JP2015205660A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire capable of attaining a desired result as an effect to reduce tire noises (or pattern noises) in a tread pattern after abraded.SOLUTION: A tire 100 comprises a center land part row 10C, an inside shoulder land part row 10Sin and an outer shoulder land part row 10Sout. The number of the pitches PC of the center land part row 10C, the number of pitches PIN of the inside shoulder land part row 10Sin and the number of pitches POUT of the outer shoulder land part row 10Sout are 30 to 120. The number of the pitches POUT is smaller than the number of the pitches PIN. The number of the pitches PIN is smaller than the number of the pitches PC. The ratio of the number of the pitches POUT and the number of the pitches PIN (i.e., the number of the pitches PIN/the number of the pitches POUT) is 1.0 to 5.0.

Description

  In the present invention, n types (n is an integer of 3 or more) pitch lengths Pi (i = 1,..., N) are set as the pitch lengths of the grooves that are intermittently arranged in one land portion row. The present invention relates to a tire having a tread pattern.

  Conventionally, various tread patterns have been proposed in order to reduce tire noise (pattern noise). For example, n types (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N) as the period (hereinafter referred to as pitch length) of grooves arranged intermittently in one land portion row. ) Has been proposed (for example, Patent Document 1).

  Specifically, among the pitch lengths Pi, the maximum pitch length Pn and the minimum pitch length P1 satisfy the relationship of 1.3 ≦ Pn / P1 ≦ 1.6, and the number Ni of pitches having each pitch length Pi. (I = 1,... N) satisfies the relationship 0.6 ≦ Ni / (Nt / n). Nt is the total number of pitches. When combinations of different pitch lengths adjacent to each other in the tire circumferential direction are represented by PiPj (i, j = 1,... N), and the number of PiPj is represented by Kij, (Kij + Kji) / The relationship of Nt ≦ 0.17 and the relationship of (Kij + Kji) / (Ni + Nj) ≦ 0.4 are satisfied.

  When the number of the minimum pitch length P1 is represented by N1, the combination of the minimum pitch lengths P1 adjacent in the tire circumferential direction is represented by P1P1, and the number of P1P1 is represented by K11, 0.1 ≦ The relationship of (K11 / Nt) ≦ 0.3 and the relationship of 0.35 ≦ (K11 / N1) ≦ 0.65 are satisfied.

Japanese Patent Laid-Open No. 10-1000061

  However, in the tire described above, it is possible to reduce tire noise (pattern noise). However, when a plurality of land portion rows are arranged in the tire width direction, each land portion row is not worn uniformly. In the subsequent tread pattern, a desired result cannot be obtained as an effect of reducing tire noise (pattern noise).

  Accordingly, the present invention has been made to solve the above-described problems, and a tire that can obtain a desired result as a reduction effect of tire noise (pattern noise) even in a tread pattern after wear. The purpose is to provide.

  The first feature is a tire arranged such that a plurality of land portion rows extending in the tire circumferential direction are arranged in the tire width direction, and the plurality of land portion rows are mounted on the vehicle. An inner shoulder land portion row located inside the vehicle in a state, an outer shoulder land portion row located outside the vehicle with the tire mounted on the vehicle, the inner shoulder land portion row and the outer shoulder land portion row A center land portion row provided between each of the plurality of land portion rows, wherein the number of pitches of the intermittently disposed grooves is 30 or more and 120 or less, and the outer shoulder land portion row The pitch number of the inner shoulder land portion row is less than the pitch number of the inner shoulder land portion row, the pitch number of the inner shoulder land portion row is less than the pitch number of the center land portion row, and the outer shoulder The ratio of the number of land portion rows to the number of inner shoulder land portion row pitches is greater than 1.0 and less than or equal to 5.0, and each of the plurality of land portion rows has a pitch length of the groove. N (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N), and among the pitch lengths Pi, the maximum pitch length Pn and the minimum pitch length P1 are 1.2 ≦ Pn / P1 ≦ 1.6, and the number of pitches Ni (i = 1,..., N) having the pitch length Pi is determined for each of the plurality of land portion rows. When the total number of pitches of the grooves to be provided is Nt, the relationship of 0.15 ≦ Ni / (Nt / n) is satisfied, and combinations of different pitch lengths adjacent to each other in the tire circumferential direction are PiPj (i , J = 1,... N), and the number of PiPj is Ki The relationship of (Kij + Kji) /Nt≦0.2 and the relationship of (Kij + Kji) / (Ni + Nj) ≦ 0.5 are satisfied, and the number of the minimum pitch lengths P1 is represented by N1. When the combination of the minimum pitch lengths P1 adjacent in the tire circumferential direction is represented by P1P1, and the number of P1P1 is represented by K11, a relationship of 0 ≦ (K11 / Nt) ≦ 0.3 And 0 ≦ (K11 / N1) ≦ 0.65 is satisfied.

