5. The two shoulder land portions 7 have substantially the same configuration.

[0021] The plurality of land portions 4 in this embodiment include two middle land portions 8 and one crown land portion 9. The middle land portion 8 is adjacent to the shoulder land portion 7 via the shoulder circumferential groove 5. The middle land portion 8 is also divided between the shoulder circumferential groove 5 and the crown circumferential groove 6. The two middle land portions 8 have substantially the same configuration. The crown land portion 9 is divided between the two crown circumferential grooves 6 and is provided on the tire equator C.

[0022] Fig. 2 shows an enlarged view of the shoulder land portion 7 and the middle land portion 8 provided on the first tread edge T1 side of the tire equator C. As shown in Fig. 2, the shoulder land portion 7 is provided with a plurality of shoulder lateral grooves 12 extending from the shoulder circumferential groove 5 to at least the first tread edge T1. As a result, the shoulder land portion 7 includes a plurality of shoulder blocks 10 divided by the plurality of shoulder lateral grooves 12.

[0023] In the present disclosure, the axial width W2 of the tread surface of each shoulder block 10 is 35% to 48% of the half tread width TWh (shown in FIG. 1, and the same applies hereinafter). The half tread width TWh is the axial distance from the tire equator C to the first tread edge T1 in the normal state, and corresponds to half the tread width TW.

[0024] Fig. 3 shows an enlarged view of three shoulder lateral grooves 12 and two shoulder blocks 10. As shown in Fig. 3, only one or more shoulder sipes 15 extending in the circumferential direction of the tire are provided on the tread surface of each shoulder block 10.

[0025] In this specification, the term "sipe" refers to a small cut between two inner walls that face each other and extend substantially parallel to each other, with the width between the two walls being 2.0 mm or less. Furthermore, "substantially parallel" refers to a configuration in which the angle between the two inner walls is 10° or less. The width of the sipe is preferably 0.5 to 1.5 mm, more preferably 0.5 to 1.0 mm. The sipe of this embodiment has a constant width from the opening to the bottom. However, the present invention is not limited to this configuration, and the sipe may open via a chamfered portion. Furthermore, the sipe may have a so-called flask bottom, with a wider width at the bottom.

[0026] Furthermore, the shoulder sipes 15 extending in the tire circumferential direction mean that the maximum angle of the center line of the shoulder sipe 15 relative to the tire circumferential direction is 30° or less in a plan view of the tread. Furthermore, the statement that only shoulder sipes 15 are provided on the tread surface of each shoulder block 10 means that, except for the shoulder sipes 15, no locally recessed elements such as grooves, sipes, or recesses are provided on the tread surface of each shoulder block 10.

[0027] By adopting the above-described configuration, the tire 1 of the present disclosure can exhibit excellent fall resistance while maintaining the wear resistance of the shoulder blocks 10. The mechanism behind this is as follows.

[0028] In the tire 1 of the present disclosure, the axial width W2 of the tread surface of each shoulder block 10 is 35% to 48% of the tread half width TWh, which optimizes the rigidity of the shoulder blocks 10 and thereby improves the rollover resistance while maintaining the wear resistance of the shoulder blocks 10.

[0029] Additionally, the tread of each shoulder block 10 is provided with only one or more shoulder sipes 15 extending circumferentially in the tire direction. This reduces the axial rigidity of the shoulder blocks 10, improving rollover resistance. Meanwhile, the circumferential rigidity of the shoulder blocks 10 is maintained without being reduced by the shoulder sipes 15, so the wear resistance of the shoulder blocks 10 can be maintained. In the present disclosure, this mechanism allows the wear resistance of the shoulder blocks 10 to be maintained while improving rollover resistance.

[0030] The following describes the configuration of this embodiment in more detail. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present disclosure can achieve the above-described effects even if it does not include the configurations described below. Furthermore, even if any one of the configurations described below is applied alone to a tire of the present disclosure having the above-described characteristics, performance improvement corresponding to each configuration can be expected. Furthermore, when several of the configurations described below are applied in combination, combined performance improvement corresponding to each configuration can be expected.

