Pneumatic radial tires for passenger cars

Abstract

To provide a pneumatic radial tire for a passenger vehicle that can improve a ground-contact shape to suppress uneven wear from occurring, while the tire has an inclined belt layer with only one layer so as to be reduced in weight.SOLUTION: In a pneumatic radial tire for a passenger vehicle according to the present invention, a cross-section width SW of the tire and an outer diameter OD of the tire satisfy a predetermined relation, and a carcass has a first tire width directional part in which carcass cords are arranged radially and a second tire width directional part in which carcass cords extend obliquely with respect to a tire circumferential direction. The second tire width directional part is positioned at a half part in a tire width direction which is positioned inside when mounted on the vehicle, where the carcass cords and belt cords of a carcass body part in the second tire width directional part extend in directions crossing each other, when viewed from outside in a tire radial direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a pneumatic radial tire for a passenger vehicle. [Background technology]

[0002] As a pneumatic radial tire for passenger cars with improved fuel economy, the present applicant has proposed a narrow-width, large-diameter pneumatic radial tire for passenger cars in which the tire cross-sectional width SW and the tire outer diameter OD have a predetermined relationship (for example, Patent Document 1). Also, in a narrow-width, large-diameter pneumatic radial tire for passenger cars, it has been proposed to have only one inclined belt layer in which belt cords are inclined with respect to the tire circumferential direction in order to reduce weight and further improve fuel economy (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 135774 Brochure [Patent Document 2] Japanese Patent Publication No. 2020-093674 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if there is only one inclined belt layer, the rigidity in the extension direction of the belt cord increases, making it difficult for the tread rubber to stretch in that direction, which deteriorates the contact shape as shown schematically in Figure 1. This promotes wear particularly in the inner half of the tire in the width direction when mounted on a vehicle, which could result in uneven wear of the tire. In particular, the small cross-sectional width SW of the tire and the fact that narrow-width, large-diameter pneumatic radial tires for passenger cars such as those described above are often used at high internal pressures also contribute to the deterioration of the contact shape.

[0005] Therefore, an object of the present invention is to provide a pneumatic radial tire for passenger cars that has only one inclined belt layer, thereby reducing the tire weight while improving the ground contact shape and suppressing the occurrence of uneven wear. [Means for solving the problem]

[0006] The gist and configuration of the present invention are as follows. (1) a pair of bead portions; a carcass consisting of one or more carcass plies formed by rubber-coating carcass cords; a belt having only one inclined belt layer formed of a belt ply formed by rubber-coating belt cords that are arranged on the radially outer side of the crown portion of the carcass and extend obliquely relative to the tire circumferential direction, The tire has a cross-sectional width SW of less than 165 (mm), The ratio SW / OD of the tire's section width SW to its outer diameter OD is 0.26 or less, or the tire's section width SW (mm) and outer diameter OD (mm) satisfy the following relational expression: OD(mm)≧-0.0187×SW(mm) 2 +9.15×SW(mm)-380(mm) the carcass has a first tire width direction portion in which the carcass cords are radially arranged and a second tire width direction portion in which the carcass cords extend obliquely with respect to the tire circumferential direction, the carcass has a carcass main body portion extending from the bead portion to an inner side of the belt in the tire radial direction, The second tire width direction portion is located in an inner half portion in the tire width direction when mounted on the vehicle, A pneumatic radial tire for passenger cars, characterized in that the carcass cords and the belt cords of the carcass main body portion in the second tire width direction portion extend in directions that intersect with each other when viewed from the outside in the tire radial direction.

[0007] In this specification, the term "rim" refers to the standard rim (Measuring Rim in the ETRTO Standards Manual, Design Rim in the TRA Year Book) for the applicable size that is described or will be described in the future, as an industrial standard in effect in the region where the tire is produced and used, such as the JATMA Year Book of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the Standards Manual of the European Tyre and Rim Technical Organization (ETRTO) in Europe, or the Year Book of the Tire and Rim Association, Inc. (TRA) in the United States. (In other words, the "rim" in the above "wheel" includes not only current sizes but also sizes that may be included in the above industrial standards in the future. An example of a "size to be described in the future" is the size listed under "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO.) However, in the case of a size not described in the above industrial standards, the term refers to a rim with a width that corresponds to the bead width of the tire. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) that corresponds to the maximum load capacity of a single wheel for the applicable size and ply rating as specified in the above JATMA etc., and in the case of sizes not specified in the above industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) that corresponds to the maximum load capacity specified for each vehicle on which the tire is fitted. Furthermore, the "maximum load" refers to the load corresponding to the maximum load capacity.