  1st characteristic WHEREIN: The ratio of the pitch number of the said outer side shoulder land part row | line | column and the pitch number of the said inner side shoulder land part row | line is larger than 1.0 and is 2.0 or less.

  1st characteristic WHEREIN: The ratio of the pitch number of the said outer side shoulder land part row | line | column and the pitch number of the said inner side shoulder land part row | line is 1.2-1.8.

  1st characteristic WHEREIN: The groove | channel provided in the said inner side shoulder land part row | line | column and the groove | channel provided in the said outer side shoulder land part row | line | column have the inclination of 0 degree or more and 30 degrees or less with respect to the said tire width direction, The angle difference between the groove provided in the inner shoulder land portion row and the groove provided in the outer shoulder land portion row is not less than 0 ° and not more than 5 °.

  ADVANTAGE OF THE INVENTION According to this invention, the tire which makes it possible to obtain a desired result as a tire noise (pattern noise) reduction effect also in the tread pattern after abrasion can be provided.

FIG. 1 is a view showing a tire 100 according to the first embodiment. FIG. 2 is a diagram for explaining the embodiment. FIG. 3 is a diagram for explaining the embodiment.

  Hereinafter, a tire according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Summary of Embodiment]
In the tire according to the embodiment, the plurality of land portion rows extending along the tire circumferential direction are arranged in the tire width direction. The plurality of land portion rows include an inner shoulder land portion row positioned on the inner side of the vehicle with the tire mounted on the vehicle, and an outer shoulder land portion row positioned on the outer side of the vehicle with the tire mounted on the vehicle. And a center land portion row provided between the inner shoulder land portion row and the outer shoulder land portion row. In each of the plurality of land portion rows, the pitch number of grooves arranged intermittently is 30 or more and 120 or less. The number of pitches of the outer shoulder land portion row is smaller than the number of pitches of the inner shoulder land portion row. The number of pitches of the inner shoulder land row is less than the number of pitches of the center land portion row. The ratio between the number of pitches of the outer shoulder land portion row and the number of pitches of the inner shoulder land portion row is greater than 1.0 and less than or equal to 5.0. Each of the plurality of land portion rows has n (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N) as the pitch lengths of the grooves. Among the pitch lengths Pi, the maximum pitch length Pn and the minimum pitch length P1 satisfy the relationship 1.2 ≦ Pn / P1 ≦ 1.6. The number of pitches Ni (i = 1,... N) having the pitch length Pi is 0.15 ≦ Ni / when the total number of pitches of grooves provided in each of the plurality of land portion rows is Nt. The relationship (Nt / n) is satisfied. When combinations of different pitch lengths adjacent to each other in the tire circumferential direction are represented by PiPj (i, j = 1,... N), and the number of PiPj is represented by Kij, (Kij + Kji) A relationship of /Nt≦0.2 and a relationship of (Kij + Kji) / (Ni + Nj) ≦ 0.5 are satisfied. The number of the minimum pitch length P1 is represented by N1, the combination of the minimum pitch lengths P1 adjacent in the tire circumferential direction is represented by P1P1, and the number of P1P1 is represented by K11. The relationship of ≦ (K11 / Nt) ≦ 0.3 and the relationship of 0 ≦ (K11 / N1) ≦ 0.65 are satisfied.

  First, in the embodiment, each of the plurality of land portion rows has n (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N) as the pitch lengths of the grooves. . As a result, noise of a specific frequency generated from a specific pitch is not generated, and a peak of a large sound pressure level is dispersed into sidebands of a small sound pressure level, so that an effect of reducing pattern noise can be obtained.

  Second, in the embodiment, the relationship of 0.15 ≦ Ni / (Nt / n) is satisfied. As a result, the pitch is not biased to a specific pitch, the uniformity is improved, and abnormal wear hardly occurs.

