Tire

Abstract

To provide a tire capable of improving noise performance while maintaining mud performance.SOLUTION: The present invention relates to a tire having a tread portion 2 . The tread portion 2 includes a first tread edge T1, a second tread edge T2, four circumferential grooves 3, and five land portions 4. The four circumferential grooves 3 include a first shoulder circumferential groove 5, a second shoulder circumferential groove 6, a first crown circumferential groove 7, and a second crown circumferential groove 8. The five land portions 4 include a first middle land portion 11, a second middle land portion 12, and a crown land portion 10. The first middle land portion 11 is provided with a plurality of first middle lateral grooves 16. The second middle land portion 12 is provided with second middle lateral grooves 17. In a tread plan view, a first end portion of each of the plurality of first middle lateral grooves 16 overlaps with a first imaginary region 21. A second end portion of each of the plurality of first middle lateral grooves 16 overlaps with a second imaginary region 22.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Patent Document 1 below proposes a tire in which the mud performance, wet performance, and handling stability performance on a dry road surface are improved by improving the shape of the blocks.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] With the recent strengthening of regulations on vehicle exterior noise, even for tires corresponding to mud roads like the above-mentioned tires, improvement in noise performance is required.

[0005] The present invention has been devised in view of the above circumstances, and the main object thereof is to provide a tire capable of improving noise performance while maintaining mud performance.

Means for Solving the Problems

[0006] The present invention relates to a tire having a tread portion, wherein the tread portion includes a first tread end and a second tread end, four circumferential grooves continuously extending in the tire circumferential direction between the first tread end and the second tread end, and five land portions divided by the plurality of circumferential grooves. The four circumferential grooves include a first shoulder circumferential groove provided closest to the first tread end side, a second shoulder circumferential groove provided closest to the second tread end side, a first crown circumferential groove provided between the first shoulder circumferential groove and the tire equator, and a second crown circumferential groove provided between the second shoulder circumferential groove and the tire equator. The five land portions include a first middle land portion divided between the first shoulder circumferential groove and the first crown circumferential groove, a second middle land portion divided between the second shoulder circumferential groove and the second crown circumferential groove, and a crown land portion divided between the first crown circumferential groove and the second crown circumferential groove. The first middle land portion is provided with a plurality of first middle transverse grooves that completely cross the first middle land portion in the tire axial direction, and the second middle land portion is provided with a plurality of second middle transverse grooves that completely cross the second middle land portion in the tire axial direction. The plurality of first middle transverse grooves and the plurality of second middle transverse grooves are each inclined with respect to the tire axial direction, and include a first end portion on a first side in the tire circumferential direction and a second end portion on a second side in the tire circumferential direction. In a tread plan view, each of the first end portions of the plurality of first middle transverse grooves overlaps the second end portion of the second middle transverse groove in a first virtual region extended on the first middle land portion parallel to the tire axial direction, and each of the second end portions of the plurality of first middle transverse grooves overlaps the first end portion of the second middle transverse groove in a second virtual region extended on the first middle land portion parallel to the tire axial direction.

Advantages of the Invention

[0007] By having the above configuration, the tire of the present invention can improve the noise performance while maintaining the mud performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Although the drawings describe the features of the present invention, in order to assist in understanding the present invention, there may be included exaggerated expressions or expressions different from the actual structural dimensional ratios. Also, throughout each embodiment, the same or common elements are given the same reference numerals, and duplicate descriptions are omitted.

[0010] FIG. 1 is a developed view of a tread part 2 of a tire 1 showing one embodiment of the present invention. The tire 1 of the present embodiment is a pneumatic tire and is suitably used for a four-wheel drive vehicle such as an SUV that can travel not only on a paved road but also on an off-road such as a mud road surface or a rock road surface. However, the tire of the present invention is not limited to such a mode.

[0011] As shown in FIG. 1, the tread part 2 of the present embodiment is composed of a first tread end T1, a second tread end T2, four circumferential grooves 3 that continuously extend in the tire circumferential direction between the first tread end T1 and the second tread end T2, and five land parts 4 divided by these circumferential grooves 3.

[0012] The first tread end T1 and the second tread end T2 respectively correspond to the ends of the contact surface when 58% of the normal load is applied to the tire 1 in the normal state and the tread part 2 is grounded on a plane at a camber angle of 0°.

[0013] For pneumatic tires for which various standards are defined, the "normal state" means that the tire is mounted on a standard rim and filled with the normal internal pressure, and moreover, it is in an unloaded state. For tires for which no various standards are defined or for non-pneumatic tires, the "normal state" means a standard use state according to the purpose of use of the tire, and it means a state where the tire is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the above-mentioned normal state.

[0014] The "standard rim" is the rim defined for each tire in a standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the "Standard Rim", in the case of TRA, it is the "Design Rim", and in the case of ETRTO, it is the "Measuring Rim".

