Pneumatic radial tire for passenger vehicle

Abstract

Provided is a pneumatic radial tire for a passenger vehicle, in which a cross-sectional width (SW) of the tire and an outer diameter (OD) of the tire satisfy a predetermined relationship, and an end portion of a carcass (when the carcass has a carcass turn-back portion) in one half of the tire in a width direction, which is located on an inner side when the tire is mounted on a vehicle, the end portion of the carcass folded-back portion is located on the inside in the tire radial direction of the end portion of the carcass folded-back portion in another half portion in the tire width direction located on the outside when the tire is mounted on the vehicle.

Description

Technical Field

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

[0002] As a pneumatic radial tire for passenger cars that improves fuel efficiency, the applicant has proposed a narrow-width, large-diameter pneumatic radial tire for passenger cars having a predetermined relationship between the tire's section width SW and outer diameter OD (eg, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: WO 2011 / 135774 A1 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The above-mentioned narrow width and large diameter pneumatic radial tires for passenger cars are designed to achieve low fuel consumption, and therefore, it is desirable to simplify the structure to further reduce fuel consumption by weight reduction. In addition, pneumatic radial tires for passenger cars such as those with narrow width and large diameter are often used at high internal pressures, and by using the tires at high internal pressures, rolling resistance is reduced, and there is a concern that ride comfort will deteriorate. Therefore, from this perspective, it is desirable to simplify the structure in order to reduce the longitudinal spring coefficient.

[0008] However, if the structure is simplified, the cut resistance against external damage caused by a curb, etc. is reduced. On the other hand, if additional components are added in order to improve the cut resistance, the weight increases and the fuel efficiency deteriorates.

[0009] Therefore, an object of the present disclosure is to provide a pneumatic radial tire for a passenger vehicle that achieves both high fuel efficiency and cutting resistance.

[0010] Solutions for solving problems

[0011] The main points of the present invention are as follows:

[0012] (1) A pneumatic radial tire for a passenger vehicle, comprising

[0013] a pair of bead portions;

[0014] a carcass composed of one or more carcass plies spanning in a toroidal manner between the pair of bead portions; and

[0015] The belt portion is composed of one or more belt layers arranged on the outer side of the crown portion of the carcass in the radial direction of the tire, wherein:

[0016] The carcass is composed of a carcass main body portion and a carcass folded portion, wherein the carcass main body portion is annularly spanned between the pair of bead portions, and the carcass folded portion is folded back from the carcass main body portion around a bead core buried in the bead portion.

[0017] The cross-sectional width SW of the tire is less than 165 (mm), and the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD of the tire is 0.26 or less, or the cross-sectional width SW of the tire is 165 (mm) or more, and the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ 2.135 × SW (mm) + 282.3 (mm), or the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ -0.0187 × SW (mm) 2 +9.15×SW(mm)-380(mm), and

[0018] An end of the carcass folded portion in one tire widthwise half located on the inner side when the tire is mounted on the vehicle is located radially inside of an end of the carcass folded portion in the other tire widthwise half located on the outer side when the tire is mounted on the vehicle.

[0019] As used herein, the term "rim" refers to a standard rim of an applicable size described or that may be described in the future in an industrial standard effective for a region where tires are produced and used (such as the JATMA Yearbook of JATMA (Japan Automobile Tire Manufacturers Association) in Japan, the standard manual of ETRTO (European Tire and Rim Technical Organization) in Europe, and the yearbook of TRA (Tire and Rim Association) in the United States) (that is, the "rim" of the above-mentioned "wheel" includes current sizes as well as sizes to be described in the future in the above-mentioned industrial standards. An example of a "size to be described in the future" may be a size listed as "future development" in the 2013 edition of ETRTO), however, for sizes not listed in these industrial standards, the term "rim" refers to a rim having a width corresponding to the bead width of the tire.

[0020] In addition, the term "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel of applicable size and ply grade as described in the above-mentioned JATMA Yearbook and other industrial standards. In the case of a size not listed in the above-mentioned industrial standards, the term "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 installed.

[0021] Furthermore, the term "maximum load" refers to a load corresponding to the above-mentioned maximum load capacity.