[0031] As shown in Figure 2, the axial width W2 of the tread surface of the shoulder block 10 is preferably 40% to 45% of the tread half width TWh. The circumferential length L4 of the shoulder block 10 is smaller than the axial width W2 of the tread surface of the shoulder block 10. Specifically, the circumferential length L4 of the shoulder block 10 is 60% to 75% of the axial width W2 of the tread surface of the shoulder block 10. This makes the tread surface of the shoulder block 10 horizontally elongated in the axial direction of the tire, and more preferably rectangular.

[0032] The shoulder lateral grooves 12 are arranged, for example, at an angle of 30° or less relative to the tire axial direction. The angle of the shoulder lateral grooves 12 relative to the tire axial direction is preferably 20° or less, and more preferably 10° or less. In a more preferable embodiment, the shoulder lateral grooves 12 of this embodiment extend parallel to the tire axial direction. This suppresses wear of the shoulder blocks 10.

[0033] To maintain the wear resistance of the shoulder blocks 10, the shoulder lateral grooves 12 extend axially from the shoulder circumferential groove 5 to the first tread edge T1 with a constant groove width. The groove width W4 of the shoulder lateral grooves 12 is preferably smaller than the groove width W3 of the shoulder circumferential groove 5. Specifically, the groove width W4 of the shoulder lateral grooves 12 is 85% to 95% of the groove width W3 of the shoulder circumferential groove 5.

[0034] Figure 4 shows a cross-sectional view taken along line AA in Figure 2. As shown in Figure 4, at least one of the shoulder lateral grooves 12 includes a plurality of tie bars 20 with raised groove bottoms that connect two adjacent shoulder blocks 10. Such tie bars 20 can further improve wear resistance. Note that in Figures 1 to 3, the outlines of the tie bars 20, which can be observed when viewing the shoulder lateral groove 12 from above, are omitted.

[0035] The tie bars 20 include, for example, an inner tie bar 21, an outer tie bar 22, and an intermediate tie bar 23. The inner tie bar 21 is provided axially inward of the axial center position of the shoulder lateral groove 12 within the tread contact patch. In a preferred embodiment, the inner tie bar 21 is provided at the axially inner end of the shoulder lateral groove 12. Such inner tie bar 21 helps to suppress uneven wear around the inner end of the shoulder lateral groove 12.

[0036] The outer tie bar 22 is provided axially outward of the axial center of the shoulder lateral groove 12 in the tread contact area. In a preferred embodiment, the outer tie bar 22 is provided at the axially outer end of the shoulder lateral groove 12 in the tread contact area. Specifically, in a cross section along the length of the shoulder lateral groove 12, the first tread edge T1 is included within a region obtained by extending the outer surface of the outer tie bar 22 radially outward. Such an outer tie bar 22 helps to suppress uneven wear near the first tread edge T1.

[0037] The intermediate tie bar 23 is provided between both axial ends of the shoulder lateral groove 12, and in this embodiment, is provided between the outer tie bar 22 and the inner tie bar 21. In a preferred embodiment, the distance between the intermediate tie bar 23 and the inner tie bar 21 is smaller than the distance between the intermediate tie bar 23 and the outer tie bar 22. Such an intermediate tie bar 23 can effectively prevent the shoulder lateral groove 12 from widening excessively, further improving wear resistance.

[0038] In this embodiment, the shoulder lateral groove 12 includes an inner tie bar 21, an outer tie bar 22, and an intermediate tie bar 23, but the present disclosure is not limited to this embodiment, and only one of these tie bars 20 may be provided in the shoulder lateral groove 12, or two of these tie bars 20 may be selected and arranged.

[0039] The axial length L6 of one tie bar 20 is, for example, 15% to 25% of the axial width W2 of the tread surface of the shoulder block 10. The total axial length of the tie bars 20 arranged in one shoulder lateral groove 12 is preferably 40% to 60% of the axial width W2 of the tread surface of the shoulder block 10. This improves a good balance between wear resistance and ride comfort. The axial length of the tie bar 20 is measured at the center position of the tie bar 20 in the height direction.

