tire

Abstract

To provide a tire that is improved in noise performance while maintaining wet performance.SOLUTION: When a region formed closer to inside in a tire width direction than groove width center lines of groove widths of circumferential main grooves 14c and 14d outermost in the tire width direction is defined as a center region CR, at least one bent groove 26 (28) whose at least one end in the tire width direction is communicated with the circumferential main grooves and which has at least two bent parts is formed on at least one land part 16 formed in the center region. A groove width W1 (W2) of a first portion 26a (28a) extending from one end of the bent groove to a front of the first bent part and a groove width W3 (W4) of a second portion 26b (28b) extending from the other end of the bent groove to the front of the first bent part are almost identical to each other over the whole circumference of a tire, where relational expressions of P2(%)>P1(%) and P2(%)>P3(%) are satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire that improves noise performance while maintaining wet performance.

Background Art

[0002] For the purpose of improving snow performance without degrading noise and vibration performance, at least one of a plurality of center sipes includes a chamfered portion at at least one of the one and the other edges in the tire circumferential direction, and these chamfered portions are alternately provided on each side of the tire equatorial plane in the tire circumferential direction. A tire is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the tire disclosed in Patent Document 1, regarding the chamfered portions adjacent to each other in the tire circumferential direction and / or the center sipes, the timing of fluctuations related to the opening and closing of the grooves (chamfered portions and sipes) may overlap when the tire rolls. In such a case, the sound generated when the tire comes into contact with the road surface is emphasized by the horn effect, so-called pass-by noise (PBN) may increase, and the noise performance may deteriorate.

[0005] On the other hand, although it is conceivable to reduce the groove area ratio in order to improve the noise performance, reducing the groove area ratio may cause deterioration of the drainage performance and, consequently, deterioration of the wet performance. For this reason, in recent years, there has been a demand for the development of a technology that improves the noise performance while maintaining the wet performance without reducing the groove area ratio.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a tire that improves noise performance while maintaining wet performance without reducing the groove area ratio.

Means for Solving the Problems

[0007] The tire of the present invention is partitioned and formed with at least three land portions by at least two circumferential main grooves. On each side in the tire width direction of the tire equatorial plane, with the groove width center line of the outermost circumferential main groove in the tire width direction as a boundary, when the inner side in the tire width direction from the groove width center line is defined as the center region and the outer side in the tire width direction from the groove width center line is defined as the shoulder region, at least one of the land portions formed in the center region has at least one end in the tire width direction communicating with the circumferential main groove and has at least two bent portions, and at least one bent groove is provided. The groove width of the first portion from one end of the bent groove to before the first bent portion and the groove width of the second portion from the other end of the bent groove to before the first bent portion are each substantially the same over the entire circumference of the tire. Let the number of bent grooves existing in the same land portion be N, and let the length measured over the entire circumference of the tire be Li (1≦i≦2N) in order for the first interval between the first portion and the second portion and the second interval which is the shortest distance between two adjacent bent grooves in the tire circumferential direction. Let the tire circumference be J (mm), the range of the attention length due to the transmission characteristics be S1 (mm), and the ranges of the attention lengths due to the sound source be S2 (mm) and S3 (mm). 12.4≦S1 (mm)≦19.5, and In the range of S1 (mm) and S2 (mm) that satisfy J / (N×1.25×1)≦S2 (mm)≦J / (N×0.75×1), let the larger of the lower limit values of the two inequalities be LFL1, and let the smaller of the upper limit values of the two inequalities be HFL1. 12.4≦S1 (mm)≦19.5, and In the range of S1 (mm) and S3 (mm) that satisfy J / (N×1.25×2) ≦ S3 (mm) ≦ J / (N×0.75×2), the larger of the lower limit values of the two inequalities is defined as LFL2, and the smaller of the upper limit values of the two inequalities is defined as HFL2. LFL1×1 < Li (mm) < HFL1×1, or Condition C1 defined by LFL2×1 < Li (mm) < HFL2×1. Other than condition C1, and LFL1×0.5 < Li (mm) < HFL1×0.5, LFL1×1.5 < Li (mm) < HFL1×1.5, LFL2×0.5 < Li (mm) < HFL2×0.5, or Condition C2 defined by LFL2×1.5 < Li (mm) < HFL2×1.5, and Set conditions other than condition C1 and other than condition C2 as condition C3 respectively. When, among up to 2N of the intervals Li, the proportion of intervals Li that satisfy condition C1 is P1 (%), the proportion of intervals Li that satisfy condition C2 is P2 (%), and the proportion of intervals Li that satisfy condition C3 is P3 (%), It is characterized by satisfying P2 (%) > P1 (%) and P2 (%) > P3 (%).

Effect of the Invention

[0008] In the tire according to the present invention, instead of reducing the groove area ratio, in the central region in the tire width direction of the tread where the sound generated when the tire contacts the road surface is likely to be emphasized by the horn effect, the variation timing regarding the opening and closing of the groove portion during tire rolling is reduced from overlapping for the groove portions adjacent in the tire circumferential direction. Specifically, for the bending groove provided in the land portion in the central region in the tire width direction, out of a maximum of 2N intervals Li, the occupancy ratio (ratio in the case of undesirability) of the intervals Li satisfying the condition C1 is P1 (%), the occupancy ratio (ratio in the case of desirability) of the intervals Li satisfying the condition C2 is P2 (%), and the occupancy ratio (ratio in the case of neither desirability nor undesirability) of the intervals Li satisfying the condition C3 is P3 (%), P2 (%) > P1 (%), and P2 (%) > P3 (%). Thereby, without deteriorating the drainage performance, the variation timing regarding the opening and closing of the groove portion can be intentionally shifted for the groove portions adjacent to each other in the tire circumferential direction, and thus the pass-by noise can be reduced between these groove portions. Therefore, according to the present invention, the noise performance can be improved while maintaining the wet performance.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] In the following description, the tire radial direction refers to the direction orthogonal to the rotation axis of the tire. The inner side in the tire radial direction refers to the side facing the rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to the circumferential direction around the rotation axis as the central axis. Furthermore, the tire width direction refers to the direction parallel to the rotation axis. The inner side in the tire width direction refers to the side facing the tire equatorial plane (tire equator line) in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane is a plane that is orthogonal to the rotation axis of the tire and passes through the center of the tire width.

[0011] Similarly, in the following description, the standard rim refers to the "Applicable Rim" defined by JATMA, the "Design Rim" defined by TRA, or the "Measuring Rim" defined by ETRTO.

