Pneumatic tire

Abstract

To provide a pneumatic tire with an improved on-ice gripping performance.SOLUTION: A width direction sipe includes: a body part formed to have a substantially constant sipe width in an extension direction of the width direction sipe; and a widening part formed continuously to the body part and having a sipe width larger than a sipe width of the body part. The widening part is formed at least in one side of a tire circumferential direction of the width direction sipe. In the widening part, in one side of a tire width direction of the width direction sipe, a tire width direction position of an end in one side of the tire circumferential direction of the width direction sipe is located on the other side of the tire width direction further than an end in one side of the tire width direction of the width direction sipe.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, in a pneumatic tire, particularly in the land portion of the tread of a studless tire, fine grooves called sipes have been provided to improve the grip performance on ice. By these sipes, water gushing out due to the melting of the ice road surface on the tire contact surface can be discharged outside the contact surface, thereby improving the grip performance on ice.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, the compatibility between the rigidity of the land portion and the discharge of water by the sipes is not sufficient, and there is room for improvement in improving the grip performance on ice.

[0006] Therefore, an object of the present invention is to provide a pneumatic tire with improved grip performance on ice.

Means for Solving the Problems

[0007] The gist configuration of the present invention is as follows. (1) A pneumatic tire having at least one land portion on a tread surface, A plurality of circumferential grooves extending in the tire width direction and terminating at both ends within the land portions are formed on the surface of the land portions. The circumferential groove has a main body portion formed with a substantially constant groove width in the extending direction of the circumferential groove, and a widened portion continuously formed on the main body portion and having a groove width wider than that of the main body portion. The widened portion is formed on at least one side in the tire circumferential direction of the circumferential groove. The widened portion is characterized in that, on one side in the tire width direction of the circumferential groove, the position in the tire width direction of the end on one side in the tire circumferential direction of the circumferential groove is located on the other side in the tire width direction than the end on one side in the tire width direction of the circumferential groove. A pneumatic tire.

[0008] Here, the "tread surface" refers to the surface of the tread that comes into contact with the road surface over the entire tire circumferential direction when the pneumatic tire is mounted on the application rim, filled with the specified internal pressure, and loaded with the maximum load. Also, the "groove" of the "circumferential groove" refers to a groove having a groove width of 1 mm or less in a region of 50% or more of the groove depth when the tire is mounted on the application rim, filled with the specified internal pressure, and in an unloaded state. Here, the groove depth is measured in a direction perpendicular to the tread surface in the above state, and the groove width is measured in a direction parallel to the tread surface in a cross section perpendicular to the extending direction on the tread surface. Also, the "end on one side in the tire width direction of the circumferential groove" refers to the intersection of the extension line of the groove wall on one side in the tire circumferential direction of the main body portion of the circumferential groove and the groove wall.

[0009] As used in this specification, the "applicable rim" refers to an industrial standard effective in the region where the tire is produced and used. In Japan, it is the JATMA YEAR BOOK of JATMA (Japan Automobile Tire Manufacturers Association); in Europe, it is the STANDARDS MANUAL of ETRTO (The European Tyre and Rim Technical Organisation); in the United States, it is the YEAR BOOK of TRA (The Tire and Rim Association, Inc.), etc. It refers to the standard rim (Measuring Rim in the STANDARDS MANUAL of ETRTO and Design Rim in the YEAR BOOK of TRA) for the applicable size described therein or to be described in the future (i.e., the above "rim" includes sizes that may be included in the above industrial standards in the future in addition to the current sizes. Examples of "sizes to be described in the future" include sizes described as "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO). In the case of a size not described in the above industrial standards, it refers to a rim having a width corresponding to the bead width of the tire. Further, the "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 and ply rating described in the above JATMA, etc. In the case of a size not described in the above industrial standards, the "specified internal pressure" shall refer to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Further, the "maximum load" refers to the load corresponding to the above maximum load capacity.

