Pneumatic tire

Abstract

In this invention, a width-direction sipe includes: a body part formed with a substantially constant sipe width along an extension direction of the width-direction sipe; and a widened part which is formed continuously with the body part and has a sipe width wider than the sipe width of the body part. The widened part is formed in the width-direction sipe at least on one side in a tire circumferential direction. In the widened part, on one side of the width-direction sipe in a tire width direction, a tire width-direction position of an end of the width-direction sipe on the one side in the tire circumferential direction is positioned further to the other side in the tire width direction than an end of the width-direction sipe on the one side in the tire width direction.

Description

pneumatic tires

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

[0002] Conventionally, pneumatic tires, especially studless tires, have had narrow grooves called sipes in the land portion of their treads to improve grip on ice. These sipes allow water that wells up when ice melts on the tire's contact surface to be expelled from the contact surface, thereby improving grip on ice.

[0003] A technology has been proposed that aims to improve grip performance on ice by arranging sipes at a high density while suppressing a decrease in rigidity of the land portion (for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2005-186827

[0005] However, in Patent Document 1, the rigidity of the land portion and the ability to drain water through the sipes were not sufficient, and there was room for improvement in terms of improving grip performance on ice.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pneumatic tire with improved grip performance on ice.

[0007] The gist of the present invention is as follows: (1) A pneumatic tire having at least one land portion on a tread surface, wherein a plurality of widthwise sipes are formed on a surface of the land portion, extending in the tire width direction and terminating at both ends within the land portion, the widthwise sipes have a main body portion formed with a substantially constant sipe width in the extension direction of the widthwise sipe, and a widened portion formed continuous with the main body portion and having a sipe width wider than the sipe width of the main body portion, the widened portion is formed on at least one side in the tire circumferential direction of the widthwise sipe, and the widened portion is located on one side in the tire width direction of the one widthwise side of the widthwise sipe, such that a position in the tire width direction of an end of the widthwise sipe on one side in the tire width direction is located on the other side in the tire width direction than the end of the widthwise sipe on one side in the tire width direction.

[0008] 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 "sipe" in "widthwise sipe" refers to a sipe whose width is 1 mm or less over an area of ​​50% or more of the sipe depth when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and unloaded. Here, the sipe depth is measured in a direction perpendicular to the tread surface, and the sipe width is measured in a direction parallel to the tread surface in a cross section perpendicular to the extension direction of the tread surface. The "end on one side of the widthwise sipe" refers to the intersection of the sipe wall and an extension line of the sipe wall on one side of the main body of the widthwise sipe in the tire circumferential direction.

[0009] 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.

[0010] Here, "sipes" refers to all sipes, including the widthwise sipes, in cases where there are sipes other than the widthwise sipes. The number n of sipes, the maximum width BW of the land portion in the tire width direction, and the outer contour area of ​​the land portion are values ​​measured in a developed view of the tread surface. The "outer contour area" refers to the area surrounded by the outer contour in a developed view of the tread surface, and therefore refers to an area that does not exclude the areas of sipes, small holes, narrow grooves, etc., even if non-contacting portions such as sipes, small holes, narrow grooves, etc. are arranged within the land portion.

[0011] According to the present invention, a pneumatic tire with improved grip performance on ice can be provided.

[0012] FIG. 1 is a plan view for explaining widthwise sipes of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view for explaining widthwise sipes of a first modified example. FIG. 3 is a plan view for explaining widthwise sipes of a second modified example. FIG. 4 is a plan view for explaining widthwise sipes of a third modified example. FIG. 5 is a plan view for explaining widthwise sipes of a fourth modified example. FIG. 6 is a diagram for explaining in detail the shape of the widthwise sipes of FIG. 2. FIG. 7 is a diagram showing the results of an FEM analysis of the behavior of rubber blocks when braking is applied on ice. FIG. 8 is a diagram showing an example of the arrangement of a communication device. FIG. 9 is a diagram showing an example of the arrangement of a communication device.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014] First, the internal structure of a pneumatic tire (hereinafter simply referred to as a tire) may be the same as that of a conventional tire. For example, the tire may have a pair of bead portions, a pair of sidewall portions connected to the pair of bead portions, and a tread portion disposed between the pair of sidewall portions. The tire may also have a carcass toroidally spanning the pair of bead portions and a belt disposed radially outward of a crown portion of the carcass. Hereinafter, unless otherwise specified, dimensions refer to dimensions when the tire is mounted on an applicable rim, inflated to a specified internal pressure, and in an unloaded state.

