tire

Abstract

To provide a tire that can exert excellent on-snow performance, while maintaining wear resistance performance.SOLUTION: A tire comprises a tread par 2. The tread part 2 includes a middle land part 7 arranged between a tread end Te and a tire equator C. The middle land part 7 is partitioned by a plurality of middle lateral grooves 10 into a plurality of middle blocks 15. At least one middle notched groove 20 extending from a first vertical edge 15a and having a choppy end 20a in a tread surface 15s is provided in at least one of the plurality of middle blocks 15. A depth of the middle notched groove 20 becomes continuously smaller as going towards the notched end 20a. At least one of the plurality of middle lateral grooves 10 includes a first middle tie-bar 13 whose groove bottom is raised at an end part at the first vertical edge 15a side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 below proposes a tire whose tread portion is divided into a plurality of blocks by a plurality of lateral grooves. This tire is expected to improve its performance on snow and ice and noise performance by improving the shape of the block wall on the lateral groove side of the block and the arrangement of sipes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-018753 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for tires to have further improved performance on snow, while at the same time, there is also a demand for tires to maintain their wear resistance.

[0005] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a tire that can exhibit excellent performance on snow while maintaining wear resistance. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion, the tread portion including a middle land portion disposed between a tread edge and the tire equator, the middle land portion being divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the plurality of middle blocks including a first longitudinal edge on the tread edge side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, at least one of the plurality of middle blocks having at least one interrupted middle groove extending from the first longitudinal edge and having an interrupted end within the tread surface, the depth of the interrupted middle groove continuously decreasing toward the interrupted end, and at least one of the plurality of middle lateral grooves including a first middle tie bar with a raised groove bottom at the end on the first longitudinal edge side. [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present disclosure can exhibit excellent performance on snow while maintaining wear resistance. [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 the middle land area of ​​FIG. [Figure 3] FIG. 3 is an enlarged view of the two middle blocks 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. 4 is a cross-sectional view taken along line CC in FIG. [Figure 7] FIG. 4 is a cross-sectional view taken along line DD in FIG. 3. [Figure 8] FIG. 2 is an enlarged view of the crown land portion of FIG. [Figure 9] FIG. 2 is an enlarged view of the shoulder land portion of FIG. [Figure 10] FIG. 10 is a cross-sectional view taken along the line EE in FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. 1 is a development view of a tread portion 2 of a tire 1 showing one embodiment of the present disclosure. The tire 1 of this embodiment is used, for example, as a pneumatic tire for winter passenger cars, and is particularly suitable for pickup trucks. However, the present disclosure is not limited to such an embodiment.

[0010] As shown in FIG. 1, the tread portion 2 includes a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction between two tread ends Te, and a plurality of land portions 4 separated by the circumferential grooves 3.

[0011] The two tread edges Te correspond to the edges of the contact patch when the tire 1 in a normal state is loaded with 70% of the normal load and the tread portion 2 is brought into contact with a flat surface at a camber angle of 0°.

[0012] "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 no load is applied. 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 condition according to the intended use of the tire, in which the tire is not mounted on a vehicle and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition.

[0013] 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."

[0014] "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."

[0015] 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.

[0016] The circumferential grooves 3 include, for example, two crown circumferential grooves 5 and two shoulder circumferential grooves 6 .

[0017] The two crown circumferential grooves 5 are provided so as to sandwich the tire equator C. The two shoulder circumferential grooves 6 are provided so as to sandwich the two crown circumferential grooves 5. The axial distance L1 from the groove center line of the crown circumferential groove 5 to the tire equator C is, for example, 5% to 15% of the tread width TW. The axial distance L2 from the groove center line of the shoulder circumferential groove 6 to the tire equator C is, for example, 20% to 35% of the tread width TW. The tread width TW is the axial distance between the two tread ends Te in the normal state.

[0018] The crown circumferential groove 5 extends linearly in parallel to the tire circumferential direction, for example. The shoulder circumferential grooves 6 extend circumferentially with a slight axial amplitude, for example. The axial amplitude of the groove centerline of the shoulder circumferential groove 6 is, for example, 50% or less of the maximum groove width of the shoulder circumferential groove 6. However, each circumferential groove 3 is not limited to this configuration.