[0015] The "normal internal pressure" is the air pressure defined for each tire in a standard system including the standards on which the tire is based. In the case of JATMA, it is the "maximum air pressure", in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "INFLATION PRESSURE".

[0016] For pneumatic tires for which various standards are defined, the "normal load" is the load defined for each tire in a standard system including the standards on which the tire is based. In the case of JATMA, it is the "maximum load capacity", in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "LOAD CAPACITY". Also, for tires for which no various standards are defined, the "normal load" refers to the maximum load applicable in using the tire according to the above-mentioned standards.

[0017] The circumferential groove 3 includes a first shoulder circumferential groove 5, a second shoulder circumferential groove 6, a first crown circumferential groove 7, and a second crown circumferential groove 8. The first shoulder circumferential groove 5 is provided closest to the first tread end T1 among the four circumferential grooves 3. The second shoulder circumferential groove 6 is provided closest to the second tread end T2 among the four circumferential grooves 3. The first crown circumferential groove 7 is provided between the first shoulder circumferential groove 5 and the tire equator C. The second crown circumferential groove 8 is provided between the second shoulder circumferential groove 6 and the tire equator C.

[0018] It is desirable that the groove width W1 of each circumferential groove 3 is at least 3 mm or more. Also, it is desirable that the groove width W1 of each circumferential groove 3 is, for example, 3.0% to 7.0% of the tread width TW. Note that the tread width TW corresponds to the distance in the tire axial direction from the first tread end T1 to the second tread end T2 in the normal state. The depth of each circumferential groove 3 is, for example, 5 to 10 mm in the case of a pneumatic tire for a passenger car.

[0019] In addition, when numerical ranges of various parameters are described in this specification, unless otherwise specified, the numerical range means the numerical range for the average value of the parameter. For this reason, for example, the groove width W1 of the circumferential groove 3 described above means the average value measured at a plurality of positions in the tire circumferential direction of the circumferential groove 3. The same applies to other parameters described later.

[0020] The five land portions 4 of the present invention include at least a crown land portion 10, a first middle land portion 11, and a second middle land portion 12. Further, the land portion 4 of the present embodiment includes a first shoulder land portion 13 and a second shoulder land portion 14. The crown land portion 10 is demarcated between a first crown circumferential groove 7 and a second crown circumferential groove 8. Thereby, the crown land portion 10 is provided on the tire equator C. The first middle land portion 11 is demarcated between a first shoulder circumferential groove 5 and the first crown circumferential groove 7. The second middle land portion 12 is demarcated between a second shoulder circumferential groove 6 and the second crown circumferential groove 8. The first shoulder land portion 13 is demarcated on the outer side in the tire axial direction of the first shoulder circumferential groove 5 and includes a first tread end T1. The second shoulder land portion 14 is demarcated on the outer side in the tire axial direction of the second shoulder circumferential groove 6 and includes a second tread end T2.

[0021] FIG. 2 shows an enlarged view of the crown land portion 10, the first middle land portion 11, and the second middle land portion 12. As shown in FIG. 2, a plurality of first middle transverse grooves 16 are provided in the first middle land portion 11. These first middle transverse grooves 16 completely cross the first middle land portion 11 in the tire axial direction. Also, a plurality of second middle transverse grooves 17 are provided in the second middle land portion 12. These second middle transverse grooves 17 completely cross the second middle land portion 12 in the tire axial direction.

[0022] The plurality of first middle transverse grooves 16 and the plurality of second middle transverse grooves 17 are each inclined with respect to the tire axial direction. In the present embodiment, the first middle transverse grooves 16 and the second middle transverse grooves 17 are inclined in the same direction with respect to the tire axial direction. In another embodiment of the present invention, the first middle transverse grooves 16 and the second middle transverse grooves 17 may be inclined in different directions with respect to the tire axial direction.

[0023] Due to the above-mentioned inclination, each of the plurality of first middle transverse grooves 16 and the plurality of second middle transverse grooves 17 includes a first end portion on the first side S1 in the tire circumferential direction (downward in each figure of this specification) and a second end portion on the second side in the tire circumferential direction (downward in each figure of this specification). That is, the first middle transverse groove 16 includes a first end portion 16a on the first side S1 and a second end portion 16b on the second side S2. Similarly, the second middle transverse groove 17 also includes a first end portion 17a on the first side S1 and a second end portion 17b on the second side S2. These end portions communicate with any one of the circumferential grooves 3.

