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 motion performance from deteriorating, 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 outside when mounted on the vehicle, where 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] This invention relates to a pneumatic radial tire for passenger cars. [Background technology]

[0002] As a pneumatic radial tire for passenger cars with improved fuel efficiency, the applicant has proposed a narrow-width, large-diameter pneumatic radial tire for passenger cars in which the relationship between the tire's cross-sectional width SW and the tire's outer diameter OD is set to a predetermined relationship (for example, Patent Document 1). Furthermore, in a narrow-width, large-diameter pneumatic radial tire for passenger cars, it has also been proposed to have only one inclined belt layer in which the belt cords are inclined with respect to the tire's circumferential direction, in order to reduce weight and further improve fuel efficiency (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 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, if only one inclined belt layer is used, the rigidity in the direction of extension of the belt cord increases, making it difficult for the tread rubber to stretch in that direction. As schematically shown in Figure 1, this can lead to a deterioration of the contact patch shape and a decrease in handling performance. In particular, the small cross-sectional width SW of the tire and the fact that narrow, large-diameter pneumatic radial tires for passenger cars, as described above, are often used at high internal pressures, also contributed to the deterioration of the contact patch shape.

[0005] Therefore, the present invention aims to provide a pneumatic radial tire for passenger cars that can reduce the weight of the tire by having only one inclined belt layer, while simultaneously improving the contact shape and suppressing a decrease in handling performance. [Means for solving the problem]

[0006] The gist of the present invention is as follows: (1) A pair of bead sections, A carcass consisting of one or more carcass plies covered with rubber, A pneumatic radial tire for passenger cars comprising a belt consisting of only one inclined belt layer, which is made up of a belt ply made of a rubber-coated belt cord that extends inclined with respect to the circumferential direction of the tire and is positioned on the radially outer side of the crown portion of the carcass, The cross-sectional width SW of the aforementioned tire is less than 165 (mm), The ratio SW / OD of the tire's cross-sectional width SW to its outer diameter OD is 0.26 or less, or the tire's cross-sectional width SW (mm) and outer diameter OD (mm) are given by the following relational expression: OD(mm)≧-0.0187×SW(mm) 2 Satisfying +9.15 × SW(mm) - 380(mm), The carcass has a first tire widthwise portion in which the carcass cords are arranged radially, and a second tire widthwise portion in which the carcass cords extend inclined with respect to the tire circumferential direction. The carcass has a carcass body portion that extends from the bead portion to the inner side of the belt in the tire radial direction, The second tire widthwise portion is located on the outer half of the tire widthwise when mounted on the vehicle. A pneumatic radial tire for passenger cars, characterized in that the carcass cords and belt cords of the carcass body in the second tire width direction portion extend in directions that intersect each other when viewed from the outside in the tire radial direction. Here, "extending in directions that intersect each other" is not limited to cases where the cords intersect when viewed from the outside in the radial direction of the tire, but also includes cases where the carcass cords or belt cords intersect when extended.

[0007] In this specification, "rim" refers to the standard rim for the applicable size (Measuring Rim in the ETRTO STANDARDS MANUAL, Design Rim in the TRA YEAR BOOK) which is an industrial standard valid in the region where the tire is produced and used, and which is listed or will be listed in the future in the STANDARDS MANUAL of the ETRTO (The European Tyre and Rim Technical Organisation) in Japan, the STANDARDS MANUAL of the ETRTO (The European Tyre and Rim Technical Organisation) in Europe, and the YEAR BOOK of the TRA (The Tire and Rim Association, Inc.) in the United States. (That is, the "rim" in "wheel" above includes not only current sizes but also sizes that may be included in the above industrial standards in the future. An example of "sizes that will be listed in the future" is the size listed as "FUTURE DEVELOPMENTS" in the ETRTO 2013 edition.) However, in the case of a size not listed in the above industrial standards, it refers to a rim with a width corresponding to the width of the tire bead. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating as described in JATMA, etc., and in the case of sizes not listed in the above industrial standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Furthermore, "maximum load capacity" refers to the load corresponding to the maximum load capacity mentioned above.