[0008] (2) A pneumatic radial tire for passenger cars according to (1) above, wherein the inclination angle of the carcass cord of the carcass main body portion in the second tire width direction portion with respect to the tire circumferential direction is larger than the inclination angle of the belt cord with respect to the tire circumferential direction.

[0009] (3) The pneumatic radial tire for passenger cars according to (1) or (2) above, wherein the inclination angle of the carcass cords of the carcass main body portion in the second tire width direction portion with respect to the tire circumferential direction is 70 to 88°.

[0010] (4) The pneumatic radial tire for passenger cars according to any one of (1) to (3), wherein the position of the inner end in the tire width direction of the second tire width direction portion is spaced outward in the tire width direction from the end in the tire width direction of the belt by 10 to 40% of the width of the belt in the tire width direction.

[0011] (5) The pneumatic radial tire for a passenger car is mounted on the right wheel of the vehicle, The belt cord extends obliquely from the lower right to the upper left when viewed from the outer side in the tire radial direction, The carcass cord further has a third tire width direction portion different from the second tire width direction portion extending obliquely with respect to the tire circumferential direction, The third tire width direction portion is located in an outer half portion in the tire width direction when mounted on the vehicle, The pneumatic radial tire for passenger cars according to any one of (1) to (4), wherein the carcass cord and the belt cord of the carcass main body portion in the third tire width direction portion extend in directions that intersect with each other when viewed from the outside in the tire radial direction.

[0012] (6) The pneumatic radial tire for passenger cars according to any one of (1) to (5) above, wherein the carcass straddles a pair of bead portions in a toroidal shape.

[0013] (7) A pneumatic radial tire for passenger cars according to any one of (1) to (5) above, wherein the carcass has a first carcass extending from a bead portion of an outer half of the tire width direction when mounted on a vehicle to the inner side of the belt in the tire radial direction, and a second carcass extending from a bead portion of an inner half of the tire width direction when mounted on a vehicle to the inner side of the belt in the tire radial direction. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a pneumatic radial tire for passenger cars that has only one inclined belt layer, thereby reducing the weight of the tire, while improving the ground contact shape and suppressing the occurrence of uneven wear. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 10 is a diagram schematically showing the ground contact shape when there is only one inclined belt layer. [Figure 2] 1 is a schematic diagram showing the section width SW and the outer diameter OD of a tire. [Figure 3] 1 is a cross-sectional view in the tire width direction of a pneumatic radial tire for passenger cars according to one embodiment of the present invention. [Figure 4] FIG. 2 is a diagram schematically illustrating the structure of a carcass, a belt, and a cap layer. [Figure 5] FIG. 2 is a schematic diagram of another carcass structure. [Figure 6] 10A and 10B are diagrams illustrating an improvement in the ground contact shape. [Figure 7] 10A and 10B are diagrams schematically showing other examples of the structure of the carcass, belt, and cap layer. [Figure 8] FIG. 10 is a diagram for explaining the arrangement of RFIDs. [Figure 9] FIG. 10 is a cross-sectional view in the tire width direction of a modified pneumatic radial tire for passenger cars. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 2 is a schematic diagram showing the section width SW and the outer diameter OD of a tire. A pneumatic radial tire for passenger cars (hereinafter simply referred to as tire) according to one embodiment of the present invention has a tire section width SW of less than 165 mm, and a ratio SW / OD of the tire section width SW to the outer diameter OD of 0.26 or less, resulting in a narrow width / large diameter shape. By narrowing the tire section width SW compared to the tire outer diameter OD, air resistance can be reduced, and by increasing the tire outer diameter OD compared to the tire section width SW, deformation of the tread rubber near the tire's contact patch can be suppressed, reducing rolling resistance, thereby improving the tire's fuel economy. The SW / OD ratio is preferably 0.25 or less, and more preferably 0.24 or less. The above ratio is preferably satisfied when the tire internal pressure is 200 kPa or higher, more preferably 220 kPa or higher, and even more preferably 280 kPa or higher, because this allows for a reduction in rolling resistance. On the other hand, the above ratio is preferably satisfied when the tire internal pressure is 350 kPa or lower, because this allows for an improvement in ride comfort. Here, the tire cross-sectional width SW is preferably 105 to 145 mm, and more preferably 115 to 135 mm. Furthermore, the aspect ratio of the tire is more preferably 45 to 70, and even more preferably 45 to 65, when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above ratio. Specific tire sizes are not particularly limited, but examples include 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17, 135 / 60R18, 135 / 60R19, 135 / 65R19, 145 / 45R21, 145 / 5 155 / 5R20, 145 / 60R16, 145 / 60R17, 145 / 60R18, 145 / 60R19, 145 / 65R19, 155 / 45R18, 155 / 45R21, 155 / 55R18, 155 / 55R19, 155 / 55R21, 155 / 60R17, 155 / 65R18, 155 / 70R17, or 155 / 70R19.