[0024] FIG. 3 shows an enlarged view of the first middle land portion 11 and the second middle land portion 12 in FIG. 2. In this figure, the crown land portion 10 shown in FIG. 2 is omitted. As shown in FIG. 3, in a tread plan view, each first end portion 16a of the plurality of first middle transverse grooves 16 overlaps with the second end portion 17b of the second middle transverse groove 17 in a first virtual region 21 extended on the first middle land portion 11 parallel to the tire axial direction. Also, each second end portion 16b of the plurality of first middle transverse grooves 16 overlaps with the first end portion 17a of the second middle transverse groove 17 in a second virtual region 22 extended on the first middle land portion 11 parallel to the tire axial direction. By having the above characteristics, the tire 1 of the present invention can improve the noise performance while maintaining the mud performance. The reason is as follows.

[0025] As described above, the tire 1 of the present invention is provided with four circumferential grooves 3 in the tread portion 2. Also, a plurality of first middle transverse grooves 16 are provided in the first middle land portion 11, and a plurality of second middle transverse grooves 17 are provided in the second middle land portion 12. Such various grooves provide reaction forces in multiple directions during driving on a mud road surface and help maintain the mud performance.

[0026] Also, conventionally, a pitch sound is known as a noise generated during tire running. One of the causes of this pitch sound is, for example, an impact force generated when a lateral groove extending in the tire axial direction contacts the road surface. Due to this impact force, the tread portion and the sidewall portion (not shown) vibrate periodically, and a pitch sound may be generated.

[0027] In the present invention, since the first middle lateral groove 16 and the second middle lateral groove 17 are arranged as described above, when the tire runs, the first middle lateral groove 16 and the second middle lateral groove 17 can alternately and continuously contact the ground without interruption. Thereby, the variation of the above-mentioned impact force can be reduced. Therefore, the tire 1 of the present invention can reduce the pitch sound caused by the impact force and improve the noise performance.

[0028] Hereinafter, a more detailed configuration of the present embodiment will be described. Each configuration described below shows a specific aspect of the present embodiment. Therefore, it goes without saying that the present invention can exhibit the above-described effects even if it does not have the configurations described below. Further, even if any one of the configurations described below is applied alone to the tire 1 of the present invention having the above-described features, an improvement in performance corresponding to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a combined improvement in performance corresponding to each configuration can be expected.

[0029] As shown in FIG. 1, the tread portion 2 of the present embodiment has a pattern that is substantially point-symmetrical with respect to a point on the tire equator C. Therefore, the configuration of the member arranged on the first tread end T1 side with respect to the tire equator C described in this specification can also be applied to the member on the second tread end T2 side with respect to the corresponding tire equator C.

[0030] FIG. 4 shows an enlarged view of the contour of the first crown circumferential groove 7 as an example of the circumferential groove 3. The configuration of the circumferential groove 3 described below can be applied not only to the first crown circumferential groove 7 but also to any of the second crown circumferential groove 8, the first shoulder circumferential groove 5, and the second shoulder circumferential groove 6 (shown in FIG. 1).

[0031] The circumferential groove 3 extends, for example, in a zigzag shape. However, the circumferential groove 3 may extend linearly parallel to the tire circumferential direction. When the circumferential groove 3 extends in a zigzag shape as in the present embodiment, its center line 3c may adopt various forms such as a triangular wave, a sine wave, or a trapezoidal wave. In the circumferential groove 3 of the present embodiment, the center line 3c extends in a trapezoidal wave shape. Thereby, not only the mud performance but also the running performance on a rocky road surface including relatively large rocks and the like can be improved.

[0032] The circumferential groove 3 is in a zigzag shape including an inner groove portion 3i, an outer groove portion 3o, and an inclined portion 3s. The inner groove portion 3i extends linearly in the tire circumferential direction on the tire equator C side. The outer groove portion 3o extends linearly in the tire circumferential direction on the outer side in the tire axial direction than the inner groove portion 3i. The inner groove portion 3i and the outer groove portion 3o of the present embodiment extend parallel to the tire circumferential direction, respectively, but are not limited to such a form. The inclined portion 3s connects the inner groove portion 3i and the outer groove portion 3o. The angle θ1 of the inclined portion with respect to the tire axial direction is, for example, 40 to 60°.

[0033] As shown in FIG. 1, the distance L1 in the tire axial direction from the tire equator C to the center line of the first crown circumferential groove 7 is 5% to 20% of the tread half-width TWh. In the present embodiment, the first shoulder circumferential groove 5 extends in a zigzag shape, and its center line extends in the tire circumferential direction while oscillating in the tire axial direction within the above range. Note that the tread half-width TWh corresponds to the distance in the tire axial direction from the tire equator C to the first tread end T1.

[0034] Similarly, the distance in the tire axial direction from the tire equator C to the center line of the second crown circumferential groove 8 (the symbol is omitted) is 5% to 20% of the tread half-width TWh. Further, the distance L2 in the tire axial direction from the tire equator C to the center line of the first shoulder circumferential groove 5 is 45% to 55% of the tread half-width TWh. Similarly, the distance in the tire axial direction from the tire equator C to the center line of the second shoulder circumferential groove 6 (the symbol is omitted) is 45% to 55% of the tread half-width TWh. With such an arrangement of the circumferential grooves 3, while suppressing chipping of each land portion, the mud performance can be improved.