[0008] (2) The pneumatic radial tire for passenger cars as described in (1) above, wherein the angle of inclination of the carcass cords of the carcass body portion in the second tire width direction portion with respect to the tire circumferential direction is greater than the angle of inclination of the belt cords with respect to the tire circumferential direction.

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

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

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

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

[0013] (7) A pneumatic radial tire for a passenger car according to any one of (1) to (5) above, wherein the carcass comprises a first carcass extending from the bead portion of the 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 the bead portion of 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. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a pneumatic radial tire for a passenger car that can reduce the weight of the tire by having only one inclined belt layer, improve the ground contact shape, and suppress a decrease in driving performance.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram schematically showing the ground contact shape in the case of having only one inclined belt layer. [Figure 2] It is a schematic diagram showing the sectional width SW and outer diameter OD of the tire. [Figure 3] It is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger car according to an embodiment of the present invention. [Figure 4] It is a diagram schematically showing the structures of the carcass, belt, and cap ply. [Figure 5] It is a schematic diagram of another carcass structure. [Figure 6] It is a diagram schematically showing the improvement of the ground contact shape. [Figure 7] It is a diagram schematically showing another example of the structures of the carcass, belt, and cap ply. [Figure 8] It is a diagram for explaining the arrangement of RFID. [Figure 9] It is a cross-sectional view in the tire width direction of a modified pneumatic radial tire for a passenger car.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be exemplified and described in detail with reference to the drawings.

[0017] FIG. 2 is a schematic diagram showing the sectional width SW and outer diameter OD of the tire. One embodiment of a passenger car pneumatic radial tire (hereinafter also simply referred to as "tire") has a tire cross section width SW of less than 165 mm, and a ratio SW / OD of the tire cross section width SW to the outer diameter OD of 0.26 or less, resulting in a narrow width and large diameter shape. By making the tire cross section width SW narrower than the tire outer diameter OD, air resistance can be reduced, and by making the tire outer diameter OD larger than the tire cross section width SW, deformation of the tread rubber near the contact surface of the tire can be suppressed, thereby reducing rolling resistance, and thus improving the fuel efficiency of the tire. The SW / OD is preferably 0.25 or less, and more preferably 0.24 or less. The above ratio is preferably met when the tire's internal pressure is 200 kPa or higher, more preferably when it is 220 kPa or higher, and even more preferably when it is 280 kPa or higher, because it can reduce rolling resistance. On the other hand, the above ratio is preferably met when the tire's internal pressure is 350 kPa or lower, because it can improve ride comfort. Here, the tire section width SW is preferably 105 to 145 mm, and more preferably 115 to 135 mm. Furthermore, when the tire's cross-sectional width SW and outer diameter OD satisfy the above ratio, the aspect ratio of the tire is more preferably 45 to 70, and more preferably 45 to 65. While there are no specific limitations on tire sizes, some 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, and 145 / 5 The tire size can be any of the following: 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's section width SW is less than 165 mm, and the tire's section width SW (mm) and outer diameter OD (mm) are related by the following formula: OD(mm)≧-0.0187×SW(mm) 2 +9.15 × SW (mm) - 380 It satisfies the requirements and has a narrow width and large diameter shape. By satisfying the above relationship, air resistance and rolling resistance can be reduced, thereby improving the fuel efficiency of the tire. In the third embodiment, the tire's cross-sectional width SW and outer diameter OD are preferably such that the ratio SW / OD satisfies the above relationship, is 0.26 or less, more preferably 0.25 or less, and even more preferably 0.24 or less. This is because it can further improve the tire's fuel efficiency. 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 it can reduce 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 it can improve ride comfort. Here, the tire section width SW is preferably 105 to 145 mm, and more preferably 115 to 135 mm. Furthermore, when the tire's cross-sectional width SW and outer diameter OD satisfy the above relationship, the aspect ratio of the tire is more preferably 45 to 70, and more preferably 45 to 65. While there are no specific limitations on tire sizes, some 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, and 145 / 5 The tire size can be any of the following: 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. This tire is particularly suitable for use on personal mobility vehicles.