[0012] Similarly, in the following description, the standard internal pressure refers to the "Maximum Air Pressure" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "INFLATION PRESSURES" defined by ETRTO. The standard load refers to the "Maximum Load Capacity" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "LOAD CAPACITY" defined by ETRTO.

[0013] FIG. 1 is a plan view showing the tread surface of the tire of the present embodiment, and shows a no-load state (non-grounded state) in which the tire is mounted on a standard rim and a standard internal pressure is applied. In FIG. 1, only one of a plurality of identical components is labeled. The tread portion of the tire 10 shown in the figure is composed of a rubber material (tread rubber). Further, the surface of the tread portion located at the outermost part in the tire radial direction (tread surface 12) comes into contact with the road surface when the vehicle is running. And, as shown in FIG. 1, a tread pattern of a predetermined pattern is formed on the tread surface. Note that the tread pattern shown in FIG. 1 has the left side as the inner side when mounted on the vehicle.

[0014] In the example shown in FIG. 1, four circumferential main grooves 14 (14a, 14b, 14c, 14d) are provided symmetrically in the tire width direction with the tire equatorial plane CL interposed therebetween on the tread surface 12. The circumferential main groove 14 has a groove width of 6 mm or more and 14 mm or less. Here, the groove width means the groove dimension (maximum value) measured in a direction perpendicular to the direction in which the groove extends (hereinafter, the same applies to other grooves). Further, the circumferential main groove 14 has a groove depth of 5 mm or more and 10 mm or less. Here, the groove depth means the groove dimension (maximum value) measured in the tire radial direction from the profile line in the case where there is no groove (hereinafter, the same applies to other grooves).

[0015] In the example shown in FIG. 1, these circumferential main grooves 14 define five land portions 16, 18, 20, 22, 24. The center land portion 16 includes the tire equatorial plane CL, and second land portions 18, 20 are defined on each side in the tire width direction thereof, and further, shoulder land portions 22, 24 are defined outside them in the tire width direction. Note that in the present embodiment, the land portions defined by the circumferential main grooves 14a to 14d include not only ribs as shown in FIG. 1 but also block rows.

[0016] In the example shown in FIG. 1, on each side in the tire width direction of the tire equatorial plane CL, with the groove width center lines (not shown) of the circumferential main grooves 14c and 14d at the outermost in the tire width direction as a boundary, the area inside the tire width direction from these groove width center lines is defined as the center region CR, and the areas outside the tire width direction from the groove width center lines are defined as the shoulder regions SR and SR.

[0017] In the center land portion 16 formed in the center region CR, a plurality of bending grooves 26 are provided, each having both ends in the tire width direction communicating with the circumferential main grooves 14a and 14b and having two bending portions.

[0018] The bending groove 26 has a groove width of 0.5 mm or more and 1.5 mm or less. Also, the bending groove 26 has a groove depth of 40% or more and 90% or less of the groove depth of the circumferential main groove.

[0019] As shown in FIG. 1, in the second land portion 18 on the outside of the vehicle mounting side formed in the center region CR, a first lug groove 30 is provided which communicates with both of the circumferential main grooves 14a and 14c on both sides in the tire width direction and whose inclination direction with respect to the tire width direction reverses midway while extending from the inside to the outside in the tire width direction. The first lug groove 30 is provided for improving wet performance on the outside of the vehicle mounting side, and by reversing the inclination direction midway in the extending direction, the pass-by noise can be reduced compared to a groove whose inclination direction does not reverse.

[0020] In the second land portion 18, a sipe 32 is formed between the adjacent first lug grooves 30 and 30 in the tire circumferential direction, extending substantially parallel to the first lug groove 30. In this specification, a sipe means a groove having a groove width of 1.5 mm or less and a groove depth of 2.0 mm or more.

[0021] In the second land portion 20 on the inner side of the vehicle mounting formed in the center region CR, a second lug groove 34 is provided for improving wet performance. The second lug groove 34 extends from the circumferential main groove 14d on the outer side in the tire width direction toward the inner side in the tire width direction and terminates within the land portion 20. Further, in the second land portion 20, a sipe 36 is formed which extends from the inner end in the tire width direction of the second lug groove 34 and communicates with the circumferential main groove 14b on the inner side in the tire width direction. Furthermore, in the second land portion 20, between the second lug grooves 34, 34 adjacent to each other in the tire circumferential direction, a sipe 38 is formed which extends substantially parallel to the second lug groove 34 and communicates with both the circumferential main grooves 14b, 14d on both sides in the tire width direction.

[0022] In the shoulder land portion 22 on the outer side of the vehicle mounting formed in the shoulder region SR, a third lug groove 40 is provided which extends toward the inner side in the tire width direction across the grounding end (not shown) and terminates within the land portion 22. Further, in the shoulder land portion 22, between the third lug grooves 40, 40 adjacent to each other in the tire circumferential direction, a sipe 42 is formed which extends from the circumferential main groove 14c toward the outer side in the tire width direction, and the sipe 42 communicates with a small groove 44 near the grounding end. Furthermore, triangular grooves 46 are provided at a constant pitch in the tire circumferential direction on the outer side in the tire width direction of the grounding end. The small groove 44 has a groove width of 0.5 mm or more and 3.0 mm or less, and a groove depth of 0.3 mm or more and 2.0 mm or less, and the triangular grooves 46 also satisfy a groove depth of 0.3 mm or more and 2.0 mm or less.

[0023] In the inner region in the tire width direction within the shoulder land portion 22, an auxiliary groove 48 is provided parallel to the circumferential main groove 14c. Generally, the shoulder land portion 22 on the outer side of the vehicle mounting contributes particularly greatly to the turning performance among the wet performance. Therefore, by providing the auxiliary groove 48 in the shoulder land portion 22, the rigidity of the shoulder land portion 22 can be suitably adjusted, and the turning performance can be efficiently enhanced. Note that the groove depth of the auxiliary groove 48 can be 0.3 times or more and 0.8 times or less the groove depth of the circumferential main groove 14c.