[0035] As shown in FIG. 2, the plurality of first middle transverse grooves 16 are inclined in a first direction (in each figure of the present embodiment, it is upward to the right) with respect to the tire axial direction. The same applies to the plurality of second middle transverse grooves 17. The first middle transverse groove 16 and the second middle transverse groove 17 of the present embodiment extend linearly with the above-described inclination, but are not limited to such a mode. Further, the first middle transverse groove 16 and the second middle transverse groove 17 are each inclined at an angle θ2 of 20 to 60° with respect to the tire axial direction. The angle θ2 is desirably 30° or more, more desirably 35° or more, desirably 50° or less, and more desirably 45° or less. Such first middle transverse grooves 16 and second middle transverse grooves 17 can easily discharge the mud and soil that have entered inside when driving on a muddy road surface. For this reason, excellent mud performance is continuously exhibited.

[0036] The first middle transverse groove 16 has a constant groove width in its length direction. The groove width W2 of the first middle transverse groove 16 is 5% to 20% of the average value of the one-pitch length P1 in the plurality of first middle transverse grooves 16, and desirably 10% to 15%. Similarly, the groove width W3 of the second middle transverse groove 17 is 5% to 20% of the average value of the one-pitch length P2 in the plurality of second middle transverse grooves 17, and desirably 10% to 15%. Thereby, the mud performance and the handling stability on a dry road surface (hereinafter simply referred to as "handling stability") are improved in a well-balanced manner.

[0037] As shown in FIG. 3, if at least a part of the first end portion 16a of the first middle transverse groove 16 overlaps with the first virtual region 21, the above-described operational effects can be expected. From the viewpoint of further enhancing the above-described operational effects, the overlapping length L4 in the tire circumferential direction between the first end portion 16a of the first middle transverse groove 16 and the first virtual region 21 is desirably 30% to 100% of the length L3 in the tire circumferential direction of the first virtual region 21, and more desirably 60% to 100%. Similarly, the overlapping length L6 in the tire circumferential direction between the second end portion 16b of the first middle transverse groove 16 and the second virtual region 22 is 30% to 100% of the length L5 in the tire circumferential direction of the second virtual region 22, and desirably 60% to 100%.

[0038] As shown in FIG. 2, each of the plurality of first middle transverse grooves 16 communicates with the connecting portion between the outer groove portion 7o and the inclined portion 7s in the first crown circumferential groove 7 so that the angle between each of the plurality of first middle transverse grooves 16 and the outer groove portion 7o of the first crown circumferential groove 7 is an obtuse angle. Thereby, when driving on a muddy road surface, mud and soil can be strongly compacted at the communicating portions of these grooves, and the mud performance can be further improved.

[0039] From the same viewpoint, each of the plurality of first middle transverse grooves 16 communicates with the connecting portion between the inner groove portion 5i and the inclined portion 5s in the first shoulder circumferential groove 5 so that the angle between each of the plurality of first middle transverse grooves 16 and the inner groove portion 5i of the first shoulder circumferential groove 5 is an obtuse angle.

[0040] Further, each of the plurality of second middle transverse grooves 17 communicates with the connecting portion between the outer groove portion 8o and the inclined portion 8s in the second crown circumferential groove 8 so that the angle between each of the plurality of second middle transverse grooves 17 and the outer groove portion 8o of the second crown circumferential groove 8 is an obtuse angle. Similarly, each of the plurality of second middle transverse grooves 17 communicates with the connecting portion between the inner groove portion 6i and the inclined portion 6s in the second shoulder circumferential groove 6 so that the angle between each of the plurality of second middle transverse grooves 17 and the inner groove portion 6i of the second shoulder circumferential groove 6 is an obtuse angle. Thereby, the mud performance can be further improved.

[0041] The first middle land portion 11 is provided with a plurality of sipes 25. In this specification, a "sipe" means a cut having a small width, and in the sipe main body portion, the width between two sipe walls is 1.5 mm or less. Further, the sipe main body portion means a portion where two sipe walls extend in the tire radial direction substantially parallel to each other. "Substantially parallel" means a mode in which the angle between two sipe walls is 10° or less. Due to the above-described configuration, when the ground pressure acts, the two sipe walls contact each other in the sipe main body portion, and the rigidity of the portion where the sipe is arranged can be maintained. Note that in this specification, for each groove, even when the ground pressure acts, the two groove walls do not contact each other, and a substantial drainage path can be maintained. From such a viewpoint, the groove width of each groove is, for example, 2.0 mm or more.

