Pneumatic tire

Abstract

To provide a pneumatic tire improving on-ice performance while maintaining noise performance.SOLUTION: A pneumatic tire according to the present invention includes a tread part 2, a pair of side wall parts 3, a pair of bead parts 4, a carcass 6, and an inner rubber 10. The inner rubber 10 includes a first portion 11 extending with a first thickness t1 and a second portion 12 extending with a second thickness t2. The first thickness t1 is larger than the second thickness t2. A row of unit patterns 15 which appear repeatedly in a tire circumferential direction is formed on a ground contact surface 2s of the tread part 2. Pitch number P1 that is the number of the unit patterns 15 repeatedly appearing is 78-100.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire. [Background technology]

[0002] Patent Document 1 below proposes a pneumatic tire for passenger cars intended for use in winter. This tire is expected to improve braking performance and cornering performance on ice by defining sipes on the shoulder blocks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-195051 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, studless and all-season tires have been required to further improve their driving and braking performance on slippery ice. One attempt to improve tire performance on ice is to increase the number of repetitions (pitch count) of the unit pattern arranged on the contact surface of the tread in the circumferential direction of the tire.

[0005] Generally, unit patterns in the tread tend to generate vibrations of a specific frequency each time they come into contact with the road surface. Therefore, tires with an increased number of unit pattern pitches have been known to produce louder pitch noise, which in turn can impair noise performance.

[0006] The present invention has been devised in view of the above circumstances, and has as its main object to provide a pneumatic tire that has improved performance on ice while maintaining noise performance. [Means for solving the problem]

[0007] The present invention is a pneumatic tire including a tread portion, a pair of sidewall portions, a pair of bead portions, a carcass extending between the pair of bead portions, and an inner rubber extending inside the carcass between the pair of bead portions, the inner rubber including a first portion extending through the tread portion at a first thickness and a second portion extending through the pair of sidewall portions at a second thickness, the first thickness being greater than the second thickness, a row of unit patterns formed on the contact surface of the tread portion that appear repeatedly in the circumferential direction of the tire, and the number of pitches, which is the number of repetitions of the unit patterns, being 78 to 100. [Effects of the Invention]

[0008] By adopting the above-described configuration, the pneumatic tire of the present invention can improve performance on ice while maintaining noise performance. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a tire according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the tread portion of FIG. 1. [Figure 3] FIG. 2 is a development view of the contact surface of the tread portion of FIG. 1. [Figure 4] 3 is an enlarged cross-sectional view of a first end of the first portion of FIG. 2. FIG. [Figure 5] FIG. 10 is an enlarged cross-sectional view of a first portion and a second portion of another embodiment of the present invention. [Figure 6] FIG. 10 is an enlarged cross-sectional view of a first portion and a second portion of yet another embodiment of the present invention. [Figure 7] FIG. 10 is an enlarged cross-sectional view of a sidewall portion according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a pneumatic tire 1 (hereinafter, sometimes simply referred to as "tire 1") illustrating one embodiment of the present invention. FIG. 1 is a cross-sectional view of tire 1 in a normal state, including the axis of rotation. As shown in FIG. 1, tire 1 of this embodiment is, for example, a pneumatic tire for passenger cars, and is suitably used as an all-season tire or a studless tire. However, the present invention is not limited to this embodiment, and may be applied to, for example, a pneumatic tire for heavy loads.

[0011] "Normal condition" means, in the case of a pneumatic tire for which various standards are established, a state in which the tire is mounted on a normal rim, inflated to the normal internal pressure, and no load is applied. In the case of a tire for which various standards are not established, the normal condition means a standard use state according to the intended use of the tire, in which the tire is not mounted on a vehicle and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition. Furthermore, for components that cannot be measured in the normal condition (for example, the internal materials of the tire 1), the values ​​are measured by placing the tire 1 in a state as close as possible to the normal condition.