  Third, in the embodiment, the maximum pitch length Pn and the minimum pitch length P1 satisfy the relationship of 1.2 ≦ Pn / P1 ≦ 1.6. That is, when the relationship of 1.2 ≦ Pn / P1 is satisfied, the effect of reducing pattern noise produced by the pitch variation can be sufficiently obtained. By satisfying the relationship of Pn / P1 ≦ 1.6, poor appearance and abnormal wear can be suppressed.

  Fourth, in the embodiment, the pitch number of the outer shoulder land portion row is smaller than the pitch number of the inner shoulder land portion row, and the pitch number of the inner shoulder land portion row is smaller than the pitch number of the center land portion row. . Thus, since the number of pitches of the center land portion row is larger than the number of pitches of the outer shoulder land portion row and the inner shoulder land portion row, the wet performance (Wetμ level) can be improved. On the other hand, since the number of pitches of the outer shoulder land row and the number of pitches of the inner shoulder land row are less than the pitch number of the center land portion row, uneven wear is suppressed and pattern noise can be reduced even after wear. continue.

  Fifth, in each of the plurality of land portion rows, the number of pitches of the outer shoulder land portion row is smaller than the number of pitches of the inner shoulder land portion row on the assumption that the number of pitches is 30 or more and 120 or less. . As a result, the steering stability can be appropriately controlled, and the steering stability can be improved.

  Note that the relationship (Kij + Kji) /Nt≦0.2 and the relationship (Kij + Kji) / (Ni + Nj) ≦ 0.5 are satisfied, and the relationship 0 ≦ (K11 / Nt) ≦ 0.3 and 0 ≦ ( It should be noted that the effect of reducing the pattern noise produced by the pitch variation is obtained by satisfying the relationship of K11 / N1) ≦ 0.65.

[First embodiment]
(tire)
Hereinafter, the tire according to the first embodiment will be described. FIG. 1 is a view showing a tire 100 according to the first embodiment. Specifically, FIG. 1 is a diagram showing a tread plan view of the tire 100, and shows a tread pattern of the tire 100.

  Hereinafter, the tire rotation direction is referred to as a tire circumferential direction TC, and the tread width direction is referred to as a tire width direction TW.

  As shown in FIG. 1, in the tire 100, a plurality of land portion rows extending along the tire circumferential direction TC are arranged in the tire width direction TW. The plurality of land portion rows include an inner shoulder land portion row 10Sin positioned on the inner side of the vehicle with the tire 100 mounted on the vehicle, and an outer shoulder land portion row 10Sout positioned on the outer side of the vehicle with the tire mounted on the vehicle. And a center land portion row 10C provided between the inner shoulder land portion row 10Sin and the outer shoulder land portion row 10Sout.

  Further, the tire 100 includes a plurality of circumferential grooves 20 (circumferential grooves 20A and 20B) extending along the tire circumferential direction TC and a plurality of widthwise grooves 30 (width direction) extending along the tire width direction TW. A groove 30IN, a width direction groove 30OUT, and a width direction groove 30C).

  Here, FIG. 1 shows a portion (tread) including a portion in contact with the road surface in a state where the load of the tire 100 is the maximum load load condition and the internal pressure of the tire 100 is the normal internal pressure. The pair of tread ground contact ends are both ends of a portion in contact with the road surface in the tire width direction TW in a state where the load of the tire 100 is a maximum load condition and the internal pressure of the tire 100 is a normal internal pressure. The maximum load load condition and the normal internal pressure are as defined in JATMA.

  The center land portion row 10C is partitioned by the circumferential groove 20A and the circumferential groove 20B. The center land portion row 10C includes a plurality of width direction grooves 30C that are intermittently arranged in the tire circumferential direction TC. The land portion provided in the center land portion row 10C includes the circumferential groove 20A and the circumferential groove. 20B and the width direction groove | channel 30C are divided.

  Here, the width direction groove 30C communicates with both the circumferential groove 20A and the circumferential groove 20B, but the embodiment is not limited to this. The width direction groove 30C may communicate with either the circumferential groove 20A or the circumferential groove 20B. Moreover, the land part provided in the center land part row | line | column 10C may have a sipe. The sipe may be a three-dimensional sipe.

  The outer shoulder land portion row 10Sout is defined by the circumferential groove 20A and the tread ground contact end. The outer shoulder land portion row 10Sout has a width direction groove 30OUT that is intermittently arranged in the tire circumferential direction TC. The land portion provided in the outer shoulder land portion row 10Sout includes the circumferential groove 20A and the width direction groove. It is partitioned by 30OUT.