[0022] (2) A pneumatic radial tire for a passenger vehicle, comprising

[0023] a pair of bead portions;

[0024] a carcass composed of one or more carcass plies spanning in a toroidal manner between the pair of bead portions; and

[0025] The belt portion is composed of one or more belt layers arranged on the outer side of the crown portion of the carcass in the radial direction of the tire, wherein:

[0026] The cross-sectional width SW of the tire is less than 165 (mm), and the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD of the tire is 0.26 or less, or the cross-sectional width SW of the tire is 165 (mm) or more, and the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ 2.135 × SW (mm) + 282.3 (mm), or the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ -0.0187 × SW (mm) 2 +9.15×SW(mm)-380(mm),

[0027] In one tire width direction half portion located on the inner side when the tire is mounted on a vehicle, the carcass is wound around a bead core buried in the bead portion and terminated therein, and,

[0028] In the other tire widthwise half located on the outside when the tire is mounted on a vehicle, the carcass is composed of a carcass main body portion and a carcass folded back portion, the carcass main body portion spanning between the pair of bead portions in an annular shape, and the carcass folded back portion folded back from the carcass main body portion around a bead core buried in the bead portion,

[0029] An end of the carcass in one tire widthwise half located inside when the tire is mounted on a vehicle is located radially inside of an end of the carcass folded portion in the other tire widthwise half located outside when the tire is mounted on a vehicle.

[0030] As used herein, “the radius of curvature of the sidewall portion” shall mean the radius of an arc when the outer contour line of the sidewall portion is approximated with an arc using the least square method in the tire width direction cross section in the above state.

[0031] Effects of the Invention

[0032] According to the present disclosure, a pneumatic radial tire for a passenger vehicle that achieves both high fuel efficiency and cut resistance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In the attached figure:

[0034] Figure 1 is a schematic diagram illustrating the cross-sectional width SW and the outer diameter OD of a tire;

[0035] Figure 2 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to one embodiment of the present disclosure;

[0036] Figure 3 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to another embodiment of the present disclosure;

[0037] Figure 4 is a diagram for explaining the configuration of an RFID;

[0038] Figure 5 is a diagram for explaining a WIND bead; and

[0039] Figure 6 1 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to a modification. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0041] Figure 1 Schematic diagram illustrating the cross-sectional width SW and the outer diameter OD of the tire. In the pneumatic radial tire for a passenger vehicle (hereinafter, simply referred to as "tire") according to one embodiment of the present disclosure, it is preferred that: when the cross-sectional width SW of the tire is less than 165 (mm), the ratio SW / OD of the cross-sectional width SW to the outer diameter OD of the tire is 0.26 or less, and when the cross-sectional width SW of the tire is 165 (mm) or more, the cross-sectional width SW (mm) and the outer diameter OD (mm) of the tire satisfy the following relational expression:

[0042] OD(mm)≥2.135×SW(mm)+282.3(mm)

[0043] (Hereinafter, referred to as "relational expression (1)").

[0044] By satisfying the ratio (SW / OD) or relationship expression (1), the cross-sectional width SW of the tire becomes relatively smaller than the outer diameter OD of the tire, which reduces air impedance, and in addition, the narrower cross-sectional width allows more space in the vehicle, and in particular, allows more space for installing drive components near the inner side of the tire when the tire is installed on the vehicle.

[0045] Furthermore, by satisfying the ratio (SW / OD) or relational expression (1), the outer diameter OD of the tire becomes relatively larger compared to the cross-sectional width SW of the tire, which reduces rolling resistance, and further, the larger diameter of the tire raises the axle, which increases the space under the floor, allowing more space in the trunk and other areas of the vehicle, and also allowing more space for mounting drive components.

[0046] As described above, by satisfying the ratio SW / OD or the relational expression (1), high fuel efficiency for supplying electric energy can be achieved and a large amount of space in the vehicle can also be ensured.