[0018] Alternatively, the tire has a section width SW of less than 165 mm, and the section width SW (mm) and the outer diameter OD (mm) of the tire satisfy the relationship: OD(mm)≧-0.0187×SW(mm) 2 +9.15×SW(mm)-380 and has a narrow width and large diameter. By satisfying the above relational expression, it is possible to reduce air resistance and rolling resistance, thereby improving the fuel economy of the tire. In the third aspect, the tire's section width SW and outer diameter OD satisfy the above-mentioned relational expression, and the ratio SW / OD is preferably 0.26 or less, more preferably 0.25 or less, and even more preferably 0.24 or less, because this can further improve the tire's fuel economy. The above relationship and / or ratio is preferably satisfied when the tire internal pressure is 200 kPa or higher, more preferably 220 kPa or higher, and even more preferably 280 kPa or higher, because this allows for a reduction in rolling resistance. On the other hand, the above relationship and / or ratio is preferably satisfied when the tire internal pressure is 350 kPa or lower, because this allows for an improvement in ride comfort. Here, the tire cross-sectional width SW is preferably 105 to 145 mm, and more preferably 115 to 135 mm. Furthermore, the aspect ratio of the tire is more preferably 45 to 70, and even more preferably 45 to 65, when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above relational expression. Specific tire sizes are not particularly limited, but examples include 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17, 135 / 60R18, 135 / 60R19, 135 / 65R19, 145 / 45R21, 145 / 5 155 / 5R20, 145 / 60R16, 145 / 60R17, 145 / 60R18, 145 / 60R19, 145 / 65R19, 155 / 45R18, 155 / 45R21, 155 / 55R18, 155 / 55R19, 155 / 55R21, 155 / 60R17, 155 / 65R18, 155 / 70R17, or 155 / 70R19.

[0019] The tire of this embodiment is a pneumatic radial tire for passenger cars, and is particularly suitable for use as a tire to be mounted on a vehicle for personal mobility.

[0020] Fig. 3 is a widthwise cross-sectional view of a pneumatic radial tire for passenger cars according to one embodiment of the present invention. Fig. 3 shows a widthwise cross-section of the tire in a standard state, in which the tire is mounted on a rim, inflated to a specified internal pressure, and no load is applied. As shown in Fig. 3, the tire 1 includes a carcass 3 made of one or more carcass plies each formed of rubber-coated carcass cords. The tire 1 also includes, on the radially outer side of the crown portion of the carcass 3, a belt 4 made of only one inclined belt layer made of a belt ply formed of rubber-coated belt cords extending at an angle with respect to the tire circumferential direction, and a tread 5, in this order.

[0021] In this example, a bead core 2a is embedded in each of the pair of bead portions 2. In the present invention, the cross-sectional shape and material of the bead core 2a are not particularly limited, and the bead core 2a may have a configuration that is normally used in pneumatic radial tires for passenger cars. In the present invention, the bead core 2a may be divided into a plurality of small bead cores. Alternatively, in the present invention, the bead core 2a may not be included.

[0022] The tire 1 in the illustrated example has a bead filler 2b with a generally triangular cross section on the tire radial outer side of the bead core 2a. The cross-sectional shape of the bead filler 2b is not limited to this example, and the material is not particularly limited either. Alternatively, the tire can be configured without the bead filler 2b to reduce its weight.

[0023] In this embodiment, the tire 1 may have a structure including a rim guard. Also, in this embodiment, additional members such as a rubber layer or a cord layer may be provided in the bead portion 2 for the purpose of reinforcement, etc. Such additional members may be provided in various positions relative to the carcass 3 and the bead filler 2b.