[0015] The tire of this embodiment has at least one land portion on the tread surface. The pneumatic tire of this embodiment has one or more circumferential main grooves. The land portion is defined between the tread edge and the circumferential main groove, or defined between two circumferential main grooves. The land portion can be a block completely divided in the tire circumferential direction by widthwise grooves. On the other hand, the land portion does not have to be completely divided in the tire circumferential direction by widthwise grooves. The number, groove width, groove depth, etc. of the circumferential main grooves and the number, groove width, groove depth, etc. of the widthwise grooves are not particularly limited, and the present disclosure can be applied to various tread patterns.

[0016] Fig. 1 is a plan view illustrating sipes of a pneumatic tire according to one embodiment of the present invention. Figs. 2 to 5 are plan views illustrating widthwise sipes of first to fourth modified examples, respectively. Figs. 1 to 5 show cases in which land portions 1 are blocks. As shown in Figs. 1 to 5, the tire of this embodiment has a plurality of widthwise sipes 2 formed on the surface of land portions (blocks) 1, extending in the tire width direction and terminating at both ends within the land portions (blocks) 1.

[0017] In the illustrated example, the multiple widthwise sipes 2 form sipe rows spaced apart in the extending direction, and multiple such sipe rows (six rows in the illustrated example) are arranged in the tire circumferential direction, thereby increasing the density of the widthwise sipes 2.

[0018] Fig. 6 is a diagram for explaining in detail the shape of the widthwise sipes shown in Fig. 2. As shown in Fig. 6, the widthwise sipes 2 have a main body portion 21 formed with a substantially constant sipe width in the extension direction of the widthwise sipe 2, and an expanded portion 22 formed continuously with the main body portion 21 and with a sipe width wider than the sipe width of the main body portion 21.

[0019] The length of the main body portion 21 along its extension direction is not particularly limited, but is preferably 3 to 15 mm from the viewpoint of maintaining the rigidity of the block land portion while fully demonstrating the tire's ice grip performance and enabling application to a variety of tires. The sipe width (opening width) of the main body portion 21 is not particularly limited, but is preferably 0.6 mm or less from the viewpoint of more effectively improving ice grip performance. The sipe depth (maximum depth) of the main body portion 21 is also not particularly limited, but is preferably 3 mm or more, and may be, for example, 10 mm or less. The main body portion 21 can extend in the tire width direction (without inclination) or can extend at an inclination angle greater than 0° and less than 90° (preferably 30° to 60°) relative to the tire width direction. If the inclination angle of the main body portion exceeds 60°, the tire width direction length w1 becomes smaller, which increases the number of sipes N for a given sipe density SD, potentially making it difficult to ensure block rigidity. The diameter of the widened portion 22 in a plan view (the maximum value of the line segment distance between any two points on the lines dividing the widened portion 22) is not particularly limited, but is preferably at least twice the sipe width of the main body portion 21 in order to ensure a distance that shifts the position of the end on one circumferential side of the tire (the leading side) from the area where the rubber constituting the land portion (block 1) is strongly constrained, and from the perspective of maintaining the rigidity of the land portion (block 1), is preferably no more than 0.6 times the length along the extension direction of the main body portion 21. Furthermore, the depth (maximum depth) of the widened portion 22 is not particularly limited, but is preferably at least 0.4 times the sipe depth of the main body portion 21, and is preferably smaller than the depth of the main body portion 21 in order to maintain the rigidity of the block land portion.

[0020] The widened portions 22 are formed on at least one circumferential side of the widthwise sipes 2. In the examples shown in Figs. 1 and 4, the widened portions 22 are formed only on one circumferential side of the widthwise sipes 2. According to this embodiment, it is possible to suppress a decrease in the rigidity of the land portions (blocks 1). On the other hand, in the examples shown in Figs. 2, 3, and 5, the widened portions 22 are formed on both circumferential sides of the widthwise sipes 2. According to this embodiment, it is possible to further improve drainage performance.

[0021] 1 and 4, the widened portion 22 is formed only on one side of the widthwise sipe 2 in the tire width direction. According to this embodiment, it is possible to suppress a decrease in the rigidity of the land portion (block 1). On the other hand, in the examples shown in FIGS. 2, 3, and 5, the widened portion 22 is formed on both sides of the widthwise sipe 2 in the tire width direction. According to this embodiment, it is possible to further improve drainage performance.

[0022] 6, the widened portion 22 is arranged such that, on one side of the widthwise sipe 2 in the tire width direction, the tire width direction position of the end P on one side of the widthwise sipe 2 in the tire circumferential direction is located on the other side in the tire width direction than the end Q on one side of the widthwise sipe 2 in the tire width direction. The effects of the pneumatic tire of this embodiment will be described below. In the following, a case will be described in which the one side in the tire circumferential direction is the leading side.