[0020] Figure 3 is a cross-sectional view in the width direction of a pneumatic radial tire for a passenger car according to one embodiment of the present invention. Figure 3 shows a cross-sectional view in the width direction of the tire in a standard state, with the tire mounted on a rim, filled to a specified internal pressure, and unloaded. As shown in Figure 3, the tire 1 comprises a carcass 3 consisting of one or more carcass plies made of carcass cords covered with rubber. The tire 1 also comprises a belt 4 and a tread 5 in sequence on the radially outer side of the crown portion of the carcass 3, consisting of only one inclined belt layer made of belt plies made of belt cords covered with rubber that extend inclined with respect to the circumferential direction of the tire.

[0021] In this example, a bead core 2a is embedded in each of the pair of bead portions 2. In this invention, the cross-sectional shape and material of the bead core 2a are not particularly limited and can be a configuration commonly used in pneumatic radial tires for passenger cars. In this invention, the bead core 2a can also be divided into a plurality of small bead cores. Alternatively, in this invention, a configuration without a bead core 2a is also possible.

[0022] The illustrated example tire 1 has a bead filler 2b with a substantially triangular cross-section on the radially outer side of the bead core 2a. The cross-sectional shape of the bead filler 2b is not limited to this example, nor is the material particularly limited. Alternatively, the tire can be made lighter by omitting the bead filler 2b.

[0023] In this embodiment, the tire 1 may have a rim guard. Furthermore, in this embodiment, additional members such as rubber layers or cord layers may be provided in the bead portion 2 for reinforcement or other purposes. Such additional members can be provided at various positions relative to the carcass 3 and bead filler 2b.

[0024] In the example shown in Figure 3, the carcass 3 consists 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 Figure 4, the carcass 3 has a first tire widthwise portion 301 in which the carcass cords are arranged radially, and a second tire widthwise portion 302 in which the carcass cords extend inclined with respect to the tire circumferential direction, and the second tire widthwise portion 302 is located on the outer half of the tire widthwise when mounted on the vehicle (only a part of this half in the illustrated example). In the example shown in Figure 3, the carcass 3 has a carcass body portion 3a that straddles a pair of bead portions 2 in a toroidal manner, and a folded portion 3b that is folded back from the carcass body portion 3a around the bead core 2a. The carcass 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 portion 3b can be wrapped around the bead core 2a, or it can be sandwiched between a plurality of divided small bead cores. The end 3c of the carcass folded portion 3b is located radially outward from the outer end of the bead filler 2b in the tire radial direction, and radially inward from the tire's maximum width position. This makes it possible to lighten the tire while ensuring the rigidity of the sidewall. On the other hand, in the present invention, the end 3c of the carcass folded portion 3b may be located radially inward from the outer end of the bead filler 2b in the tire radial direction, or radially outward from the tire's maximum width position. Alternatively, the end 3c of the carcass folded portion 3b can be an envelope structure located radially between the carcass body 2a and the belt 4, and radially inward from the end of the belt 4 (for example, the end of the belt layer 4b). Furthermore, if the carcass 3 is composed of multiple carcass plies, the positions of the ends 3c of the carcass folded portion 3b (e.g., the position in the radial direction of the tire) can be the same or different between the carcass plies. The number of cords driven into the carcass 3 is not particularly limited, but can be in the range of 20 to 60 cords / 50 mm, for example. Also, various structures can be adopted for the carcass lines.For example, in the radial direction of the tire, the maximum width position of the carcass can be brought closer to the bead portion 2 side or closer to the tread 5 side. For example, the maximum width position of the carcass can be set in the range of 50% to 90% of the tire cross-sectional height relative to the bead baseline, radially outward from the bead baseline. The above "radial arrangement" is 85° or more with respect to the circumferential direction of the tire, preferably 90° with respect to the circumferential direction of the tire. As shown in Figure 4, due to the folding of the carcass, the inclination direction of the belt cord in the second tire width direction portion 302 is opposite in the carcass body portion 3a and the carcass folded portion 3b, as shown in the figure. As shown in Figure 3, the carcass 3 can be configured to straddle the pair of bead portions 2 in a toroidal manner. Alternatively, as schematically shown in Figure 5, the carcass 3 may have a configuration comprising a first carcass 351 extending from the bead portion 2 in the widthwise half of the outer tire when mounted on the vehicle to the radially inner side of the belt 4, and a second carcass 352 extending from the bead portion 2 in the widthwise half of the inner tire when mounted on the vehicle to the radially inner side of the belt. In order to improve the rigidity of the outer side when mounted on the vehicle, which contributes greatly to the dynamic performance, the second carcass 352 may have a radially extended portion 352a that extends from the radially outer side to the inner side of the first carcass 351 and terminates on or near the radially extended side of the bead portion in the widthwise half of the outer tire when mounted on the vehicle, as shown in the figure, or it may be configured without the radially extended portion 352a for weight reduction.