[0010] (2) The widened portion is formed only on one side in the tire circumferential direction of the width-direction groove of the pneumatic tire according to (1).

[0011] (3) The widened portion is formed on both sides in the tire circumferential direction of the width-direction groove of the pneumatic tire according to (1).

[0012] (4) The widened portion is formed only on one side in the tire width direction of the width-direction groove of the pneumatic tire according to (1) or (2).

[0013] (5) The widened portion is formed on both sides in the tire width direction of the tire width of the circumferential width dimension, the pneumatic tire according to (3) above.

[0014] (6) One side in the tire circumferential direction is the depression side when the tire rolls, the pneumatic tire according to any one of (1) to (5) above.

[0015] (7) The widened portion is semi-circular in plan view, the pneumatic tire according to any one of (1) to (6) above.

[0016] (8) The plurality of circumferential width grooves are inclined in the same direction as the circumferential width groove adjacent in the tire width direction, the pneumatic tire according to any one of (1) to (7) above.

[0017] (9) The land portion is partitioned by a circumferential width edge extending in the tire width direction, and the main body portions of the plurality of circumferential width grooves are inclined in the same direction as the circumferential width edge, the pneumatic tire according to any one of (1) to (8) above.

[0018] (10) When the tire width direction length of the groove is w1 (mm) and the depth of the groove is h (mm), w1 × h is 150 (mm 2 ) or less, The number of the grooves in the land portion is n, the maximum width in the tire width direction of the land portion is BW (mm), the equivalent land portion tire circumferential direction length BL (mm) obtained by dividing the outer contour area (mm 2 ) of the land portion by BW (mm) is defined as the equivalent groove number N as w1 × n / BW, the average groove interval in the tire circumferential direction is expressed as BL / (N + 1), and when the groove density SD is defined as the reciprocal of the average groove interval in the tire circumferential direction, SD = (N + 1) / BL = ((w1 × n / BW) + 1) / BL, the pneumatic tire according to any one of (1) to (9) above, wherein SD is 0.15 (1 / mm) or more. Here, "groove" means all the grooves including the circumferential width grooves and other grooves when there are other grooves in addition to the circumferential width grooves. Note that the number n of sipes, the maximum width BW in the tire width direction of the land portion, and the outer contour area of the land portion are values measured in the developed view of the tread surface. The "outer contour area" refers to the area surrounded by the outer contour in the developed view of the tread surface. Therefore, even when non-ground portions such as sipes, small holes, and fine grooves are arranged within the land portion, it means the area excluding the areas of such sipes, small holes, and fine grooves.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a pneumatic tire with improved ice grip performance.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be illustrated and described in detail with reference to the drawings.

[0022] First, regarding the internal structure, etc. of a pneumatic tire (hereinafter also simply referred to as a tire), it can have the same structure as the conventional one. As an example, the tire can have a pair of bead portions, a pair of sidewall portions continuous with the pair of bead portions, and a tread portion disposed between the pair of sidewall portions. Further, the tire can have a carcass straddling toroidally between the pair of bead portions, and a belt disposed on the outer side in the tire radial direction of the crown portion of the carcass. Hereinafter, unless otherwise specified, dimensions, etc. refer to the dimensions, etc. when the tire is mounted on an applicable rim, filled with a specified internal pressure, and in an unloaded state.

[0023] The tire of the present embodiment has at least one land portion on the tread surface. The pneumatic tire of the present embodiment has one or more circumferential main grooves. The land portion is partitioned between the tread edge and the circumferential main groove, or between two circumferential main grooves. The land portion can be a block completely divided in the tire circumferential direction by a width direction groove. On the other hand, the land portion may not be completely divided in the tire circumferential direction by the width direction groove. The number of circumferential main grooves, groove width, groove depth, etc., and the number of width direction grooves, groove width, groove depth, etc. are not particularly limited, and the present disclosure can be applied to various tread patterns.