[0019] The groove width W1 of the circumferential groove 3 is, for example, 3.0 mm or more. The groove width W1 of the circumferential groove 3 is preferably, for example, 3.0% to 6.0% of the tread width TW. The depth (not shown) of the circumferential groove 3 is, for example, 5.0 to 15.0 mm.

[0020] The land portion 4 includes at least a middle land portion 7. The middle land portion 7 is disposed between the tread edge Te and the tire equator C, and in this embodiment, is divided between the crown circumferential groove 5 and the shoulder circumferential groove 6. In this embodiment, two middle land portions 7 are provided so as to sandwich the tire equator C therebetween.

[0021] The land portion 4 of this embodiment includes two shoulder land portions 9 and one crown land portion 8. The shoulder land portion 9 is defined axially outward of the shoulder circumferential groove 6 and includes the tread edge Te. The crown land portion 8 is defined between the two crown circumferential grooves 5. As a result, the crown land portion 8 is adjacent to the middle land portion 7 axially inward via the crown circumferential groove 5. The crown land portion 8 is also provided on the tire equator C.

[0022] Fig. 2 shows an enlarged view of the middle land portion 7 in Fig. 1. As shown in Fig. 2, the middle land portion 7 is provided with a plurality of middle lateral grooves 10 that completely cross the middle land portion 7 in the tire axial direction. The middle land portion 7 is divided into a plurality of middle blocks 15 by the plurality of middle lateral grooves 10. Each of the plurality of middle blocks 15 includes a first longitudinal edge 15a on the tread edge Te side, a second longitudinal edge 15b on the tire equator C side, and a tread surface 15s between the first longitudinal edge 15a and the second longitudinal edge 15b.

[0023] Figure 3 shows an enlarged view of two middle blocks 15 from Figure 2. As shown in Figure 3, at least one of the middle blocks 15 has at least one interrupted middle groove 20 extending from the first longitudinal edge 15a and having an interrupted end 20a within the tread surface 15s.

[0024] Fig. 4 shows a cross section taken along line AA in Fig. 2 as a diagram illustrating a cross section of the interrupted middle groove 20. As shown in Fig. 4, the depth of the interrupted middle groove 20 decreases continuously toward the interrupted end 20a.

[0025] Fig. 5 shows a cross section of the middle lateral groove 10 taken along line BB in Fig. 2. As shown in Fig. 5, at least one of the middle lateral grooves 10 includes a first middle tie bar 13 with a raised groove bottom at the end on the first longitudinal edge 15a side. By adopting the above-described configuration, the tire 1 of the present disclosure can exhibit excellent on-snow performance while maintaining wear resistance. The following mechanism is believed to be the reason for this.

[0026] When driving on snow, the tire 1 of the present disclosure exerts a large grip force by compacting snow inside the above-mentioned middle lateral grooves 10 and middle-discontinuous grooves 20, forming snow pillars, and then shearing these snow pillars (hereinafter, the grip force obtained by this mechanism may be referred to as snow pillar shear force). In particular, because the depth of the middle-discontinuous grooves 20 decreases continuously toward the discontinuous ends 20a, snow trapped in the middle-discontinuous grooves 20 is strongly compacted toward the shoulder circumferential grooves 6 (shown in FIG. 2), forming hard snow pillars. This allows for the expectation of a larger snow pillar shear force.

[0027] The above-mentioned middle-interrupted grooves 20 can suppress a decrease in rigidity of the middle blocks 15. Furthermore, in the present disclosure, the first middle tie bars 13 are provided at the ends of the middle lateral grooves 10 on the first longitudinal edges 15a side, and the middle-interrupted grooves 20 and the first middle tie bars 13 are provided on the same side in the tire axial direction, suppressing a decrease in rigidity of the middle blocks 15 and effectively maintaining wear resistance. It is believed that this mechanism allows the tire 1 of the present disclosure to exhibit excellent on-snow performance while maintaining wear resistance.

[0028] 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.