[0025] The tire of this embodiment preferably has only one inclined belt layer, which consists of a belt ply made of a belt cord that extends inclined with respect to the circumferential direction of the tire and is covered with rubber. 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. The "contact width" refers to the distance in the tire width direction between the contact ends E. The "contact ends" refer to both ends in the tire width direction of the contact surface when the tire is mounted on the rim, filled to the specified internal pressure, and subjected to the maximum load. In this embodiment, metal cords, particularly steel cords, are most preferably used as the belt cords for the belt layer, but non-metallic materials, such as organic fiber cords (e.g., Kevlar®), can also be used. Steel cords mainly consist of steel and may contain various trace elements such as carbon, manganese, silicon, phosphorus, sulfur, copper, and chromium. In this embodiment, monofilament cords, cords made of multiple filaments, and cords made of multiple filaments twisted together can be used for the belt cords in the belt layer. Various twisting structures can be adopted, and the cross-sectional structure, twist pitch, twisting direction, and distance between adjacent filaments can also vary. Furthermore, cords made of filaments of different materials twisted together can be used, and the cross-sectional structure is not particularly limited, with various twisting structures such as single twist, layer twist, and multi-twist being possible. In this embodiment, it is preferable that the inclination angle of the belt cords in the belt layer be 10° or more with respect to the tire circumferential direction. In this embodiment, it is preferable that the inclination angle of the belt cords in the belt layer be a high angle, specifically 20° or more with respect to the tire circumferential direction, and particularly in the range of 20° to 45° with respect to the tire circumferential direction. This is because setting the inclination angle to 20° or more increases the rigidity in the tire width direction, which can improve handling stability, especially during cornering. It is also because it can reduce shear deformation of the interlayer rubber, thereby reducing rolling resistance.

[0026] In this embodiment, as shown in Figure 4, the carcass cords and belt cords of the carcass body 3a in the second tire widthwise portion 302 extend in directions that intersect each other when viewed from the outside in the tire radial direction. The inclination angle of the carcass cords of the carcass body 3a in the second tire widthwise portion 302 with respect to the tire circumferential direction is greater 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 body 3a in the second tire widthwise 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 widthwise portion 301. In the illustrated example, the width of the cap layer 8 in the tire widthwise direction is smaller than the width of the belt 4 in the tire widthwise direction. Preferably, the position of the inner end of the second tire width direction portion 302 in the tire width direction is such that it is spaced 10 to 40% of the width of the belt 4 in the tire width direction outward from the tire width direction end of the belt 4.

[0027] In the illustrated example, the tread rubber constituting the tread 5 consists of one layer. However, in this embodiment, the tread rubber constituting the tread 5 may be formed by laminating multiple different rubber layers in the tire radial direction. The multiple rubber layers can have different tangent loss, modulus, hardness, glass transition temperature, material, etc. Furthermore, the ratio of the thicknesses of the multiple rubber layers in the tire radial direction may change in the tire width direction, and the bottom of the circumferential main groove, for example, may be made of a different rubber layer from the surrounding area. The tread rubber constituting the tread 5 may also be formed of multiple different rubber layers in the tire width direction. The multiple rubber layers can have different tangent loss, modulus, hardness, glass transition temperature, material, etc. Furthermore, the ratio of the widths of the multiple rubber layers in the tire width direction may change in the tire radial direction, and only a limited part of the area, such as only near the circumferential main groove, only near the contact edge, only the shoulder land area, or only the center land area, may be made of a different rubber layer from the surrounding area.

[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 inner surface 6 of the tire). The thickness of the inner liner 7 is preferably about 1.5 mm to 2.8 mm. This is because it can effectively reduce in-vehicle noise in the 80 to 100 Hz range. The air permeability coefficient of the rubber composition constituting the inner liner 7 is 1.0 × 10⁻⁶. -14 cc·cm / (cm 2 ·s·cmHg) or more, 6.5×10 -10 cc·cm / (cm 2 It is preferable that the value be less than or equal to (s·cmHg).