[0023] FIG. 7 shows the results of an FEM analysis of the behavior of rubber blocks during braking on ice. While water on the road surface flows from the trailing edge to the leading edge when the tire is rolling, water flows to the leading edge of the widthwise sipes. Improving the ability of water flowing to the leading edge to be stored improves drainage, potentially improving the tire's wet grip performance. As shown in FIG. 7 , in the comparative example, the edge pressure is low at the edge on one circumferential side (leading edge) of the tire (shown as a lighter color in FIG. 7 ). This is thought to be due to the strong constraint by the block rubber at the ends of the widthwise sipes. On the other hand, in the example of the invention, the edge pressure is high at the edge on one circumferential side (leading edge) of the tire (shown as a darker color in FIG. 7 ). This is thought to be due to the position of the edge on one circumferential side (leading edge) of the tire being shifted from the region where the block rubber is strongly constrained.

[0024] In the tire of this embodiment, as described above, the widened portion 22 is arranged such that, on one side of the widthwise sipe 2 in the tire width direction, the tire widthwise position of the end P on one side of the widthwise sipe 2 in the tire circumferential direction is located on the other side in the tire width direction than the end Q on one side of the widthwise sipe 2 in the tire width direction. Therefore, as shown in the FEM analysis of FIG. 7 and in the examples described later, the drainage performance of the tire can be improved by increasing the edge pressure of the end P on one side of the tire circumferential direction of the widthwise sipe 2. As described above, the pneumatic tire of this embodiment can improve wet grip performance.

[0025] As shown in FIGS. 1 to 3 , the widened portion 22 can be semicircular in plan view. Furthermore, as shown in FIGS. 4 and 5 , the widened portion 22 can also be circular in plan view. In the example of FIG. 2 , both widened portions 22 formed on both sides in the tire width direction are formed on one side in the tire circumferential direction. In the example of FIG. 3 , the widened portion 22 formed on one side in the tire width direction is formed on one side in the tire circumferential direction, and the widened portion 22 formed on the other side in the tire width direction is formed on the other side in the tire circumferential direction. In the example of FIG. 4 , the widened portion 22 formed only on one side in the tire width direction is widened on both sides in the tire circumferential direction. In the example of FIG. 5 , the widened portions 22 formed on both sides in the tire width direction are widened on both sides in the tire circumferential direction. In the present disclosure, the widening portion 22 can have various shapes in a planar view, such as an ellipse, a semi-ellipse, a triangle, or other polygonal shape, as long as the tire width direction position of the end P on one side of the width direction sipe 2 in the tire circumferential direction is located on the other side of the tire width direction than the end Q on one side of the width direction sipe 2 in the tire width direction.

[0026] It is preferable that the multiple widthwise sipes 2 are inclined in the same direction as the widthwise sipes 2 adjacent to them in the tire width direction. This is because it is easier to arrange the sipes densely and it is possible to uniform the rigidity of the land portion. It is also possible to prevent the formation of portions where the land portion is locally small. For the same reason, it is preferable that all widthwise sipes 2 within a land portion 1 are inclined in the same direction.

[0027] The land portions 1 are defined by widthwise edges (groove walls of widthwise grooves) extending in the tire width direction, and the main body portions 21 of the multiple widthwise sipes 2 are preferably inclined in the same direction as the widthwise edges, because this can prevent the formation of locally small portions of the land portions, thereby further improving wet grip performance.

[0028] When the length of the sipe in the tire width direction is w1 (mm) and the depth of the sipe is h (mm), w1 x h is 150 (mm ２ ) or less, the number of sipes in the land portion 1 is n, the maximum width of the land portion 1 in the tire width direction is BW (mm), and the outer contour area of ​​the land portion 1 (mm ２ When the circumferential length of the equivalent land portion 1 is defined as BL (mm), the number of equivalent sipes N is defined as w1×n / BW, the average circumferential spacing of the sipes in the tire is expressed as BL / (N+1), and the sipe density SD is defined as the reciprocal of the average circumferential spacing of the sipes in the tire, SD = (N+1) / BL = ((w1×n / BW)+1) / BL, it is preferable that SD be 0.15 (1 / mm) or more. This is because increasing the sipe density can further improve wet grip performance. On the other hand, from the viewpoint of ensuring the rigidity of the land portion 1, it is preferable that SD be 0.3 (1 / mm) or less.