[0024] On the shoulder land portion 24 on the inner side of the vehicle mounting formed in the shoulder region SR, a fourth lug groove 50 is provided which extends inward in the tire width direction across a ground end (not shown) and terminates within the land portion 24. Further, on the shoulder land portion 24, a sipe 52 extending outward in the tire width direction from the circumferential main groove 14d is formed between adjacent fourth lug grooves 50, 50 in the tire circumferential direction, and the sipe 52 communicates with a small groove 54 near the ground end. Furthermore, an auxiliary groove 56 is provided in the inner region in the tire width direction within the shoulder land portion 24 in parallel with the circumferential main groove 14d. Note that the groove depth of the auxiliary groove 56 can be 0.3 times or more and 0.8 times or less the groove depth of the circumferential main groove 14d.

[0025] Figure 2 is a plan view showing the groove width of the bending groove shown in Figure 1. Hereinafter, only two adjacent bending grooves 26, 28 in the tire circumferential direction among a plurality of bending grooves provided in the tire circumferential direction will be described. For the two types of bending grooves 26 (28) shown in Figure 1, the groove width W1 (W2) of the first portion 26a (28a) from one end shown in Figure 2 to before the first bending portion, and the groove width W3 (W4) of the second portion 26b (28b) from the other end of the bending groove 26 (28) to before the first bending portion are each substantially the same over the entire tire circumference.

[0026] For the groove width W1 (W2) of the first portion 26a (28a), the first portion 26a (28a) is divided into five equal parts in its extending direction, the dimension in the direction perpendicular to the extending direction at the central portion in the extending direction of each of the five equal parts is calculated, and the average value of the calculated values for the five sections is used. The same applies to the groove width W3 (W4) of the second portion 26b (28b).

[0027] The first portion 26a (28a) and the second portion 26b (28b) may be linear or curved in the extending direction. Further, the bending portion is a portion connected to the first portion 26a (28a) and / or the second portion 26b (28b), and refers to the portion from the point where the curvature of the groove width center line changes with respect to the first portion 26a (28a) or the second portion 26b (28b) to the point where the curvature changes again.

[0028] The fact that the groove width W1 and the groove width W2 are substantially the same means that, for the portions 26a and 28a, the ratio (standard deviation / average value) of the standard deviation calculated from each portion to the average value calculated from each portion is in the range of 0 or more and 0.1 or less. Similarly, the fact that the groove width W3 and the groove width W4 are substantially the same means that, for the portions 26b and 28b, the ratio (standard deviation / average value) of the standard deviation calculated from each portion to the average value calculated from each portion is in the range of 0 or more and 0.1 or less.

[0029] Note that the groove widths W1 and W3 of the groove portions included in the bent groove 26 may be the same or different from each other. Similarly, the groove widths W2 and W4 of the groove portions included in the bent groove 28 may be the same or different from each other. In the example shown in FIG. 2, the groove widths W1 to W4 are all the same. However, when the groove width W1 and the groove width W3 (or the groove width W2 and the groove width W4) are different, even due to the difference in the groove width itself between these groove portions (for example, between the first portion 26a and the second portion 26b), the timing of variation regarding the opening and closing of the groove portions is likely to be different. For this reason, when the groove width W1 and the groove width W3 (or the groove width W2 and the groove width W4) are different, the effect of reducing the pass-by noise is enhanced compared to the case where they are the same, and thus it is more preferable.

[0030] FIG. 3 is a plan view showing the intervals between the groove portions of the bent groove shown in FIG. 1. Also for FIG. 3, only two adjacent bent grooves 26 and 28 in the tire circumferential direction among the plurality of bent grooves provided in the tire circumferential direction will be described. Let the number of bent grooves existing in the center land portion 16 shown in FIG. 1 be N, and let the first interval D1 (D2) between the first portion 26a (28a) and the second portion 26b (28b), and the second interval D3 which is the shortest distance between two adjacent bent grooves 26 and 28 in the tire circumferential direction, be the lengths when measured over the entire tire circumference in order Li (1 ≦ i ≦ 2N).

[0031] For example, when only one bending groove is provided in the center land portion 16 (only the bending groove 26), the first interval D1 shown in FIG. 3 can be defined, but the first interval D2 and the second interval D3 cannot be defined, so only i = 1. On the other hand, for example, when 30 bending grooves are provided in the center land portion 16, there is one first interval D1 and D2 shown in FIG. 3 for each bending groove, and the second interval D3 also exists as many as the number of bending grooves, so the maximum number of i is N × 2 = 60.

[0032] The first interval D1 for the bending groove 26 is determined as the shortest distance between a virtual line created based on the groove width center points (not shown) in each of the five equal sections used when obtaining the groove width W1 shown in FIG. 2, where the groove portions of one bending groove (for example, the first portion 26a and the second portion 26b) are parallel, and a virtual line created based on the groove width center points (not shown) in each of the five equal sections used when obtaining the groove width W3 shown in FIG. 2. Each virtual line is set so that the five groove width center points are as far away from the virtual line as possible. The first interval D2 for the bending groove 28 shown in FIG. 3 is also determined in the same manner as the first interval D1 (based on the groove width W2 and the groove width W4).

[0033] On the other hand, when the groove portions of one bending groove are not parallel to each other (for example, the first portion 26a and the second portion 26b), the first interval D1 for the bending groove 26 is determined as follows. That is, first, when obtaining the groove width W1 shown in FIG. 2, the groove width center points (not shown) in each of the five equal sections are defined as point a1, point b1, point c1, point d1, and point e1 in order from the vehicle-mounted side. When obtaining the groove width W3 shown in FIG. 2, the groove width center points (not shown) in each of the five equal sections are defined as point a3, point b3, point c3, point d3, and point e3 in order from the vehicle-mounted side. Next, the distance sa between point a1 and point a3, the distance sb between point b1 and point b3, the distance sc between point c1 and point c3, the distance sd between point d1 and point d3, and the distance se between point e1 and point e3 are defined. Then, the average value from the distance sa to the distance se is calculated and set as the first interval D1. Note that the first interval D2 for the bending groove 28 shown in FIG. 3 is also determined in the same manner as the first interval D1 (based on the groove widths W2 and W4).

[0034] The second interval D3 for the bending grooves 26 and 28 is determined as the shortest distance between a virtual line created based on the groove width center points (not shown) in each of the five equal sections used when obtaining the groove width W3 shown in FIG. 2 and a virtual line created based on the groove width center points (not shown) in each of the five equal sections used when obtaining the groove width W2 shown in FIG. 2, when the groove portions of two adjacent bending grooves in the tire circumferential direction are parallel to each other (for example, the second portion 26b and the first portion 28a). Each virtual line is set so that the five groove width center points are as far away from the virtual line as possible.