[0042] The sipe 25 of this embodiment extends in the tire radial direction with a constant width, for example. The sipe 25 may have a chamfered portion formed at its edge. Further, the sipe 25 may have a so-called flask bottom with an enlarged width at its bottom.

[0043] The sipes 25 provided in the first middle land portion 11 include, for example, a central sipe 26, an inner sipe 27, and an outer sipe 28. These sipes 25 are inclined, for example, in a second direction (downward to the right in each figure of this specification) with respect to the tire axial direction. Thereby, the first middle transverse groove 16 and these sipes 25 are inclined in a direction opposite to the tire axial direction. The angle of the sipe 25 with respect to the tire axial direction is, for example, 20 to 40°.

[0044] The central sipe 26 extends from the first crown circumferential groove 7 to the first shoulder circumferential groove 5. In a desirable mode, the central sipe 26 extends from the connection portion of the first middle transverse groove 16 and the first crown circumferential groove 7 to the connection portion of the first middle transverse groove 16 and the first shoulder circumferential groove 5. Such a central sipe 26 provides a large frictional force on a mud road surface or a rock road surface and helps to improve off-road performance.

[0045] The inner sipe 27 extends, for example, from the first crown circumferential groove 7 and is interrupted within the first middle land portion 11 without communicating with other grooves or sipes. The inner sipe 27 communicates with the connection portion between the outer groove portion 7o and the inclined portion 7s of the first crown circumferential groove 7. The inner sipe 27 of the present embodiment has an angular difference of, for example, 5° or less with respect to the central sipe 26, and in a more desirable aspect, these sipes extend in parallel. Also, the length of the inner sipe 27 (the so-called peripheral length, and the same applies hereinafter) is 50% or less of the length of the central sipe 26, desirably 20% to 40%. Such an inner sipe 27 helps to enhance the mud performance and handling stability in a well-balanced manner.

[0046] Similarly, the outer sipe 28 extends, for example, from the first shoulder circumferential groove 5 and is interrupted within the first middle land portion 11 without communicating with other grooves or sipes. The outer sipe 28 communicates with the connection portion between the inner groove portion 5i and the inclined portion 5s of the first shoulder circumferential groove 5. The outer sipe 28 of the present embodiment has an angular difference of, for example, 5° or less with respect to the central sipe 26, and in a more desirable aspect, these sipes extend in parallel. Also, the length of the outer sipe 28 is 50% or less of the length of the central sipe 26, desirably 20% to 40%.

[0047] The second middle land portion 12 is provided with sipes similar to those of the first middle land portion 11. The sipes of the second middle land portion 12 have the same characteristics as the sipes 25 provided in the first middle land portion 11, and the description here is omitted.

[0048] The crown land portion 10 is provided with a plurality of first crown transverse grooves 31 and a plurality of second crown transverse grooves 32. The first crown transverse groove 31 communicates with the first crown circumferential groove 7. The first crown transverse groove 31 communicates with the first crown circumferential groove 7 at a position different from that of the first middle transverse groove 16 in the tire circumferential direction. Thus, in the present embodiment, a three-way intersection formed by the first crown circumferential groove 7 and the first middle transverse groove 16 and a three-way intersection formed by the first crown circumferential groove 7 and the first crown transverse groove 31 are alternately arranged in the tire circumferential direction. In a similar manner, the second crown transverse groove 32 communicates with the second crown circumferential groove 8.

[0049] The first crown transverse groove 31 of the present embodiment is interrupted, for example, within the crown land portion 10. The length L7 of the first crown transverse groove 31 in the tire axial direction is 15% to 30% of the maximum width W4 of the crown land portion 10 in the tire axial direction. The angle of the first crown transverse groove 31 with respect to the tire axial direction is, for example, 10° or less. The second crown transverse groove 32 has substantially the same configuration as the first crown transverse groove 31.

[0050] In the tread plan view, a third virtual region 23 obtained by extending each of the plurality of first crown transverse grooves 31 parallel to the tire axial direction on the first middle land portion 11 does not overlap with either the first virtual region 21 or the second virtual region 22. Also, in the tread plan view, a fourth virtual region 24 obtained by extending each of the plurality of second crown transverse grooves 32 parallel to the tire axial direction on the first middle land portion 11 does not overlap with either the first virtual region 21 or the second virtual region 22. With such an arrangement of the grooves, the wear resistance performance of the first middle land portion 11 and the crown land portion 10 is improved.

[0051] Figure 5 shows an enlarged view of the first shoulder land portion 13. As shown in Figure 5, the first shoulder land portion 13 is provided with a plurality of through shoulder transverse grooves 36 and a plurality of non-through shoulder transverse grooves 37. In this embodiment, these transverse grooves are alternately provided in the tire circumferential direction. The through shoulder transverse groove 36 extends from the first shoulder circumferential groove 5 to at least the first tread end T1. The non-through shoulder transverse groove 37 extends outward in the tire axial direction from the first shoulder circumferential groove 5 and is interrupted inside the tire axial direction from the first tread end T1.