[0040] In this embodiment, the inner tie bar 21, the outer tie bar 22, and the intermediate tie bar 23 are configured to have the same height. The maximum height h1 of the tie bar 20 is, for example, 25% to 60% of the maximum depth d1 of the shoulder lateral groove 12, and preferably 30% to 50%.

[0041] 3, the shoulder sipes 15 of this embodiment extend from the shoulder lateral grooves 12 and terminate within the shoulder blocks 10. The angle of the shoulder sipes 15 relative to the tire circumferential direction is preferably 5 to 15 degrees. This allows the axial rigidity of the tire to be reduced while maintaining the circumferential rigidity of the shoulder blocks 10, further improving rollover resistance.

[0042] As shown in FIG. 4, the shoulder sipe 15 communicates with the shoulder lateral groove 12 at the position where one of the tie bars 20 is formed. In this embodiment, the shoulder sipe 15 communicates with the shoulder lateral groove 12 at the position where the intermediate tie bar 23 is formed. This further improves wear resistance. Note that the above-mentioned configuration means that, in a cross section along the length of the shoulder lateral groove 12, the shoulder sipe 15 is included within a region obtained by extending the outer surface of the tie bar 20 radially outward in the tire. Furthermore, the center position in the height direction of the tie bar 20 is the boundary between the outer surface of the tie bar 20 and other surfaces.

[0043] As shown in FIG. 3, the shoulder sipes 15 include a first shoulder sipe 16 and a second shoulder sipe 17. The first shoulder sipe 16 communicates with a shoulder lateral groove 12 located on one circumferential side of the shoulder block 10 (the lower side in FIG. 3). The second shoulder sipe 17 communicates with a shoulder lateral groove 12 located on the other circumferential side of the shoulder block 10 (the upper side in FIG. 3). As a more desirable aspect, in this embodiment, one first shoulder sipe 16 and one second shoulder sipe 17 are provided in each shoulder block 10. Furthermore, both the first shoulder sipe 16 and the second shoulder sipe 17 communicate with the shoulder lateral groove 12 at the position where the intermediate tie bar 23 is formed. This improves ride comfort while achieving the above-mentioned effects.

[0044] The first shoulder sipes 16 and the second shoulder sipes 17 are preferably located axially inward of the axial center position 10a (shown by a dashed line in FIG. 3 ) of the shoulder block 10. In a more preferred embodiment, the entire edge of the first shoulder sipe 16 and the entire edge of the second shoulder sipe 17 are located axially inward of the center position 10a. This reduces the rigidity of the axially inner region of the shoulder block 10, further improving ride comfort.

[0045] On the other hand, if the first shoulder sipes 16 and second shoulder sipes 17 are too close to the shoulder circumferential grooves 5, this may result in uneven wear of the shoulder blocks 10. For this reason, it is desirable that the axial distance L3 from the connection between the shoulder lateral groove 12 and the first shoulder sipe 16 or second shoulder sipe 17 to the axially inner end of the shoulder lateral groove 12 be, for example, 30% to 45% of the axial width W2 of the tread surface of the shoulder block 10 (shown in FIG. 2, and the same applies hereinafter).

[0046] The connecting portion 17a between the shoulder lateral groove 12 and the second shoulder sipe 17 is preferably axially offset from the connecting portion 16a between the shoulder lateral groove 12 and the first shoulder sipe 16. The axial distance L9 between the connecting portions 16a and 17a is preferably 5% to 10% of the axial width W2 of the tread surface of the shoulder block 10. This further improves the wear resistance of the shoulder block 10.

[0047] From the same viewpoint, it is desirable that the first shoulder sipes 16 and the second shoulder sipes 17 are inclined in the same direction relative to the tire circumferential direction. In this embodiment, the first shoulder sipes 16 and the second shoulder sipes 17 are inclined at the same angle relative to the tire circumferential direction. In addition, it is desirable that the angle θ1 between the shoulder lateral grooves 12 and the shoulder sipes 15 is 25 to 85°.

