tire

Abstract

To provide a tire that is improved in noise performance while maintaining snow performance.SOLUTION: At least two bent grooves 26 (28) whose at least one end parts in a tire width direction are communicated with a circumferential main groove and which have at least two bent parts are formed. Groove widths are different between at least one pair of groove parts formed adjacently in a tire circumferential direction. PTA1 (%) is 0% or more and less than 50%, and relational expressions of PTB2(%)>PTB1(%) and PTB2(%)>PTB3(%) are satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire that improves noise performance while maintaining snow 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 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. There is a known tire (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 fluctuation timing regarding 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 contacts 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, it is also conceivable to reduce the groove area ratio in order to improve the noise performance, but reducing the groove area ratio may cause deterioration of the drainage performance and thus deterioration of the snow performance. For this reason, in recent years, there has been a demand for the development of a technology that improves noise performance while maintaining snow 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 snow 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 two bent grooves are 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 different between at least one set of groove portions adjacent to each other in the tire circumferential direction, Taking the number of bent grooves existing in the same land portion as N, When the length measured over the entire tire circumference of the first interval, which is the distance between two adjacent bent grooves in the tire circumferential direction, is sequentially Ai (1 ≦ i ≦ N), When the length measured over the entire tire circumference of the second interval between the first portion and the second portion is sequentially Bi (1 ≦ i ≦ N), Taking the tire circumference as J (mm), the range of the attention length due to the transmission characteristics as S1 (mm), and the ranges of the attention lengths due to the sound source as S2 (mm) and S3 (mm), 12.4 ≦ S1 (mm) ≦ 19.5, and In the ranges of S1 (mm) and S2 (mm) that satisfy J / (N × 1.25 × 1) ≦ S2 (mm) ≦ J / (N × 0.75 × 1), the larger of the lower limit values of the two inequalities is defined as LFL1, and the smaller of the upper limit values of the two inequalities is defined as 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 < Ai (mm) < HFL1×1, or LFL2×1 < Ai (mm) < HFL2×1, the condition TA1 defined thereby LFL1×1 < Bi (mm) < HFL1×1, or LFL2×1 < Bi (mm) < HFL2×1, the condition TB1 defined thereby Conditions other than condition TB1, and LFL1×0.5 < Bi (mm) < HFL1×0.5, or LFL2×0.5 < Bi (mm) < HFL2×0.5, the condition TB2 defined thereby, and The condition TB3 defined as a condition other than TB1 and other than TB2 are respectively set. When the existence ratio of the interval Ai that satisfies condition TA1 is PTA1 (%), the existence ratio of the interval Bi that satisfies condition TB1 is PTB1 (%), the existence ratio of the interval Bi that satisfies condition TB2 is PTB2 (%), and the existence ratio of the interval Bi that satisfies condition TB3 is PTB3 (%), PTA1 (%) is 0% or more and less than 50%, PTB2 (%) > PTB1 (%), and PTB2 (%) > PTB3 (%) It is characterized by satisfying the above.

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 timing of variation regarding the opening and closing of the groove portion during tire rolling is reduced from overlapping for groove portions adjacent to each other in the tire circumferential direction. Specifically, regarding the zigzag groove provided in the land portion in the central region in the tire width direction, on the premise that the groove widths of grooves adjacent to each other in the tire circumferential direction are made different, PTA1(%) is set to be 0% or more and less than 50%, and PTB2(%) > PTB1(%), and PTB2(%) > PTB3(%). Thereby, without deteriorating the drainage performance, it is possible to intentionally shift the timing of variation regarding the opening and closing of the groove portion during tire rolling for groove portions adjacent to each other in the tire circumferential direction, and thus it is possible to reduce the pass-by noise between these groove portions. Therefore, according to the present invention, it is possible to improve the noise performance while maintaining the snow performance.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

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 with the above rotation axis as the central axis. Furthermore, the tire width direction refers to the direction parallel to the above 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. Note that the tire equatorial plane is a plane orthogonal to the rotation axis of the tire and passing 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. Also, 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 regular rim and a regular 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 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 when there is no groove (hereinafter, the same applies to other grooves).