[0029] The main body portion 21 of the widthwise sipe 2 may be linear in plan view or may be zigzag in plan view. The main body portion 21 of the widthwise sipe 2 may be flat, or may be a so-called three-dimensional sipe. The widthwise sipe 2 may extend from a portion of the main body portion 21 and have an extending portion that differs from the extending direction of the main body portion 21. Specifically, the widthwise sipe 2 may have a trident shape, a cross shape, or the like in plan view. When the widthwise sipe 2 is divided into two regions in the tire width direction, the widened portion 22 is preferably formed only in one region, because this prevents a decrease in the rigidity of the land portion 1. Furthermore, when the widthwise sipe 2 is divided into three regions in the tire width direction (two end regions and a central region therebetween), the widened portion 2 is preferably formed only in one of the end regions, because this prevents a decrease in the rigidity of the land portion 1.

[0030] [Example of Arrangement of Communication Devices] FIGS. 8 and 9 are diagrams showing examples of arrangement of communication devices. 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, 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, improving the productivity of tires equipped with RF tags. In this example, the RF tag may be arranged, for example, sandwiched between a bead filler and another component adjacent to the bead filler. The RF tag may be embedded in any of the components that constitute the tire. This reduces the load on the RF tag compared to when the RF tag is arranged 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Examples of the present invention will be described below, but the present invention is not limited to the following examples in any way.

[0043] To verify the effectiveness of the present invention, measurements of the wet friction coefficient μ on icy roads were conducted using 3DP samples simulating rubber blocks equipped with comparative sipes and inventive sipes. Measurements were conducted using a block size equivalent to a tire size of 185 / 60R15, with an average contact pressure of 250 kPa and a speed of 10 km / h. The evaluation results were expressed as an index, with the comparative example being assigned a value of "100," and the higher the value, the greater the wet friction coefficient μ. The inventive example achieved a score of "105." This demonstrates that the inventive example demonstrated improved grip performance on ice compared to the comparative example.

[0044] 1: Land portion (block), 2: Width direction sipe, 21: Main body portion, 22: Widened portion, 100: Communication device, 200: Communication device, P: One end of width direction sipe in tire circumferential direction, Q: One end of width direction sipe in tire width direction

Claims

1. A pneumatic tire having at least one land portion on a tread surface, wherein a plurality of widthwise sipes are formed on a surface of the land portion, extending in the tire width direction with both ends terminating within the land portion, the widthwise sipes having a main body portion formed with a substantially constant sipe width in the extension direction of the widthwise sipe, and a widened portion formed continuous with the main body portion and having a sipe width wider than the sipe width of the main body portion, the widened portion being formed on at least one circumferential side of the widthwise sipe, and the widened portion being characterized in that, on one side of the widthwise sipe, a tire width position of an end of the widthwise sipe on one side in the tire width direction of the widthwise sipe is located on the other side in the tire width direction than an end of the widthwise sipe on one side in the tire width direction.

2. The pneumatic tire according to claim 1, wherein the widened portion is formed only on one side of the widthwise sipe in the tire circumferential direction.

3. The pneumatic tire according to claim 1, wherein the widened portion is formed on both sides of the widthwise sipe in the tire circumferential direction.

4. The pneumatic tire according to claim 1 or 2, wherein the widened portion is formed only on one side in the tire width direction of the widthwise sipe.

5. The pneumatic tire according to claim 3, wherein the widened portion is formed on both sides of the widthwise sipe in the tire width direction.

6. The pneumatic tire according to any one of claims 1 to 5, wherein the one circumferential side of the tire is a leading side when the tire is rolling.

7. The pneumatic tire according to any one of claims 1 to 6, wherein the widened portion is semicircular in plan view.

8. A pneumatic tire according to any one of claims 1 to 7, wherein the plurality of widthwise sipes are inclined in the same direction as the widthwise sipes adjacent thereto in the tire width direction.

9. A pneumatic tire according to any one of claims 1 to 8, wherein the land portions are partitioned by widthwise edges extending in the tire width direction, and the main body portions of the plurality of widthwise sipes are inclined in the same direction as the widthwise edges.

10. If the length of the sipe in the tire width direction is w1 (mm) and the depth of the sipe is h (mm), then w1 x h is 150 (mm ２ ), the number of sipes in the land portion is n, the maximum width of the land portion in the tire width direction is BW (mm), and the outer contour area of ​​the land portion is (mm ２ 10. The pneumatic tire according to claim 1, wherein the circumferential length of the equivalent land portion is defined as BL (mm), the number of equivalent sipes N is defined as w1×n / BW, the average circumferential spacing of the sipes is expressed as BL / (N+1), and the sipe density SD is defined as the reciprocal of the average circumferential spacing of the sipes in the tire direction, so that SD = (N+1) / BL = ((w1×n / BW)+1) / BL, and SD is 0.15 (1 / mm) or more.

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