[0048] As shown in FIG. 2, the first shoulder sipes 16 and the second shoulder sipes 17 provided in one shoulder block 10 are arranged on a single imaginary belt 19 (marked with dots in FIG. 2) that extends with a very small width in a plan view of the tread portion 2. The imaginary belt 19 is an imaginary region that extends with a constant width and inclined in the same direction as the first shoulder sipes 16 and the second shoulder sipes 17. In a preferred embodiment, the first shoulder sipes 16 and the second shoulder sipes 17 are arranged so that the imaginary belt 19 has a width of 10 mm or less. In a more preferred embodiment, the first shoulder sipes 16 and the second shoulder sipes 17 are arranged on substantially the same imaginary straight line in this embodiment. This can further improve ride comfort.

[0049] It is desirable that the shoulder sipes 15 terminate within the shoulder blocks 10 without crossing the circumferential center positions 10b (shown by dashed lines in FIG. 2) of the shoulder blocks 10. Specifically, it is desirable that the circumferential length L5 of the shoulder sipes 15 is 25% to 35% of the circumferential length L4 of the shoulder blocks 10. Such shoulder sipes 15 help to improve wear resistance and ride comfort in a balanced manner.

[0050] As shown in Fig. 2, the middle land portion 8 is provided with a plurality of middle lateral grooves 26. The middle lateral grooves 26 completely traverse the middle land portion 8 in the tire axial direction. As a result, the middle land portion 8 includes a plurality of middle blocks 25 that are divided into the plurality of middle lateral grooves 26.

[0051] The axial width W5 of the tread surface of the middle block 25 is preferably smaller than the axial width W2 of the tread surface of the shoulder block 10. Specifically, the axial width W5 of the tread surface of the middle block 25 is 55% to 70% of the axial width W2 of the tread surface of the shoulder block 10. This allows the shoulder blocks 10 and middle blocks 25 to wear evenly, suppressing uneven wear.

[0052] The middle lateral grooves 26 are, for example, inclined relative to the tire axial direction. The angle θ2 of the middle lateral grooves 26 relative to the tire axial direction is larger than the angle of the shoulder lateral grooves 12 relative to the tire axial direction. In the middle lateral grooves 26 of this embodiment, the angle θ2 relative to the tire axial direction increases toward the axially inner side. The angle θ2 is, for example, 10 to 45°. As a result, the middle lateral grooves 26 are curved convexly toward one side in the tire circumferential direction (the lower side in FIG. 2). Such middle lateral grooves 26 can improve wet performance in addition to improving wear resistance and ride comfort.

[0053] The groove width W6 of the middle lateral grooves 26 is larger than, for example, the groove width W4 of the shoulder lateral grooves 12. Specifically, the groove width W6 of the middle lateral grooves 26 is 110% to 130% of the groove width W4 of the shoulder lateral grooves 12. This allows the shoulder land portions 7 and the middle land portions 8 to wear evenly, thereby suppressing uneven wear.

[0054] Figure 5 shows a cross-sectional view taken along line BB in Figure 2. As shown in Figure 5, at least one of the middle lateral grooves 26 includes at least one middle tie bar 30 with a raised groove bottom that connects two adjacent middle blocks 25. In this embodiment, one middle tie bar 30 is preferably configured in each middle lateral groove 26. The middle tie bar 30 increases the circumferential rigidity of the middle land portion 8 and helps improve wear resistance.

[0055] In this embodiment, one middle tie bar 30 is provided between both axial ends of the middle lateral groove 26. However, this is not limited to this, and multiple middle tie bars 30 may be provided in one middle lateral groove 26. The axial length L7 of the middle tie bar 30 is, for example, 40% to 55% of the axial width W5 (shown in FIG. 2) of the middle block 25. The maximum height h2 of the middle tie bar 30 is 25% to 40% of the maximum depth d2 of the middle lateral groove 26. In addition, the middle tie bar 30 in this embodiment is provided, for example, at a position that straddles the axial center of the middle lateral groove 26. This improves wear resistance and ride comfort in a well-balanced manner.