[0015] These circumferential main grooves 14 define and form 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 and formed on each side in the tire width direction thereof, and further, shoulder land portions 22, 24 are defined and formed on the outer sides in the tire width direction thereof. Note that in the present embodiment, the land portions defined and formed by the four circumferential main grooves 14a to 14d include not only ribs as shown in FIG. 1 but also block rows.

[0016] On each side in the tire width direction of the tire equatorial plane CL, with the groove width center lines (not shown) of the outermost circumferential main grooves 14c, 14d in the tire width direction as a boundary, the inner side in the tire width direction from these groove width center lines is defined as the center region CR, and the outer side in the tire width direction from the groove width center lines is defined as the shoulder regions SR, SR.

[0017] On the center land portion 16 formed in the center region CR, a plurality of bending grooves are provided, both ends in the tire width direction communicating with the circumferential main grooves 14a and 14b and having two bending portions. In the example shown in FIG. 1, as the bending grooves, two types of bending grooves 26 and 28 having different groove widths are alternately provided in the tire circumferential direction.

[0018] The bending groove 26 (28) has a groove width greater than 1.5 mm in order to ensure excellent snow performance. The upper limit value of the groove width is preferably 5 mm. Further, the bending groove 26 (28) has a depth of 40% or more of the groove depth of the circumferential main groove 14 in order to ensure excellent snow performance. The upper limit value of the groove depth is preferably 90% or less of the groove depth of the circumferential main groove 14.

[0019] As shown in FIG. 1, on the second land portion 18 on the outer side for vehicle mounting 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 in which the inclination direction with respect to the tire width direction is reversed on the way of extending from the inner side to the outer side in the tire width direction. The first lug groove 30 is provided on the outer side for vehicle mounting to improve snow performance, and by reversing the inclination direction with respect to the tire width direction on the way of extending, the pass-by noise can be reduced as compared with a groove in which the inclination direction is not reversed.

[0020] In the second land portion 18, a sipe 32 is formed between the first lug grooves 30 adjacent to each other in the tire circumferential direction and extending substantially parallel to the first lug groove 30. In the present specification, a sipe means a groove having a groove width of 0.5 mm or more and 1.5 mm or less and a groove depth of 20% or more and 80% or less of the groove depth of the circumferential main groove 14.

[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 snow 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. The sipe 42 communicates with a small groove 44 near the grounding end. In this specification, the small groove means a groove having 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. 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.

[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 makes a particularly large contribution to the turning performance among the snow performances. 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. 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. As shown in Figure 2, for the bending groove 26 (28), the groove width W1 (W2) of the first portion 26a (28a) from one end 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 different between at least one set of groove portions among adjacent groove portions in the tire circumferential direction. That is, in Figure 2, the groove width W1 and the groove width W2 are different, and the groove width W3 and the groove width W4 are different. Note that the relationship between the groove width W1 and the groove width W3 is not particularly limited and may be different or the same. The relationship between the groove width W2 and the groove width W4 is also not particularly limited and may be different or the same.

[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 this calculated value for the five sections is used. The same applies to the groove width W3 (W4) of the second portion 26b (28b).

[0027] The first part 26a (28a) and the second part 26b (28b) may be linear or curved in the extending direction. Further, the bent portion is a portion connected to the first part 26a (28a) and / or the second part 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 part 26a (28a) or the second part 26b (28b) to the point where the curvature changes again.

[0028] Although the groove width W1 and the groove width W2, or the groove width W3 and the groove width W4 are different as described above, in this embodiment, as long as the groove widths are different between at least one set of groove portions adjacent to each other in the tire circumferential direction, the groove widths of the other groove portions may be different or the same. When providing three types of bent grooves A, bent groove B, and bent groove C with different groove widths in the center land portion 16, examples of the bent groove unit serving as the repeating unit are as follows. In this paragraph, hereinafter, the bent groove A is denoted as A, the bent groove B is denoted as B, and the bent groove C is denoted as C. The examples shown below are merely illustrative, and other examples (when providing four or more types of bent grooves) are also included in the scope of this embodiment. ·ABC ·ABBCC ·ABBBCCC ·ABAC ·ABBACC ·ABBBACCC ·AABC ·AABBCC ·AABBBCCC ·AABAAC ·AABBAACC ·AABBBAACCC ·AAABC ·AAABBCC ·AAABBBCCC ·AAABAAAC ·AAABBAAACC

[0029] When providing a plurality of types of bent grooves with different groove widths in the groove portion of the center land portion 16, the widths of the groove portions of the plurality of types of bent grooves are set such that the ratio of the standard deviation calculated from each portion to the average value calculated from each portion (standard deviation / average value) is in the range of 0 or more and 0.1 or less. For example, in the example shown in FIG. 2, for the portions 26a and 28a (portions 26b and 28b), the ratio of the standard deviation calculated from each portion to the average value calculated from each portion (standard deviation / average value) is set to be in the range of 0 or more and 0.1 or less.