[0052] The through shoulder transverse groove 36 communicates with, for example, the connection portion between the outer groove portion 5o and the inclined portion 5s of the first shoulder circumferential groove 5. The through shoulder transverse groove 36 has, for example, an increasing groove width continuously toward the first tread end T1 side. Thereby, the angle θ3 between the two groove edges of the through shoulder transverse groove 36 is, for example, 3 to 8°. Such a through shoulder transverse groove 36 can quickly discharge the mud that has entered inside during driving on a muddy road surface and can continuously exhibit excellent mud performance.

[0053] The through shoulder transverse groove 36 is arranged, for example, at a smaller angle with respect to the tire axial direction than the first middle transverse groove 16 (shown in Figure 2). The angle of the through shoulder transverse groove 36 with respect to the tire axial direction is, for example, 5° or less. Such a through shoulder transverse groove 36 helps to enhance the traction performance on a muddy road surface.

[0054] The non-through shoulder transverse groove 37 communicates, for example, with the connection portion between the inner groove portion 5i and the inclined portion 5s of the first shoulder circumferential groove 5. The non-through shoulder transverse groove 37 of the present embodiment includes a short groove portion 37a communicating with the first shoulder circumferential groove 5, and a main body portion 37b continuous with the outer side in the tire axial direction of the short groove portion 37a. The short groove portion 37a is inclined, for example, in the second direction with respect to the tire axial direction. The main body portion 37b extends, for example, outward in the tire axial direction from the short groove portion 37a. The angle of the main body portion 37b with respect to the tire axial direction is, for example, 5° or less. The non-through shoulder transverse groove 37 has a constant groove width W6 in its longitudinal direction. The groove width W6 of the non-through shoulder transverse groove 37 is 40% to 60% of the groove width W5 on the first tread end T1 of the through shoulder transverse groove 36. Such a non-through shoulder transverse groove 37 helps to enhance the mud performance and handling stability in a well-balanced manner.

[0055] The distance L8 in the tire axial direction from the outer end of the non-through shoulder transverse groove 37 to the first tread end T1 is, for example, 15% or less of the maximum width W7 in the tire axial direction of the first shoulder land portion 13, and specifically 5% to 10%. Such a non-through shoulder transverse groove 37 can suppress uneven wear and chipping around the first tread end T1.

[0056] As shown in FIG. 1, the second shoulder land portion 14 has substantially the same configuration as the above-described first shoulder land portion 13. Therefore, the configuration of the above-described first shoulder land portion 13 can also be applied to the second shoulder land portion 14.

[0057] From the viewpoint of fully exerting the mud performance, the land ratio of the tread portion 2 of the present embodiment is, for example, 60% to 80%, and preferably 65% to 75%. In this specification, the "land ratio" corresponds to the ratio of the actual contact area to the virtual contact area in a state where all the grooves and sipes of the tread portion 2 are filled.

[0058] The land ratio of the crown land portion 10 is, for example, 80% to 95%, desirably 90% to 95%. Further, the land ratio of the first middle land portion 11 or the second middle land portion 12 is, for example, 75% to 95%, desirably 80% to 90%. Further, the land ratio of the first shoulder land portion 13 or the second shoulder land portion 14 is, for example, 70% to 90%, desirably 75% to 85%. Thereby, the mud performance and the handling stability are improved in a well - balanced manner.

[0059] As described above, the tire according to one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above - described specific embodiments and can be implemented in various modes.

[0060] [Appendix] The present invention includes the following aspects.