[0029] As shown in FIG. 2 , the middle blocks 15 include first middle blocks 16 and second middle blocks 17, each having a first longitudinal edge 15a with a slightly different shape. In this embodiment, the first middle blocks 16 and second middle blocks 17 are arranged alternately in the tire circumferential direction. The first longitudinal edge 15a of the first middle block 16 extends linearly along the tire circumferential direction. The first longitudinal edge 15a of the second middle block 17 is bent at an obtuse angle so as to be concave toward the tire equator C. Therefore, the first longitudinal edge 15a of the second middle block 17 includes a first inclined portion 18 inclined relative to the tire circumferential direction and a second inclined portion 19 inclined in the opposite direction to the first inclined portion 18.

[0030] The middle lateral grooves 10 are, for example, inclined with respect to the tire axial direction. The maximum angle θ1 of the middle lateral grooves 10 with respect to the tire axial direction is, for example, 20 to 40°. The middle lateral grooves 10 include first middle lateral grooves 11 that extend with a constant groove width and second middle lateral grooves 12 that have a groove width that decreases toward the tire equator C. In this embodiment, the first middle lateral grooves 11 and the second middle lateral grooves 12 are arranged alternately in the tire circumferential direction. Such first middle lateral grooves 11 and second middle lateral grooves 12 are useful for improving steering stability on dry roads (hereinafter sometimes simply referred to as "steering stability") and performance on snow in a well-balanced manner.

[0031] 5, the middle lateral groove 10 of this embodiment includes the above-mentioned first middle tie bar 13 and a second middle tie bar 14 provided at the end on the second longitudinal edge 15b side, thereby further improving wear resistance.

[0032] The axial length L3 of the first middle tie bar 13 and the axial length L4 of the second middle tie bar 14 are 15% to 25% of the axial width W2 of the tread surface of the middle block 15 (shown in FIG. 2, and the same applies below). If the axial length of the tie bar varies in the radial direction, the lengths L3 and L4 are measured at the radially central position. The depth d1 from the tread surface 15s of the middle block 15 to the outer surface of the first middle tie bar 13 and the depth d2 from the tread surface 15s to the outer surface of the second middle tie bar 14 are each 60% to 90% of the maximum depth da of the middle lateral grooves 10. Such first middle tie bars 13 and second middle tie bars 14 help to improve wear resistance and snow performance in a well-balanced manner.

[0033] As shown in Figure 3, the interrupted middle grooves 20 are, for example, inclined with respect to the tire axial direction. In a preferred embodiment, the middle lateral grooves 10 and the interrupted middle grooves 20 are inclined in opposite directions with respect to the tire axial direction. The maximum angle of the interrupted middle grooves 20 with respect to the tire axial direction is, for example, 5 to 15 degrees. Furthermore, the angle of the interrupted middle grooves 20 is preferably smaller than the maximum angle θ1 (shown in Figure 2) of the interrupted middle lateral grooves 10 with respect to the tire axial direction. This suppresses uneven wear around the interrupted middle grooves 20.

[0034] The interrupted middle groove 20 terminates, for example, closer to the first longitudinal edge 15a than the axial center of the middle block 15. In a preferred embodiment, the interrupted end 20a of the interrupted middle groove 20 is located closer to the second longitudinal edge 15b than the first middle tie bar 13 (shown in FIG. 5). The axial length L5 of the interrupted middle groove 20 is, for example, 20% to 30% of the axial width W2 of the tread surface of the middle block 15. Such interrupted middle grooves 20 help to improve wear resistance and performance on snow in a well-balanced manner.

[0035] The middle-interrupted groove 20 provided in the second middle block 17 preferably extends from between the first inclined portion 18 and the second inclined portion 19 of the first longitudinal edge 15a. This allows the middle-interrupted groove 20 and the shoulder circumferential groove 6 to cooperate to form a solid snow column, further improving on-snow performance.