  Here, the width direction groove 30OUT communicates (opens) with the tread grounding end and terminates in the land portion without communicating with the circumferential groove 20A, but the embodiment is not limited to this. The width direction groove 30OUT communicates (opens) with the tread grounding end, and may communicate with the circumferential direction groove 20A. The width direction groove 30OUT may be a bent groove having a bent portion. Moreover, the land part provided in the outer side shoulder land part row | line | column 10Sout may have a sipe. The sipe may be a three-dimensional sipe.

  The inner shoulder land portion row 10Sin is partitioned by the circumferential groove 20B and the tread ground contact end. The inner shoulder land portion row 10Sin has a width direction groove 30IN that is intermittently arranged in the tire circumferential direction TC, and the land portion provided in the inner shoulder land portion row 10Sin includes a circumferential groove 20B and a width direction groove. It is partitioned by 30IN.

  Here, the width direction groove 30IN communicates (opens) with the tread grounding end and terminates in the land portion without communicating with the circumferential groove 20B, but the embodiment is not limited thereto. The width direction groove 30IN communicates (opens) with the tread grounding end, and may communicate with the circumferential groove 20B. The width direction groove 30IN may be a bent groove having a bent portion. Moreover, the land part provided in the inner side shoulder land part row | line | column 10Sin may have a sipe. The sipe may be a three-dimensional sipe.

  Hereinafter, among the plurality of width direction grooves 30C provided in the center land portion row 10C, the interval between the width direction grooves 30C adjacent to each other in the tire circumferential direction TC is referred to as a pitch PC. Among the plurality of width direction grooves 30OUT provided in the outer shoulder land portion row 10Sout, an interval between the width direction grooves 30OUT adjacent to each other in the tire circumferential direction TC is referred to as a pitch POUT. Among the plurality of width direction grooves 30IN provided in the inner shoulder land portion row 10Sin, an interval between the width direction grooves 30IN adjacent to each other in the tire circumferential direction TC is referred to as a pitch PIN.

  In the first embodiment, the number of pitch PCs is 30 or more and 120 or less, the number of pitches POUT is 30 or more and 120 or less, and the number of pitch PINs is 30 or more and 120 or less. . The number of pitches POUT of the outer shoulder land portion row 10Sout is smaller than the number of pitches PIN of the inner shoulder land portion row 10Sin. The number of pitch PINs of the inner shoulder land row 10Sin is smaller than the number of pitch PCs of the center land portion row 10C. That is, the relationship of the number of pitches POUT <the number of pitches PIN <the number of pitches PC is satisfied.

  In the first embodiment, the center land portion row 10C has n types (n is an integer of 3 or more) of pitch lengths Pi (i = 1,... N) as pitch lengths of the pitch PC. Similarly, the outer shoulder land portion row 10Sout has n types (n is an integer of 3 or more) of pitch lengths Pi (i = 1,... N) as pitch lengths of the pitch POUT. The shoulder land portion row 10Sin has n (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N) as pitch lengths of the pitch PIN. Under such a premise, each of the pitch PC, the pitch POUT, and the pitch PIN has the following relationship.

  First, among the pitch lengths Pi, the maximum pitch length Pn and the minimum pitch length P1 satisfy the relationship 1.2 ≦ Pn / P1 ≦ 1.6. By satisfying the relationship of 1.2 ≦ Pn / P1, the effect of reducing the pattern noise produced by the pitch variation can be sufficiently obtained. By satisfying the relationship of Pn / P1 ≦ 1.6, poor appearance and abnormal wear can be suppressed.

  Second, the number Ni (i = 1,... N) of pitches having a pitch length Pi is 0.15 ≦ when the total number of pitches of grooves provided in each of the plurality of land portion rows is Nt. The relationship of Ni / (Nt / n) is satisfied. As a result, the pitch is not biased to a specific pitch, the uniformity is improved, and abnormal wear hardly occurs.

  Third, a combination of different pitch lengths adjacent to each other in the tire circumferential direction is represented by PiPj (i, j = 1,... N), and the number of PiPj is represented by Kij. The relationship of (Kij + Kji) /Nt≦0.2 and the relationship of (Kij + Kji) / (Ni + Nj) ≦ 0.5 are satisfied. Thereby, the effect of reducing the pattern noise produced by the pitch variation can be obtained.