[0030] Note that the groove widths W1 and W3 of the groove portions included in the bent groove 26 may be the same or different. Similarly, the groove widths W2 and W4 of the groove portions included in the bent groove 28 may be the same or different. In the example shown in FIG. 2, the groove width W1 and the groove width W3 are the same, and the groove width W2 and the groove width W4 are 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, the timing of variation regarding the opening and closing of the groove portion is likely to be 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). 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.

[0031] FIG. 3 is a plan view showing the intervals between the groove portions of the bent grooves shown in FIG. 1. Regarding FIG. 3 as well, 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. Here, let the number of bent grooves existing in the center land portion 16 shown in FIG. 1 be N.

[0032] When the length of the first interval D1, which is the distance between two adjacent bent grooves 26 and 28 in the tire circumferential direction, measured over the entire tire circumference is sequentially Ai (1 ≦ i ≦ N), and the length of the second interval D2 between the first portion 26a and the second portion 26b, as well as the length of the second interval D3 between the first portion 28a and the second portion 28b, measured over the entire tire circumference are sequentially Bi (1 ≦ i ≦ N).

[0033] For example, when only two bending grooves are provided in the center land portion 16 (only the bending groove 26 and the bending groove 28), one first interval D1 shown in FIG. 3 is defined, and a total of two second intervals D2 and D3 are defined. On the other hand, for example, when 30 bending grooves are provided in the center land portion 16, since one first interval D1 shown in FIG. 3 exists for each bending groove, a total of 30 are defined, and the second intervals D2 and D3 also exist in the same number as the number of bending grooves, so a total of 30 are defined.

[0034] The first interval D1 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 W1 shown in FIG. 2, where the groove portions of two adjacent bending grooves in the tire circumferential direction (for example, the first portions 26a and 28a) 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 W2 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.

[0035] On the other hand, when the groove portions of two adjacent bending grooves in the tire circumferential direction (for example, the first portions 26a and 28a) are not parallel, the first interval D1 for the bending grooves 26 and 28 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 sequentially designated as point a1, point b1, point c1, point d1, and point e1 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 sequentially designated as point a2, point b2, point c2, point d2, and point e2 from the vehicle-mounted side. Next, let the distance between point a1 and point a2 be Sa, the distance between point b1 and point b2 be Sb, the distance between point c1 and point c2 be Sc, the distance between point d1 and point d2 be Sd, and the distance between point e1 and point e2 be Se. Then, the average value from the distance Sa to the distance Se is calculated and set as the first interval D1.

[0036] The second interval D2 for the bending groove 26 is determined as the shortest distance between a virtual line created based on the center points of the groove widths (not shown) in each of the five equal sections used when obtaining the groove width W1 shown in FIG. 2 and a virtual line created based on the center points of the groove widths (not shown) in each of the five equal sections used when obtaining the groove width W3 shown in FIG. 2, in the case where the groove portions of one bending groove (for example, the first portion 26a and the second portion 26b) are parallel to each other. Each virtual line is set so that the five above-mentioned center points of the groove widths are as far away from the virtual line as possible. The second interval D3 for the bending groove 28 shown in FIG. 3 is also determined in the same manner as the second interval D2 (based on the groove widths W2 and W4).

[0037] On the other hand, when the groove portions of one bending groove (for example, the first portion 26a and the second portion 26b) are not parallel to each other, the second interval D2 for the bending groove 26 is determined as follows. That is, first, the center points of the groove widths (not shown) in each of the five equal sections used when obtaining the groove width W1 shown in FIG. 2 are designated as points a1, b1, c1, d1, and e1 in order from the vehicle-mounted side, and the center points of the groove widths (not shown) in each of the five equal sections used when obtaining the groove width W3 shown in FIG. 2 are designated as points a3, b3, c3, d3, and 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 defined as the first interval D1. The second interval D3 for the bending groove 28 shown in FIG. 3 is also determined in the same manner as the second interval D2 (based on the groove widths W2 and W4).