[0036] As shown in Fig. 4, the maximum depth d3 of the interrupted middle grooves 20 is, for example, 40% to 60% of the maximum depth dc of the shoulder circumferential grooves 6. The depth d3 of the interrupted middle grooves 20 is preferably smaller than the depth d1 (shown in Fig. 5) from the tread 15s to the outer surface of the first middle tie bar 13. Specifically, the depth d3 of the interrupted middle grooves 20 is 65% to 80% of the depth d1. This improves on-snow performance while maintaining wear resistance and steering stability.

[0037] In a cross section along the longitudinal direction of the middle-interrupted groove 20, the bottom 20d extends linearly. The angle θ3 of the bottom 20d with respect to the tire normal is, for example, 35 to 55°. Such middle-interrupted groove 20 can improve wear resistance and on-snow performance in a well-balanced manner.

[0038] As shown in FIG. 3, the middle block 15 is provided with a first middle sipe 21 and a second middle sipe 22. In this specification, a "sipe" refers to a small cut, with the width between two sipe walls in the sipe body being 1.5 mm or less. The sipe body refers to a portion where two sipe walls extend substantially parallel to each other in the tire radial direction. "Substantially parallel" refers to an aspect where the angle between the two sipe walls is 10 degrees or less. The sipe may open via a chamfered portion. The sipe may also have a so-called flask bottom, with an expanded width at the bottom.

[0039] The first middle sipes 21 and the second middle sipes 22 each extend in a zigzag pattern. When ground pressure acts on the middle block 15, the opposing sipe walls of the first middle sipes 21 and the second middle sipes 22 mesh with each other, increasing the apparent rigidity of the middle block 15. This improves on-snow performance while maintaining steering stability and wear resistance.

[0040] The first middle sipes 21 extend, for example, from the first longitudinal edge 15a or the interrupted middle groove 20 and are interrupted within the tread surface 15s. In this embodiment, the first middle sipes 21 provided on the first middle block 16 extend from the first longitudinal edge 15a, and the first middle sipes 21 provided on the second middle block 17 extend from the interrupted middle groove 20. Such an arrangement of the first middle sipes 21 helps to turn the impact sound when the first middle block 16 and the second middle block 17 contact the ground into white noise.

[0041] The first middle sipes 21 desirably cross the axial center of the middle blocks 15. The axial length L6a of the first middle sipes 21 is, for example, 50% to 90% of the maximum axial width W2 of the tread surfaces 15s of the middle blocks 15. In a preferred embodiment, the length L6a of each of the first middle sipes 21 provided on the first middle blocks 16 and the first middle sipes 21 provided on the second middle blocks 17 is 60% or more of the width W2. This improves wear resistance and performance on snow in a balanced manner.

[0042] The first middle sipes 21 are, for example, inclined relative to the tire axial direction. It is desirable that the first middle sipes 21 and the middle lateral grooves 10 are inclined in the same direction relative to the tire axial direction. The angle of the first middle sipes 21 relative to the tire axial direction (when the sipes are zigzag, this means the angle of the center line of the amplitude relative to the tire axial direction) is desirably larger than the maximum angle of the middle discontinuous grooves 20 relative to the tire axial direction, specifically 20 to 40 degrees. Such first middle sipes 21 can also provide frictional force in the tire axial direction when driving on snow.

[0043] FIG. 6 shows a cross section of the first middle sipe 21 taken along line CC in FIG. 3. Note that in FIG. 6, ridges formed on the sipe walls due to the zigzag extension of the sipes are omitted. As shown in FIG. 6, the first middle sipe 21 desirably has a smaller depth at both ends. The depth d5 ​​at both ends is 20% to 35% of the maximum depth d4 of the first middle sipe 21. Such a first middle sipe 21 can improve on-snow performance while effectively maintaining wear resistance.

[0044] 3, the second middle sipes 22 extend from the second longitudinal edge 15b and terminate within the tread surface 15s. The second middle sipes 22 desirably cross the axial center of the middle block 15, for example. The axial length L6b of the second middle sipes 22 is, for example, 70% to 85% of the maximum axial width W2 of the tread surface 15s of the middle block 15. This improves wear resistance and performance on snow in a balanced manner.

[0045] The angle of the second middle sipes 22 with respect to the tire axial direction and the cross-sectional shape of the second middle sipes 22 can be the same as the configuration of the first middle sipes 21 described above.