[0024] In the example shown in FIG. 3, the carcass 3 is made up of one carcass ply. However, in the present invention, the number of carcass plies is not particularly limited and can be two or more. Also, as shown in FIG. 4, the carcass 3 has a first tire width direction portion 301 in which the carcass cords are radially arranged and a second tire width direction portion 302 in which the carcass cords extend at an angle relative to the tire circumferential direction, and the second tire width direction portion 302 is located in the inner half of the tire width direction when mounted on a vehicle (only a part of this half in the illustrated example). In the example shown in FIG. 3, the carcass 3 has a carcass main body portion 3a that spans a pair of bead portions 2 in a toroidal shape and a folded-up portion 3b that is folded back from the carcass main body portion 3a around the bead core 2a. The carcass main body portion 3a extends from the bead portion 2 to the inner side of the belt 4 in the tire radial direction. On the other hand, in the present invention, the carcass folded-up portion 3b can be wrapped around the bead core 2a, or can be sandwiched between multiple divided small bead cores. The end 3c of the carcass folded-up portion 3b is located radially outward of the radially outer end of the bead filler 2b and radially inward of the maximum tire width position. This allows the tire to be lightweight while ensuring the rigidity of the sidewall portion. On the other hand, in the present invention, the end 3c of the carcass folded-up portion 3b may be located radially inward of the radially outer end of the bead filler 2b, or may be located radially outward of the maximum tire width position. Alternatively, the end 3c of the carcass folded-up portion 3b can have an envelope structure in which it is located radially inward of the end of the belt 4 (e.g., the end of the belt layer 4b) so as to be located between the carcass main body 2a and the belt 4 in the tire radial direction. Furthermore, when the carcass 3 is made up of multiple carcass plies, the positions (e.g., tire radial positions) of the ends 3c of the carcass folded-up portions 3b between the carcass plies can be the same or different. The end count of the cords in the carcass 3 is not particularly limited, but can be, for example, in the range of 20 to 60 cords / 50 mm. Various structures can also be adopted for the carcass line.For example, in the tire radial direction, the carcass maximum width position can be moved closer to the bead portion 2 side or closer to the tread 5 side. For example, the carcass maximum width position can be located in a range of 50% to 90% of the tire cross-sectional height outward from the bead baseline in the tire radial direction. The "radial arrangement" is at an angle of 85° or more with respect to the tire circumferential direction, preferably 90° with respect to the tire circumferential direction. As shown in FIG. 4, by folding back the carcass, the inclination directions of the belt cords in the second tire width direction portion 302 are opposite between the carcass main body portion 3a and the carcass folded back portion 3b. As shown in FIG. 3, the carcass 3 can be configured to straddle a pair of bead portions 2 in a toroidal shape. 5, the carcass 3 may have a first carcass 351 extending from the bead portion 2 on the outer half of the tire width direction when mounted on a vehicle to the inner side of the belt 4 in the tire radial direction, and a second carcass 352 extending from the bead portion 2 on the inner half of the tire width direction when mounted on a vehicle to the inner side of the belt in the tire radial direction. In order to improve the rigidity of the outer side when mounted on a vehicle, which greatly contributes to driving performance, as shown in the figure, the second carcass 352 may have a radially extending portion 352a that extends from the outer side to the inner side in the tire radial direction along the first carcass 351 and terminates at or near the inner side in the tire width direction of the bead portion on the outer half when mounted on a vehicle, or may have no radially extending portion 352a to reduce weight.

[0025] The tire of this embodiment preferably has only one inclined belt layer made of a belt ply formed by rubber-coating belt cords extending at an angle to the tire circumferential direction, and the width of the belt layer in the tire width direction is preferably 90 to 115% of the contact width, and particularly preferably 100 to 105% of the contact width. Note that "contact width" refers to the distance in the tire width direction between contact edges E. "Contact edges" refers to both ends in the tire width direction of the contact surface when the tire is mounted on a rim, inflated to a specified internal pressure, and subjected to a maximum load. In this embodiment, it is most preferable to use metal cords, particularly steel cords, as the belt cords of the belt layer. However, non-metallic cords, such as organic fiber cords (e.g., Kevlar (registered trademark) and the like), can also be used. Steel cords are primarily composed of steel and can contain trace amounts of various elements, such as carbon, manganese, silicon, phosphorus, sulfur, copper, and chromium. In this embodiment, the belt cords of the belt layer can be monofilament cords, cords made of multiple parallel filaments, or cords made of multiple twisted filaments. Various twist structures can be employed, including various cross-sectional structures, twist pitches, twist directions, and distances between adjacent filaments. Furthermore, cords made of twisted filaments of different materials can also be used. The cross-sectional structure is not particularly limited, and various twist structures, such as single twist, multi-layer twist, and multi-twist, can be employed. In this embodiment, the inclination angle of the belt cords of the belt layer is preferably 10° or more with respect to the tire circumferential direction. In this embodiment, the inclination angle of the belt cords of the belt layer is preferably high, specifically 20° or more with respect to the tire circumferential direction, and particularly preferably in the range of 20° to 45° with respect to the tire circumferential direction. This is because an inclination angle of 20° or more can increase rigidity in the tire width direction and improve steering stability, particularly during cornering. In addition, shear deformation of the interlayer rubber can be reduced, thereby reducing rolling resistance.