[0035] On the other hand, when the groove portions of two adjacent bending grooves in the tire circumferential direction (for example, the second portion 26b and the first portion 26a) are not parallel, the second interval D3 for the bending grooves 26 and 28 is determined as follows. That is, first, when obtaining the groove width W3 shown in FIG. 2, the groove width center points (not shown) in each of the five equal sections are defined as point a3, point b3, point c3, point d3, and point e3 in order from the vehicle-mounted side, and when obtaining the groove width W2 shown in FIG. 2, the groove width center points (not shown) in each of the five equal sections are defined as point a2, point b2, point c2, point d2, and point e2 in order from the vehicle-mounted side. Next, the distance Sa between point a3 and point a2, the distance Sb between point b3 and point b2, the distance Sc between point c3 and point c2, the distance Sd between point d3 and point d2, and the distance Se between point e3 and point e2 are defined. Then, the average value from the distance Sa to the distance Se is calculated and taken as the second interval D3.

[0036] Next, define the tire circumference as J (mm), the attention length due to the transmission characteristics as S1 (mm), and the attention lengths due to the sound source as S2 (mm) and S3 (mm).

[0037] Here, the attention length S1 (mm) due to the transmission characteristics means the range sandwiched by the lower limit value and the upper limit value calculated by dividing the representative speed of the pass-by noise by the lower limit and the upper limit of the frequency range emphasized in the center region due to the horn effect when measuring the acoustic characteristics of the tire peripheral space.

[0038] Also, the range S2 (mm) of the attention length due to the sound source means the range of the primary pitch order ±25% when the block formed by the bending groove contacts the road surface, and the range S3 (mm) of the attention length due to the sound source means the range of the secondary pitch order ±25% when the block formed by the bending groove contacts the road surface.

[0039] Next, the range of the attention length S1 (mm) due to the transmission characteristics such that the sound generated from the bending groove 26 provided in the center land portion 16 is emphasized by the horn effect is as follows. 12.4 < S1 (mm) < 19.5

[0040] In addition, the ranges of the attention lengths S2 (mm) and S3 (mm) caused by the sound source, where the bending groove provided in the center land portion 16 causes pass-by noise, are as follows. J / (N×1.25×1) < S2 (mm) < J / (N×0.75×1) J / (N×1.25×2) < S3 (mm) < J / (N×0.75×2)

[0041] Based on the above ranges of S1 (mm), S2 (mm), and S3 (mm), S1 (mm) ≤ 19.5, and In the range of S1 (mm) and S2 (mm) that satisfy J / (N×1.25×1) ≤ S2 (mm) ≤ J / (N×0.75×1), let the larger of the lower limit values of these two inequalities be LFL1, and the smaller of the upper limit values of the two inequalities be HFL1.

[0042] Similarly, 12.4 ≤ S1 (mm) ≤ 19.5, and In the range of S1 (mm) and S3 (mm) that satisfy J / (N×1.25×2) ≤ S3 (mm) ≤ J / (N×0.75×2), let the larger of the lower limit values of these two inequalities be LFL2, and the smaller of the upper limit values of the two inequalities be HFL2.

[0043] Furthermore, based on the above findings, LFL1×1 < Li (mm) < HFL1×1, or The condition defined by LFL2×1 < Li (mm) < HFL2×1 is set as condition C1.

[0044] Conditions other than condition C1, and LFL1×0.5 < Li (mm) < HFL1×0.5, LFL1×1.5 < Li (mm) < HFL1×1.5, LFL2×0.5 < Li (mm) < HFL2×0.5, or The condition defined by LFL2×1.5 < Li (mm) < HFL2×1.5 is designated as condition C2.

[0045] Conditions other than condition C1 and other than condition C2 are designated as condition C3.

[0046] Then, among a maximum of 2N intervals Li, the occupancy ratio of the intervals Li that satisfy condition C1 is P1 (%), the occupancy ratio of the intervals Li that satisfy condition C2 is P2 (%), and the occupancy ratio of the intervals Li that satisfy condition C3 is P3 (%).

[0047] Satisfying condition C1 means that when the tire is rolling, since the timing of variation regarding the opening and closing of the groove portion is likely to overlap between adjacent groove portions in the tire circumferential direction, the pass-by noise is large, which is an undesirable case.

[0048] Satisfying condition C2 means that when the tire is rolling, since the timing of variation regarding the opening and closing of the groove portion is unlikely to overlap between adjacent groove portions in the tire circumferential direction, the pass-by noise is small, which is a desired case.

[0049] Satisfying condition C3 (when neither condition C1 nor condition C2 is satisfied) means that when the tire is rolling, since the timing of variation regarding the opening and closing of the groove portion is moderately likely to overlap between adjacent groove portions in the tire circumferential direction, the pass-by noise is moderate, which means a case that is neither undesirable nor desired.

[0050] Regarding each of the above inequalities used to derive any one of conditions C1 to C3, they are the result of extensive research and numerous experiments by the inventors. Although the inventors have not clearly found a technical basis for these inequalities, they are supported by a vast amount of experimental data, and ultimately, they have obtained the knowledge that these are useful inequalities for improving noise performance.

[0051] Under the above premises, this embodiment satisfies P2(%) > P1(%) and P2(%) > P3(%). That is, these regulations compare the ratio P2 in the desired case, the ratio P1 in the undesired case, and the ratio P3 in the case that is neither desired nor undesired, and show that among these three ratios, the ratio P2 in the desired case is higher than either of the other ratios P1 and P3.

[0052] As shown above, in the tire 10 of this embodiment, instead of reducing the groove area ratio with respect to the conventional tire, the shape and arrangement of the bending grooves 26 provided in a specific land portion (specifically, the center land portion 16 etc. included in the central region in the tire width direction) are changed. For this reason, wet performance (a combination of drainage performance, handling stability performance, turning performance, traction performance, etc. The same applies hereinafter.) can be maintained at the conventional level.

[0053] Also, in the tire 10 of this embodiment, so that the sound generated particularly when the tire comes into contact with the road surface is reduced from the center land portion 16 etc. where the sound is likely to be emphasized by the horn effect, the groove portions 26a, 26b adjacent to each other in the tire circumferential direction within the same groove (see FIGS. 2 and 3), and the groove portions 26b, 28a adjacent to each other in the tire circumferential direction across other grooves (see FIGS. 2 and 3), the timing of variation regarding the opening and closing of the groove portions can be intentionally shifted during tire rolling, and thus the pass-by noise caused by these groove portions can be reduced. In the example shown in FIG. 1, in particular, by providing four main circumferential grooves, the width of the center land portion 16 where the contribution to pass-by noise reduction is the largest is made relatively small to reduce the rigidity of the land portion 16, so that the pass-by noise can be efficiently reduced.