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

[0030] The cap layer 8 is formed by a ribbon-shaped member consisting of a rubberized layer of cords arranged substantially parallel to each other, which is wound spirally in the circumferential direction of the tire. 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. For example, organic fiber cords can be used for the cords of the cap layer 8.

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

[0032] The pneumatic radial tire for passenger cars in this embodiment is a narrow-width, large-diameter tire in which the tire's cross-sectional width SW and the tire's outer diameter satisfy the above-mentioned relationship, and in particular, the cross-sectional width SW is less than 165 mm. With such a tire, air resistance can be reduced, and rolling resistance can also be reduced, thereby improving the tire's fuel efficiency. In this embodiment, the tire is equipped with a belt consisting of only one inclined belt layer, so the tread rubber is less likely to stretch in the direction of the inclination of the belt cord (upward to the right and downward to the left in Figure 4). In contrast, the tire of this embodiment further has a first tire widthwise portion 301 having radially arranged carcass cords and a second tire widthwise portion 302 having inclined carcass cords. When mounted on a vehicle, the carcass cords and belt cords of the carcass body portion 3a in the second tire widthwise portion 302, which is located in the outer half of the tire widthwise, extend in directions that intersect each other when viewed from the outside in the radial direction of the tire. As a result, a force acts on the carcass cords of the carcass body portion 3a in the second tire widthwise portion 302 to restore them to a radial arrangement, which promotes the stretching of the tread rubber in the direction of this force (upward to the right and downward to the left in Figure 4). This mitigates the difficulty of the tread rubber stretching in the direction of the belt cord's inclination, improving the contact shape as schematically shown in Figure 6, and thereby improving handling stability and other dynamic performance characteristics.

[0033] Here, it is preferable that the inclination angle of the carcass cords of the carcass body portion 3a in the second tire width direction portion 302 with respect to the tire circumferential direction is greater 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 greater than the inclination angle of the belt cords with respect to the tire circumferential direction, it is possible to ensure rigidity to support the load and lateral rigidity, and torsional deformation to correct the contact shape.

[0034] Furthermore, the inclination angle of the carcass cords of the carcass body portion 3a in the second tire width direction portion 302 with respect to the tire circumferential direction is preferably 70 to 88°. This is because setting it to 70° or more allows for a balance between torsional deformation and rigidity, while setting it to 88° or less allows for sufficient restoring force against torsion. For similar reasons, it is even more preferable that the inclination angle be 76 to 84°.

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

[0036] As shown in Figure 7, the tire further has a third tire widthwise portion 303 that is different from the second tire widthwise portion 302 in which the carcass cords extend at an inclination with respect to the tire circumferential direction. The third tire widthwise portion 303 is located in the inner half of the tire widthwise when mounted on the vehicle, and it is preferable that the carcass cords and belt cords of the carcass body portion 3a in the third tire widthwise portion 303 extend in directions that intersect each other when viewed from the outer side in the radial direction of the tire. Even in the inner half when mounted on the vehicle, the force that attempts to restore the radial arrangement of the carcass cords of the carcass body portion 3a in the third tire widthwise portion 303 promotes the stretching of the tread rubber in the direction of the force (upward to the right and downward to the left in Figure 7), further mitigating the difficulty of the tread rubber stretching in the inclination direction of the belt cords. Therefore, the contact shape can be further improved and the handling performance can be further enhanced. In addition, for passenger car pneumatic radial tires, the tire may be mounted on the left wheel of the vehicle, and the belt cord may extend in a sloping manner from the lower left to the upper right when viewed from the outside in the radial direction of the tire (Figure 7), or it may be mounted on the right wheel of the vehicle, and the belt cord may extend in a sloping manner from the lower right to the upper left when viewed from the outside in the radial direction of the tire.