[0012] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

[0013] "Normal internal pressure" is the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0014] The tire 1 includes a tread portion 2, a pair of sidewall portions 3, and a pair of bead portions 4. The sidewall portions 3 are connected to the axially outer side of the tread portion 2 and extend in the radial direction of the tire. The bead portions 4 are connected to the radially inner side of the sidewall portions 3. The tire 1 also includes a carcass 6 and an inner rubber 10. The carcass 6 extends between the pair of bead portions 4. In other words, the carcass 6 extends from one bead portion 4, through one sidewall portion 3, the tread portion 2, and the other sidewall portion 3, to the other bead portion 4. The inner rubber 10 is disposed inside the carcass 6 and extends between the pair of bead portions 4. As a result, the inner rubber 10 forms the tire cavity surface 1A. The inner rubber 10 is made of vulcanized rubber and is different from a sealant material used to prevent punctures.

[0015] The carcass 6 is composed of, for example, one carcass ply 6A. The carcass ply 6A includes, for example, a main body portion 6a and a turned-up portion 6b. The main body portion 6a extends, for example, between the pair of bead portions 4. The turned-up portion 6b is, for example, continuous with the main body portion 6a and turned up around the bead core 5 from the inside to the outside in the tire axial direction.

[0016] The carcass ply 6A includes a plurality of carcass cords and a topping rubber covering the cords (not shown), and the carcass cords are made of organic fiber cords such as aramid, rayon, etc. The carcass cords are preferably arranged at an angle of 70 to 90 degrees with respect to the tire equator C, for example.

[0017] FIG. 2 shows an enlarged cross-sectional view of the tread portion 2 of FIG. 1. As shown in FIG. 2, the tread portion 2 of this embodiment includes, for example, a belt layer 7 and a band layer 8 disposed radially outward of the carcass 6. However, the tread portion 2 is not limited to this configuration. The belt layer 7 includes a first belt ply 7A adjacent to the carcass 6 and a second belt ply 7B disposed radially outward of the first belt ply 7A. Each of the first belt ply 7A and the second belt ply 7B includes a plurality of belt cords arranged at an angle of 15 to 45 degrees with respect to the tire circumferential direction and a topping rubber covering the belt cords. The belt cords of the first belt ply 7A and the belt cords of the second belt ply 7B are inclined in opposite directions with respect to the tire circumferential direction. This effectively reinforces the tread portion 2.

[0018] The axial length of the second belt ply 7B is preferably shorter than the axial length of the first belt ply 7A, so that a pair of axially outer ends 7b of the second belt ply 7B are located axially more inward than a pair of axially outer ends 7a of the first belt ply 7A.

[0019] The band layer 8 is composed of, for example, one band ply 8A. The band ply 8A includes, for example, a band cord arranged at an angle of 5° or less with respect to the tire circumferential direction, and a topping rubber covering the band cord. The band layer 8 in this embodiment is arranged so as to cover the entire belt layer 7.

[0020] As shown in Fig. 1, the inner rubber 10 includes a first portion 11 and a second portion 12. The first portion 11 extends through the tread portion 2 at a first thickness t1. The second portion 12 extends through the pair of sidewall portions 3 at a second thickness t2. The first thickness t1 and the second thickness t2 refer to the thickness from the inner surface 6i of the carcass 6 to the tire cavity surface 1A, and do not include the topping rubber of the carcass ply.

[0021] In the present invention, the first thickness t1 is greater than the second thickness t2. This configuration means that the average thickness of the first portion 11 is greater than the average thickness of the second portion 12. The average thickness of the first portion 11 corresponds to the value obtained by dividing the cross-sectional area of ​​the first portion 11 in the transverse cross section of the tread portion 2 by the length of the first portion 11 along the tire cavity surface. The same applies to the average thickness of the second portion 12. As a desirable aspect, in this embodiment, the above-mentioned thickness relationship is maintained over the entire circumference of the tire. However, the present invention is not limited to this aspect.