  Fourth, when the number of the minimum pitch length P1 is represented by N1, the combination of the minimum pitch lengths P1 adjacent in the tire circumferential direction is represented by P1P1, and the number of P1P1 is represented by K11. The relationship of 0 ≦ (K11 / Nt) ≦ 0.3 and the relationship of 0 ≦ (K11 / N1) ≦ 0.65 are satisfied. Thereby, the effect of reducing the pattern noise produced by the pitch variation can be obtained.

  In the first embodiment, the ratio between the number of pitches POUT of the outer shoulder land portion row 10Sout and the number of pitch PINs of the inner shoulder land portion row 10Sin is greater than 1.0 and less than or equal to 5.0. When the ratio between the number of pitches POUT and the number of pitches PIN is larger than 1.0, steering stability is appropriately controlled, and steering stability is improved. On the other hand, when the ratio between the number of pitches POUT and the number of pitches PIN is 5.0 or less, unevenness of block rigidity and the like are suppressed, and uniformity is improved.

  The ratio between the number of pitches POUT and the number of pitches PIN is preferably larger than 1.0 and not larger than 2.0. When the ratio between the number of pitches POUT and the number of pitch PINs is 2.0 or less, the uniformity is further improved.

  The ratio of the number of pitches POUT to the number of pitches PIN is preferably 1.2 or more and 1.8 or less. When the ratio between the number of pitches POUT and the number of pitches PIN is 1.2 or more, steering stability is appropriately controlled, and steering stability is improved. On the other hand, when the ratio between the number of pitches POUT and the number of pitches PIN is 1.8 or less, the uniformity is further improved.

In the first embodiment, the width direction groove 30OUT provided in the outer shoulder land portion row 10Sout has an inclination α with respect to the tire width direction TW. The inclination α of the width direction groove 30OUT is an angle formed by the center line of the width direction groove 30OUT and a straight line along the tire width direction TW. When the width direction groove 30OUT is a bent groove having a bent portion, the inclination α of the width direction groove 30OUT may be an average value of two inclined grooves constituting the width direction groove 30OUT. Alternatively, the inclination α of the width direction groove 30OUT may be an inclination of an inclination groove disposed on the tread grounding end side among two inclination grooves constituting the width direction groove 30OUT.
The width direction groove 30IN provided in the inner shoulder land portion row 10Sin has an inclination β with respect to the tire width direction TW. The inclination β of the width direction groove 30IN is an angle formed by the center line of the width direction groove 30IN and a straight line along the tire width direction TW. When the width direction groove 30IN is a bent groove having a bent portion, the inclination β of the width direction groove 30IN may be an average value of two inclined grooves constituting the width direction groove 30IN. Alternatively, the inclination β of the width direction groove 30IN may be an inclination of an inclination groove disposed on the tread grounding end side among two inclination grooves constituting the width direction groove 30IN.

  Here, the inclination α of the width direction groove 30OUT and the inclination β of the width direction groove 30IN are not less than 0 ° and not more than 30 °. The angle difference between the inclination α of the width direction groove 30OUT and the inclination β of the width direction groove 30IN is 0 ° or more and 5 ° or less. By satisfying such a relationship, the pattern noise frequency is less likely to deviate from the initial assumption even after wear.

(Function and effect)
First, in the first embodiment, each of the plurality of land portion rows has n types (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N) as the pitch lengths of the grooves. Have As a result, noise of a specific frequency generated from a specific pitch is not generated, and a peak of a large sound pressure level is dispersed into sidebands of a small sound pressure level, so that an effect of reducing pattern noise can be obtained.

  Second, in the first embodiment, the relationship of 0.15 ≦ Ni / (Nt / n) is satisfied. As a result, the pitch is not biased to a specific pitch, the uniformity is improved, and abnormal wear hardly occurs.

  Third, in the first embodiment, the maximum pitch length Pn and the minimum pitch length P1 satisfy the relationship of 1.2 ≦ Pn / P1 ≦ 1.6. That is, when the relationship of 1.2 ≦ Pn / P1 is satisfied, the effect of reducing pattern noise produced by the pitch variation can be sufficiently obtained. By satisfying the relationship of Pn / P1 ≦ 1.6, poor appearance and abnormal wear can be suppressed.