[0037] Furthermore, the carcass 3 can straddle the pair of bead portions 2 in a toroidal manner, or, as shown in Figure 5, the carcass 3 can have a first carcass 351 extending from the bead portion 2 in the outer half of the tire width direction when mounted on the 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 in the inner half of the tire width direction when mounted on the vehicle to the inner side of the belt 4 in the tire radial direction. Furthermore, as shown in Figure 9, let m1 be a straight line passing through a point on the tread surface at the tire's equatorial plane and parallel to the tire's width direction, and let m2 be a straight line passing through the contact end E and parallel to the tire's width direction. The distance between lines m1 and m2 in the tire's radial direction is the drop height L. CR Let TW be the tread width of the tire, and the ratio L CR It is preferable that / TW is greater than 0.045. This results in a relatively rounded crown shape, allowing the contact patch to be rounded, with the contact length of the shoulder portion being shorter than that of the center portion. This prevents the contact patch from becoming too elongated when the camber angle changes, further suppressing deterioration of the contact patch. "Contact edge" refers to both ends of the tire width direction of the contact surface (the surface that contacts the road surface) when the tire is mounted on the rim, filled 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 the rim, filled to the specified internal pressure, and unloaded.

[0038] <Tire and rim assembly> The tire-rim assembly described here is formed by incorporating the above-mentioned pneumatic radial tire for passenger cars into a rim. With this tire-rim assembly, the same effects and advantages as those described for the above-mentioned pneumatic radial tire for passenger cars can be obtained. 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 higher 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. This is because it can improve ride comfort.

[0039] <How to use pneumatic radial tires for passenger cars> The method of using the passenger car pneumatic radial tire described here involves using the passenger car pneumatic radial tire described above. By using the passenger car pneumatic radial tire in this manner, the same effects and advantages as those described above can be obtained. In this case, it is preferable to use an internal pressure of 200 kPa or higher, more preferably 220 kPa or higher, and even more preferably 280 kPa or higher. This is because a higher internal pressure can further reduce rolling resistance. On the other hand, it is preferable to use an internal pressure of 350 kPa or lower. This is because it can improve ride comfort.

[0040] <Examples with communication devices> As shown in Figure 8, the tire may be equipped with an RF tag as a communication device 500. The RF tag comprises an IC chip and an antenna. The RF tag may be positioned, for example, sandwiched between multiple identical or different components that make up the tire. This makes it easier to attach the RF tag during tire production and improves the productivity of tires equipped with RF tags. In this example, the RF tag may be positioned, for example, sandwiched between the bead filler and other components adjacent to the bead filler. The RF tag may also be embedded within any of the components that make up the tire. This reduces the load on the RF tag compared to when it 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 within a rubber component such as tread rubber or side rubber. It is preferable that the RF tag is not positioned at a boundary between components with different rigidity 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. This prevents the RF tag from being positioned in a location where strain is likely to concentrate due to rigidity differences. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. In this example, it is preferable that the RF tag is not placed at a boundary between the end of the carcass and a member adjacent to the end of the carcass (e.g., side rubber) in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. A tire may have only one RF tag or two or more RF tags. Here, an RF tag is used as an example of a communication device, but a different communication device may be used.

[0041] The RF tag may be placed, for example, on the tire tread. In this way, the RF tag will not be damaged by side cuts of the tire. The RF tag may be placed, for example, in the center of the tread in the tire width direction. The center of the tread is a position where flexing is less likely to concentrate in the tread. In this way, the load on the RF tag can be reduced. This can improve the durability of the RF tag. In addition, differences in communication with the RF tag from both outer sides of the tire in the tire width direction can be suppressed. In this example, the RF tag may be placed, for example, within a range of 1 / 2 of the tread width centered on the tire equator in the tire width direction. The RF tag may be placed, for example, at the tread edge in the tire width direction. If the position of the reader that communicates with the RF tag is predetermined, the RF tag may be placed, for example, at one tread edge close to this reader. In this example, the RF tag may be placed, for example, within a range of 1 / 4 of the tread width in the tire width direction, with the tread edge as the outer edge.