[0022] Fig. 3 shows a developed view of the contact patch 2s of the tread portion 2 of Fig. 1. The contact patch 2s of the tread portion 2 corresponds to the surface between the first tread edge T1 and the second tread edge T2 on the outer surface of the tread portion 2. The first tread edge T1 and the second tread edge T2 each correspond to the axially outermost contact points of the tire when 70% of the normal load is applied to the tire 1 in the normal state and the tread portion 2 contacts the ground flatly with a camber angle of 0°.

[0023] For pneumatic tires for which various standards are established, "normal load" refers to the load specified for each tire in the standard system including the standard on which the tire is based. For JATMA, this is "maximum load capacity," for TRA, this is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, this is "LOAD CAPACITY." For tires for which various standards are not established, "normal load" refers to the maximum load that can be applied when using the tire in accordance with the above standards.

[0024] 3, a row of unit patterns 15 that appear repeatedly in the tire circumferential direction is formed on the contact surface 2s of the tread portion 2 of the present invention. In the present invention, the pitch number P1, which is the number of repetitions of the unit patterns, is set to 78 to 100.

[0025] The tire 1 of the present invention, due to the above-mentioned characteristics, can improve performance on ice while maintaining noise performance for the following reasons.

[0026] In the tire 1 of the present invention, the pitch number P1 of the unit pattern 15 is 78 to 100, which is larger than that of conventional tires. This allows the unit pattern 15 to exert a large frictional force when driving on ice, improving performance on ice. Meanwhile, as shown in Fig. 1, in the tire 1 of the present invention, for the inner rubber 10 of the carcass 6, the first thickness t1 of the first portion 11 extending through the tread portion 2 is larger than the second thickness t2 of the second portion 12 extending through the sidewall portion 3. This allows the first portion 11 of the inner rubber 10 to suppress vibrations when the unit pattern 15 comes into contact with the ground, reducing pitch noise and maintaining noise performance.

[0027] The following describes the configuration of this embodiment in more detail. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the above-described effects even if it does not have the configuration described below. Furthermore, even if any one of the configurations described below is applied alone to a tire of the present invention having the above-described characteristics, performance improvements corresponding to each configuration can be expected. Furthermore, when several of the configurations described below are applied in combination, combined performance improvements corresponding to those configurations can be expected.

[0028] As shown in Fig. 3, the tread portion 2 is divided into, for example, a plurality of circumferential grooves that extend continuously in the tire circumferential direction. The circumferential grooves include a first crown circumferential groove 23, a second crown circumferential groove 24, a first shoulder circumferential groove 21, and a second shoulder circumferential groove 22. The first crown circumferential groove 23 and the second crown circumferential groove 24 are arranged on either side of the tire equator C. The first shoulder circumferential groove 21 is provided between the first tread edge T1 and the first crown circumferential groove 23. The second shoulder circumferential groove 22 is provided between the second tread edge T2 and the second crown circumferential groove 24.

[0029] Each unit pattern 15 includes a lateral groove 25 extending in the tire axial direction and a block 35 adjacent to the lateral groove 25. The lateral grooves 25 include first shoulder lateral grooves 26, second shoulder lateral grooves 27, first middle lateral grooves 28, second middle lateral grooves 29, and crown lateral grooves 30. The first shoulder lateral grooves 26 extend from the first tread edge T1 to the first shoulder circumferential groove 21. The second shoulder lateral grooves 27 extend from the second tread edge T2 to the second shoulder circumferential groove 22. The first middle lateral grooves 28 extend from the first shoulder circumferential groove 21 to the first crown circumferential groove 23. The second middle lateral grooves 29 extend from the second shoulder circumferential groove 22 to the second crown circumferential groove 24. The crown lateral grooves 30 extend from the first crown circumferential groove 23 to the second crown circumferential groove 24.