[0038] Next, define the tire circumference as J (mm), the range of the attention length due to the transmission characteristics as S1 (mm), and the ranges of the attention lengths due to the sound source as S2 (mm) and S3 (mm).

[0039] Here, the range S1 (mm) of the attention length due to transmission characteristics means the range sandwiched between 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, respectively.

[0040] Also, the range S2 (mm) of the attention length due to the sound source means the range of the fundamental 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 second pitch order ±25% when the block formed by the bending groove contacts the road surface.

[0041] Next, the range of the attention length S1 (mm) due to transmission characteristics such that the sound generated from the bending grooves 26 and 28 provided in the center land portion 16 is emphasized by the horn effect is as follows. 12.4 < S1 (mm) < 19.5

[0042] Also, the ranges of the attention lengths S2 (mm) and S3 (mm) due to the sound source such that the bending grooves 26 and 28 provided in the center land portion 16 cause the 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)

[0043] Based on the above ranges of S1 (mm), S2 (mm), and S3 (mm), S1 (mm) ≤ 19.5, and In the ranges 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 said inequalities be HFL1.

[0044] Similarly, 12.4 ≤ S1 (mm) ≤ 19.5, and In the range of S1(mm) and S3(mm) that satisfies J / (N×1.25×2) ≦ S3(mm) ≦ J / (N×0.75×2), the larger of the lower limit values of these two inequalities is defined as LFL2, and the smaller of the upper limit values of the two inequalities is defined as HFL2.

[0045] Furthermore, based on the above findings, LFL1×1 < Ai(mm) < HFL1×1, or LFL2×1 < Ai(mm) < HFL2×1, the conditions defined by this are defined as condition TA1.

[0046] LFL1×1 < Bi(mm) < HFL1×1, or LFL2×1 < Bi(mm) < HFL2×1, the conditions defined by this are defined as condition TB1.

[0047] The conditions that are other than condition TB1 and LFL1×0.5 < Bi(mm) < HFL1×0.5, or LFL2×0.5 < Bi(mm) < HFL2×0.5, the conditions defined by this are defined as condition TB2.

[0048] The conditions defined as the conditions other than condition TB1 and condition TB2 are defined as condition TB3.

[0049] And the existence ratio of the interval Ai that satisfies condition TA1 is defined as PTA1(%), the existence ratio of the interval Bi that satisfies condition TB1 is defined as PTB1(%), the existence ratio of the interval Bi that satisfies condition TB2 is defined as PTB2(%), and the existence ratio of the interval Bi that satisfies condition TB3 is defined as PTB3(%).

[0050] When condition TA1 is satisfied, or when condition TB1 is satisfied, it means that during tire rolling, since the timing of the variation regarding the opening and closing of the groove part is likely to overlap between the groove parts adjacent in the tire circumferential direction, the pass - by noise is large, which is an undesirable case.

[0051] Satisfying condition TB2 means that when the tire is rolling, since the timing of the opening and closing of the groove portion is unlikely to overlap between the groove portions adjacent to each other in the tire circumferential direction, the pass-by noise is small, which means a desired case.

[0052] Satisfying condition TB3 (when neither condition TB1 nor condition TB2 is satisfied) means that when the tire is rolling, since the timing of the opening and closing of the groove portion has a medium possibility of overlapping between the groove portions adjacent to each other in the tire circumferential direction, the pass-by noise is medium, which means a case that is neither undesirable nor desired.

[0053] Regarding each of the above inequalities used to derive any one of condition TA1, condition TB1, condition TB2, and condition TB3, the inventors have intensively conducted numerous experiments with deliberation. Although the inventors have not clearly found a technical basis for these inequalities, they have a basis supported by a large amount of experimental data, and finally have obtained the knowledge that these inequalities are useful for improving the noise performance.

[0054] Under the above premises, in this embodiment, on the premise of making the groove widths of the grooves adjacent to each other in the tire circumferential direction different as described above, PTA1 (%) is 0% or more and less than 50%, and PTB2 (%) > PTB1 (%) and PTB2 (%) > PTB3 (%) are satisfied.