[0054] Therefore, according to the tire 10 of this embodiment, the noise performance can be improved while maintaining the wet performance.

[0055] In the example shown in FIG. 1, only the bending groove 26 described above is provided in the center land portion 16. However, the present embodiment is not limited to such an example, and other grooves can also be provided in the center land portion 16. However, if a groove other than the bending groove is provided in the center land portion 16, the effect of providing the bending groove (the timing of the opening and closing of the groove portion can be intentionally shifted during tire rolling, and thus the pass-by noise can be reduced between these groove portions) may be diminished due to the presence of other grooves. Therefore, from the viewpoint of reducing pass-by noise, it is not preferable to provide a groove other than the bending groove in the center land portion 16.

[0056] In the example shown in FIG. 1, the bending groove 26 is provided only in the center land portion 16. However, the present embodiment is not limited to such a case. As long as it is a land portion (land portions 16, 18, 20) partitioned and formed in the center region CR, the bending groove can be provided in any land portion, and the same effect as that of the tread pattern shown in FIG. 1 can be obtained.

[0057] FIG. 4 is a plan view showing a modified example of the tread surface shown in FIG. 1. For each component not labeled in FIG. 4, the reference numerals attached to the corresponding components in FIG. 1 are omitted. In the example shown in FIG. 4, different from the example shown in FIG. 1, bending grooves 26 and 58 are respectively provided in two land portions (center land portion 16 and second land portion 20) partitioned and formed in the center region CR. Thus, when bending grooves are provided in two or more land portions, for the groove widths W1 to W4 shown in FIG. 2 and the intervals D1 to D3 shown in FIG. 3, they are calculated for each land portion, while for the ratios P1 to P3 described above, they are calculated for the entire tire.

[0058] In the example shown in FIG. 1 or FIG. 4, it is preferable that the difference between the ratio P2 and the ratio P1 is 20% or more, and the difference between the ratio P2 and the ratio P3 is 10% or more. When these conditions are satisfied, since the ratio P1 in the above-described undesirable case is lower than the ratio P3 in the case that is neither undesirable nor desirable, the ratio P1 of the undesirable case in the whole can be further reduced. As a result, regarding the groove portions adjacent to each other in the tire circumferential direction, the variation timing regarding the opening and closing of the groove portions during tire rolling can be intentionally shifted to a higher level, and thus, pass-by noise can be further reduced between these groove portions.

[0059] In the example shown in FIG. 1 or FIG. 4, it is preferable that the ratio P1 is 30% or less. When such a condition is satisfied, the ratio P1 of the undesirable case in the whole can be further reduced. As a result, regarding the groove portions adjacent to each other in the tire circumferential direction, the variation timing regarding the opening and closing of the groove portions during tire rolling can be intentionally shifted to a higher level, and thus, pass-by noise can be further reduced between these groove portions.

[0060] When the ratio P1 is 30% or less and the ratio P2 > ratio P3 > ratio P1 are satisfied, the variation timing regarding the opening and closing of the groove portions during tire rolling can be intentionally shifted to an even higher level, and thus, pass-by noise can be further reduced between these groove portions.

[0061] In the example shown in FIG. 1 or FIG. 4, it is preferable that the average number of formation of the grooves having a tire width direction component (hereinafter, may be referred to as "width direction grooves") provided in the shoulder lands 22 and 24 partitioned and formed in the shoulder region SR is larger than the average number of formation of the width direction grooves provided in the lands 16, 18, and 20 partitioned and formed in the center region CR. Here, the groove having a tire width direction component (width direction groove) refers to all grooves other than the grooves extending in the tire circumferential direction. For example, in FIG. 1 or FIG. 4, the width direction grooves include grooves (including sipes) 26, 30, 32, 34, 36, 38, 40, 42, 44, 46, 50, 52, 54, and 58.

[0062] In this way, by controlling the average number of formed widthwise grooves between the shoulder region SR and the center region CR, it is possible to reduce the number of widthwise grooves provided in the center region CR where the sound generated during contact with the road surface is difficult to be emphasized by the horn effect without changing (increasing) the groove area ratio in the entire tire. Thereby, it is possible to reduce the pass-by noise and improve the drainage performance, and thus the wet performance.

[0063] In the examples shown in FIGS. 1 and 4, auxiliary grooves 48 and 56 are provided on each side where the tire is mounted on the vehicle. The groove widths of the auxiliary grooves 48 and 56 with respect to the groove widths of the circumferential main grooves 14c and 14d at the outermost side in the tire width direction (groove width ratio of the auxiliary grooves) are preferably 5% or more and 40% or less. Note that the groove width ratio of the auxiliary grooves is calculated with respect to a predetermined circumferential main groove (that is, the circumferential main groove at the outermost side of the tire, which is the circumferential main groove closer to the target auxiliary groove).

[0064] By setting the groove width ratio of the auxiliary grooves 48 and 56 to 5% or more, the block rigidity of the shoulder land portions 22 and 24 can be reduced, and in the shoulder land portions 22 and 24, the timing of fluctuations regarding the opening and closing of the grooves (including the sipe) adjacent to each other in the tire circumferential direction can be efficiently shifted, and the pass-by noise can be further reduced.

[0065] On the other hand, by setting the groove width ratio of the auxiliary grooves 48 and 56 to 40% or less, it is possible to ensure the handling stability performance at a high level among the wet performance without excessively reducing the block rigidity of the shoulder land portions 22 and 24.

[0066] The groove width ratio of the auxiliary grooves 48 and 56 is more preferably 8% or more and 37% or less, and extremely preferably 10% or more and 35% or less.

[0067] FIG. 5 is a plan view showing two types of circumferential lengths of the bending grooves shown in FIG. 1 or FIG. 4. As shown in FIG. 5, it is preferable that the tire circumferential length DG1 (DG2) between one end and the other end of the bending groove 26 (28) is equal to or greater than the tire circumferential length DB1 (DB2) of the third portion 26c (28c) of the bending groove 26 (28) (the portion other than the first and second portions in each bending groove).