  Fourth, in the first embodiment, the number of pitches POUT of the outer shoulder land portion row 10Sout is smaller than the number of pitch PINs of the inner shoulder land portion row 10Sin, and the pitch PIN of the inner shoulder land portion row 10Sin is the center. The number is smaller than the number of pitch PCs in the land portion row 10C. As described above, since the number of pitch PCs is larger than the number of pitches POUT and the number of pitch PINs, wet performance (Wetμ level) can be improved. On the other hand, since the number of pitches POUT and the number of pitches PIN are smaller than the number of pitches PC, uneven wear is suppressed, and the effect of reducing pattern noise continues even after wear.

  Fifth, the number of pitches POUT is smaller than the number of pitches PIN on the premise that the number of pitches is 30 or more and 120 or less in each of the plurality of land portion rows. As a result, the steering stability can be appropriately controlled, and the steering stability can be improved. Specifically, when the ratio between the number of pitches POUT and the number of pitches PIN is larger than 1.0, steering stability is appropriately controlled, and steering stability is improved. On the other hand, when the ratio between the number of pitches POUT and the number of pitches PIN is 5.0 or less, unevenness of block rigidity and the like are suppressed, and uniformity is improved.

[Evaluation result 1]
Hereinafter, the evaluation result 1 will be described. Specifically, the conventional example, the example 1-1, and the example 1-2 were prepared as samples having different types of pitches and different numbers of pitches. These samples were used to evaluate the main groove drainage rate, passing noise, uneven wear level, and WETμ (Wet Grip Index).

  The number of types of pitches and the number of pitches of each sample are as shown in FIG. Specifically, in the conventional example, the number of types of pitches is 4, and the number of pitches in the center land portion row and the number of pitches in the shoulder land portion row are the same. In Example 1-1, the number of types of pitches is 7, and the number of pitches of the shoulder land portion row is smaller than the pitch number of the center land portion row (the number of pitches of the shoulder land portion row / the pitch of the center land portion row). Number ≈ 0.42). In Example 1-2, the number of types of pitch is 7, and the number of pitches of the shoulder land portion row is smaller than the number of pitches of the center land portion row (pitch number of the shoulder land portion row / pitch of the center land portion row). Number ≈ 0.93). In each sample, one sipe is provided in the land portion provided in the center land portion row. In Example 1-1, the sipe is a three-dimensional sipe (3D sipe).

  About such a sample, the result of having attached to the 4WD passenger car on the following conditions and evaluating each performance is as showing in FIG.

・ Rim size: 7J × 16
・ Internal pressure: 2.2kgf / cm2
・ Number of passengers: 2 ・ Running road surface: smooth road ・ Vehicle speed: 55 km / h
The main groove drainage rate, passing noise, uneven wear level, and WETμ are expressed by indices. Regarding the main groove drainage rate and WETμ, the index means that the larger the value of the index, the better results were obtained. For passing noise and uneven wear level, the index means that the smaller the value of the index, the better results were obtained.

  As shown in FIG. 2, in any performance of the main groove drainage rate, passing noise, uneven wear level and WETμ, the number of pitches of the shoulder land portion row is smaller than the pitch number of the center land portion row. It was confirmed that 1-1 and Example 1-2 were superior to the conventional example.

[Evaluation result 2]
Hereinafter, the evaluation result 2 will be described. Specifically, the conventional example, Example 2-1, and Example 2-2 were prepared as samples having different types of pitches and different numbers of pitches. Using these samples, passing noise, uneven wear level, uniformity higher-order component level, and steering stability level were evaluated.

  The number of types of pitches and the number of pitches of each sample are as shown in FIG. Specifically, in the conventional example, the number of types of pitches is 4, and the number of pitches in the inner shoulder land portion row and the number of pitches in the outer shoulder land portion row are the same. In Example 2-1, the number of types of pitch is 7, and the number of pitches of the outer shoulder land portion row is smaller than the pitch number of the inner shoulder land portion row (the number of pitches of the outer shoulder land portion row / inner shoulder land). The number of sub-sequence pitches ≈ 0.76). In other words, the ratio of the pitch number of the outer shoulder land portion row to the pitch number of the inner shoulder land portion row (the pitch number of the inner shoulder land portion row / the pitch number of the outer shoulder land portion row) is 1.32. In Example 2-2, the number of types of pitches is 7, and the number of pitches of the outer shoulder land portion row is smaller than the pitch number of the inner shoulder land portion row (the number of pitches of the outer shoulder land portion row / the inner shoulder land). The number of sub-sequence pitches = 0.875). In other words, the ratio of the number of outer shoulder land rows to the number of inner shoulder land rows (the number of inner shoulder land rows / the number of outer shoulder land rows) is about 1.14. .

