Pneumatic tire

Abstract

A pneumatic tire according to the present invention is such that: a plurality of sipes extending in an inclined manner with respect to the tire width direction are disposed in a land part; when the sipes that are adjacent in the tire circumferential direction are projected in the tire width direction, at least a portion thereof overlap in the tire circumferential direction or there is no interval in the tire circumferential direction; and the number distribution of the sipes is at a maximum for intermediate sipes from among large sipes, the intermediate sipes, and small sipes.

Description

pneumatic tires

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

[0002] It has been proposed to arrange sipes on rib-shaped land portions at intervals in the tire circumferential direction and extending at an angle relative to the tire width direction (see, for example, Patent Document 1). Such a configuration is believed to be able to reduce running noise.

[0003] Special Publication No. 2016-540675

[0004] However, when sipes are arranged with pitch variation as described above, the circumferential lengths of the blocks defined between the sipes in the tire circumferential direction vary greatly across the tire width, which can lead to uneven wear of the blocks and, ultimately, to a deterioration in the uneven wear resistance of the blocks and, ultimately, the tire.

[0005] Therefore, an object of the present invention is to provide a pneumatic tire that can improve noise reduction while suppressing a decrease in uneven wear resistance.

[0006] The gist of the present invention is as follows: (1) A pneumatic tire having, on its tread surface, two or more circumferential grooves extending in the tire circumferential direction, rib-shaped land portions defined between the circumferential grooves, a plurality of sipes extending at an angle with respect to the tire width direction arranged in the land portions, the sipes adjacent in the tire circumferential direction at least partially overlap in the tire circumferential direction when projected in the tire width direction, or there is no gap between them in the tire circumferential direction, the sipes consist of three types: large sipes having a maximum inclination angle with respect to the tire width direction, small sipes having a minimum inclination angle with respect to the tire width direction, and medium sipes having an inclination angle with respect to the tire width direction intermediate between the large sipes and the small sipes, and the sipe number distribution is such that the number of medium sipes is the largest among the large sipes, medium sipes, and small sipes.

[0007] Here, "tread surface" refers to the entire circumferential surface of the tread that comes into contact with the road when the pneumatic tire is mounted on an applicable rim, inflated to the specified internal pressure, and subjected to the maximum load. The "groove" in "circumferential groove" refers to a groove with an opening width of 1 mm or more when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and unloaded (hereinafter referred to as the "standard state"). The term "sipe" refers to a sipe with a width that causes partial closure of the sipe walls when the pneumatic tire is mounted on an applicable rim, inflated to the specified internal pressure, and subjected to the maximum load. The term "no circumferential spacing" also includes cases where the circumferential spacing is 5% or less of the sipe pitch length, taking into account manufacturing tolerances.

[0008] In this specification, the term "applicable rim" refers to the standard rim (referred to as "Measuring Rim" in the ETRTO STANDARDS MANUAL and "Design Rim" in the TRA YEAR BOOK) for the applicable size, which is an industrial standard valid in the region where the tire is produced and used, and which is described in the JATMA YEAR BOOK of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the STANDARDS MANUAL of the European Tire and Rim Technical Organization (ETRTO) in Europe, and the YEAR BOOK of the Tire and Rim Association, Inc. (TRA) in the United States, or which will be described in the future. "rim" refers to the rim (i.e., the above "rim" includes not only current sizes but also sizes that may be included in the above industry standards in the future. An example of a "size to be described in the future" is a size listed under "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO). However, for sizes not listed in the above industry standards, it refers to a rim with a width corresponding to the bead width of the tire. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel for the applicable size / ply rating listed in the above JATMA etc., and for sizes not listed in the above industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Furthermore, "maximum applied load" refers to the load corresponding to the above maximum load capacity.

[0009] According to the present invention, it is possible to provide a pneumatic tire that can improve noise reduction while suppressing a decrease in uneven wear resistance.

[0010] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The internal structure of a pneumatic tire (hereinafter also simply referred to as "tire") can be configured similarly to conventional structures, and therefore a detailed description will be omitted. As an example, the tire may include a pair of bead portions, a pair of sidewall portions connected between the pair of bead portions, and a tread portion connected between the sidewall portions. The tire may further include a carcass toroidally spanning the pair of bead portions, and a belt disposed radially outward of the crown portion of the carcass. Hereinafter, dimensions and the like refer to dimensions and the like in the reference state.