[0055] In the tire 10 of this embodiment, the groove widths are made different between at least one set of the groove portions adjacent to each other in the tire circumferential direction, so that the timing of the opening and closing of the groove portion can be intentionally shifted to some extent when the tire is rolling (operation 1).

[0056] Then, regarding the ratio of the undesired case ratio PTA1 to the whole with respect to the interval between adjacent bending grooves, make it less than half, and compare the desired case ratio PTB2, the undesired case ratio PTB1, and the neither desired nor undesired case ratio PTC3 with respect to the interval between the groove portions included in each bending groove. By making the desired case ratio PTB2 higher than either of the other case ratios PTB1 and PTB3 among these three ratios, it is possible to further shift the timing of variation regarding the opening and closing of the groove portions during tire rolling (Effect 2).

[0057] By combining the above-mentioned Effect 1 and Effect 2, the tire 10 of the present embodiment can surely shift the timing of variation regarding the opening and closing of the groove portions during tire rolling. As a result, the pass-by noise can be reduced and the noise performance can be improved.

[0058] The tire 10 of the present embodiment does not reduce the groove area ratio compared to conventional tires. Instead, by focusing on a specific land portion (specifically, the center land portion 16 included in the central region in the tire width direction, etc.), the pass-by noise is reduced by the above-mentioned Effects 1 and 2. Therefore, according to the tire 10 of the present embodiment, the snow performance (a combination of drainage performance, handling stability performance, turning performance, traction performance, etc. The same shall apply hereinafter.) can be maintained at the conventional level, and the above-mentioned improvement in noise performance can be realized. In the example shown in FIG. 1, in particular, by providing four circumferential main grooves, the width of the center land portion 16, which contributes the most to pass-by noise reduction, is made relatively small to reduce the rigidity of the land portion 16, so that the pass-by noise can be efficiently reduced.

[0059] In the example shown in FIG. 1, the bending grooves 26 are provided only in the center land portion 16, but 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, bending grooves can be provided in any land portion, and the same effect as that of the tread pattern shown in FIG. 1 can be obtained.

[0060] In addition, for example, when bending grooves are provided in the center land portion 16 and the second land portion 20 (not shown), the groove widths W1 to W4 shown in FIG. 2 and the intervals D1 to D3 shown in FIG. 3 are calculated for each land portion, and the above-described ratios PTA1, PTB1, PTB2, and PTB3 are calculated for the entire tire.

[0061] In the example shown in FIG. 1, by setting PTA1 (%) to less than 40%, the variation timing regarding the opening and closing of the groove portion during tire rolling can be further shifted, and as a result, the pass-by noise can be further reduced. Furthermore, by setting PTA1 (%) to less than 30%, the variation timing regarding the opening and closing of the groove portion during tire rolling can be further shifted, and as a result, the pass-by noise can be significantly reduced.

[0062] In the example shown in FIG. 1, it is preferable that the difference between the ratio PTB2 and the ratio PTB1 is 20% or more, and the difference between the ratio PTB2 and the ratio PTB3 is 10% or more. When these conditions are satisfied, since the ratio PTB1 in the above-described undesirable case is lower than the ratio PTB3 in the case that is neither undesirable nor desirable, the ratio PTB1 in the undesirable case occupying 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 portion during tire rolling can be intentionally shifted to a higher level, and thus, the pass-by noise can be further reduced between these groove portions.

[0063] In the tire 10 shown in FIG. 1, it is preferable that the ratio PTB1 is 30% or less. When such conditions are satisfied, the ratio PTB1 in the undesirable case occupying 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 portion during tire rolling can be intentionally shifted to a higher level, and thus, the pass-by noise can be further reduced between these groove portions.

[0064] When the ratio PTB1 is 30% or less and the ratio PTB2 > ratio PTB3 > ratio PTB1 are satisfied, it is possible to intentionally shift the timing of variation regarding the opening and closing of the groove portion to an even higher level during tire rolling. As a result, the pass-by noise can be further reduced between these groove portions.

[0065] FIG. 4 is a plan view showing two types of circumferential lengths of the bending groove shown in FIG. 1. As shown in FIG. 4, it is preferable that the circumferential length DG1 (DG2) of the tire between one end and the other end of the bending groove 26 (28) is equal to or greater than the circumferential length DB1 (DB2) of the third portion 26c (28c) (the portion other than the first and second portions in each bending groove) of the bending groove 26 (28). Here, the circumferential lengths DG1 and DG2 may be the same or different. Also, the circumferential lengths DB1 and DB2 may be the same or different.