[0061] [Invention 1] A tire having a tread portion, The tread portion includes a first tread end and a second tread end, four circumferential grooves continuously extending in the tire circumferential direction between the first tread end and the second tread end, and five land portions divided by the plurality of circumferential grooves. The four circumferential grooves include a first shoulder circumferential groove provided on the side closest to the first tread end, a second shoulder circumferential groove provided on the side closest to the second tread end, a first crown circumferential groove provided between the first shoulder circumferential groove and the tire equator, and a second crown circumferential groove provided between the second shoulder circumferential groove and the tire equator. The five land portions include a first middle land portion divided between the first shoulder circumferential groove and the first crown circumferential groove, a second middle land portion divided between the second shoulder circumferential groove and the second crown circumferential groove, and a crown land portion divided between the first crown circumferential groove and the second crown circumferential groove. In the first middle land portion, a plurality of first middle transverse grooves that completely cross the first middle land portion in the tire axial direction are provided. In the second middle land part, a plurality of second middle transverse grooves that completely cross the second middle land part in the tire axial direction are provided. Each of the plurality of first middle transverse grooves and the plurality of second middle transverse grooves is inclined with respect to the tire axial direction, and includes a first end portion on a first side in the tire circumferential direction and a second end portion on a second side in the tire circumferential direction. In a tread plan view, Each of the first end portions of the plurality of first middle transverse grooves overlaps with the second end portion of the second middle transverse groove in a first virtual region extended on the first middle land part parallel to the tire axial direction. Each of the second end portions of the plurality of first middle transverse grooves overlaps with the first end portion of the second middle transverse groove in a second virtual region extended on the first middle land part parallel to the tire axial direction. Tire. [Invention 2] The tire according to Invention 1, wherein each of the first middle transverse groove and the second middle transverse groove is inclined at an angle of 20 to 60° with respect to the tire axial direction. [Invention 3] The tire according to Invention 1 or 2, wherein a circumferential overlapping length of the first end portion of the first middle transverse groove and the first virtual region is 30% to 100% of a circumferential length of the first virtual region. [Invention 4] The tire according to any one of Inventions 1 to 3, wherein a circumferential overlapping length of the second end portion of the first middle transverse groove and the second virtual region is 30% to 100% of a circumferential length of the second virtual region. [Invention 5] The tire according to any one of Inventions 1 to 4, wherein a distance in the tire axial direction from the tire equator to a center line of the first crown circumferential groove is 5% to 20% of a tread half-width that is a distance in the tire axial direction from the tire equator to the first tread end. [Invention 6] The tire according to any one of Inventions 1 to 5, wherein a distance in the tire axial direction from the tire equator to a center line of the second crown circumferential groove is 5% to 20% of the tread half-width. [The present invention 7] The groove width of the first middle transverse groove is 5% to 20% of the average value of the length of one pitch in the plurality of first middle transverse grooves. The tire according to any one of claims 1 to 6 of the present invention. [The present invention 8] The groove width of the second middle transverse groove is 5% to 20% of the average value of the length of one pitch in the plurality of second middle transverse grooves. The tire according to any one of claims 1 to 7 of the present invention. [The present invention 9] The land ratio of the crown land portion is 80% to 95%. The tire according to any one of claims 1 to 8 of the present invention. [The present invention 10] The first crown circumferential groove and the second crown circumferential groove each extend in a zigzag shape in the tire circumferential direction. The tire according to any one of claims 1 to 9 of the present invention. [The present invention 11] The first crown circumferential groove is in a zigzag shape including an inner groove portion that extends linearly in the tire circumferential direction on the tire equator side, an outer groove portion that extends linearly in the tire circumferential direction on the outer side in the tire axial direction from the inner groove portion, and an inclined portion that is inclined with respect to the tire circumferential direction and connects the inner groove portion and the outer groove portion. Each of the plurality of first middle transverse grooves communicates with a connection portion between the outer groove portion and the inclined portion such that an angle between the outer groove portion and the first crown circumferential groove is an obtuse angle. The tire according to claim 10 of the present invention. [The present invention 12] The second crown circumferential groove is in a zigzag shape including an inner groove portion that extends linearly in the tire circumferential direction on the tire equator side, an outer groove portion that extends linearly in the tire circumferential direction on the outer side in the tire axial direction from the inner groove portion, and an inclined portion that is inclined with respect to the tire circumferential direction and connects the inner groove portion and the outer groove portion. Each of the plurality of second middle transverse grooves communicates with a connection portion between the outer groove portion and the inclined portion such that an angle between the outer groove portion and the second crown circumferential groove is an obtuse angle. The tire according to claim 10 or 11 of the present invention. [The present invention 13] A plurality of first crown transverse grooves communicating with the first crown circumferential groove are provided in the crown land portion. In the tread plan view, for each of the plurality of first crown lateral grooves, a third virtual region extended onto the first middle land portion in parallel with the tire axial direction does not overlap with either the first virtual region or the second virtual region. The tire according to any one of claims 1 to 12 of the present invention. [Inventive concept 14] A plurality of second crown lateral grooves communicating with the second crown circumferential groove are provided in the crown land portion. In the tread plan view, for each of the plurality of second crown lateral grooves, a fourth virtual region extended onto the first middle land portion in parallel with the tire axial direction does not overlap with either the first virtual region or the second virtual region. The tire according to any one of claims 1 to 13 of the present invention.