[0056] In a more preferable embodiment, when comparing the axial lengths of the tie bars at each location, the middle tie bar 30 is preferably longer than any of the inner tie bar 21, outer tie bar 22, and intermediate tie bar 23 (shown in FIG. 4) provided in the shoulder lateral grooves 12. On the other hand, the axial length L7 of the middle tie bar 30 is preferably shorter than the combined axial length of the inner tie bar 21, outer tie bar 22, and intermediate tie bar 23. This optimizes the rigidity distribution of the shoulder land portion 7 and middle land portion 8, further improving wear resistance.

[0057] As shown in FIG. 2 , each of the multiple middle blocks 25 has at least one middle sipe 28. The middle sipe 28 communicates with at least one middle lateral groove 26 on one circumferential side of the tire, and in this embodiment, it communicates with the middle lateral grooves 26 on both circumferential sides of the tire. As a result, the middle sipe 28 completely traverses the middle block 25 in the tire circumferential direction. It is also desirable that both circumferential ends of the middle sipe 28 communicate with the center portions of the middle lateral groove 26 when the middle lateral groove 26 is divided into three equal parts in the longitudinal direction. Such middle sipes 28 help to reduce the axial rigidity of the middle block 25 and improve ride comfort.

[0058] The middle sipes 28 are, for example, inclined relative to the tire circumferential direction. The middle sipes 28 are desirably inclined in the same direction as the shoulder sipes 15. The angle θ3 between the middle sipes 28 and the middle lateral grooves 26 is, for example, 75 to 90°. Such middle sipes 28 are useful for improving wear resistance and ride comfort in a well-balanced manner.

[0059] In a preferred embodiment, the total number Ns of shoulder lateral grooves 12 in one shoulder land portion 7 is greater than the total number Nm of middle lateral grooves 26 in one middle land portion 8. This allows the circumferential length of the shoulder blocks 10 to be relatively small, thereby improving rollover resistance while maintaining overall wear resistance of the land portions and various driving performance characteristics, including steering stability. In a more preferred embodiment, the total number Ns is 110% or less of the total number Nm. This improves the above-mentioned performance in a balanced manner.

[0060] 5, it is desirable that the middle sipes 28 communicate with the middle lateral grooves 26 at the positions where the middle tie bars 30 are formed. This allows the connection between the middle lateral grooves 26 and the middle sipes 28 to be reinforced by the middle tie bars 30, suppressing uneven wear around the connection.

[0061] 2, each middle block 25 of this embodiment is not provided with any grooves or sipes except for the above-mentioned middle sipe 28. This can further enhance the above-mentioned effects.

[0062] Fig. 6 shows an enlarged view of the crown land portion 9. As shown in Fig. 6, the width W7 of the crown land portion 9 in the tire axial direction is, for example, 10% to 20% of the tread width TW (shown in Fig. 1). In addition, the width W7 of the crown land portion 9 is preferably smaller than the width W2 of the shoulder block 10 in the tire axial direction.

[0063] The crown land portion 9 is provided with a plurality of first crown lateral grooves 36 and a plurality of second crown lateral grooves 37. The first crown lateral grooves 36 extend from a crown circumferential groove 6 arranged on one axial side (left side in FIG. 6 ) of the crown land portion 9 toward the tire equator C and terminate within the crown land portion 9. The second crown lateral grooves 37 extend from a crown circumferential groove 6 arranged on the other axial side (right side in FIG. 6 ) of the crown land portion 9 toward the tire equator C and terminate within the crown land portion 9. The first crown lateral grooves 36 and the second crown lateral grooves 37 can improve wet performance while maintaining the rigidity of the crown land portion 9.

[0064] In order to improve wear resistance and ride comfort in a well-balanced manner, the axial length L8 of the first crown lateral groove 36 or the second crown lateral groove 37 is preferably 45% to 55% of the axial width W7 of the crown land portion 9.