[0030] The blocks 35 include a first shoulder block 36, a second shoulder block 37, a first middle block 38, a second middle block 39, and a crown block 40. The first shoulder block 36 is adjacent to the first shoulder lateral groove 26. The second shoulder block 37 is adjacent to the second shoulder lateral groove 27. The first middle block 38 is adjacent to the first middle lateral groove 28. The second middle block 39 is adjacent to the second middle lateral groove 29. The crown block 40 is adjacent to the crown lateral groove 30.

[0031] In this embodiment, the unit patterns 15 including these lateral grooves 25 and blocks 35 are arranged at the above-mentioned pitch number P1. In another embodiment, the number of pitches may differ for each block row. That is, the number of pitches of the unit patterns 15 consisting of the first shoulder lateral grooves 26 and the first shoulder blocks 36 may differ from the number of pitches of the unit patterns 15 consisting of the crown lateral grooves 30 and the crown blocks 40. However, even in this case, it is desirable that the number of pitches in each block row be within the above-mentioned range.

[0032] The contact surface of each block 35 is preferably provided with a plurality of axially extending transverse sipes 45. This provides excellent performance on ice. In this specification, the term "sipe" refers to a very small cut with a width of 1.5 mm or less between two opposing sipe walls.

[0033] The number of pitches P1 of the unit pattern 15 is preferably set to 83 to 95. This improves the running performance on dry roads (hereinafter referred to as dry performance) and the performance on ice in a well-balanced manner.

[0034] The land ratio of the tread portion 2 is, for example, 75% or less, preferably 70% or less, and more preferably 65% ​​or less. This improves performance on ice. From the viewpoint of maintaining dry performance, the lower limit of the land ratio is, for example, 50% or more, preferably 55% or more. In this specification, the term "land ratio" refers to the ratio Sb / Sa of the actual total contact area Sb to the total area Sa of the virtual contact area formed by filling all of the grooves and sipes arranged on the contact surface 2s of the tread portion 2.

[0035] For example, the mounting orientation of the tire 1 of this embodiment on a vehicle is specified. As a result, the first tread edge T1 is located on the outer side of the vehicle when mounted on the vehicle. The second tread edge T2 is located on the inner side of the vehicle when mounted on the vehicle. The mounting orientation on the vehicle is indicated, for example, by letters or symbols on the outer surface of the sidewall portion 3 (shown in FIG. 1). However, the tire 1 of the present invention is not limited to this embodiment, and the mounting orientation on the vehicle may not be specified.

[0036] As shown in Fig. 2, the first portion 11 includes a first end portion 13 on the first tread edge T1 side and a second end portion 14 on the second tread edge T2 side. At the first end portion 13, the first thickness t1 continuously decreases toward the outer end 11a of the first portion 11 on the first tread edge T1 side. At the second end portion 14, the first thickness t1 continuously decreases toward the outer end 11b of the first portion 11 on the second tread edge T2 side. In this embodiment, the position where the reduction in the first thickness t1 ends corresponds to the axially outer ends 11a, 11b of the first portion 11.

[0037] From the viewpoint of reliably reducing interior noise, the outer end 11a of the first portion 11 of this embodiment on the first tread end T1 side is, for example, located closer to the first tread end T1 than the first crown circumferential groove 23, and more preferably, located closer to the first tread end T1 than the first shoulder circumferential groove 21.

[0038] FIG. 4 shows an enlarged cross-sectional view of the first end 13 of the first portion 11. As shown in FIG. 4, the outer end 11a of the first portion 11 on the first tread edge T1 side is preferably located axially at the same position as the axially outer end 7b of the second belt ply 7B, or is located axially more inward than the outer end 7b of the second belt ply 7B. In a more preferable embodiment, the axial distance L3 between the outer end 11a of the first portion 11 and the outer end 7b of the second belt ply 7B is set to 5 mm or less. This allows the belt layer 7 to suppress deformation around the outer end 11a of the first portion 11 during tire running while ensuring a sufficient axial length of the first portion 11, and ultimately suppresses separation of the inner rubber 10 around the outer end 11a.