[0024] FIG. 1 is a plan view for explaining the sipe of a pneumatic tire according to an embodiment of the present invention. FIGS. 2 to 5 are plan views for explaining the width direction sipe of the first to fourth modified examples, respectively. In FIGS. 1 to 5, the case where the land portion 1 is a block is shown. As shown in FIGS. 1 to 5, in the tire of the present embodiment, a plurality of width direction sipers 2 extending in the tire width direction and having both ends terminating within the land portion (block) 1 are formed on the surface of the land portion (block) 1.

[0025] In the illustrated example, the plurality of width direction sipers 2 form a siper row provided at intervals in the extending direction, and such siper rows are arranged in a plurality of rows (six rows in the illustrated example) in the tire circumferential direction. Thereby, the density of the width direction siper 2 can be increased.

[0026] FIG. 6 is a diagram for explaining in detail the shape of the widthwise sipe in FIG. 2. As shown in FIG. 6, the widthwise sipe 2 has a main body portion 21 formed with a substantially constant sipe width in the extending direction of the widthwise sipe 2, and an enlarged width portion 22 continuously formed on the main body portion 21 and having a sipe width wider than that of the main body portion 21.

[0027] The length along the extending direction of the main body portion 21 is not particularly limited, but from the viewpoints of maintaining the rigidity of the block land portion while sufficiently exhibiting the ice grip performance in the tire and enabling application to various tires, it is preferably 3 to 15 mm. The sipe width (opening width) of the main body portion 21 is not particularly limited, but from the viewpoint of more effectively improving the ice grip performance, it is preferably 0.6 mm or less. Further, the sipe depth (maximum depth) of the main body portion 21 is not particularly limited, but it is preferably 3 mm or more, and may be, for example, 10 mm or less. Further, the main body portion 21 can extend in the tire width direction (without inclination) or extend obliquely at an inclination angle of more than 0° and less than 90° (preferably 30° or more and 60° or less) with respect to the tire width direction. When the inclination angle of the main body portion exceeds 60°, the length w1 in the tire width direction becomes small, the number of sipelines N increases with respect to the setting of a predetermined sipe density SD, and it may be difficult to ensure the block rigidity. The diameter in the plan view of the enlarged width portion 22 (the maximum value of the line segment distance between any two points among the lines defining the enlarged width portion 22) is not particularly limited, but in order to secure a distance for shifting the position of the end on one side in the tire circumferential direction (the stepping-in side) from a region where the restraint by the rubber constituting the land portion (block 1) is strong, it is preferably at least twice the sipe width of the main body portion 21, and from the viewpoint of maintaining the rigidity of the land portion (block 1), it is preferably 0.6 times or less the length along the extending direction of the main body portion 21. Further, the depth (maximum depth) of the enlarged width portion 22 is not particularly limited, but it is preferably 0.4 times or more the sipe depth of the main body portion 21, and preferably smaller than the depth of the main body portion 21 from the viewpoint of maintaining the rigidity of the block land portion.

[0028] The widened portion 22 is formed at least on one side in the tire circumferential direction of the width-direction groove 2. In the examples shown in FIGS. 1 and 4, the widened portion 22 is formed only on one side in the tire circumferential direction of the width-direction groove 2. According to such an aspect, 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 in the tire circumferential direction of the width-direction groove 2. According to such an aspect, the drainage performance can be further improved.

[0029] In the examples shown in FIGS. 1 and 4, the widened portion 22 is formed only on one side in the tire width direction of the width-direction groove 2. According to such an aspect, 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 in the tire width direction of the width-direction groove 2. According to such an aspect, the drainage performance can be further improved.

[0030] As shown in FIG. 6, in the widened portion 22, on one side in the tire width direction of the width-direction groove 2, the tire width direction position of the end P on one side in the tire circumferential direction of the width-direction groove 2 is located on the other side in the tire width direction than the end Q on one side in the tire width direction of the width-direction groove 2. Hereinafter, the operation and effect of the pneumatic tire of the present embodiment will be described. In the following, the case where one side in the tire circumferential direction is the stepping-in side will be described.