[0012] Fig. 1 is a development view showing a part of the tread surface of a pneumatic tire according to one embodiment of the present invention. As shown in Fig. 1, the tire has two or more (two in the illustrated range) circumferential grooves 2 (2a, 2b) extending in the tire circumferential direction on the tread surface 1.

[0013] In the illustrated example, the circumferential grooves 2 extend without inclination in the tire circumferential direction, but may extend at an inclination angle of 5° or less with respect to the tire circumferential direction. In the illustrated example, the circumferential grooves 2 extend linearly, but may extend in a zigzag or bent shape. The groove width (opening width) of the circumferential grooves 2 is not particularly limited, but may be, for example, 3 to 15 mm. The groove depth (maximum depth) of the circumferential grooves 2 is not particularly limited, but may be, for example, 4 to 10 mm.

[0014] Rib-shaped land portions 3 are defined between the circumferential grooves 2. In other words, the land portions 3 are not completely divided in the tire circumferential direction by the widthwise grooves.

[0015] A plurality of sipes 4, 5, and 6 extending at an angle with respect to the tire width direction are arranged in the land portion 3.

[0016] The sipes 4, 5, and 6 may be flat sipes. The sipes 4, 5, and 6 may extend linearly or zigzag in a plan view. The sipes 4, 5, and 6 may be three-dimensional sipes in which the sipe wall surfaces are uneven along the depth direction. The three-dimensional sipe may be, for example, a sipe that extends while bending in the depth direction, or a sipe that extends while changing in a wavy shape along the depth direction.

[0017] The sipe width (opening width) of the sipes 4, 5, and 6 is not particularly limited, but may be, for example, 0.1 to 2 mm. The groove depth (maximum depth) of the sipes 4, 5, and 6 is not particularly limited, but may be, for example, 0.1 to 10 mm.

[0018] The sipes 4, 5, 6 adjacent to each other in the tire circumferential direction are arranged so that at least a portion of them overlap in the tire circumferential direction when projected in the tire width direction, or so that there is no gap between them in the tire circumferential direction, thereby allowing the sipes 4, 5, 6 to be densely arranged in the tire circumferential direction.

[0019] The sipes 4, 5, and 6 are of three types: large sipes 4, which have the largest inclination angle relative to the tire width direction; small sipes 5, which have the smallest inclination angle relative to the tire width direction; and medium sipes 6, which have an inclination angle relative to the tire width direction intermediate between those of the large sipes 4 and the small sipes 5.

[0020] The inclination angle of the large sipes 4 relative to the tire width direction is not particularly limited as long as it is greater than the inclination angles of the medium sipes 6 and the small sipes 5 relative to the tire width direction, but can be any value in the range of, for example, 12 to 83°.

[0021] The inclination angle of the medium sipes 6 with respect to the tire width direction is in the range of inclination angles intermediate between the inclination angle of the large sipes 4 with respect to the tire width direction and the inclination angle of the small sipes 5 with respect to the tire width direction, and is not particularly limited, but can be any value in the range of, for example, 10 to 81 degrees.

[0022] The inclination angle of the small sipes 5 relative to the tire width direction is smaller than the inclination angles of the large sipes 4 and the medium sipes 6 relative to the tire width direction, and is not particularly limited, but can be any value in the range of, for example, 8 to 79 degrees.

[0023] Here, the distribution of the numbers of the sipes 4, 5, and 6 is such that the number of medium sipes 6 is the largest among the large sipes 4, medium sipes 6, and small sipes 5. In other words, the number of medium sipes 6 is greater than the number of large sipes 4 and the number of small sipes 5 over the entire circumferential area of ​​the tire.

[0024] The number of medium sipes 6 relative to the total number of sipes (the sum of the large sipes 4, medium sipes 6, and small sipes 5) is preferably 33.4% to 60%, and more preferably 37% to 50%.

[0025] In this embodiment, the distribution of the number of arrangements of two circumferentially adjacent sipes over the entire circumferential area of ​​the tire is such that the number of arrangements in which a large sipe 4 and a small sipe 5 are adjacent in the tire circumferential direction is the smallest. In other words, over the entire circumferential area of ​​the tire, among the pairs of two circumferentially adjacent sipes, the number of pairs of large sipes 4 and small sipes 5 is the smallest (this is less than the number of pairs of large sipes 4, the number of pairs of medium sipes 6, the number of small sipes 5, the number of pairs of large sipes 4 and medium sipes 6, and the number of pairs of medium sipes 6 and small sipes 5).