[0039] Furthermore, the first end portion 13 is connected to a portion extending at a constant first thickness t1 on the tire equator C (shown in FIG. 1) side. The axial length L4 of the first end portion 13 is 2.0% to 4.0% of the tread width TW (shown in FIG. 1). This makes it possible to prevent a sudden change in the thickness of the inner rubber 10, and suppress damage such as peeling of the inner rubber 10. The tread width TW corresponds to the axial distance of the tire from the first tread edge T1 to the second tread edge T2 in the normal state.

[0040] As shown in FIG. 2 , the first portion 11 has the same configuration on the second tread edge T2 side as on the first tread edge T1 side. That is, the outer end 11b of the first portion 11 on the second tread edge T2 side is located, for example, closer to the second tread edge T2 than the second crown circumferential groove 24, and more preferably closer to the second tread edge T2 than the second shoulder circumferential groove 22. The outer end 11b of the first portion 11 on the second tread edge T2 side is preferably axially aligned with the axially outer end 7b of the second belt ply 7B, or is preferably axially inward of the outer end 7b of the second belt ply 7B. The axial distance between the outer end 11b of the first portion 11 and the outer end 7b of the second belt ply 7B is 5 mm or less. The second end 14 has the same configuration as the first end 13.

[0041] By arranging the outer ends 11a, 11b of the first portion 11 as described above, the axial length L5 of the first portion 11 of this embodiment is preferably set to 90% to 110% of the tread width TW, thereby making it possible to reliably reduce interior noise while suppressing an increase in tire weight.

[0042] In the first portion 11 of this embodiment, a first length L6 from the tire equator C to the outer end 11a on the first tread edge T1 side and a second length L7 from the tire equator C to the outer end 11b on the second tread edge T2 side are substantially the same. More specifically, the difference between the first length L6 and the second length L7 is 3% or less of the first length L6. This can improve tire uniformity. In another embodiment, for example, the second length L7 may be greater than the first length L6. Specifically, the second length L7 is 105% to 110% of the first length L6. In this embodiment, a sufficient length of the first portion 11 is ensured on the second tread edge T2 side, which is on the vehicle inner side when mounted on a vehicle, thereby further reducing interior noise.

[0043] The first portion 11 extends with a constant first thickness t1 between the first end 13 and the second end 14. As a result, the first thickness t1 is substantially constant at the tire equator C and at a position on the first tread edge T1 side of the first shoulder circumferential groove 21. In a desirable embodiment, the first thickness t1 is substantially constant from the tire equator C to a position beyond the first shoulder circumferential groove 21. Note that the term "substantially constant" means that unavoidable errors in rubber products such as tires can be tolerated, and includes an embodiment in which the difference between the maximum and minimum thickness values ​​is 5% or less of the maximum value.

[0044] The first portion 11 may have a region extending with a constant first thickness t1 that extends to the first tread edge T1 (not shown). In other words, the first thickness t1 may be substantially constant from the position of the tire equator C to the position of the first tread edge T1 (a virtual line that passes through the first tread edge T1 and extends parallel to the tire radial direction). In this case, the outer end 11a of the first portion 11 is located axially outward of the first tread edge T1. This embodiment can further reduce interior noise.

[0045] It is desirable that the first portion 11 has the same configuration as described above between the tire equator C and the second tread edge T2. That is, the first thickness t1 is substantially constant at the position of the tire equator C and at a position on the second tread edge T2 side of the second shoulder circumferential groove 22. In a desirable aspect, the first thickness t1 is substantially constant from the position of the tire equator C to a position beyond the second shoulder circumferential groove 22. In another embodiment, the first portion 11 may have a region extending with a constant first thickness t1 extending to the second tread edge T2.

[0046] The first thickness t1 is preferably 1.5 to 3.5 times, and more preferably 1.5 to 2.5 times, the second thickness t2 (shown in FIG. 1, and the same applies hereinafter). This makes it possible to maintain noise performance while suppressing an increase in the weight of the tire 1.