[0031] FIG. 7 is a diagram showing the result of FEM analysis of the behavior of the rubber block at the time of braking input on ice. When the tire rolls, the water on the road surface flows from the kicking-out side to the stepping-in side, and the water flows to the stepping-in side of the width-direction groove. If the function of storing the water flowing to the stepping-in side is enhanced, the drainage performance is improved, so the wet grip performance of the tire can be improved. As shown in FIG. 7, in the comparative example, the edge pressure is low (shown in a light color in FIG. 7) at the end on one side in the tire circumferential direction (the stepping-in side). This is considered to be because the restraint by the block rubber is strong at the end of the width-direction groove. On the other hand, in the inventive example, at one end in the tire circumferential direction (the side where the tire is depressed), the edge pressure becomes high (shown in dark color in FIG. 7). This is presumably because the position of one end in the tire circumferential direction (the side where the tire is depressed) is shifted from the region where the restraint by the block rubber is strong.

[0032] In the tire of the present embodiment, as described above, in the tire width direction on one side of the width direction sipe 2, the tire width direction position of the end P in the tire circumferential direction on one side of the width direction sipe 2 is located on the other side in the tire width direction than the end Q in the tire width direction on one side of the width direction sipe 2. For this reason, as shown in the FEM analysis of FIG. 7 and the examples described later, the drainage performance of the tire can be improved by increasing the edge pressure at the end P in the tire circumferential direction on one side of the width direction sipe 2. As described above, according to the pneumatic tire of the present embodiment, the wet grip performance can be improved.

[0033] As shown in FIGS. 1 to 3, the widened portion 22 can be semi-circular in plan view. Also, 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 extends 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 each extend on both sides in the tire circumferential direction. In the present disclosure, as long as the tire width direction position of the end P in the tire circumferential direction on one side of the width direction sipe 2 is located on the other side in the tire width direction than the end Q in the tire width direction on one side of the width direction sipe 2 in the tire width direction on one side of the width direction sipe 2, in plan view, it can have various shapes such as an ellipse, a semi-ellipse, a triangular shape, and other polygonal shapes.

[0034] Preferably, the plurality of width-direction sipes 2 are inclined in the same direction as the width-direction sipes 2 adjacent in the tire width direction. This is because it is easy to arrange the sipes densely and the rigidity of the land portion can be made uniform. Also, it is possible to prevent the formation of a portion where the land portion becomes locally small. For the same reason, it is preferable that all the width-direction sipes 2 in the land portion 1 are inclined in the same direction.

[0035] The land portion 1 is partitioned by width-direction edges (groove walls of the width-direction grooves) extending in the tire width direction, and preferably, the main body portions 21 of the plurality of width-direction sipes 2 are inclined in the same direction as the width-direction edges. This is because the wet grip performance can be further improved by preventing the formation of a portion where the land portion becomes locally small.

[0036] When the tire width-direction length of the sipe is w1 (mm) and the depth of the sipe is h (mm), w1 × h is 150 (mm 2 ) or less. Let the number of sipes in the land portion 1 be n, the maximum width in the tire width direction of the land portion 1 be BW (mm), and the equivalent land portion tire circumferential length BL (mm) obtained by dividing the outer contour area (mm 2 ) of the land portion 1 by BW (mm). Define the equivalent sipe number N as w1 × n / BW. Express the average sipe interval in the tire circumferential direction as BL / (N + 1). By defining the sipe density SD as the reciprocal of the average sipe interval in the tire circumferential direction, when expressed as SD = (N + 1) / BL = ((w1 × n / BW) + 1) / BL, it is preferable that SD is 0.15 (1 / mm) or more. This is because the wet grip performance can be further improved by increasing the sipe density. On the other hand, from the viewpoint of ensuring the rigidity of the land portion 1, it is preferable that SD is 0.3 (1 / mm) or less.