[0026] In this embodiment, the distribution of the number of arrangements of two circumferentially adjacent sipes over the entire circumferential direction of the tire is such that the number of arrangements in which two medium sipes 6 are adjacent to each other in the tire circumferential direction is the largest. In other words, over the entire circumferential direction of the tire, among the pairs of two circumferentially adjacent sipes, the number of pairs of medium sipes 6 is the largest (greater than the number of pairs of large sipes 4, the number of pairs of small sipes 5, the number of pairs of large sipes 4 and medium sipes 6, the number of pairs of large sipes 4 and small sipes 5, and the number of pairs of medium sipes 6 and small sipes 5).

[0027] The effects of the pneumatic tire of this embodiment will be described below.

[0028] In the pneumatic tire of this embodiment, first, a plurality of sipes 4, 5, and 6 extending at an angle relative to the tire width direction are arranged in the land portion 3. Adjacent sipes 4, 5, and 6 in the tire circumferential direction are arranged so that, when projected in the tire width direction, at least a portion of the sipes 4, 5, and 6 overlap in the tire circumferential direction, or there is no circumferential gap between them. This improves tire quietness. Furthermore, in the pneumatic tire of this embodiment, the number of medium sipes 6 is the largest among the large sipes 4, medium sipes 6, and small sipes 5. This reduces tire widthwise variation in the tire circumferential length of the blocks defined between the sipes, thereby suppressing a decrease in the uneven wear resistance of the blocks and, ultimately, the uneven wear resistance of the tire. As described above, the pneumatic tire of this embodiment can improve quietness while suppressing a decrease in uneven wear resistance.

[0029] It is preferable that the distribution of the number of arrangements of two circumferentially adjacent sipes 4, 5, 6 throughout the tire circumferential direction is such that the number of arrangements in which a large sipe 4 and a small sipe 6 are adjacent in the tire circumferential direction is the smallest. This is because it is possible to further reduce variation in the tire circumferential length of the blocks defined between the sipes in the tire width direction, and further suppress deterioration in the uneven wear resistance of the blocks, and ultimately the uneven wear resistance of the tire.

[0030] In the overall tire circumferential area, the distribution of the number of arrangements of two circumferentially adjacent sipes 4, 5, 6 is preferably such that the number of arrangements in which two intermediate sipes 6 are adjacent to each other in the tire circumferential direction is the largest. This is because it is possible to further reduce variation in the tire width direction of the tire circumferential lengths of the blocks defined between the sipes, and further suppress deterioration in the uneven wear resistance of the blocks, and ultimately the uneven wear resistance of the tire.

[0031] The number of intermediate sipes 6 relative to the total number of sipes is preferably 33.4% to 60%. By making it 34% or more, the effect of suppressing a decrease in the uneven wear resistance of the tire can be more reliably exhibited, while by making it 50% or less, the effect of improving noise reduction can be more reliably exhibited. For the same reason, the number of intermediate sipes 6 relative to the total number of sipes is preferably 37% to 50%.

[0032] [Example of Arrangement of Communication Device] Figures 2 and 3 are diagrams showing an example of arrangement of the communication device. A tire may include an RF tag as the communication device 100, 200. The RF tag includes an IC chip and an antenna. The RF tag may be arranged, for example, by being sandwiched between multiple components of the same or different types that constitute the tire. This makes it easy to attach the RF tag during tire production, thereby improving the productivity of tires equipped with RF tags. In this example, the RF tag may be arranged, for example, by being sandwiched between a bead filler and another component adjacent to the bead filler. The RF tag may also be embedded in any of the components that constitute the tire. This reduces the load applied to the RF tag compared to when the RF tag is arranged by being sandwiched between multiple components that constitute the tire. This improves the durability of the RF tag. In this example, the RF tag may be embedded in a rubber component such as tread rubber or side rubber. It is preferable that the RF tag is not arranged at a position that is a boundary between components with different rigidities in the periphery length direction, which is the direction along the outer surface of the tire in a cross-sectional view in the tire width direction. By doing so, the RF tag is not placed in a position where distortion is likely to concentrate due to a difference in rigidity. Therefore, the load applied to the RF tag can be reduced. This can improve the durability of the RF tag. In this example, it is preferable that the RF tag is not placed in a position that is, for example, the boundary between the end of the carcass and a member adjacent to the end of the carcass (for example, a side rubber, etc.) in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. A tire may be equipped with only one RF tag, or may be equipped with two or more RF tags. Here, an RF tag is described as an example of a communication device, but a communication device other than an RF tag may also be used.