[0065] The first crown lateral grooves 36 are curved so as to be convex toward one side in the tire circumferential direction (upper side in FIG. 6), and the second crown lateral grooves 37 are curved so as to be convex toward the other side in the tire circumferential direction (lower side in FIG. 6). This further suppresses uneven wear of the crown land portion 9.

[0066] As shown in Figure 1, the first crown lateral grooves 36 and the middle lateral grooves 26 adjacent to the first crown lateral grooves 36 on the first tread edge T1 side are curved convexly in opposite directions. Also, the second crown lateral grooves 37 and the middle lateral grooves 26 adjacent to the second crown lateral grooves 37 on the second tread edge T2 side are curved convexly in opposite directions. This arrangement of lateral grooves ensures that the wear of each land portion progresses uniformly, suppressing uneven wear of each land portion.

[0067] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above-described specific embodiment and can be modified and implemented in various aspects. [Example]

[0068] Pneumatic tires of size 235 / 60R17C having the basic pattern of FIG. 1 were prototyped based on the specifications in Table 1. Additionally, tires having the pattern shown in FIG. 1 but with shoulder block tread widths outside the range of the present disclosure were prototyped as Comparative Examples 1 and 2. Except for the above-mentioned features, the comparative tire was substantially the same as the example tire. Furthermore, these test tires were tested for shoulder block wear resistance and rollover resistance. The common specifications and test methods for each test tire are as follows: Rim: 17 x 6.0J Tire pressure: 525kPa on all wheels Test vehicle: 3000cc, four-wheel drive Tire mounting position: All wheels

[0069] <Wear resistance of shoulder blocks> After each test tire was run under certain conditions on a drum testing machine, the remaining height of the shoulder blocks was measured. The results were expressed as an index, with the remaining height of Comparative Example 1 being set at 100. A larger index indicates better wear resistance of the shoulder blocks.

[0070] <Fall resistance performance> The test vehicle was driven onto an asphalt test course at a speed of 80 km / h, and the steering wheel was turned sharply to give a steering angle of +α°, and then the vehicle was immediately steered to the other side to give a steering angle of -α°. It was then visually confirmed whether the tire lifted more than 5 cm. The test results are shown in Table 1.

[0071] [Table 1]

[0072] As shown in Table 1, the wear resistance of the shoulder blocks of each Example was maintained at 103 to 117 points, while no tire lift occurred, demonstrating excellent rollover resistance. In contrast, Comparative Example 1, in which the tread width of the shoulder blocks was narrow, had poor shoulder block wear resistance, while Comparative Example 2, in which the tread width of the shoulder blocks was wide, experienced tire lift. In other words, the test results confirmed that the Example tires maintained the wear resistance of the shoulder blocks while demonstrating excellent rollover resistance.

[0073] [Note] The present disclosure includes the following aspects.