[0046] The middle block 15 is provided with a middle recessed portion 28, the sidewall of which is recessed on the crown circumferential groove 5 side. FIG. 7 shows a cross section of the middle recessed portion 28, taken along line DD in FIG. 3. As shown in FIG. 7, the axial width W3 of the middle recessed portion 28 on the tread surface 15s is, for example, 10% or less of the width W2 of the tread surface 15s of the middle block 15. The maximum depth d7 of the middle recessed portion 28 is 50% to 65% of the maximum depth d6 of the crown circumferential groove 5. Such a middle recessed portion 28 can improve on-snow performance while maintaining steering stability and wear resistance.

[0047] 3, the middle recessed portion 28 communicates with the end portion of the second middle lateral groove 12 on the tire equator C side. The length L8 of the middle recessed portion 28 in the tire circumferential direction is 40% to 60% of the length L7 of the second longitudinal edge 15b in the tire circumferential direction.

[0048] Fig. 8 shows an enlarged view of the crown land portion 8 in Fig. 1. As shown in Fig. 8, the crown land portion 8 is provided with a plurality of crown lateral grooves 30 that completely cross the crown land portion 8 in the tire axial direction. As a result, the crown land portion 8 is divided into a plurality of crown blocks 35 by the plurality of crown lateral grooves 30. Each crown block 35 includes a first longitudinal edge 35a on one side in the tire axial direction (the left side in Fig. 8), a second longitudinal edge 35b on the other side in the tire axial direction (the right side in Fig. 8), and a tread surface 35s between the first longitudinal edge 35a and the second longitudinal edge 35b.

[0049] The crown lateral grooves 30 are inclined, for example, in the opposite direction to the middle lateral grooves 10 (shown in FIG. 2). The angle θ4 of the crown lateral grooves 30 relative to the tire axial direction is, for example, 15 to 35°. Such crown lateral grooves 30 can provide a large snow column shear force in a direction different from that of the middle lateral grooves 10, further improving on-snow performance.

[0050] It is desirable that the maximum groove width W5 of the crown lateral grooves 30 is smaller than the maximum groove width W4 (shown in FIG. 2) of the middle lateral grooves 10. Specifically, the groove width W5 of the crown lateral grooves 30 is 50% to 90% of the groove width W4 of the middle lateral grooves 10. This improves the wear resistance and steering stability, and also improves noise performance by converting the pitch noise of the crown lateral grooves 30 and the middle lateral grooves 10 into white noise.

[0051] The cross-sectional shape of the crown lateral grooves 30 can be the same as that of the middle lateral grooves 10. Therefore, the crown lateral grooves 30 include a first crown tie bar whose groove bottom is raised at the end on the first longitudinal edge 35a side, and a second crown tie bar whose groove bottom is raised at the end on the second longitudinal edge 35b side (not shown).

[0052] The crown blocks 35 are provided with crown-interrupted grooves 40 that extend from the first longitudinal edge 35a or the second longitudinal edge 35b and have discontinued ends within the tread surface 35s. In this embodiment, crown blocks 35 with crown-interrupted grooves 40 extending from the first longitudinal edge 35a and crown blocks 35 with crown-interrupted grooves 40 extending from the second longitudinal edge 35b are alternately arranged in the tire circumferential direction. This suppresses uneven wear of the crown land portion 8.

[0053] The crown-interrupted grooves 40 are inclined, for example, in the same direction as the middle-interrupted grooves 20 with respect to the tire axial direction. The maximum angle θ5 of the crown-interrupted grooves 40 with respect to the tire axial direction is larger than the maximum angle of the middle-interrupted grooves 20 with respect to the tire axial direction. Specifically, the angle θ5 of the crown-interrupted grooves 40 is 20 to 30°. Such crown-interrupted grooves 40 can provide snow column shear force also in the tire axial direction when driving on snow.