[0037] The main body 21 of the width-direction sipe 2 can be linear in plan view, or it can be zigzag in plan view. The main body 21 of the width-direction sipe 2 can be flat-plate-shaped, or it can be a so-called three-dimensional sipe. The width-direction sipe 2 may extend from a part of the main body 21 and have an extending portion different from the extending direction of the main body 21. Specifically, it can be in a three-fold shape, a cross shape, etc. in plan view. The widening portion 22 is preferably formed only in one of the two regions when the width-direction sipe 2 is divided into two regions in the tire width direction, because the rigidity of the land portion 1 can be prevented from decreasing. Further, the widening portion 2 is preferably formed only in one of the end regions when the width-direction sipe 2 is divided into three regions in the tire width direction (the two end regions and the central region therebetween), because the rigidity of the land portion 1 can be prevented from decreasing.

[0038] [Arrangement Example of Communication Device] Figures 8 and 9 are diagrams showing an arrangement example of communication devices. The tire may be provided with RF tags as communication devices 100 and 200. The RF tag includes an IC chip and an antenna. The RF tag may be arranged, for example, sandwiched between a plurality of members of the same or different types constituting the tire. By doing so, it is easy to attach the RF tag during tire production, and the productivity of the tire provided with the RF tag can be improved. In this example, the RF tag may be arranged, for example, sandwiched between a bead filler and another member adjacent to the bead filler. The RF tag may be embedded in any member constituting the tire. By doing so, the load applied to the RF tag can be reduced as compared with the case where it is arranged sandwiched between a plurality of members constituting the tire. Thereby, the durability of the RF tag can be improved. In this example, the RF tag may be embedded, for example, in a rubber member such as tread rubber or side rubber. The RF tag is preferably not arranged at a position that becomes a boundary between members having different rigidities in the peripheral 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 arranged at a position where distortion is likely to concentrate due to a rigidity step. Therefore, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. In this example, the RF tag is preferably not arranged, for example, at a position that becomes a boundary between an end portion of the carcass and a member (such as side rubber) adjacent to the end portion of the carcass in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. The tire may be provided with only one RF tag or may be provided with two or more RF tags. Here, as an example of the communication device, an RF tag is illustrated and described, but a communication device different from the RF tag may be used.

[0039] The RF tag may be disposed, for example, in the tread portion of the tire. By doing so, the RF tag will not be damaged by a side cut of the tire. The RF tag may be disposed, for example, at the center of the tread in the tire width direction. The center of the tread is a position where deflection hardly concentrates in the tread portion. By doing so, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. Also, it is possible to suppress a difference in communication performance 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 end in the tire width direction. When the position of the reader that communicates with the RF tag is predetermined, the RF tag may be disposed, for example, at the tread end on one side closer to this reader. In this example, the RF tag may be disposed, for example, within a range of 1 / 4 of the tread width with the tread end as the outer end in the tire width direction.

[0040] The RF tag may be disposed on the inner cavity side of the tire, for example, from a carcass including one or more carcass plies straddling between bead portions. By doing so, it becomes difficult for the RF tag to be damaged against impacts applied from the outside of the tire and damages such as side cuts and punctures. As an example, the RF tag may be disposed in close contact with the surface on the inner cavity side of the carcass. As another example, when there is another member on the inner cavity side of the tire from the carcass, the RF tag may be disposed, for example, between the carcass and another member located on the inner cavity side of the tire from this carcass. Examples of another member located on the inner cavity side of the tire from the carcass include, for example, an inner liner forming the inner surface of the tire. As another example, the RF tag may be attached to the inner surface of the tire facing the inner cavity of the tire. By configuring the RF tag to be attached to the inner surface of the tire, it becomes easy to attach the RF tag to the tire and to inspect and replace the RF tag. That is, the attachability and maintainability of the RF tag can be improved. Further, by attaching the RF tag to the inner surface of the tire, it is possible to prevent the RF tag from becoming the core of a tire failure as compared with a configuration in which the RF tag is embedded in the tire. Further, when the carcass includes a plurality of carcass plies and there is a position where the plurality of carcass plies are overlapped, the RF tag may be disposed between the overlapped carcass plies.