[0042] The RF tag may be positioned on the inner side of the tire cavity, for example, beyond the carcass, which includes one or more carcass plies that span between the bead portions. This makes the RF tag less susceptible to damage from impacts applied from outside the tire, such as side cuts or nail punctures. As an example, the RF tag may be positioned in close contact with the inner surface of the carcass facing the inner cavity. As another example, if there is another component on the inner side of the tire cavity beyond the carcass, the RF tag may be positioned, for example, between the carcass and the other component located on the inner side of the carcass facing the inner cavity. An example of another component located on the inner side of the tire cavity beyond the carcass is the inner liner that forms the inner surface of the tire. As yet another example, the RF tag may be attached to the inner surface of the tire facing the inner cavity. By configuring the RF tag to be attached to the inner surface of the tire, it becomes easier to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the ease of attachment and maintenance of 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 a tire failure compared to a configuration in which the RF tag is embedded inside the tire. Also, if the carcass has multiple carcass plies and there are positions where multiple carcass plies overlap, the RF tag may be placed between the overlapping carcass plies.

[0043] The RF tag may be positioned, for example, on the tire tread, outside the belt consisting of only one belt ply in the tire radial direction. For example, the RF tag may be positioned outside the belt in the tire radial direction, in close contact with the belt. Another example is when a reinforcing belt layer is provided, in which case the RF tag may be positioned outside the reinforcing belt layer in the tire radial direction, in close contact with the reinforcing belt layer. Another example is when the RF tag is embedded in the tread rubber, outside the belt in the tire radial direction. By positioning the RF tag on the tire tread, outside the belt in the tire radial direction, communication with the RF tag from the outside of the tire in the tire radial direction is less likely to be hindered by the belt. Therefore, communication with the RF tag from the outside of the tire in the tire radial direction can be improved. Alternatively, the RF tag may be positioned, for example, on the tire tread, inside the belt in the tire radial direction. In this way, the outside of the RF tag in the tire radial direction is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail punctures. As an example, the RF tag may be positioned in the tire tread between the belt and the carcass located radially inward from the belt.

[0044] The RF tag may be placed, for example, in the sidewall or bead portion of the tire. The RF tag may be placed, for example, in the sidewall or bead portion on one side that is close to the reader that can communicate with the RF tag. This improves the communication between the RF tag and the reader. As an example, the RF tag may be placed between the carcass and the side rubber, or between the tread rubber and the side rubber. The RF tag may be placed, for example, between the position of the tire's maximum width and the position of the tread surface in the tire's radial direction. This improves the communication between the RF tag and the outside of the tire in the tire's radial direction compared to a configuration where the RF tag is placed inside the tire's maximum width position in the tire's radial direction. The RF tag may be placed, for example, inside the tire's maximum width position in the tire's radial direction. This places the RF tag near the highly rigid bead portion. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. As an example, the RF tag may be placed adjacent to the bead core in the tire's radial or tire width direction. Strain is less likely to concentrate near the bead core. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. In particular, it is preferable to position the RF tag radially inward from the position of the tire's maximum width, and radially outward from the bead core of the bead portion. By doing so, the durability of the RF tag can be improved, and communication between the RF tag and the reader is less likely to be hindered by the bead core, thereby improving the communication performance of the RF tag. Furthermore, if the side rubber is composed of multiple identical or different rubber members adjacent in the radial direction of the tire, the RF tag may be positioned sandwiched between the multiple rubber members that make up the side rubber.

[0045] The RF tag may be positioned sandwiched between the bead filler and a member adjacent to the bead filler. In this way, the RF tag can be positioned in a location where strain is less likely to concentrate due to the placement of the bead filler. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. The RF tag may also be positioned sandwiched between, for example, the bead filler and the carcass. The part of the carcass that sandwiches the RF tag together with the bead filler may be located on the outside in the tire width direction relative to the bead filler, or on the inside in the tire width direction. If the part of the carcass that sandwiches the RF tag together with the bead filler is located on the outside in the tire width direction relative to the bead filler, the load on the RF tag due to impacts and damage from the outside of the tire in the tire width direction can be further reduced. This improves the durability of the RF tag. The bead filler may also have a portion that is positioned adjacent to the side rubber. In such cases, the RF tag may be positioned sandwiched between the bead filler and the side rubber. Furthermore, the bead filler may have a portion positioned adjacent to the rubber chafer. In such cases, the RF tag may be positioned sandwiched between the bead filler and the rubber chafer.