[0054] The crown-interrupted groove 40 is, for example, interrupted within the crown block 35 without crossing the axial center position of the crown block 35. The axial length L9 of the crown-interrupted groove 40 is desirably greater than the axial length L5 (shown in FIG. 3) of the middle-interrupted groove 20. The length L9 of the crown-interrupted groove 40 is 25% to 35% of the axial width W6 of the tread surface 35s of the crown block 35. Such a crown-interrupted groove 40 helps to improve wear resistance and performance on snow in a well-balanced manner.

[0055] The cross-sectional shape of the crown-interrupted grooves 40 can be the same as that of the middle-interrupted grooves 20. This further improves on-snow performance.

[0056] The crown block 35 is provided with first crown sipes 41 and second crown sipes 42. The first crown sipes 41 extend from the first longitudinal edge 35a and terminate within the tread surface 35s. The second crown sipes 42 extend from the second longitudinal edge 35b and terminate within the tread surface 35s. The first crown sipes 41 and second crown sipes 42 are inclined in the opposite direction to the first middle sipes 21 and second middle sipes 22 with respect to the tire axial direction. In other configurations, the configuration of the first middle sipes 21 or second middle sipes 22 can be applied to the first crown sipes 41 and second crown sipes 42.

[0057] Figure 9 shows an enlarged view of the shoulder land portion 9 in Figure 1. As shown in Figure 9, the shoulder land portion 9 is provided with a plurality of shoulder lateral grooves 50. The shoulder lateral grooves 50 extend from the shoulder circumferential groove 6 to a position beyond the tread edge Te. As a result, the shoulder land portion 9 is divided into a plurality of shoulder blocks 55 by the shoulder lateral grooves 50.

[0058] The shoulder lateral grooves 50 include a first groove portion 51 and a second groove portion 52. The first groove portion 51 extends axially from the shoulder circumferential groove 6. In a preferred embodiment, the first groove portion 51 is inclined in the opposite direction to the middle lateral grooves 10 (shown in FIG. 2) with respect to the tire axial direction. The maximum angle θ6 of the first groove portion 51 with respect to the tire axial direction is smaller than the maximum angle θ1 of the middle lateral grooves 10 with respect to the tire axial direction. Specifically, the angle θ6 of the first groove portion 51 is 20 to 30°. Such a first groove portion 51 helps improve traction performance and cornering performance when driving on snow.

[0059] The second groove portions 52 are inclined in the same direction as the first groove portions 51 relative to the tire axial direction. The maximum angle θ7 of the second groove portions 52 relative to the tire axial direction is smaller than the angle θ6 of the first groove portions 51. Specifically, the angle θ7 of the second groove portions 52 is 10° or less. Such second groove portions 52 are useful for improving wandering performance when driving on snow.

[0060] FIG. 10 shows a cross section of the shoulder lateral groove 50, taken along line E-E in FIG. 9 . As shown in FIG. 10 , the shoulder lateral groove 50 is provided with a shoulder tie bar 53, which has a raised groove bottom in the first groove portion 51. The shoulder tie bar 53 has a height that changes, for example, in a step-like manner. As a result, the shoulder tie bar 53 includes a first outer surface 53a located radially outward and a second outer surface 53b located radially inward of the first outer surface 53a. The depth d9 from the tread surface 55s of the shoulder block 55 to the first outer surface 53a is 10% to 25% of the maximum depth d8 of the shoulder lateral groove 50. The depth d10 from the tread surface 55s to the second outer surface 53b is, for example, 65% to 80% of the depth d8 of the shoulder lateral groove 50. Such a shoulder tie bar 53 improves wear resistance and steering stability and can prevent snow from clogging the shoulder lateral groove 50.

[0061] As shown in Figure 9, each shoulder block 55 is provided with at least one shoulder sipe 58. In this embodiment, one shoulder block 55 is provided with two shoulder sipes 58. The shoulder sipes 58 extend from the shoulder circumferential groove 6 to near the tread edge Te. In this embodiment, the shoulder sipes 58 terminate just before the tread edge Te, but they may extend beyond the tread edge Te. Such shoulder sipes 58 are useful for improving on-snow performance.