[0047] From the same viewpoint, the maximum value of the first thickness t1 is preferably 2.0 mm or more, more preferably 2.5 mm or more, and preferably 4.5 mm or less, more preferably 4.0 mm or less, and even more preferably 3.5 mm or less. On the other hand, the second thickness t2 is, for example, greater than 0.5 mm and less than 2.0 mm. In a desirable embodiment, the second thickness t2 is 1.0 to 1.5 mm. Note that the second portion 12 of this embodiment is continuous with the first portion 11 and extends to the bead portion 4 (shown in FIG. 1), and the second thickness t2 is constant throughout the entire portion. However, the second portion 12 is not limited to this embodiment.

[0048] As shown in Figure 2, the first portion 11 and the second portion 12 of the inner rubber 10 are made of an air-impermeable rubber material. For example, a butyl-based or halogenated butyl-based rubber material can be used as the rubber material. In this embodiment, the first portion 11 and the second portion 12 are made of the same rubber material.

[0049] However, the present invention is not limited to this embodiment. Fig. 5 shows an enlarged cross-sectional view of the first portion 11 and the second portion 12 of another embodiment of the present invention. As shown in Fig. 5, the first portion 11 of the inner rubber 10 of this embodiment includes an inner liner layer 16 made of an air-impermeable rubber material (hereinafter referred to as the first rubber material), and an additional layer 17 disposed between the inner liner layer 16 and the carcass 6. This additional layer 17 is made of a second rubber material different from the first rubber material. As the second rubber material, for example, an air-permeable rubber material is adopted. That is, the first portion 11 of this embodiment is formed by combining an air-impermeable rubber material and an air-permeable rubber material.

[0050] In this embodiment, the first portion 11 includes the additional layer 17, thereby improving various performances. For example, a rubber material having a larger loss tangent tanδ than the first rubber material forming the inner liner layer 16 can be used as the second rubber material forming the additional layer 17. In this embodiment, the tread portion 2 can further absorb vibrations from the road surface, thereby further reducing interior noise. The loss tangent tanδ is measured under the following conditions using a viscoelasticity spectrometer in accordance with the provisions of JIS-K6394. Initial distortion: 5% Amplitude: ±1% Frequency: 10Hz Deformation mode: tension Measurement temperature: 70℃

[0051] The position of the additional layer 17 is not limited to the embodiment shown in Fig. 5. Fig. 6 shows an enlarged cross-sectional view of the first portion 11 and the second portion 12 of yet another embodiment of the present invention. As shown in Fig. 6, the additional layer 17 may be disposed radially inward of the inner liner layer 16 in the tire radial direction. The additional layer 17 may also constitute a part of the tire cavity surface 1A.

[0052] As shown in Figures 5 and 6, even in an embodiment in which the additional layer 17 is included in the first portion 11 of the inner rubber 10, the first thickness t1 corresponds to the thickness from the inner surface 6i of the carcass 6 in the tread portion 2 to the tire cavity surface 1A.

[0053] As shown in Figure 2, the tread portion 2 includes a cap rubber layer 2C that forms the contact patch 2s and a base rubber layer 2B disposed radially inward of the cap rubber layer 2C. The ratio Tc / Tb of the thickness Tc of the cap rubber layer to the thickness Tb of the base rubber layer is preferably 0.66 to 2.33. This improves dry performance and ice performance in a well-balanced manner.

[0054] From the same viewpoint, the rubber hardness of the cap rubber layer 2C is preferably 45 to 65. In this specification, the rubber hardness means the durometer A hardness measured in an environment of 23°C using a durometer type A according to JIS-K6253.