[0066] Regarding the third portion 26c (28c) of the bending groove 26 (28) shown in FIG. 4 (FIG. 1), 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, it is preferable to provide the longitudinal portion so as to extend from the inner side to the outer side in the tire width direction from the depressed side to the kicking side of the tire in consideration of the drainage performance.

[0067] By setting the circumferential length DG1 (DG2) to be equal to or greater than the 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 enhancing the noise performance.

[0068] In the example shown in FIG. 1, only the above-described bending grooves 26 and 28 are 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 change regarding 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 attenuated 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.

[0069] As a modification of the example shown in FIG. 1, 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 (preferably three or more) circumferential main grooves are provided, excellent noise performance can be obtained while maintaining the desired drainage performance, and thus snow performance, in the present embodiment.

[0070] In the tire 10 shown in FIG. 1, it is preferable that the position (tilt direction change position) where the extending direction of the first lug groove 30 is in 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 of the second land portion 18 means the region from the position of 50% or more to less than 100% (preferably 90% or less) of the position 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.

[0071] By setting the tilt 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 tilt 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 tilt direction change position.

[0072] When the tire is rolling under snowfall conditions, the closer it is to the tire equatorial plane CL, the higher the possibility of contacting the snow or water film deposited on the road surface. Therefore, for the same groove, particularly excellent drainage performance is required in the inner part in the tire width direction. For this reason, for the first lug groove 30 as well, the drainage performance in the inner groove part is more important than that in the outer groove part. 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 part larger than the length of the outer groove part), after performing drainage in the same direction to some extent in the inner groove part where the possibility of contacting the water film or the like is higher, the direction of the water flow can be changed and drainage can be continuously performed in the outer groove part, so that the snow performance can be further enhanced.

[0073] 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 a region from a 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 set as the 0% position and the inner end in the tire width direction is set as the 100% position.

[0074] Since the second lug groove 34 extends to the position of the inner region in the tire width direction within the second land portion 20, the drainage performance, and thus the snow performance, can be further enhanced. Further, since the second lug groove 34 terminates within the second land portion 20, the generation of noise in the inner part in the tire width direction of the second lug groove 34 can be suppressed, and the pass-by noise can be further reduced.

[0075] In the example shown in FIG. 1, as described above, in the second land portion 20, a sipe 36 is formed that 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. In the present embodiment, in addition to the example shown in FIG. 1, an example in which the second lug groove 34 does not terminate within the land portion 20 but also communicates with the circumferential main groove 14b is included. However, when the second lug groove 34 communicates with the circumferential main groove 14b on the inner side in the tire width direction, the sound generated in the inner portion of the second lug groove 34 in the tire width direction is relatively large, and it is difficult to reduce the pass-by noise. On the other hand, as shown in FIG. 1, by terminating the second lug groove 34 within the land portion and forming a sipe 36 that is thinner than the second lug groove 34 on the extension line thereof, the sound generated in the inner portion of the sipe 36 in the tire width direction can be made relatively small, and the pass-by noise can be efficiently reduced without deteriorating the drainage performance.

[0076] In the tire 10 shown in FIG. 1, the third lug groove 40 extends from the grounding end on the outer side of the vehicle mounting (or the position on the outer side in the tire width direction of the grounding end), crosses the auxiliary groove 48, and terminates within the land portion 22. Also, the fourth lug groove 50 extends from the grounding end on the inner side of the vehicle mounting (or the position on the outer side in the tire width direction of the grounding end), 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 of the lug groove 40 (50) in the tire width direction is located more inward in the tire width direction than the inner end of the auxiliary groove 48 (56), and the outer end of the lug groove 40 (50) in the tire width direction is located more outward in the tire width direction than the outer end of the auxiliary groove 48 (56).