[0033] The RF tag may be disposed, for example, in the tread portion of the tire. In this manner, the RF tag will not be damaged by a side cut of the tire. The RF tag may be disposed, for example, in the tread center portion in the tire width direction. The tread center portion is a position in the tread portion where flexure is less likely to concentrate. In this manner, the load applied to the RF tag can be reduced. This improves the durability of the RF tag. Also, it is possible to prevent differences in communication with the RF tag from both outer sides of the tire in the tire width direction. In this example, the RF tag may be disposed, for example, within a range of 1 / 2 of the tread width centered on the tire equatorial plane in the tire width direction. The RF tag may be disposed, for example, at the tread edge in the tire width direction. If the position of a reader that communicates with the RF tag is predetermined, the RF tag may be disposed, for example, at the tread edge on one side closer to the reader. In this example, the RF tag may be disposed, for example, within a range of 1 / 4 of the tread width in the tire width direction, with the tread edge as the outer end.

[0034] The RF tag may be positioned, for example, closer to the tire cavity than a carcass including one or more carcass plies spanning between bead portions. This configuration makes the RF tag less susceptible to damage from impacts applied from outside the tire or damage such as side cuts or nail penetration. As an example, the RF tag may be positioned in close contact with the surface of the carcass facing the tire cavity. As another example, if there is another component closer to the tire cavity than the carcass, the RF tag may be positioned, for example, between the carcass and another component located closer to the tire cavity than the carcass. An example of another component located closer to the tire cavity than the carcass is an inner liner that forms the tire inner surface. As another example, the RF tag may be attached to the tire inner surface facing the tire cavity. Configuring the RF tag to be attached to the tire inner surface makes it easier to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the ease of attaching and maintaining the RF tag can be improved. Furthermore, by attaching the RF tag to the inner surface of the tire, it is possible to prevent the RF tag from becoming a nucleus of tire failure, compared to a configuration in which the RF tag is embedded in the tire. Furthermore, when the carcass has multiple carcass plies and there is a position where multiple carcass plies are overlapped, the RF tag may be disposed between the overlapped carcass plies.

[0035] The RF tag may be arranged, for example, in the tread portion of the tire, radially outward of a belt including one or more belt plies. As one example, the RF tag may be arranged radially outward of the belt in the tire radial direction and in close contact with the belt. As another example, if a reinforcing belt layer is provided, the RF tag may be arranged radially outward of the reinforcing belt layer in close contact with the reinforcing belt layer. As another example, the RF tag may be embedded in the tread rubber radially outward of the belt. By arranging the RF tag radially outward of the belt in the tread portion of the tire, communication with the RF tag from the outside of the tire in the tire radial direction is less likely to be obstructed by the belt. Therefore, communication with the RF tag from the outside of the tire in the tire radial direction can be improved. As another example, the RF tag may be arranged radially inward of the belt in the tread portion of the tire. In this way, the outer side of the RF tag in the tire radial direction is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail penetration. As one example, the RF tag may be disposed in the tread portion of the tire between the belt and the carcass located radially inward of the belt. Furthermore, if the belt has multiple belt plies, the RF tag may be disposed in the tread portion of the tire between any two belt plies. In this manner, the outer side of the RF tag in the tire radial direction is covered by one or more belt plies, making the RF tag less susceptible to damage from impacts from the tread surface, nail penetration, and the like.

[0036] In the case of truck and bus tires, the RF tag may be sandwiched between the cushion rubber and the tread rubber or between the cushion rubber and the side rubber, for example. In this way, the cushion rubber can absorb impacts on the RF tag. This improves the durability of the RF tag. The RF tag may also be embedded in the cushion rubber, for example. Furthermore, the cushion rubber may be made up of multiple adjacent rubber members of the same or different types. In such cases, the RF tag may be sandwiched between the multiple rubber members that make up the cushion rubber.