[0068] Regarding the third portion 26c (28c) of the bending groove 26 (28) shown in FIG. 5 (FIG. 1 or FIG. 4), since the longitudinal portion (the center line in the tire width direction) excluding the bent portion is located on the tire equatorial plane CL, it extends in the tire circumferential direction. However, when the longitudinal portion (the center line in the tire width direction) is displaced to either side in the tire width direction from the tire equatorial plane CL, in consideration of drainage performance, it is preferable to provide the longitudinal portion so as to extend from the inside to the outside in the tire width direction from the depressed side to the kicking side of the tire.

[0069] By setting the tire circumferential length DG1 (DG2) to be equal to or greater than the tire circumferential length DB1 (DB2), when the tire 10 comes into contact with the road surface, the first portion 26a (28a) and the second portion 26b (28b) of the bending groove 26 (28) are more likely to deform, further reducing the pass-by noise and further enhancing the noise performance.

[0070] As a modification of the tire 10 shown in FIGS. 1 and 4, without changing the groove area ratio, three circumferential main grooves can be provided to partition and form two land portions in the center region. If two or more circumferential main grooves are provided, excellent noise performance can be obtained while maintaining the desired drainage performance and thus the wet performance in this embodiment.

[0071] In the tire 10 shown in FIG. 1 or FIG. 4, it is preferable that the groove widths of the circumferential main grooves 14c and 14d located at the outermost side in the tire width direction are smaller than the groove widths of the other circumferential main grooves (14a, 14b). By adopting such a configuration, in the center region that makes a high contribution to drainage performance, the groove width of the circumferential main groove can be increased, and as a result, the drainage performance, and thus the wet performance, can be further enhanced.

[0072] When comparing the example shown in FIG. 1 and the example shown in FIG. 4, regarding the second land portion 20 partitioned and formed in the center region CR, in the example shown in FIG. 1, the second lug grooves 34, the sipes 36, and the sipes 38 are provided, whereas in the example shown in FIG. 4, only the bending groove 58 is provided, and no other grooves or sipes are provided. The bending groove 58 shown in FIG. 4 exhibits the same effect as the bending groove 26 shown in FIG. 1 described above (reduction of pass-by noise resulting from intentionally shifting the variation timing regarding the opening and closing of the groove portion during tire rolling). In contrast, in the example shown in FIG. 1, such an effect is not achieved. Therefore, in the example shown in FIG. 4, the noise performance can be further enhanced as compared with the example shown in FIG. 1.

[0073] In the tire 10 shown in FIG. 1, the number of grooves (width direction grooves) having a tire width direction component provided in the land portions other than the center land portion 16 (the second land portions 18 and 20 and the shoulder land portions 22 and 24) (the number of width direction grooves in the non-center land portions) is preferably 1.3 times or more and 2.6 times or less the number of bending grooves 26 provided in the center land portion 16 (the number of bending grooves in the center land portion).

[0074] By setting the number of width direction grooves in the non-center land portions to be 1.3 times or more the number of bending grooves in the center land portion, the drainage performance, and thus the wet performance, can be further enhanced. On the other hand, by setting it to be 2.6 times or less, the generation of slip noise can be suppressed without excessively reducing the rigidity of the land portions other than the center land portion 16, and thus the pass-by noise can be further reduced.

[0075] It is more preferable that the number of widthwise grooves in the non-center land portion is 1.5 times or more and 2.4 times or less the number of bending grooves in the center land portion, and extremely preferably 1.6 times or more and 2.3 times or less.

[0076] In the tire 10 shown in FIG. 1 or FIG. 4, it is preferable that a position (inclination direction change position) where the extending direction of the first lug groove 30 becomes the tire width direction exists in the outer region in the tire width direction within the second land portion 18. Here, the outer region in the tire width direction within the second land portion 18 means a region from 50% or more to less than 100% (preferably 90% or less) when the inner end in the tire width direction of the second land portion 18 is set as the 0% position and the outer end in the tire width direction is set as the 100% position.

[0077] By setting the inclination direction change position in the outer region in the tire width direction within the second land portion 18, in the second land portion 18, regarding the first lug groove 30, the length of the portion (inner groove portion) extending from the circumferential main groove 14a on the inner side in the tire width direction to the inclination direction change position can be made larger than the length of the portion (outer groove portion) extending from the circumferential main groove 14c on the outer side in the tire width direction to the inclination direction change position.

[0078] When the tire is rolling under rainfall conditions, the closer to the tire equatorial plane CL, the higher the possibility of contacting the water film on the road surface. Therefore, for the same groove, particularly excellent drainage performance is required in the inner portion in the tire width direction. For this reason, regarding the first lug groove 30 as well, the drainage performance in the inner groove portion is more important than that in the outer groove portion. Considering that the water flow is from the inner side to the outer side in the tire width direction during drainage, by adopting the above-described configuration (making the length of the inner groove portion larger than the length of the outer groove portion), after performing drainage in a certain direction in the inner groove portion where the possibility of contacting the water film is higher, the direction of the water flow can be changed and drainage can be continuously performed in the outer groove portion, so that the wet performance can be further enhanced.

[0079] In the tire 10 shown in FIG. 1, it is preferable that the second lug groove 34 terminates in the inner region in the tire width direction within the second land portion 20. Here, the inner region in the tire width direction within the second land portion 20 means the region from the position of 50% or more to less than 100% (preferably 90% or less) when the outer end in the tire width direction of the second land portion 20 is taken as the position of 0% and the inner end in the tire width direction is taken as the position of 100%.

[0080] Since the second lug groove 34 extends to the position in the inner region in the tire width direction within the second land portion 20, the drainage performance, and thus the wet performance, can be further enhanced. On the other hand, since the second lug groove 34 terminates within the second land portion 20, the generation of sound in the inner portion in the tire width direction of the second lug groove 34 can be suppressed, and the pass-by noise can be further reduced.

[0081] In the tire 10 shown in FIG. 1 or FIG. 4, the third lug groove 40 extends from the grounding end on the outer side of vehicle mounting, crosses the auxiliary groove 48, and terminates within the land portion 22, and the fourth lug groove 50 extends from the grounding end on the inner side of vehicle mounting, crosses the auxiliary groove 56, and terminates within the land portion 24. Here, the fact that the lug groove 40 (50) crosses the auxiliary groove 48 (56) means that the inner end in the tire width direction of the lug groove 40 (50) is located more inward in the tire width direction than the inner end in the tire width direction of the auxiliary groove 48 (56), and the outer end in the tire width direction of the lug groove 40 (50) is located more outward in the tire width direction than the outer end in the tire width direction of the auxiliary groove 48 (56).