[0074] [Disclosure 1] A tire having a tread portion, the tread portion includes a first tread edge, a shoulder circumferential groove adjacent to the first tread edge and extending continuously in the tire circumferential direction, and a shoulder land portion including the first tread edge and divided by the shoulder circumferential groove, The shoulder land portion is provided with a plurality of shoulder lateral grooves extending from the shoulder circumferential groove to at least the first tread edge, the shoulder land portion includes a plurality of shoulder blocks divided by the plurality of shoulder lateral grooves, The width of the tread surface of each shoulder block in the tire axial direction is 35% to 48% of the tread half width from the tire equator to the first tread edge, The tread surface of each shoulder block is provided with only one or more shoulder sipes extending in the tire circumferential direction. tire. [Disclosure 2] The tire according to Disclosure 1, wherein at least one of the shoulder lateral grooves includes a plurality of tie bars having raised groove bottoms that connect two adjacent shoulder blocks. [Disclosure 3] The tire according to Disclosure 2, wherein the shoulder sipe is in communication with the shoulder lateral groove at a position where any one of the plurality of tie bars is formed in the tire axial direction. [Disclosure 4] The tire according to Disclosure 2 or 3, wherein the tie bars include an inner tie bar provided axially inward of the axial center position of the shoulder lateral groove. [Disclosure 5] The tire according to any one of Disclosures 2 to 4, wherein the tie bars include an outer tie bar provided axially outward of the axial center position of the shoulder lateral groove. [Disclosure 6] The tire according to any one of Disclosures 2 to 5, wherein the tie bars include an intermediate tie bar provided between both axial end portions of the shoulder lateral groove. [Disclosure 7] the tread portion includes a middle land portion adjacent to the shoulder land portion via the shoulder circumferential groove, The middle land portion is provided with a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the middle land portion includes a plurality of middle blocks that are divided into the plurality of middle lateral grooves, The tire according to any one of Disclosures 1 to 6, wherein at least one of the middle lateral grooves includes at least one middle tie bar having a raised groove bottom portion so as to connect two adjacent middle blocks. [Disclosure 8] Each of the plurality of middle blocks is provided with at least one middle sipe communicating with the middle lateral groove, The tire according to Disclosure 7, wherein the middle sipe is in communication with the middle lateral groove at a position where the middle tie bar is formed in the tire axial direction. [Disclosure 9] The tire according to Disclosure 7 or 8, wherein the total number of the shoulder lateral grooves in the entire shoulder land portion is greater than the total number of the middle lateral grooves in the entire middle land portion. [Explanation of symbols]

[0075] 2 Tread section 5 Shoulder circumferential groove 7 Shoulder Land Section 12 Shoulder groove 10 Shoulder Block 15 Shoulder sipes TWh Tread half width T1 First tread edge

Claims

1. A tire having a tread portion, the tread portion includes a first tread edge, a shoulder circumferential groove adjacent to the first tread edge and extending continuously in the tire circumferential direction, and a shoulder land portion including the first tread edge and divided by the shoulder circumferential groove, a plurality of shoulder lateral grooves extending from the shoulder circumferential groove to at least the first tread edge are provided in the shoulder land portion, the shoulder land portion includes a plurality of shoulder blocks divided by the plurality of shoulder lateral grooves, the width of the tread surface of each shoulder block in the tire axial direction is 35% to 48% of the half tread width from the tire equator to the first tread edge, Only one or more shoulder sipes extending in the tire circumferential direction are provided on the tread surface of each shoulder block. tire.

2. The tire according to claim 1 , wherein at least one of the shoulder lateral grooves includes a plurality of tie bars having raised groove bottoms that connect two adjacent shoulder blocks.

3. The tire according to claim 2 , wherein the shoulder sipe communicates with the shoulder lateral groove at a position where any one of the plurality of tie bars is formed in the tire axial direction.

4. The tire according to claim 2 or 3, wherein the tie bars include an inner tie bar provided axially inward of the axial center position of the shoulder lateral groove.

5. The tire according to claim 2 , wherein the tie bars include an outer tie bar provided axially outward of the axial center position of the shoulder lateral groove.

6. The tire according to claim 2 , wherein the tie bars include an intermediate tie bar provided between both axial end portions of the shoulder lateral groove.

7. the tread portion includes a middle land portion adjacent to the shoulder land portion via the shoulder circumferential groove, The middle land portion is provided with a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the middle land portion includes a plurality of middle blocks that are divided into the plurality of middle lateral grooves, 7. The tire according to claim 1, wherein at least one of the middle lateral grooves includes at least one middle tie bar having a raised groove bottom portion so as to connect two adjacent middle blocks.

8. Each of the plurality of middle blocks is provided with at least one middle sipe communicating with the middle lateral groove, The tire according to claim 7 , wherein the middle sipe communicates with the middle lateral groove at a position where the middle tie bar is formed in the tire axial direction.

9. The tire according to claim 7 or 8, wherein the total number of the shoulder lateral grooves in the entire shoulder land portion is greater than the total number of the middle lateral grooves in the entire middle land portion.

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