[0037] The RF tag may be disposed, for example, in a sidewall portion or a bead portion of the tire. The RF tag may be disposed, for example, in one sidewall portion or one bead portion that is closer to a reader capable of communicating with the RF tag. This improves communication between the RF tag and the reader. As an example, the RF tag may be disposed between the carcass and the side rubber or between the tread rubber and the side rubber. The RF tag may be disposed, for example, between the tire's maximum width position and the tread surface position in the tire radial direction. This improves communication with the RF tag from the tire's outer side in the tire radial direction compared to a configuration in which the RF tag is disposed radially inward of the tire's maximum width position. The RF tag may be disposed, for example, radially inward of the tire's maximum width position. This allows the RF tag to be disposed near the bead portion, which has high rigidity. This reduces the load applied to the RF tag. This improves durability of the RF tag. As an example, the RF tag may be disposed adjacent to the bead core in the tire radial direction or the tire width direction. Distortion is less likely to concentrate near the bead core. This reduces the load on the RF tag, improving the durability of the RF tag. In particular, it is preferable that the RF tag be positioned radially inward of the tire's maximum width position and radially outward of the bead core of the bead portion. This improves the durability of the RF tag, and communication between the RF tag and a reader is less likely to be obstructed by the bead core, improving the communication performance of the RF tag. Furthermore, when the side rubber is composed of multiple rubber members of the same or different types adjacent in the tire radial direction, the RF tag may be sandwiched between the multiple rubber members that make up the side rubber.

[0038] In the case of a passenger vehicle tire, the RF tag may be sandwiched between a bead filler and a member adjacent to the bead filler. This allows the RF tag to be placed in a position where strain is less likely to concentrate due to the placement of the bead filler. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. The RF tag may be sandwiched between, for example, the bead filler and the carcass. The portion of the carcass that sandwiches the RF tag together with the bead filler may be located on the outer side of the bead filler in the tire width direction, or on the inner side of the bead filler in the tire width direction. When the portion of the carcass that sandwiches the RF tag together with the bead filler is located on the outer side of the bead filler in the tire width direction, the load on the RF tag due to impact or damage from the outside of the tire in the tire width direction can be further reduced. This improves the durability of the RF tag. The bead filler may also have a portion that is located adjacent to the side rubber. In this case, the RF tag may be disposed by being sandwiched between the bead filler and the side rubber. Furthermore, the bead filler may have a portion disposed adjacent to the rubber chafer. In this case, the RF tag may be disposed by being sandwiched between the bead filler and the rubber chafer.

[0039] In the case of truck and bus tires, the RF tag may be disposed sandwiched between a stiffener and a member adjacent to the stiffener. This allows the RF tag to be disposed in a position where strain is less likely to concentrate due to the stiffener. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. The RF tag may be disposed sandwiched between the stiffener and a side rubber, for example. The RF tag may also be disposed sandwiched between the stiffener and a carcass, for example. The portion of the carcass that sandwiches the RF tag together with the stiffener may be located on the outer side of the stiffener in the tire width direction, or on the inner side of the tire width direction. When the portion of the carcass that sandwiches the RF tag together with the stiffener is located on the outer side of the stiffener in the tire width direction, the load on the RF tag due to impact or damage from the outside of the tire in the tire width direction can be further reduced. This improves the durability of the RF tag. The stiffener may have a portion disposed adjacent to the rubber chafer. In such a case, the RF tag may be disposed sandwiched between the stiffener and the rubber chafer. The stiffener may have a portion adjacent to the hat rubber on the outer side in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the stiffener and the hat rubber. The stiffener may be composed of a plurality of rubber members having different hardnesses. In such a case, the RF tag may be disposed sandwiched between the plurality of rubber members constituting the stiffener. The RF tag may be disposed sandwiched between the hat rubber and a member adjacent to the hat rubber. The RF tag may be disposed sandwiched, for example, between the hat rubber and the carcass ply. In this way, impacts on the RF tag can be mitigated by the hat rubber. This can improve the durability of the RF tag.

[0040] The RF tag may be arranged, for example, sandwiched between the rubber chafer and the side rubber. In this way, the RF tag can be arranged in a position where the placement of the rubber chafer makes it less likely for distortion to concentrate. This reduces the load on the RF tag. This improves the durability of the RF tag. The RF tag may be arranged, for example, sandwiched between the rubber chafer and the carcass. In this way, it reduces the load on the RF tag due to impacts or damage from the rim. This improves the durability of the RF tag.