[0055] FIG. 7 shows an enlarged cross-sectional view of the sidewall portion 3 of another embodiment of the present invention. As shown in FIG. 7, the second portion 12 of this embodiment includes an inner liner layer 16 made of a first rubber material having air impermeability and an intermediate layer 18 disposed between the inner liner layer 16 and the carcass 6. In FIG. 7, this intermediate layer 18 is dotted. The intermediate layer 18 is made of a rubber material different from the first rubber material. The intermediate layer 18 may be made of, for example, the same second rubber material as the additional layer 17 of the first portion 11 described in FIGS. 5 and 6. By including such an intermediate layer 18 in the second portion 12, transmission of vibrations generated in the tread portion 2 to the vehicle side can be further suppressed. The intermediate layer 18 may also be made of a rubber material different from the first rubber material and the second rubber material.

[0056] The intermediate layer 18 overlaps, for example, the band layer 8 in the tire axial direction. In a preferred embodiment, the intermediate layer 18 overlaps with the belt layer 7 in the tire axial direction. The intermediate layer 18 may be continuous with the first portion 11 of the inner rubber 10. Also, it is preferred that the intermediate layer 18 extends radially inward of the tire radially outer end of the turned-up portion 6b of the carcass 6. Such an intermediate layer 18 helps to further reduce interior noise.

[0057] Although a tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and can be modified and practiced in various aspects. [Example]

[0058] A prototype tire with the basic structure and pattern shown in Figures 1 and 3 was manufactured based on the specifications in Table 1, and its performance on ice and noise performance were tested. The common specifications and test methods are as follows:

[0059] <Common specifications> Tire size: 195 / 65R15 Rim size: 15x6.0JJ Air pressure: 200kPa Test vehicle: Front-wheel drive mid-size passenger car

[0060] <Ice performance> A test vehicle fitted with prototype tires was driven on an icy test course, and the steering stability performance was evaluated by a test driver's sensory evaluation. Similar tests were conducted by multiple test drivers, and the total score was calculated. The results were expressed as an index, with the total score for Comparative Example 1 being 100, and the higher the index value, the better the on-ice performance.

[0061] <Noise performance> A test driver drove the test vehicle on a dry test course, and the noise generated by the tires was evaluated sensorily. The results are expressed as an index, with Comparative Example 1 being set at 100, and the larger the index, the better the noise performance.

[0062] [Table 1]

[0063] As is clear from Table 1, it was confirmed that the tires of the examples had significantly improved noise performance compared to the comparative example.

[0064] [Note] The present invention includes the following aspects.

[0065] [Invention 1] A pneumatic tire, A tread portion; A pair of sidewall portions; a pair of bead portions; a carcass extending between the pair of bead portions; an inner rubber extending between the pair of bead portions on the inner side of the carcass, the inner rubber includes a first portion extending through the tread portion at a first thickness and a second portion extending through the pair of sidewall portions at a second thickness, the first thickness is greater than the second thickness; A row of unit patterns that appears repeatedly in the tire circumferential direction is formed on the contact surface of the tread portion, The pitch number, which is the number of repetitions of the unit pattern, is 78 to 100. Pneumatic tires. [Invention 2] A belt layer is disposed in the tread portion on the outer side of the carcass in the tire radial direction, the belt layer includes a first belt ply and a second belt ply disposed outward of the first belt ply in the tire radial direction, a pair of outer ends of the second belt ply in the tire axial direction are located axially more inward than a pair of outer ends of the first belt ply in the tire axial direction, The pneumatic tire according to Invention 1, wherein, on each side of the tire equator, an axially outer end of the first portion is located at the same position in the tire axial direction as the outer end of the second belt ply, or is located axially inward of the outer end of the second belt ply and within 5 mm in the tire axial direction. [Invention 3] 3. The pneumatic tire according to claim 1 or 2, wherein the thickness of the first portion is 1.5 to 2.5 times the thickness of the second portion. [Invention 4] 4. The pneumatic tire according to any one of claims 1 to 3, wherein the first portion is formed of an air-impermeable rubber material. [Invention 5] the first portion is formed by combining a first rubber material that is air-impermeable and a second rubber material that is air-permeable, 4. The pneumatic tire according to any one of claims 1 to 3, wherein the second rubber material has a loss tangent tan δ greater than that of the first rubber material. [Invention 6] the tread portion includes a cap rubber layer that forms the ground contact surface, 6. The pneumatic tire according to any one of claims 1 to 5, wherein the cap rubber layer has a rubber hardness of 45 to 65. [Invention 7] the tread portion includes a cap rubber layer that forms the ground contact surface, and a base rubber layer that is disposed radially inward of the cap rubber layer, 7. The pneumatic tire according to any one of claims 1 to 6, wherein a ratio Tc / Tb of a thickness Tc of the cap rubber layer to a thickness Tb of the base rubber layer is 0.66 to 2.33. [Invention 8] The pneumatic tire according to any one of claims 1 to 7, wherein the unit pattern includes a lateral groove extending in the tire axial direction and a block adjacent to the lateral groove. [Invention 9] 9. The pneumatic tire according to invention 8, wherein a plurality of lateral sipes extending in the tire axial direction are provided on the contact surface of the block. [Explanation of symbols]