[0082] Since the lug grooves 40 (50) extend from the grounding ends on the outer side (inner side) of the vehicle mounting, the rigidity of the land portion near each grounding end is reduced to some extent, resulting in improved traction performance. Further, since the lug grooves 40 (50) cross the auxiliary grooves 48 (56) and terminate within the land portions 22 (24), the length of the lug grooves 40 (50) in the tire width direction is ensured to some extent, further improving the drainage performance. Also, by not connecting the lug grooves 40 (50) to the circumferential main grooves 14c (14d), the generation of noise in the inner portion of the lug grooves 40 (50) in the tire width direction can be suppressed, further reducing the pass-by noise.

[0083] In the example shown in FIG. 1 or FIG. 4, the lug grooves 40 (50) cross the auxiliary grooves 48 (56) and terminate within the land portions 22 (24). However, the present embodiment is not limited to such an example, and examples in which the lug grooves cross the auxiliary grooves and terminate within the land portions only on either the outer side or the inner side of the vehicle mounting are also included.

[0084] In the tire 10 shown in FIG. 1, the average inclination angle of the second lug groove 34 with respect to the tire width direction (average angle of the second lug groove) is preferably larger than the average inclination angle of the fourth lug groove 50 with respect to the tire width direction (average angle of the fourth lug groove). Here, the average angle of the second lug groove means the angle formed by the line segment connecting the innermost position and the outermost position of the second lug groove 34 in the tire width direction with respect to the tire width direction. Also, the average angle of the fourth lug groove means the angle formed by the line segment connecting the innermost position and the grounding end position of the fourth lug groove 34 in the tire width direction with respect to the tire width direction.

[0085] By making the average angle of the second lug groove larger than the average angle of the fourth lug groove, the points at the grounding ends on the extension line extending the second lug groove 34 outward in the tire width direction in FIG. 1 (the points at the grounding ends in the series of curves continuous with the second lug groove 34, the sipe 52, and the small groove 54 from the inner side to the outer side in the tire width direction) and the points at the grounding ends of the fourth lug groove 50 can be dispersed on the grounding end line, further reducing the pass-by noise.

[0086] In the tire 10 shown in FIG. 1, both the outer portion in the tire width direction of the first lug groove 30 and the inner portion in the tire width direction of the third lug groove 40 are inclined to the same side with respect to the tire width direction, and both the outer portion in the tire width direction of the second lug groove 34 and the inner portion in the tire width direction of the fourth lug groove 50 are inclined to the same side with respect to the tire width direction. According to such a configuration, in FIG. 1, the point at the grounding end of the extension line obtained by extending the first lug groove 30 outward in the tire width direction and the point at the grounding end of the third lug groove 40 can be dispersed on the grounding end line on the outer side of the vehicle mounting, and the pass-by noise can be further reduced. Also, in FIG. 1, the point at the grounding end of the extension line obtained by extending the second lug groove 34 outward in the tire width direction and the point at the grounding end of the fourth lug groove 50 can be dispersed on the grounding end line on the inner side of the vehicle mounting, and thus the pass-by noise can be further reduced.

Example

[0087] Tire sizes were set to 245 / 70R18 110H (as defined by JATMA), and each test tire (the tires of the comparative example and the tires of Invention Examples 1 to 14), which had four circumferential main grooves and satisfied the various conditions shown in Table 1, was manufactured. Note that each term in Table 1 conforms to the terms described in this embodiment. Also, among the components of each test tire, the components not shown in Table 1 conform to the tire shown in FIG. 1.

[0088] Next, each test tire was mounted on a rim of size 18x71 / 2J, and the air pressure was set to 230 kPa, and these were mounted on a 4WD vehicle with a displacement of 3500 cc. For all of these test tires, evaluations were performed on noise performance (relating to pass-by noise) and wet performance (relating to lap time during driving on a wet road surface) according to the following procedure.

[0089] (Evaluation method for noise performance) On the test course, for each test tire, the noise level (dB) of the passing sound when the engine was stopped with the transmission in neutral from the state of traveling at a speed of 50 km / h was measured. For the tires of each inventive example, the difference in the noise level from the tire of the comparative example was obtained, and this difference itself was used as the score. The lower these scores are, the better the noise performance. The results are also shown in Table 1.

[0090] (Evaluation method of wet performance) On the test course, for each test tire, the lap time when traveling on a wet road surface was measured. Next, for the tires of each inventive example, the score was obtained when the comparative example was set to 100. The larger these scores are, the better the wet performance. The results are also shown in Table 1.

[0091]

Table 1

[0092] According to Table 1, it can be seen that the tires of Inventive Examples 1 to 14 belonging to the technical scope of the present invention (i.e., satisfying P2(%) > P1(%) and P2(%) > P3(%)) all have improved noise performance while maintaining wet performance as compared with the tires of the comparative examples that do not belong to the technical scope of the present invention.

Explanation of symbols

[0093] 10 Tire 12 Tread surface 14, 14a, 14b, 14c, 14d Circumferential main grooves 16 Center land 18, 20 Second land 22, 24 Shoulder land 26, 28, 58 Flexure grooves 26a, 28a First part 26b, 28b Second part 26c, 28c Third part 30 First lug groove 32, 36, 38, 42, 52 Sipes 34 Second lug groove 40 Third lug groove 44, 54 Small groove 46 Triangular groove 48, 56 Auxiliary groove 50 Fourth lug groove CL Tire equatorial plane CR Center region D1, D2 First interval D3 Second interval DB Tire circumferential length of the third part 26c (28c) of the bending groove 26 (28) DG Tire circumferential length between one end and the other end of the bending groove 26 (28) SR Shoulder region W1, W2, W3, W4 Groove width