[0026] 4, in this embodiment, the carcass cords and belt cords of the carcass main body 3a in the second tire width direction portion 302 extend in directions that intersect with each other when viewed from the outside in the tire radial direction. The inclination angle of the carcass cords of the carcass main body 3a in the second tire width direction portion 302 with respect to the tire circumferential direction is larger than the inclination angle of the belt cords with respect to the tire circumferential direction. The inclination angle of the carcass cords of the carcass main body 3a in the second tire width direction portion 302 with respect to the tire circumferential direction is preferably 70 to 88°, and more preferably 76 to 84°. In the illustrated example, the end of the belt 4 is located within the first tire width direction portion 301. In the illustrated example, the width of the cap layer 8 in the tire width direction is smaller than the width of the belt 4 in the tire width direction. The position of the tire widthwise inner end of the second tire widthwise portion 302 is preferably spaced outward in the tire widthwise direction from the tire widthwise end of the belt 4 (the end of the same tire widthwise half portion) by 10 to 40% of the tire widthwise width of the belt 4.

[0027] In the illustrated example, the tread rubber constituting the tread 5 consists of a single layer. However, in this embodiment, the tread rubber constituting the tread 5 may be formed by stacking multiple different rubber layers in the tire radial direction. The multiple rubber layers may have different tangent loss, modulus, hardness, glass transition temperature, material, etc. The thickness ratio of the multiple rubber layers in the tire radial direction may vary in the tire width direction, and only the bottom of the circumferential main groove may be a rubber layer different from its surroundings. The tread rubber constituting the tread 5 may be formed by multiple rubber layers that are different in the tire width direction. The multiple rubber layers may have different tangent loss, modulus, hardness, glass transition temperature, material, etc. The width ratio of the multiple rubber layers in the tire width direction may vary in the tire radial direction, and only limited regions, such as the vicinity of the circumferential main groove, the vicinity of the tread edge, the shoulder land portion, or the center land portion, may be a rubber layer different from its surroundings.

[0028] The tire 1 of this embodiment has an inner liner 7 on the inner surface 6 of the tire (also simply referred to as the tire inner surface 6). The thickness of the inner liner 7 is preferably about 1.5 mm to 2.8 mm, because this can effectively reduce interior noise in the range of 80 to 100 Hz. The air permeability coefficient of the rubber composition constituting the inner liner 7 is 1.0×10 -14 cc·cm / (cm 2 ·s·cmHg) or more, 6.5×10 -10 cc·cm / (cm 2 ·s·cmHg) or less is preferable.

[0029] As shown in FIG. 3, the tire further includes one or more cap layers 8 (one layer in the illustrated example) on the outer side of the belt 4 in the tire radial direction.

[0030] The cap layer 8 is formed by spirally winding a ribbon-shaped member made of a rubberized layer of cords arranged approximately in parallel in the tire circumferential direction. In the illustrated example, the width of the cap layer 8 in the tire width direction is smaller than the width of the belt 4 in the tire width direction. The cords of the cap layer 8 can be, for example, organic fiber cords.

[0031] The following describes the effects of the pneumatic radial tire for passenger cars according to this embodiment.