[0041] The RF tag may be disposed, for example, outside the belt including one or more belt plies in the tire tread portion, on the outer side in the tire radial direction. As an example, the RF tag may be disposed in close contact with the belt on the outer side in the tire radial direction with respect to the belt. Further, as another example, when a reinforcing belt layer is provided, the RF tag may be disposed in close contact with the reinforcing belt layer on the outer side in the tire radial direction with respect to the reinforcing belt layer. Further, as another example, the RF tag may be embedded in the tread rubber on the outer side in the tire radial direction from the belt. By disposing the RF tag outside the belt in the tire radial direction in the tire tread portion, communication with the RF tag from the outer side of the tire in the tire radial direction is less likely to be inhibited by the belt. Therefore, the communication performance with the RF tag from the outer side of the tire in the tire radial direction can be improved. Further, the RF tag may be disposed, for example, inside the belt in the tire tread portion in the tire radial direction. By doing so, since the outer side of the RF tag in the tire radial direction is covered by the belt, the RF tag is less likely to be damaged by impacts from the tread surface or punctures. As an example of this, the RF tag may be disposed between the belt and the carcass located inside the belt in the tire radial direction in the tire tread portion. Further, when the belt includes a plurality of belt plies, the RF tag may be disposed between any two belt plies in the tire tread portion. By doing so, since the outer side of the RF tag in the tire radial direction is covered by one or more belt plies, the RF tag is less likely to be damaged by impacts from the tread surface or punctures.

[0042] In the case of a truck / bus tire, the RF tag may be disposed, for example, sandwiched between the cushion rubber and the tread rubber or between the cushion rubber and the side rubber. By doing so, the impact on the RF tag can be mitigated by the cushion rubber. Therefore, the durability of the RF tag can be improved. Further, the RF tag may be embedded in the cushion rubber, for example. Further, the cushion rubber may be composed of a plurality of adjacent rubber members of the same or different types. In such a case, the RF tag may be disposed sandwiched between the plurality of rubber members constituting the cushion rubber.

[0043] The RF tag may be arranged, for example, at the position of the sidewall portion or the bead portion of the tire. The RF tag may be arranged, for example, at the sidewall portion on one side closer to the reader capable of communicating with the RF tag or at the bead portion on one side. By doing so, the communication performance between the RF tag and the reader can be enhanced. As an example, the RF tag may be arranged between the carcass and the side rubber or between the tread rubber and the side rubber. The RF tag may be arranged, for example, between the position where the tire has its maximum width and the position of the tread surface in the tire radial direction. By doing so, compared with the configuration in which the RF tag is arranged inside the tire in the radial direction from the position where the tire has its maximum width, the communication performance between the RF tag and the outside of the tire in the tire radial direction can be enhanced. The RF tag may be arranged, for example, inside the tire in the radial direction from the position where the tire has its maximum width. By doing so, the RF tag is arranged near the bead portion with high rigidity. Therefore, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. As an example, the RF tag may be arranged at a position adjacent to the bead core in the tire radial direction or the tire width direction. It is difficult for distortion to concentrate near the bead core. Therefore, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. In particular, it is preferable that the RF tag be arranged at a position inside the tire in the radial direction from the position where the tire has its maximum width and outside the bead core of the bead portion in the tire radial direction. By doing so, the durability of the RF tag can be improved, and the communication between the RF tag and the reader is less likely to be inhibited by the bead core, and the communication performance of the RF tag can be enhanced. Further, when the side rubber is composed of a plurality of rubber members of the same kind or different kinds adjacent to each other in the tire radial direction, the RF tag may be arranged sandwiched between the plurality of rubber members constituting the side rubber.