[0046] The RF tag may be positioned, for example, sandwiched between a rubber chafer and a side rubber. In this way, the RF tag can be positioned in a location where strain is less likely to concentrate due to the placement of the rubber chafer. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. The RF tag may also be positioned, for example, sandwiched between a rubber chafer and a carcass. In this way, the load on the RF tag due to impacts and damage from the rim can be reduced. Therefore, the durability of the RF tag can be improved.

[0047] The RF tag may be disposed sandwiched between a wire chafer and another member adjacent to the inner or outer side of the wire chafer in the tire width direction. By doing so, when the tire is deformed, the position of the RF tag becomes difficult 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. Another member adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a rubber member such as a rubber chafer. Also, another member adjacent to the wire chafer on the inner or outer side 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 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 width direction position. By doing so, load noise and flat spots can be reduced without degrading high-speed durability.

[0049] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments at all. For example, in the above example, an example having a single layer of cap layer was shown, but for weight reduction of the tire, a configuration without a cap layer can also be adopted.

[0050] [Contribution to the Sustainable Development Goals (SDGs) led by the United Nations] SDGs have been proposed towards the realization of a sustainable society. One embodiment of the present invention can be considered as a technology that contributes to "No. 7 - Energy for all. And cleanly" and "No. 13 - Specific measures against climate change", etc. [Explanation of Symbols]

[0051] 1: Passenger car pneumatic radial tire (tire), 2: Bead section, 2a: Bead core, 2b: Bead filler, 3: Carcass, 301: First tire width direction portion, 302: Second tire width direction portion, 303: Third tire widthwise section, 4: Belt, 5: Tread, 6: Inner surface of tire, 7: Inner liner, 8: Cap layer, 500: Communication device, CL: Tire equatorial plane

Claims

1. A pair of bead sections, A carcass consisting of one or more carcass plies covered with rubber, A pneumatic radial tire for passenger cars comprising a belt consisting of only one inclined belt layer, which is made up of a belt ply made of a rubber-coated belt cord that extends inclined with respect to the circumferential direction of the tire and is positioned on the radially outer side of the crown portion of the carcass, The cross-sectional width SW of the aforementioned tire is less than 165 (mm), The ratio SW / OD of the tire's cross-sectional width SW to its outer diameter OD is 0.26 or less, or the tire's cross-sectional width SW (mm) and outer diameter OD (mm) are given by the following relational expression: OD (mm)≧-0.0187×SW (mm) ２ Satisfying +9.15 × SW (mm) - 380 (mm), The carcass has a first tire widthwise portion in which the carcass cords are arranged radially, and a second tire widthwise portion in which the carcass cords extend inclined with respect to the tire circumferential direction. The carcass has a carcass body portion that extends from the bead portion to the inner side of the belt in the tire radial direction, The aforementioned second tire widthwise portion is located on the outer half of the tire widthwise when mounted on the vehicle. In the second tire widthwise portion, the carcass cords and belt cords of the carcass body extend in directions that intersect each other when viewed from the outside in the tire radial direction. A pneumatic radial tire for passenger cars, characterized in that the position of the inner end in the tire width direction of the second tire width direction portion is 10 to 40% of the width of the belt in the tire width direction, located outward from the tire width direction end of the belt.

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

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

4. The aforementioned passenger car pneumatic radial tire is mounted on the left wheel of the vehicle. The aforementioned belt cord extends inclined from the lower left to the upper right when viewed from the outer side in the radial direction of the tire. The carcass cord further has a third tire widthwise portion that is different from the second tire widthwise portion that extends at an inclination with respect to the tire circumferential direction, The third tire widthwise portion is located on the inner half of the tire widthwise when mounted on the vehicle. The pneumatic radial tire for passenger cars according to claim 1 or 2, wherein the carcass cords and belt cords of the carcass body portion in the third tire width direction portion extend in directions that intersect each other when viewed from the outside in the tire radial direction.

5. The carcass straddles a pair of bead portions in a toroidal manner, as described in claim 1 or 2, for a pneumatic radial tire for a passenger car.

6. The pneumatic radial tire for a passenger car according to claim 1 or 2, wherein the carcass comprises a first carcass extending from the bead portion in the outer half of the tire width direction when mounted on a vehicle to the radially inner side of the belt, and a second carcass extending from the bead portion in the inner half of the tire width direction when mounted on a vehicle to the radially inner side of the belt.

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