[0032] The pneumatic radial tire for passenger cars of this embodiment is a narrow-width, large-diameter tire in which the tire's section width SW and outer diameter satisfy the above-mentioned relationship, and has a narrow section width SW of less than 165 (mm). Such a tire can particularly reduce air resistance and also reduce rolling resistance, thereby improving the tire's fuel efficiency. Here, since the tire of this embodiment has a belt consisting of only one inclined belt layer, the tread rubber is less likely to stretch in the inclined direction of the belt cord (the upward and downward directions to the left and right in FIG. 4). In contrast, the tire of this embodiment further has a first tire width direction portion 301 having radially arranged carcass cords and a second tire width direction portion 302 having inclined carcass cords. The carcass cords and belt cords of the carcass main body portion 3a in the second tire width direction portion 302, which is located in the outer half of the tire width direction when mounted on a vehicle, extend in directions that intersect with each other when viewed from the outside in the tire radial direction. Therefore, a force acts on the carcass cords of the carcass main body portion 3a in the second tire width direction portion 302 to return them to their radial arrangement, which can promote stretching of the tread rubber in the direction of the force (the upward and downward directions to the left and right in FIG. 4). This alleviates the difficulty in stretching the tread rubber in the inclined direction of the belt cord, improving the ground contact shape as shown schematically in Figure 6, and improving driving performance such as steering stability.

[0033] Here, the inclination angle of the carcass cords of the carcass main body 3a in the second tire widthwise portion 302 with respect to the tire circumferential direction is preferably larger than the inclination angle of the belt cords with respect to the tire circumferential direction. This is because, by making the inclination angle of the carcass cords with respect to the tire circumferential direction larger than the inclination angle of the belt cords with respect to the tire circumferential direction, it is possible to ensure both rigidity to support the load and lateral rigidity, and torsional deformation that corrects the contact patch shape.

[0034] Furthermore, the inclination angle of the carcass cords of the carcass main body 3a in the second tire width direction portion 302 with respect to the tire circumferential direction is preferably 70 to 88 degrees. By setting the angle to 70 degrees or more, both torsional deformation and rigidity can be achieved, while by setting the angle to 88 degrees or less, a sufficient restoring force against torsion can be generated. For the same reason, the inclination angle is more preferably 76 to 84 degrees.

[0035] Furthermore, the position of the inner end in the tire width direction of the second tire width direction portion 302 is preferably spaced outward in the tire width direction from the tire width direction end of the belt 4 by 10 to 40% of the width of the belt 4 in the tire width direction. By setting the distance to 10% or more, the effect of correcting the ground contact shape can be obtained over the entire inner half when mounted on a vehicle, while by setting the distance to 40% or less, both torsional deformation and rigidity can be achieved. For the same reason, it is even more preferable that the position of the inner end in the tire width direction of the second tire width direction portion 302 is spaced outward in the tire width direction from the tire width direction end of the belt 4 by 20 to 30% of the width of the belt 4 in the tire width direction.

[0036] As shown in Fig. 7, the carcass cords further include a third tire widthwise portion 303 different from the second tire widthwise portion 302 extending at an angle relative to the tire circumferential direction. The third tire widthwise portion 303 is preferably located in the outer half of the tire widthwise direction when mounted on a vehicle, and the carcass cords and belt cords of the carcass main body portion 3a in the third tire widthwise portion 303 extend in directions that intersect with each other when viewed from the outer side in the tire radial direction. Even in the outer half when mounted on a vehicle, the force that attempts to restore the radial arrangement of the carcass cords of the carcass main body portion 3a in the third tire widthwise portion 303 has the effect of promoting elongation of the tread rubber in the direction of the force (upward and downward in Fig. 7), thereby further mitigating the difficulty of the tread rubber stretching in the oblique direction of the belt cords. This can further improve the ground contact shape and driving performance. The pneumatic radial tire for a passenger car may be mounted on the right wheel of the vehicle, and the belt cord may extend at an angle from the lower right to the upper left when viewed from the outside in the radial direction of the tire (FIG. 7), or may be mounted on the left wheel of the vehicle, and the belt cord may extend at an angle from the lower left to the upper right when viewed from the outside in the radial direction of the tire.

[0037] The carcass 3 may also be toroidally spanning a pair of bead portions 2, or may have a first carcass 351 extending from the bead portion 2 on the outer half of the tire width direction when mounted on a vehicle to the inner side of the belt 4 in the tire radial direction, as shown in Figure 5, and a second carcass 352 extending from the bead portion 2 on the inner half of the tire width direction when mounted on a vehicle to the inner side of the belt 4 in the tire radial direction. As shown in FIG. 9, a line passing through a point on the tread surface at the tire equatorial plane and parallel to the tire width direction is defined as m1, and a line passing through the contact edge E and parallel to the tire width direction is defined as m2. The distance in the tire radial direction between the lines m1 and m2 is defined as the drop height L. CR When the tire tread width is TW, the ratio L CR It is preferable that / TW is greater than 0.045. This results in a tire with a relatively rounded crown shape, allowing the contact patch shape to be rounded with the contact patch length at the shoulders shorter than at the center. This prevents the contact patch from becoming too elongated when the camber angle changes, further suppressing deterioration of the contact patch shape. "Contact edge" refers to both ends in the tire width direction of the contact patch (the surface in contact with the road surface) when the tire is mounted on a rim, inflated to the specified internal pressure, and subjected to the maximum load. "Tread width" refers to the distance in the tire width direction between the contact edges when the tire is mounted on a rim, inflated to the specified internal pressure, and no load is applied.