[0077] Since the lug grooves 40 (50) extend from the grounding end on the outer side (inner side) of the vehicle mounting (or the position outside the tire width direction of the grounding end), the rigidity of the land portion near each grounding end is reduced to a certain extent, resulting in improved traction performance. On the other hand, since the lug grooves 40 (50) cross the auxiliary grooves 48 (56) and terminate within the land portions 22 (24), the tire width direction length of the lug grooves 40 (50) is ensured to a certain extent to further improve 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 in the tire width direction of the lug grooves 40 (50) can be suppressed, and the pass-by noise can be further reduced.

[0078] In the example shown in FIG. 1, 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 where 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.

[0079] 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 the pass-by noise can be further reduced.

[0080] In the tire 10 shown in FIG. 1, it is preferable that 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 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 in the tire width direction of the second lug groove 34 with respect to the tire width direction. Further, 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 in the tire width direction of the fourth lug groove 34 with respect to the tire width direction.

[0081] By making the average angle of the second lug groove larger than the average angle of the fourth lug groove, in FIG. 1, the point at the grounding end on the extension line extending the second lug groove 34 outward in the tire width direction (the point at the grounding end in a 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 point at the grounding end of the fourth lug groove 50 can be dispersed on the grounding end line, and the pass-by noise can be further reduced.

Example

[0082] Tire sizes were set to 245 / 70R17 110T (specified by JATMA), and each test tire (the tires of the comparative example and the tires of Invention Examples 1 to 11) having four circumferential main grooves and satisfying 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 components shown in FIG. 1.

[0083] Next, each test tire was mounted on a rim of size 17x7J, 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 made on noise performance (relating to pass-by noise) and snow performance (relating to lateral acceleration performance and braking performance) according to the following procedures.

[0084] (Evaluation method of noise performance) On a 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 a state of traveling at a speed of 50 km / h was measured. For the tires of each inventive example, the difference in noise level from the tire of the comparative example was determined, and this difference itself was used as a score. The lower these scores are, the better the noise performance. The results are also shown in Table 1.

[0085] (Method for Evaluating Snow Performance) On a test course, for each test tire, an evaluation of the lateral acceleration performance (snow performance 1) and an evaluation of the braking performance (snow performance 2) when traveling on a snow-covered road surface were performed. For snow performance 1, a test course on a snow-covered road surface with a radius of 7 m was traveled 5 times at different speeds, and the lateral acceleration was calculated from the lap time of each lap. The results of the tires of the comparative example were evaluated using an index with a value of 100. For snow performance 2, the vehicle was traveled on a snow-covered road surface, and the braking distance when the braking force was applied at 30 km / h to activate the ABS was measured. The reciprocal was calculated, and the results of the tires of the comparative example were evaluated using an index with a value of 100. The larger these scores are, the better snow performance 1 and 2 are. These results are also shown in Table 1.

[0086] [Table 1]

[0087] According to Table 1, the tires of Inventive Examples 1 to 12 belonging to the technical scope of the present invention (that is, on the premise that the groove widths of adjacent grooves in the tire circumferential direction are different, PTA1 (%) is 0% or more and less than 50%, and PTB2 (%) > PTB1 (%) and PTB2 (%) > PTB3 (%) are satisfied) can be seen to have improved noise performance while maintaining snow performance compared to the tires of the comparative examples that do not belong to the technical scope of the present invention. [Explanation of Reference Signs]

[0088] 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 bending 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 grooves 46 triangular groove 48, 56 auxiliary grooves 50 fourth lug groove CL tire equatorial plane CR center region D1 first interval D2, D3 second interval DB1 circumferential length of the third part 26c of the bending groove 26 in the tire circumferential direction DB2 circumferential length of the third part 28c of the bending groove 28 in the tire circumferential direction DG1 circumferential length between one end and the other end of the bending groove 26 in the tire circumferential direction DG2 circumferential length between one end and the other end of the bending groove 28 in the tire circumferential direction SR shoulder region W1, W2, W3, W4 groove widths