[0047] In addition, it is preferred that the cross-sectional width SW (mm) and the outer diameter OD (mm) of the tire satisfy the following relational expression:

[0048] OD(mm)≥-0.0187×SW(mm) 2 +9.15×SW(mm)-380(mm)

[0049] (hereinafter referred to as "relational expression (2)")

[0050] By satisfying relationship expression (2), the cross-sectional width SW of the tire becomes relatively small compared to the outer diameter OD of the tire, which reduces air impedance, and in addition, the narrower cross-sectional width allows more space in the vehicle, and in particular, allows more space for installing drive components near the inner side of the tire when the tire is mounted on the vehicle.

[0051] Furthermore, by satisfying relational expression (2), the outer diameter OD of the tire becomes relatively larger compared to the cross-sectional width SW of the tire, which reduces rolling resistance, and further, the larger diameter of the tire raises the axle, which increases the space under the floor, allowing more space in the trunk and other areas of the vehicle, and also allowing more space for mounting drive components.

[0052] In each of the above examples, the tire preferably satisfies the ratio SW / OD and / or relational expression (2), or satisfies relational expression (1) and / or relational expression (2).

[0053] Figure 2 1 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to one embodiment of the present disclosure. Figure 2 The figure shows a cross-sectional view in the tire width direction of the tire under the reference condition when the tire is mounted on the rim, filled to a specified internal pressure and without load. Figure 2As shown, the tire 1 includes a carcass 3, which is composed of one or more layers of cords made of meridian-arranged cords annularly spanning between a pair of bead portions 2. In addition, the tire 1 includes a belt portion 4 composed of two belt layers 4a and 4b in the example shown, and a tread 5 in sequence on the tire radial direction outer side of the carcass 3.

[0054] In this example, a bead core 2a is embedded in each bead portion 2. In the present disclosure, the cross-sectional shape and material of the bead core 2a are not particularly limited, and can be made to have a structure commonly used in pneumatic radial tires for passenger cars. In the present disclosure, the bead core 2a can be divided into a plurality of small bead cores. Alternatively, in the present disclosure, the bead portion 2 can be constructed without a bead core 2a.

[0055] In the example shown, the tire 1 has a bead filler 2b having a substantially triangular cross section outside the bead core 2a in the tire radial direction. The cross-sectional shape of the bead filler 2b is not limited to this example, and the material is also not limited to this example. Alternatively, the tire can be lightweighted by omitting the bead filler 2b.

[0056] In this embodiment, the tire 1 may also have a rim protection portion. In addition, in this embodiment, the bead portion 2 may also have additional components, such as a rubber layer or a cord layer for reinforcement purposes. These additional components may be arranged at various positions relative to the carcass 3 and the bead filler 2b.

[0057] exist Figure 2 In the example shown, the carcass 3 is composed of a single carcass ply. On the other hand, in the present disclosure, the number of carcass plies is not particularly limited, and may be two or more layers. Figure 3In the example shown, the carcass 3 has a carcass main body portion 3a extending in a ring shape between the pair of bead portions 2 and a carcass folded-back portion 3b folded back from the carcass main body portion 3a around the bead core 2a. In the present embodiment, it is preferred that the end 3c of the carcass folded-back portion in one tire width direction half (right side in the figure) is located radially inward of the end 3c of the carcass folded-back portion in the other tire width direction half (left side in the figure). In the present example, the end 3c of the carcass folded-back portion 3b is located radially outward of the tire radial outer end of the bead filler 2b and radially inward of the tire at the position of maximum width of the tire. This makes it possible to lightweight the tire while maintaining the rigidity of the sidewall portion. On the other hand, in the present disclosure, the end 3c of the carcass folded-back portion 3b may be located radially inward of the tire radial outer end of the bead filler 2b, or it may be located radially outward of the tire at the position of maximum width of the tire. Alternatively, the carcass may have an encapsulation structure in which the end 3c of the carcass folded portion 3b is located on the tire width direction inner side of the end of the belt portion 4 (e.g., the end of the belt layer 4b), so that the end 3c of the carcass folded portion 3b is located between the carcass main body portion 2a and the belt portion 4 in the tire radial direction. In addition, for example, in one tire width direction half, the end 3c of the carcass folded portion 3b may be located on the tire radial direction outer side of the tire radial direction outer end of the bead filler 2b and on the tire radial direction inner side of the tire maximum width position, and in the other tire width direction half, the end 3c of the carcass folded portion 3b may be located on the tire radial direction outer side of the tire maximum width position. In addition, when the carcass 3 is composed of a plurality of carcass plies, the position (e.g., the position in the tire radial direction) of the end 3c of the carcass folded portion 3b may be the same or different between the carcass plies. There is no particular limitation on the number of carcass cords per unit width in the carcass 3, but, for example, it may be in the range of 20 to 60 cords / 50 mm. In addition, the carcass cord may adopt various structures. For example, in the radial direction of the tire, the carcass maximum width position may be close to the bead portion 2 side or to the tread portion 5 side. For example, the carcass maximum width position may be set within the range of 50% to 90% of the cross-sectional height of the tire from the bead base line to the radial outside of the tire. The above-mentioned "meridian configuration" refers to a configuration in which the carcass cords extend at an angle of 85° or more and preferably 90° relative to the circumferential direction of the tire.