[0038] <Tire and rim assembly> The tire-rim assembly herein is formed by mounting the above-mentioned pneumatic radial tire for passenger cars onto a rim. This tire-rim assembly can achieve the same effects as those described for the above-mentioned pneumatic radial tire for passenger cars. In this case, the internal pressure of the tire-rim assembly is preferably 200 kPa or more, more preferably 220 kPa or more, and even more preferably 280 kPa or more. This is because a high internal pressure can further reduce rolling resistance. On the other hand, the internal pressure of the tire-rim assembly is preferably 350 kPa or less, because this can improve ride comfort.

[0039] <How to use pneumatic radial tires for passenger cars> The method for using a pneumatic radial tire for passenger cars herein uses the above-mentioned pneumatic radial tire for passenger cars. According to this method for using a pneumatic radial tire for passenger cars, the same effects as those described for the pneumatic radial tire for passenger cars can be obtained. In this case, the internal pressure is preferably 200 kPa or more, more preferably 220 kPa or more, and even more preferably 280 kPa or more. This is because a high internal pressure can further reduce rolling resistance. On the other hand, it is preferable to use an internal pressure of 350 kPa or less, because this can improve ride comfort.

[0040] <Example with communication device> As shown in FIG. 8 , a tire may include an RF tag serving as a communication device 500. The RF tag includes an IC chip and an antenna. The RF tag may be sandwiched between multiple components of the same or different types that make up the tire. This facilitates attachment of the RF tag during tire production, improving the productivity of tires equipped with RF tags. In this example, the RF tag may be 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 make up the tire. This reduces the load on the RF tag compared to when the RF tag is sandwiched between multiple components that make up 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 a tread rubber or side rubber. It is preferable that the RF tag is not placed at 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. This prevents the RF tag from being placed in a location where strain is likely to concentrate due to a difference in rigidity. Therefore, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. In this example, it is preferable that the RF tag is not placed at a position that is, for example, a boundary between the end of the carcass and a member adjacent to the end of the carcass (for example, a side rubber) 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.

[0041] 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 the tread width centered on the tire equatorial plane in the tire width direction. The RF tag may be disposed, for example, at a 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 a 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 the tread width in the tire width direction, with the tread edge as the outer end.

[0042] The RF tag may be positioned closer to the tire cavity than the carcass, which includes one or more carcass plies spanning the bead portions. This configuration makes the RF tag less susceptible to damage from external impacts to the tire, side cuts, nail penetration, and other damage. 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 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 inner surface of the tire facing the tire cavity. Configuring the RF tag to be attached to the inner surface of the tire 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 the core 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.

[0043] The RF tag may be arranged, for example, in the tread portion of the tire, radially outward of a belt consisting of only one belt ply. 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 outside the tire in the tire radial direction is less likely to be obstructed by the belt. Therefore, communication with the RF tag from outside 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 radially outward side of the RF tag is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail penetration. As an example of this, the RF tag may be arranged in the tread portion of the tire, between the belt and the carcass located radially inward of the belt.

[0044] 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 arrangement 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 arrangement improves communication with the RF tag from outside the tire 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 arrangement allows the RF tag to be disposed near the bead portion, which has high rigidity. This reduces the load applied to the RF tag, thereby improving the 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 its durability. In particular, it is preferable that the RF tag be positioned radially inward of the tire's maximum width 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 RF tag's communication performance. Furthermore, when the side rubber is composed of multiple rubber members of the same or different types adjacent to each other in the tire radial direction, the RF tag may be sandwiched between the multiple rubber members that make up the side rubber.

[0045] The RF tag may be disposed sandwiched between the bead filler and a member adjacent to the bead filler. This allows the RF tag to be disposed in a position where strain is less likely to be concentrated 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 disposed 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 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 disposed 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.