[0041] In the case of truck and bus tires, the RF tag may be sandwiched between a nylon chafer and another member adjacent to the nylon chafer on the outer or inner side in the tire width direction. This makes it difficult for the position of the RF tag to fluctuate when the tire deforms. Therefore, the load applied to the RF tag when the tire deforms can be reduced. This improves the durability of the RF tag. The nylon chafer may, for example, have a portion adjacent to the rubber chafer on the outer side in the tire width direction. In such a case, the RF tag may be sandwiched between the nylon chafer and the rubber chafer. The nylon chafer may, for example, have a portion adjacent to the side rubber on the outer side in the tire width direction. In such a case, the RF tag may be sandwiched between the nylon chafer and the side rubber. The nylon chafer may, for example, have a portion adjacent to the stiffener on the inner side in the tire width direction. In such a case, the RF tag may be sandwiched between the nylon chafer and the side rubber. Furthermore, the nylon chafer may have a portion adjacent to the hat rubber, for example, on the inner side in the tire width direction. In such a case, the RF tag may be disposed by being sandwiched between the nylon chafer and the hat rubber. Furthermore, the nylon chafer may have a portion adjacent to the carcass, for example, on the inner side in the tire width direction. In such a case, the RF tag may be disposed by being sandwiched between the nylon chafer and the carcass. Furthermore, the nylon chafer may have a portion adjacent to the wire chafer, for example, on the inner side in the tire width direction. In such a case, the RF tag may be disposed by being sandwiched between the nylon chafer and the wire chafer. In this way, the RF tag may be disposed by being sandwiched between the nylon chafer and another member adjacent to the nylon chafer on the outer or inner side in the tire width direction. In particular, by covering the outer side of the RF tag in the tire width direction with the nylon chafer, the load applied to the RF tag due to impact or damage from the outside of the tire in the tire width direction can be further reduced. Therefore, the durability of the RF tag can be further improved.

[0042] The RF tag may be sandwiched between the wire chafer and another adjacent member on the inner or outer side of the wire chafer in the tire width direction. This makes it difficult for the position of the RF tag to fluctuate when the tire deforms. Therefore, the load applied to the RF tag when the tire deforms can be reduced. This improves the durability of the RF tag. The other adjacent member on the inner or outer side of the wire chafer in the tire width direction may be, for example, a rubber member such as a rubber chafer. Furthermore, the other adjacent member on the inner or outer side of the wire chafer in the tire width direction may be, for example, a carcass.

[0043] In the case of a tire for a passenger vehicle, a belt reinforcing layer may be further provided on the radially outer side of the belt. For example, the belt reinforcing layer may be formed by winding a cord made of polyethylene terephthalate continuously and spirally in the tire circumferential direction. Here, the cord may be 6.9 x 10 －２ The belt reinforcement layer may be formed by applying an adhesive treatment under a tension of 29.4 N / tex or more, and may have an elastic modulus of 2.5 mN / dtex% or more when measured at 160°C under a load of 29.4 N. Furthermore, the belt reinforcement layer may be arranged to cover the entire belt or only both ends of the belt. Furthermore, the winding density per unit width of the belt reinforcement layer may vary depending on the position in the width direction. By doing so, road noise and flat spots can be reduced without reducing high-speed durability.

[0044] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is thought to be a technology that can contribute to "No. 12: Responsible Consumption and Production" and "No. 13: Take concrete action against climate change."

[0045] 1: tread surface, 2: circumferential groove, 3: land portion, 4: large sipe, 5: small sipe, 6: medium sipe

Claims

1. A pneumatic tire having, on its tread surface, two or more circumferential grooves extending in the tire circumferential direction, rib-shaped land portions defined between the circumferential grooves, a plurality of sipes extending at an angle relative to the tire width direction being arranged in the land portions, wherein adjacent sipes in the tire circumferential direction at least partially overlap in the tire circumferential direction when projected in the tire width direction, or there is no circumferential gap between them, the sipes being of three types: large sipes with the largest angle of inclination relative to the tire width direction, small sipes with the smallest angle of inclination relative to the tire width direction, and medium sipes with an angle of inclination relative to the tire width direction intermediate between the large sipes and the small sipes, and wherein the sipe count distribution is such that the number of medium sipes is the largest among the large sipes, medium sipes, and small sipes.

2. A pneumatic tire as described in claim 1, wherein the distribution of the number of arrangements of two circumferentially adjacent sipes over the entire circumferential area of ​​the tire is such that the number of arrangements in which the large sipe and the small sipe are adjacent in the circumferential direction of the tire is the smallest.

3. A pneumatic tire according to claim 1 or 2, wherein the number of intermediate sipes relative to the total number of sipes is 33.4% to 60%.

4. The pneumatic tire according to claim 3, wherein the number of intermediate sipes relative to the total number of sipes is 37% to 50%.

5. A pneumatic tire according to any one of claims 1 to 4, wherein the distribution of the number of arrangements of two circumferentially adjacent sipes over the entire circumferential area of ​​the tire is such that the number of arrangements in which the central sipes are adjacent to each other in the circumferential direction of the tire is the largest.

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