Explanation of reference numerals

[0062] 2 Tread portion 3 Circumferential groove 4 Land portion 5 First shoulder circumferential groove 6 Second shoulder circumferential groove 7 First crown circumferential groove 8 Second crown circumferential groove 10 Crown land portion 11 First middle land portion 12 Second middle land portion 16 First middle lateral groove 17 Second middle lateral groove 21 First virtual region 22 Second virtual region T1 First tread end T2 Second tread end

Claims

1. A tire having a tread portion, wherein the tread portion includes a first tread end and a second tread end, four circumferential grooves continuously extending in the tire circumferential direction between the first tread end and the second tread end, and five land portions divided by the plurality of circumferential grooves, the four circumferential grooves include a first shoulder circumferential groove provided closest to the first tread end side, a second shoulder circumferential groove provided closest to the second tread end side, a first crown circumferential groove provided between the first shoulder circumferential groove and the tire equator, and a second crown circumferential groove provided between the second shoulder circumferential groove and the tire equator, the five land portions include a first middle land portion divided between the first shoulder circumferential groove and the first crown circumferential groove, a second middle land portion divided between the second shoulder circumferential groove and the second crown circumferential groove, and a crown land portion divided between the first crown circumferential groove and the second crown circumferential groove, a plurality of first middle transverse grooves that completely cross the first middle land portion in the tire axial direction are provided in the first middle land portion, a plurality of second middle transverse grooves that completely cross the second middle land portion in the tire axial direction are provided in the second middle land portion, the plurality of first middle transverse grooves and the plurality of second middle transverse grooves are each inclined with respect to the tire axial direction, and include a first end portion on a first side in the tire circumferential direction and a second end portion on a second side in the tire circumferential direction, in a tread plan view, each of the first end portions of the plurality of first middle transverse grooves overlaps with the second end portion of the second middle transverse grooves in a first virtual region extended on the first middle land portion parallel to the tire axial direction, each of the second end portions of the plurality of first middle transverse grooves overlaps with the first end portion of the second middle transverse grooves in a second virtual region extended on the first middle land portion parallel to the tire axial direction, a tire.

2. The tire according to claim 1, wherein the first middle transverse grooves and the second middle transverse grooves are each inclined at an angle of 20 to 60° with respect to the tire axial direction.

3. The tire according to claim 1 or 2, wherein a circumferential overlapping length between the first end portion of the first middle transverse groove and the first virtual region is 30% to 100% of a circumferential length of the first virtual region.

4. The overlapping length in the tire circumferential direction between the second end portion of the first middle transverse groove and the second virtual region is 30% to 100% of the length in the tire circumferential direction of the second virtual region. The tire according to claim 1 or 2.

5. The distance in the tire axial direction from the tire equator to the center line of the first crown circumferential groove is 5% to 20% of the tread half-width, which is the distance in the tire axial direction from the tire equator to the first tread end. The tire according to claim 1 or 2.

6. The distance in the tire axial direction from the tire equator to the center line of the second crown circumferential groove is 5% to 20% of the tread half-width. The tire according to claim 5.

7. The groove width of the first middle transverse groove is 5% to 20% of the average value of the length of one pitch in the plurality of first middle transverse grooves. The tire according to claim 1 or 2.

8. The groove width of the second middle transverse groove is 5% to 20% of the average value of the length of one pitch in the plurality of second middle transverse grooves. The tire according to claim 1 or 2.

9. The land ratio of the crown land portion is 80% to 95%. The tire according to claim 1 or 2.

10. The first crown circumferential groove and the second crown circumferential groove each extend in a zigzag shape in the tire circumferential direction. The tire according to claim 1 or 2.

11. The first crown circumferential groove is in a zigzag shape including an inner groove portion that extends linearly in the tire circumferential direction on the tire equator side, an outer groove portion that extends linearly in the tire circumferential direction on the outer side in the tire axial direction than the inner groove portion, and an inclined portion that is inclined with respect to the tire circumferential direction and connects the inner groove portion and the outer groove portion. Each of the plurality of first middle transverse grooves communicates with the connection portion between the outer groove portion and the inclined portion so that the angle between the outer groove portion and the first crown circumferential groove is an obtuse angle. The tire according to claim 10.

12. The second crown circumferential groove is in a zigzag shape including an inner groove portion that extends linearly in the tire circumferential direction on the tire equator side, an outer groove portion that extends linearly in the tire circumferential direction on the outer side in the tire axial direction than the inner groove portion, and an inclined portion that is inclined with respect to the tire circumferential direction and connects the inner groove portion and the outer groove portion. Each of the plurality of second middle transverse grooves communicates with the connection portion between the outer groove portion and the inclined portion so that the angle between the outer groove portion and the second crown circumferential groove is an obtuse angle. The tire according to claim 10.

13. The crown land portion is provided with a plurality of first crown transverse grooves communicating with the first crown circumferential groove. In a tread plan view, a third virtual region obtained by extending each of the plurality of first crown transverse grooves parallel to the tire axial direction on the first middle land portion does not overlap with either the first virtual region or the second virtual region. The tire according to claim 1 or 2. **Claim 14** The crown land portion is provided with a plurality of second crown transverse grooves communicating with the second crown circumferential groove. In a tread plan view, a fourth virtual region obtained by extending each of the plurality of second crown transverse grooves parallel to the tire axial direction on the first middle land portion does not overlap with either the first virtual region or the second virtual region. The tire according to claim 1 or 2.

Images