[0046] The RF tag may be disposed, for example, sandwiched between the rubber chafer and the side rubber. In this way, the RF tag can be disposed 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 disposed, for example, sandwiched between the rubber chafer and the carcass. In this way, it reduces the load on the RF tag due to impact or damage from the rim. This improves the durability of the RF tag.

[0047] 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. This reduces the load applied to the RF tag when the tire deforms. 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.

[0048] 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 in a spiral shape in the circumferential direction of the tire. Here, the cord has a diameter of 6.9 × 10 -2 The belt reinforcement layer may be formed by applying an adhesive treatment under a tension of 100 N / tex or more, and have an elastic modulus of 2.5 mN / dtex·% or more when measured at 160°C with 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. This makes it possible to reduce road noise and flat spots without reducing high-speed durability.

[0049] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, although the above examples show an example having one cap layer, a tire without a cap layer may be used to reduce the tire weight.

[0050] [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 goals such as "No. 7 - Affordable and clean energy for all," "No. 12 - Responsible consumption and production," and "No. 13 - Take concrete action against climate change." [Explanation of symbols]

[0051] 1: Passenger car pneumatic radial tires (tires), 2: bead portion, 2a: bead core, 2b: bead filler, 3: carcass, 301: first tire width direction portion; 302: second tire width direction portion; 303: third tire width direction portion; 4: belt; 5: tread; 6: tire inner surface, 7: inner liner, 8: Cap layer, 500: Communication device, CL: Tire equatorial plane

Claims

1. a pair of bead portions; a carcass comprising one or more carcass plies each formed by rubber-coating a carcass cord; a belt having only one inclined belt layer formed of a belt ply formed by rubber-coating belt cords extending at an angle with respect to the tire circumferential direction, the belt ply being disposed radially outward of a crown portion of the carcass, The tire has a cross-sectional width SW of less than 165 (mm), A ratio SW / OD of a section width SW to an outer diameter OD of the tire is 0.26 or less, or the section width SW (mm) and the outer diameter OD (mm) of the tire satisfy the following relational expression: OD (mm)≧-0.0187×SW (mm) ２ +9.15 × SW (mm) -380 (mm) is satisfied, the carcass has a first tire width direction portion in which the carcass cords are radially arranged and a second tire width direction portion in which the carcass cords extend obliquely with respect to the tire circumferential direction, the carcass has a carcass main body portion extending from the bead portion to an inner side of the belt in the tire radial direction, the second tire width direction portion is located in an inner half of the tire width direction when mounted on a vehicle, the carcass cords and the belt cords of the carcass main body portion in the second tire width direction portion extend in directions intersecting each other when viewed from an outer side in the tire radial direction, a position of an inner end in the tire width direction of the second tire width direction portion is spaced outward in the tire width direction from the end of the belt in the tire width direction by 10 to 40% of a width of the belt in the tire width direction.

2. 2. The pneumatic radial tire for passenger cars according to claim 1, wherein an inclination angle of the carcass cords of the carcass main body portion in the second tire width direction portion with respect to the tire circumferential direction is larger than an inclination angle of the belt cords with respect to the tire circumferential direction.

3. 3. The pneumatic radial tire for passenger cars according to claim 1, wherein an inclination angle of the carcass cords of the carcass main body portion in the second tire width direction portion with respect to the tire circumferential direction is 70 to 88 degrees.

4. The pneumatic radial tire for a passenger vehicle is mounted on a right wheel of a vehicle, The belt cord extends obliquely from the lower right to the upper left when viewed from the outer side in the tire radial direction, The carcass cord further has a third tire width direction portion different from the second tire width direction portion extending obliquely with respect to the tire circumferential direction, the third tire width direction portion is located in an outer half portion in the tire width direction when mounted on a vehicle, 3. The pneumatic radial tire for passenger cars according to claim 1, wherein the carcass cords and the belt cords of the carcass main body portion in the third tire width direction portion extend in directions that intersect with each other when viewed from the outside in the tire radial direction.

5. 3. The pneumatic radial tire for passenger vehicles according to claim 1, wherein the carcass is toroidally shaped and extends between a pair of bead portions.

6. 3. The pneumatic radial tire for passenger cars according to claim 1, wherein the carcass includes a first carcass extending from a bead portion of an outer half of the tire width direction when mounted on a vehicle to a radially inner side of the belt, and a second carcass extending from a bead portion of an inner half of the tire width direction when mounted on a vehicle to a radially inner side of the belt.

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