Claims

1. At least three land portions are defined by at least two circumferential main grooves, On each side in the tire width direction of the tire equatorial plane, with the groove width center line of the outermost circumferential main groove in the tire width direction as a boundary, when the inner side in the tire width direction from the groove width center line is defined as the center region and the outer side in the tire width direction from the groove width center line is defined as the shoulder region, at least one of the land portions formed in the center region has at least one end in the tire width direction communicating with the circumferential main groove and having at least two bent portions, and at least one bent groove is provided, The groove width of the first portion from one end of the bent groove to before the first bent portion and the groove width of the second portion from the other end of the bent groove to before the first bent portion are each substantially the same over the entire circumference of the tire, Let the number of bent grooves existing in the same land portion be N, and let the length measured over the entire circumference of the tire be Li (1 ≤ i ≤ 2N) in order for the first interval between the first portion and the second portion and the second interval which is the shortest distance between two adjacent bent grooves in the tire circumferential direction, Let the tire circumference be J (mm), the attention length due to the transmission characteristic be S1 (mm), and the attention lengths due to the sound source be S2 (mm) and S3 (mm), 12.4 ≤ S1 (mm) ≤ 19.5, and In the range of S1 (mm) and S2 (mm) satisfying J / (N×1.25×1) ≤ S2 (mm) ≤ J / (N×0.75×1), let the larger of the lower limit values of the two inequalities be LFL1 and the smaller of the upper limit values of the two inequalities be HFL1, 12.4 ≤ S1 (mm) ≤ 19.5, and In the range of S1 (mm) and S3 (mm) satisfying J / (N×1.25×2) ≤ S3 (mm) ≤ J / (N×0.75×2), let the larger of the lower limit values of the two inequalities be LFL2 and the smaller of the upper limit values of the two inequalities be HFL2, LFL1×1 < Li (mm) < HFL1×1, or LFL2×1 < Li (mm) < HFL2×1, the condition C1 defined by Other than condition C1, and LFL1×0.5 < Li (mm) < HFL1×0.5, LFL1×1.5 < Li (mm) < HFL1×1.5, LFL2×0.5 < Li (mm) < HFL2×0.5, or LFL2×1.5 < Li (mm) < HFL2×1.5, the condition C2 defined by Set condition C3 as other than condition C1 and other than condition C2 respectively, When the occupancy ratio of the intervals Li satisfying the condition C1 is P1 (%), the occupancy ratio of the intervals Li satisfying the condition C2 is P2 (%), and the occupancy ratio of the intervals Li satisfying the condition C3 is P3 (%) among up to 2N of the intervals Li, A tire characterized in that P2 (%) > P1 (%) and P2 (%) > P3 (%). **Claim 2** The tire according to claim 1, wherein P1 (%) is 30% or less. **Claim 3** The tire according to claim 1 or 2, wherein the average number of grooves having a tire width direction component of the land portion in the shoulder region is larger than the average number of grooves having a tire width direction component of the land portion in the center region. **Claim 4** The tire according to claim 1 or 2, wherein an auxiliary groove extending in the tire circumferential direction and having a groove width of 5% or more and 40% or less of the groove width of the circumferential main groove on the outermost side in the tire width direction is provided in the shoulder region. **Claim 5** The tire according to claim 1 or 2, wherein the tire circumferential direction length DG between one end and the other end of the bending groove is equal to or greater than the tire circumferential direction length DB of a third portion other than the first portion and the second portion of the bending groove. **Claim 6** The tire according to claim 1 or 2, wherein at least four land portions are defined by at least three circumferential main grooves. **Claim 7** The tire according to claim 1 or 2, wherein five land portions are defined by four circumferential main grooves, and the groove width of the circumferential main groove located on the outermost side in the tire width direction is smaller than the groove widths of the other circumferential main grooves. **Claim 8** The tire according to claim 1 or 2, wherein only the bending grooves are provided in the land portion of the center region. **Claim 9** The tire according to claim 1 or 2, wherein five land portions are defined by four circumferential main grooves, the bending grooves are provided only in the third center land portion counted from the outermost side in the tire width direction on each side where the tire is mounted on the vehicle among the five land portions, and the number of grooves having a tire width direction component provided in the land portions other than the center land portion is 1.3 times or more and 2.6 times or less the number of the bending grooves provided in the center land portion. **Claim 10** Of the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, in the second land portion on the outer side of the vehicle mounting side, there is provided a first lug groove that communicates with both of the circumferential main grooves on both sides in the tire width direction and whose inclination direction with respect to the tire width direction reverses midway while extending from the inner side to the outer side in the tire width direction, and the position where the extending direction of the first lug groove becomes the tire width direction exists in the outer region in the tire width direction within the second land portion. The tire according to claim 1 or 2.

11. Of the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, in the second land portion on the inner side of the vehicle mounting side, there is provided a second lug groove that communicates with the circumferential main groove on the outer side in the tire width direction, extends from the outer side to the inner side in the tire width direction, and terminates in the inner region in the tire width direction within the second land portion. The tire according to claim 1 or 2.

12. On the outer side of the vehicle mounting, there is provided a third lug groove that extends from the grounding end toward the circumferential main groove, and the third lug groove crosses the auxiliary groove, and / or On the inner side of the vehicle mounting, there is provided a fourth lug groove that extends from the grounding end toward the circumferential main groove, and the fourth lug groove crosses the auxiliary groove. The tire according to claim 4.

13. On the inner side of the vehicle mounting, there is provided a fourth lug groove that extends from the grounding end toward the circumferential main groove, and the fourth lug groove crosses the auxiliary groove. The average inclination angle of the second lug groove with respect to the tire width direction is larger than the average inclination angle of the fourth lug groove with respect to the tire width direction. The tire according to claim 11.

14. Of the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, in the second land portion on the outer side of the vehicle mounting side, there is provided a first lug groove that communicates with both of the circumferential main grooves on both sides in the tire width direction and whose inclination direction with respect to the tire width direction reverses midway while extending from the inner side to the outer side in the tire width direction, and the point where the extending direction of the first lug groove becomes the tire width direction exists in the outer region in the tire width direction of the second land portion. Of the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, in the second land portion on the inner side of the vehicle mounting, a second lug groove is provided which communicates with the circumferential main groove on the outer side in the tire width direction, extends from the outer side to the inner side in the tire width direction, and terminates in the inner region in the tire width direction of the second land portion. On the outer side of the vehicle mounting, a third lug groove is provided which extends from the grounding end toward the circumferential main groove. The third lug groove crosses the auxiliary groove and / or On the inner side of the vehicle mounting, a fourth lug groove is provided which extends from the grounding end toward the circumferential main groove. The fourth lug groove crosses the auxiliary groove. Both the outer portion in the tire width direction of the first lug groove and the inner portion in the tire width direction of the third lug groove are inclined to the same side with respect to the tire width direction. Both the outer portion in the tire width direction of the second lug groove and the inner portion in the tire width direction of the fourth lug groove are inclined to the same side with respect to the tire width direction. The tire according to claim 1 or 2.

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