[0062] 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]

[0063] Pneumatic tires of size LT265 / 70R17 having the basic pattern shown in Figure 1 were prototyped based on the specifications in Table 1. As a comparative example, a tire was prototyped in which no middle-interrupted grooves were provided in the middle blocks and no first middle tie bars were provided in the middle lateral grooves. The comparative tire had substantially the same configuration as the tire shown in Figure 1, except for the above-mentioned points. The wear resistance and snow performance of each test tire were tested. The common specifications and test methods for each test tire are as follows: Rim: 17 x 7.5J Tire pressure: Front: 410kPa, Rear: 520kPa Test vehicle: 4600cc, four-wheel drive Tire mounting position: All wheels

[0064] <Wear resistance> After the test vehicle was driven a certain distance, the remaining land height of the middle land area was measured. The results were expressed as an index, with the remaining land height of the comparative example being 100, and the larger the index, the better the wear resistance.

[0065] <Snow performance> The driving performance of the test vehicle on snowy roads was evaluated by the driver. The results are given as a score with the comparative example being 100, with a higher score indicating better snow performance. The test results are shown in Table 1.

[0066] [Table 1]

[0067] As shown in Table 1, it was confirmed that the tires of the examples exhibited excellent performance on snow while maintaining wear resistance.

[0068] [Note] The present disclosure includes the following aspects.

[0069] [Disclosure 1] A tire having a tread portion, The tread portion includes a middle land portion disposed between a tread edge and a tire equator, The middle land portion is divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, The plurality of middle blocks include a first longitudinal edge on the tread end side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, At least one of the plurality of middle blocks is provided with at least one middle interrupted groove extending from the first longitudinal edge and having an interrupted end within the tread surface, The depth of the middle interrupted groove continuously decreases toward the interrupted end, At least one of the plurality of middle lateral grooves includes a first middle tie bar having a groove bottom raised at an end portion on the first longitudinal edge side. tire. [Disclosure 2] The tire described in Disclosure 1, wherein the maximum depth of the middle discontinuous groove is smaller than the depth from the tread surface to the outer surface of the first middle tie bar. [Disclosure 3] The tire according to Disclosure 1 or 2, wherein the discontinuous end is located closer to the second vertical edge than the first middle tie bar. [Disclosure 4] the first vertical edge includes a first inclined portion inclined with respect to the tire circumferential direction and a second inclined portion inclined in an opposite direction to the first inclined portion with respect to the tire circumferential direction, The tire according to any one of Disclosures 1 to 3, wherein the middle-discontinuous groove extends from between the first inclined portion and the second inclined portion. [Disclosure 5] The tire according to any one of Disclosures 1 to 4, wherein the middle lateral groove and the middle discontinuous groove are inclined in opposite directions relative to the tire axial direction. [Disclosure 6] The tire according to Disclosure 5, wherein the maximum angle of the middle discontinuous groove relative to the tire axial direction is smaller than the maximum angle of the middle lateral groove relative to the tire axial direction. [Disclosure 7] A tire described in any one of Disclosures 1 to 6, wherein at least one of the plurality of middle blocks is provided with at least one first middle sipe extending from the first longitudinal edge or the middle-interrupted groove and interrupted within the tread surface. [Disclosure 8] The tire according to Disclosure 7, wherein the length of the first middle sipe in the tire axial direction is 60% or more of the maximum width of the middle block in the tire axial direction. [Disclosure 9] The tire according to Disclosure 7 or 8, wherein the first middle sipe and the middle lateral groove are inclined in the same direction relative to the tire axial direction. [Disclosure 10] The tire according to any one of claims 7 to 9, wherein the first middle sipe extends in a zigzag pattern. [Explanation of symbols]

[0070] 2 Tread section 7 Middle Track 10 Middle Yokomizo 13 First middle tie bar 15 Middle Block 15a First vertical edge 15b Second vertical edge 15s tread 20 Middle Intermittent Groove 20a End Te tread edge

Claims

1. A tire having a tread portion, The tread portion includes a middle land portion disposed between a tread edge and a tire equator, The middle land portion is divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the plurality of middle blocks include a first longitudinal edge on the tread end side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, At least one of the plurality of middle blocks is provided with at least one interrupted middle groove extending from the first longitudinal edge and having an interrupted end within the tread surface, The depth of the middle interrupted groove continuously decreases toward the interrupted end, At least one of the plurality of middle lateral grooves includes a first middle tie bar having a groove bottom raised at an end portion on the first longitudinal edge side, The maximum depth of the middle discontinuous groove is smaller than the depth from the tread surface to the outer surface of the first middle tie bar. tire.