  About such a sample, the result of having attached to a 4WD passenger car on the following conditions and evaluating each performance is as showing in FIG.

・ Rim size: 7J × 16
・ Internal pressure: 2.2kgf / cm2
・ Number of passengers: 2 ・ Running road: Asphalted road ・ Vehicle speed: 55km / h
Passing noise, uneven wear level, uniformity higher-order component level, and steering stability level are expressed by indices. Regarding the steering stability level, the index means that the larger the value of the index, the better the results obtained. In the case of passing noise, uneven wear level, and uniformity higher-order component level, the index means that the smaller the value of the index, the better results were obtained.

  As shown in FIG. 3, the pitch number of the outer shoulder land portion row is larger than the pitch number of the inner shoulder land portion row in any performance of passing noise, uneven wear level, uniformity higher-order component level, and steering stability level. It was confirmed that Example 2-1 and Example 2-2 were superior to the conventional example.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment, the tire 100 has one center land portion row 10C, but the embodiment is not limited thereto. The tire 100 may have two or more center land portion rows 10C.

  10C: Center land portion row, 10Sin ... Inner shoulder land portion row, 10Sout ... Outer shoulder land portion row, 20 ... Circumferential groove, 30 ... Width direction groove, 100 ... Tire

Claims (4)

A plurality of land portion rows extending in the tire circumferential direction are arranged so as to be aligned in the tire width direction,
The plurality of land portion rows include an inner shoulder land portion row positioned on the inner side of the vehicle with the tire mounted on the vehicle, and an outer shoulder land portion row positioned on the outer side of the vehicle with the tire mounted on the vehicle. And a center land portion row provided between the inner shoulder land portion row and the outer shoulder land portion row,
In each of the plurality of land portion rows, the pitch number of the grooves arranged intermittently is 30 or more and 120 or less,
The pitch number of the outer shoulder land portion row is less than the pitch number of the inner shoulder land portion row,
The pitch number of the inner shoulder land portion row is less than the pitch number of the center land portion row,
The ratio between the number of pitches of the outer shoulder land portion row and the number of pitches of the inner shoulder land portion row is greater than 1.0 and less than or equal to 5.0,
Each of the plurality of land portion rows has n (n is an integer of 3 or more) pitch lengths Pi (i = 1,... N) as the pitch lengths of the grooves.
Among the pitch lengths Pi, the maximum pitch length Pn and the minimum pitch length P1 satisfy the relationship 1.2 ≦ Pn / P1 ≦ 1.6,
The number of pitches Ni (i = 1,... N) having the pitch length Pi is 0.15 ≦ Ni / when the total number of pitches of grooves provided in each of the plurality of land portion rows is Nt. (Nt / n) is satisfied,
When combinations of different pitch lengths adjacent to each other in the tire circumferential direction are represented by PiPj (i, j = 1,... N), and the number of PiPj is represented by Kij, (Kij + Kji) /Nt≦0.2 and (Kij + Kji) / (Ni + Nj) ≦ 0.5 are satisfied,
The number of the minimum pitch length P1 is represented by N1, the combination of the minimum pitch lengths P1 adjacent in the tire circumferential direction is represented by P1P1, and the number of P1P1 is represented by K11. A tire characterized by satisfying a relationship of ≦ (K11 / Nt) ≦ 0.3 and a relationship of 0 ≦ (K11 / N1) ≦ 0.65.   2. The tire according to claim 1, wherein a ratio between a pitch number of the outer shoulder land portion row and a pitch number of the inner shoulder land portion row is greater than 1.0 and less than or equal to 2.0.   The tire according to claim 2, wherein the ratio of the number of pitches of the outer shoulder land portion row to the number of pitches of the inner shoulder land portion row is 1.2 or more and 1.8 or less. The groove provided in the inner shoulder land portion row and the groove provided in the outer shoulder land portion row have an inclination of 0 ° or more and 30 ° or less with respect to the tire width direction,
The tire according to claim 1, wherein an angle difference between a groove provided in the inner shoulder land portion row and a groove provided in the outer shoulder land portion row is 0 ° or more and 5 ° or less.

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