[0044] In the case of a passenger car tire, the RF tag may be disposed sandwiched between a bead filler and a member adjacent to the bead filler. By doing so, the RF tag can be disposed at a position where it is difficult for distortion to concentrate due to the arrangement of the bead filler. Therefore, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. The RF tag may be disposed, for example, sandwiched between a bead filler and a carcass. The portion of the carcass that sandwiches the RF tag together with the bead filler may be located outside the bead filler in the tire width direction or inside 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 outside the bead filler in the tire width direction, the load applied to the RF tag can be further reduced by an impact or damage from the outside of the tire in the tire width direction. Thereby, the durability of the RF tag can be further improved. Further, the bead filler may include a portion disposed adjacent to the side rubber. In such a case, the RF tag may be disposed sandwiched between the bead filler and the side rubber. Furthermore, the bead filler may include a portion disposed adjacent to the rubber chafer. In such a case, the RF tag may be disposed sandwiched between the bead filler and the rubber chafer.

[0045] In the case of a tire for a truck bus, the RF tag may be disposed sandwiched between a stiffener and a member adjacent to the stiffener. By doing so, the RF tag can be disposed at a position where it is difficult for distortion to concentrate due to the arrangement of the stiffener. Therefore, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. The RF tag may be disposed, for example, sandwiched between a stiffener and a side rubber. Further, the RF tag may be disposed, for example, sandwiched between a stiffener and a carcass. The portion of the carcass that sandwiches the RF tag together with the stiffener may be located outside the stiffener in the tire width direction or may be located inside the stiffener in the tire width direction. When the portion of the carcass that sandwiches the RF tag together with the stiffener is located outside the stiffener in the tire width direction, the load applied to the RF tag can be further reduced due to an impact or damage from the outside of the tire in the tire width direction. Thereby, the durability of the RF tag can be further improved. The stiffener may include a portion disposed adjacent to a rubber chafer. In such a case, the RF tag may be disposed sandwiched between the stiffener and the rubber chafer. The stiffener may include a portion adjacent to a hat rubber outside 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 a hat rubber and a member adjacent to the hat rubber. The RF tag may be disposed, for example, sandwiched between a hat rubber and a carcass ply. By doing so, the impact on the RF tag can be mitigated by the hat rubber. Therefore, the durability of the RF tag can be improved.

[0046] The RF tag may be disposed, for example, sandwiched between a rubber chafer and a side rubber. By doing so, the RF tag can be disposed at a position where it is difficult for distortion to concentrate due to the arrangement of the rubber chafer. Therefore, the load applied to the RF tag can be reduced. Thereby, the durability of the RF tag can be improved. The RF tag may be disposed, for example, sandwiched between a rubber chafer and a carcass. By doing so, the load applied to the RF tag can be reduced due to the impact or damage applied from the rim. Therefore, the durability of the RF tag can be improved.

[0047] In the case of a tire for a truck bus, the RF tag may be disposed sandwiched between a nylon chafer and another member adjacent to the outside or inside of the nylon chafer in the tire width direction. By doing so, when the tire is deformed, the position of the RF tag is less likely to fluctuate. Therefore, the load applied to the RF tag when the tire is deformed can be reduced. Thereby, the durability of the RF tag can be improved. The nylon chafer may include, for example, a portion adjacent to the rubber chafer on the outside in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the nylon chafer and the rubber chafer. The nylon chafer may include, for example, a portion adjacent to the side rubber on the outside in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the nylon chafer and the side rubber. The nylon chafer may include, for example, a portion adjacent to the stiffener on the inside in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the nylon chafer and the stiffener. Further, the nylon chafer may include, for example, a portion adjacent to the hat rubber on the inside in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the nylon chafer and the hat rubber. Furthermore, the nylon chafer may include, for example, a portion adjacent to the carcass on the inside in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the nylon chafer and the carcass. Furthermore, the nylon chafer may include, for example, a portion adjacent to the wire chafer on the inside in the tire width direction. In such a case, the RF tag may be disposed sandwiched between the nylon chafer and the wire chafer. Thus, the RF tag may be disposed sandwiched between a nylon chafer and another member adjacent to the outside or inside of the nylon chafer in the tire width direction. In particular, since the outside in the tire width direction of the RF tag is covered by 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.