2. A tire having a tread portion, The tread portion includes a middle land portion disposed between a tread edge and a tire equator, The middle land portion is divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the plurality of middle blocks include a first longitudinal edge on the tread end side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, At least one of the plurality of middle blocks is provided with at least one interrupted middle groove extending from the first longitudinal edge and having an interrupted end within the tread surface, The depth of the middle interrupted groove continuously decreases toward the interrupted end, At least one of the plurality of middle lateral grooves includes a first middle tie bar having a groove bottom raised at an end portion on the first longitudinal edge side, The interrupted end is located closer to the second vertical edge than the first middle tie bar. tire.

3. A tire having a tread portion, The tread portion includes a middle land portion disposed between a tread edge and a tire equator, The middle land portion is divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the plurality of middle blocks include a first longitudinal edge on the tread end side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, At least one of the plurality of middle blocks is provided with at least one interrupted middle groove extending from the first longitudinal edge and having an interrupted end within the tread surface, The depth of the middle interrupted groove continuously decreases toward the interrupted end, At least one of the plurality of middle lateral grooves includes a first middle tie bar having a groove bottom raised at an end portion on the first longitudinal edge side, the first vertical edge includes a first inclined portion inclined with respect to the tire circumferential direction and a second inclined portion inclined in an opposite direction to the first inclined portion with respect to the tire circumferential direction, The middle discontinuous groove extends from between the first inclined portion and the second inclined portion. tire.

4. A tire having a tread portion, The tread portion includes a middle land portion disposed between a tread edge and a tire equator, The middle land portion is divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the plurality of middle blocks include a first longitudinal edge on the tread end side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, At least one of the plurality of middle blocks is provided with at least one interrupted middle groove extending from the first longitudinal edge and having an interrupted end within the tread surface, The depth of the middle interrupted groove continuously decreases toward the interrupted end, At least one of the plurality of middle lateral grooves includes a first middle tie bar having a groove bottom raised at an end portion on the first longitudinal edge side, At least one of the plurality of middle blocks is provided with at least one first middle sipe extending from the first longitudinal edge or the middle interrupted groove and interrupted within the tread surface, The length of the first middle sipe in the tire axial direction is 60% or more of the maximum width of the middle block in the tire axial direction. tire.

5. A tire having a tread portion, The tread portion includes a middle land portion disposed between a tread edge and a tire equator, The middle land portion is divided into a plurality of middle blocks by a plurality of middle lateral grooves that completely cross the middle land portion in the tire axial direction, the plurality of middle blocks include a first longitudinal edge on the tread end side, a second longitudinal edge on the tire equator side, and a tread surface between the first longitudinal edge and the second longitudinal edge, At least one of the plurality of middle blocks is provided with at least one interrupted middle groove extending from the first longitudinal edge and having an interrupted end within the tread surface, The depth of the middle interrupted groove continuously decreases toward the interrupted end, At least one of the plurality of middle lateral grooves includes a first middle tie bar having a groove bottom raised at an end portion on the first longitudinal edge side, At least one of the plurality of middle blocks is provided with at least one first middle sipe extending from the first longitudinal edge or the middle interrupted groove and interrupted within the tread surface, The first middle sipe and the middle lateral groove are inclined in the same direction with respect to the tire axial direction. tire.

6. A tire as described in claim 4 or 5, wherein the first middle sipe extends in a zigzag pattern.

7. A tire described in any one of claims 1 to 6, wherein the middle lateral groove and the middle interrupted groove are inclined in opposite directions to each other with respect to the tire axial direction.

8. A tire as described in claim 7, wherein the maximum angle of the middle interrupted groove relative to the tire axial direction is smaller than the maximum angle of the middle lateral groove relative to the tire axial direction.

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