[0066] 2 Tread section 2s ground plane 3 Sidewall 4 Bead section 6. Carcass 10 Inner rubber 11 Part 1 12 Part 2 t1 First thickness t2 Second thickness 15 unit patterns P1 Number of pitches

Claims

1. A pneumatic tire, A tread portion; A pair of sidewall portions; a pair of bead portions; a carcass extending between the pair of bead portions; an inner rubber extending between the pair of bead portions on the inner side of the carcass, the inner rubber includes a first portion extending through the tread portion at a first thickness and a second portion extending through the pair of sidewall portions at a second thickness, the first thickness is greater than the second thickness; A row of unit patterns that appears repeatedly in the tire circumferential direction is formed on the contact surface of the tread portion, The pitch number, which is the number of repetitions of the unit pattern, is 78 to 100. Pneumatic tires.

2. A belt layer is disposed in the tread portion on the outer side of the carcass in the tire radial direction, the belt layer includes a first belt ply and a second belt ply disposed outward of the first belt ply in the tire radial direction, a pair of outer ends of the second belt ply in the tire axial direction are located axially more inward than a pair of outer ends of the first belt ply in the tire axial direction, 2. The pneumatic tire according to claim 1, wherein, on each side of the tire equator, an axially outer end of the first portion is located at the same position as the outer end of the second belt ply in the tire axial direction, or is located axially inward of the outer end of the second belt ply and within 5 mm in the tire axial direction.

3. The pneumatic tire according to claim 1 or 2, wherein the thickness of the first portion is 1.5 to 2.5 times the thickness of the second portion.

4. The pneumatic tire according to claim 1 or 2, wherein the first portion is formed of an air-impermeable rubber material.

5. the first portion is formed by combining a first rubber material that is air-impermeable and a second rubber material that is air-permeable, The pneumatic tire according to claim 1 or 2, wherein the second rubber material has a loss tangent tanδ greater than that of the first rubber material.

6. the tread portion includes a cap rubber layer that forms the ground contact surface, The pneumatic tire according to claim 1 or 2, wherein the cap rubber layer has a rubber hardness of 45 to 65.

7. the tread portion includes a cap rubber layer that forms the ground contact surface, and a base rubber layer that is disposed radially inward of the cap rubber layer, 3. The pneumatic tire according to claim 1, wherein a ratio Tc / Tb of a thickness Tc of the cap rubber layer to a thickness Tb of the base rubber layer is 0.66 to 2.

33.

8. The pneumatic tire according to claim 1 or 2, wherein the unit pattern includes a lateral groove extending in the tire axial direction and a block adjacent to the lateral groove.

9. The pneumatic tire according to claim 8 , wherein a plurality of lateral sipes extending in the tire axial direction are provided on the contact surface of the block.

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