[0048] The RF tag may be disposed sandwiched between a wire chafer and another member adjacent to the inside or outside in the tire width direction of the wire chafer. By doing so, when the tire deforms, the position of the RF tag becomes difficult to fluctuate. Therefore, the load applied to the RF tag when the tire deforms can be reduced. Thereby, the durability of the RF tag can be improved. Another member adjacent to the inside or outside in the tire width direction of the wire chafer may be a rubber member such as a rubber chafer. Further, another member adjacent to the inside or outside in the tire width direction of the wire chafer may be, for example, a carcass.

[0049] In the case of a passenger car tire, 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 continuously winding a cord made of polyethylene terephthalate in a spiral shape in the tire circumferential direction. Here, the cord is subjected to an adhesive treatment under a tension of 6.9×10 -2 N / tex or more, and the elastic modulus at a load of 29.4 N measured at 160 °C may be 2.5 mN / dtex·% or more. Further, the belt reinforcing layer may be arranged to cover the entire belt or may be arranged to cover only both ends of the belt. Further, the winding density per unit width of the belt reinforcing layer may vary depending on the position in the width direction. By doing so, load noise and flat spots can be reduced without degrading high-speed durability.

Examples

[0050] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples at all.

[0051] In order to confirm the effects of the present invention, the wet friction coefficient μ on an ice road was measured using a 3D sample simulating a rubber block equipped with a comparative example sip and an inventive example sip. The measurement of the wet friction coefficient μ was carried out at a block size corresponding to a tire size of 185 / 60R15, an average contact pressure of 250 kPa, and a speed of 10 km / h. When the evaluation result indicates that the larger the numerical value in the exponential display with the result of the comparative example set as "100", the larger the wet friction coefficient μ, the invention example was "105". From this, it can be seen that in the invention example, the ice grip performance was improved compared to the comparative example.

Explanation of Reference Signs

[0052] 1: Land part (block), 2: Lateral groove, 21: Main body part, 22: Widening part, 100: Communication device, 200: Communication device, P: End on one side in the tire circumferential direction of the lateral groove, Q: End on one side in the tire width direction of the lateral groove

Claims

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

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

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

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 in the tire width direction of the widthwise sipe.

6. The pneumatic tire according to claim 1 or 2, wherein the one side in the tire circumferential direction is the depression side during tire rolling.

7. The pneumatic tire according to claim 1 or 2, wherein the widened portion is semicircular in plan view.

8. The pneumatic tire according to claim 1 or 2, wherein the plurality of widthwise sipes are inclined in the same direction as the adjacent widthwise sipes in the tire width direction.

9. The pneumatic tire according to claim 1 or 2, wherein the land portion is partitioned by a widthwise edge extending in the tire width direction, and the main body portion of the plurality of widthwise sipes is inclined in the same direction as the widthwise edge.

10. When the tire-width direction length of the sipe is w1 (mm) and the depth of the sipe is h (mm), w1 × h is 150 (mm ２ ) or less, Let the number of the sipes in the land part be n, the maximum width in the tire width direction of the land part be BW (mm), and the equivalent land part tire circumferential length obtained by dividing the outer contour area (mm ２ ) of the land part by BW (mm) be BL (mm). The equivalent number of sipes N is defined as w1 × n / BW, the average sipe interval in the tire circumferential direction is expressed as BL / (N + 1), and the sipe density SD is defined as the reciprocal of the average sipe interval in the tire circumferential direction. When expressed as SD = (N + 1) / BL = ((w1 × n / BW) + 1) / BL, the pneumatic tire according to claim 1 or 2, wherein SD is 0.15 (1 / mm) or more.

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