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 two bent grooves are 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 different between at least one set of groove portions adjacent to each other in the tire circumferential direction, Let the number of bent grooves existing in the same land portion be N, When the length measured over the entire tire circumference of the first interval, which is the distance between two adjacent bent grooves in the tire circumferential direction, is sequentially denoted as Ai (1 ≤ i ≤ N), Let the length measured over the entire tire circumference of the second interval between the first portion and the second portion be sequentially denoted as Bi (1 ≤ i ≤ N), 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 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), 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 < Ai (mm) < HFL1×1, or LFL2×1 < Ai (mm) < HFL2×1, the condition TA1 defined thereby, LFL1×1 < Bi (mm) < HFL1×1, or LFL2×1 < Bi (mm) < HFL2×1, the condition TB1 defined thereby, Conditions other than the condition TB1, and LFL1×0.5 < Bi (mm) < HFL1×0.5, or Condition TB2 defined by LFL2×0.5 < Bi (mm) < HFL2×0.5, and condition TB3 defined as a condition other than condition TB1 and other than condition TB2 are each set, when the occupancy ratio of interval Ai satisfying condition TA1 is PTA1 (%), the occupancy ratio of interval Bi satisfying condition TB1 is PTB1 (%), the occupancy ratio of interval Bi satisfying condition TB2 is PTB2 (%), and the occupancy ratio of interval Bi satisfying condition TB3 is PTB3 (%) PTA1 (%) is 0% or more and less than 50%, PTB2 (%) > PTB1 (%), and PTB2 (%) > PTB3 (%) A tire characterized by satisfying the above. **Claim 2** The tire according to claim 1, wherein PTB1 (%) is 30% or less. **Claim 3** The tire according to claim 1 or 2, wherein the circumferential direction length DG of the tire between one end and the other end of the bending groove is equal to or greater than the circumferential direction length DB of the third portion other than the first portion and the second portion of the bending groove. **Claim 4** The tire according to claim 1 or 2, wherein only the bending groove is provided in the land portion of the center region. **Claim 5** The tire according to claim 1 or 2, wherein at least four land portions are defined by at least three circumferential main grooves. **Claim 6** Among the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, the second land portion on the outer side of the vehicle mounting has 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 during extension 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. **Claim 7** Among the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, the second land portion on the inner side of the vehicle mounting has a second lug groove that communicates with the circumferential main groove on the outer side in the tire width direction and 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. **Claim 8** The tire according to claim 7, wherein a sipe is formed in the second land portion on the inner side of the vehicle mounting, which communicates with the second lug groove and also communicates with the circumferential main groove on the inner side in the tire width direction. **Claim 9** In the shoulder region on the outer side of the vehicle mounting, an auxiliary groove is provided that extends in the tire circumferential direction and has a groove width that is 5% or more and 40% or less of the groove width of the circumferential main groove at the outermost side in the tire width direction. At least a third lug groove extending from the grounding end toward the circumferential main groove is provided. The third lug groove crosses the auxiliary groove and terminates within the land portion, and / or In the shoulder region on the inner side of the vehicle mounting, an auxiliary groove is provided that extends in the tire circumferential direction and has a groove width that is 5% or more and 40% or less of the groove width of the circumferential main groove at the outermost side in the tire width direction. At least a fourth lug groove extending from the grounding end toward the circumferential main groove is provided. The fourth lug groove crosses the auxiliary groove and terminates within the land portion. The tire according to claim 1 or 2.

10. Among 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, a first lug groove is provided that communicates with both of the circumferential main grooves on both sides in the tire width direction and has an inclination direction with respect to the tire width direction reversed midway while extending from the inner side to the outer side in the tire width direction. 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. Among 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 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 of the second land portion. In the shoulder region on each side of the vehicle mounting, an auxiliary groove is provided that extends in the tire circumferential direction and has a groove width that is 5% or more and 40% or less of the groove width of the circumferential main groove at the outermost side in the tire width direction. On the outer side of the vehicle mounting, a third lug groove extending from the grounding end toward the circumferential main groove is provided. The third lug groove crosses the auxiliary groove and terminates within the land portion, and / or On the inner side of the vehicle mounting, a fourth lug groove extending from the grounding end toward the circumferential main groove is provided. The fourth lug groove crosses the auxiliary groove and terminates within the land portion. 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. The tire according to claim 1 or 2, wherein 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.

11. Among the second land portions adjacent to each side in the tire width direction of the center land portion including the tire equatorial plane, the second land portion on the inner side of the vehicle mounting has 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 of the second land portion. 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 on each side of the vehicle mounting. On the inner side of the vehicle mounting, a fourth lug groove extending from the grounding end toward the circumferential main groove is provided, and the fourth lug groove crosses the auxiliary groove and terminates within the land portion. The tire according to claim 1 or 2, wherein 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.

Images