[0058] In the present embodiment, the tire preferably has one or more inclined belt layers made of rubber-coated cord layers extending at an angle relative to the tire circumferential direction, and two layers are most preferred in terms of the balance between achieving lightweight and controlling the distortion of the shape of the contact patch. From the perspective of lightweight, the belt layer can be made into one layer, and from the perspective of controlling the distortion of the shape of the contact patch, the belt layer can be made into three or more layers. Figure 2In the example shown, of the two belt layers 4a and 4b, the tire width direction width of the belt layer 4b located on the outer side of the tire radial direction is smaller than the tire width direction width of the belt layer 4a located on the inner side of the tire radial direction. On the other hand, the tire width direction width of the belt layer 4b located on the outer side of the tire radial direction may be greater than or equal to the tire width direction width of the belt layer 4a located on the inner side of the tire radial direction. The tire width direction width of the belt layer having the maximum width in the tire width direction (in the example shown, the belt layer 4a) is preferably 90% to 115% of the ground contact width, and particularly preferably 100% to 105% of the ground contact width. It will be noted that the "ground contact width" refers to the distance between the ground contact ends E in the tire width direction. The "ground contact ends" refer to the two ends of the tire ground contact surface in the tire width direction when the tire is mounted on the rim, filled with a specified internal pressure and loaded with a maximum load.

[0059] In the present embodiment, as the belt cords of the belt layers 4a, 4b, metal cords, particularly steel cords, are most preferably used, but non-metal cords such as organic fiber cords (e.g., Kevlar (registered trademark) etc.) may also be used. Steel cords are mainly made of steel, and may also contain various trace elements such as carbon, manganese, silicon, phosphorus, sulfur, copper and chromium. In the present embodiment, the belt cords of the belt layers 4a, 4b may be monofilament cords, cords made of a plurality of filaments arranged in parallel, or cords made of a plurality of filaments twisted together. Various twisting structures may be used, and the cross-sectional structure, twisting pitch, twisting direction and distance between adjacent filaments may also be changed. In addition, cords made of twisted filaments of different materials may also be used, and there is no particular limitation on the cross-sectional structure, and various twisting structures such as single twist, layer twist and multi-twist may be used.

[0060] In the present embodiment, the inclination angle of the belt cords in the belt layers 4a, 4b relative to the tire circumferential direction is preferably 10° or more. In the present embodiment, the inclination angle of the belt cords in the belt layers 4a, 4b relative to the tire circumferential direction is preferably a higher angle, specifically 20° or more and preferably 35° or more, particularly in the range of 55° to 85° relative to the tire circumferential direction. This is because, by making the inclination angle 20° or more (preferably 35° or more), the rigidity in the tire width direction can be increased, and the steering stability performance, especially the steering stability performance during cornering, can be improved. In addition, this is because the rolling resistance is reduced by reducing the shear deformation of the interlayer rubber.

[0061] In the example shown, the tread rubber constituting the tread 5 is composed of a single layer. On the other hand, in the present embodiment, the tread rubber constituting the tread 5 can be formed by laminating a plurality of rubber layers in the tire radial direction. The plurality of rubber layers may have different loss tangents, moduli, hardness, glass transition temperatures, materials, etc. In addition, the thickness ratio of the plurality of rubber layers in the tire radial direction may vary in the tire width direction, and the bottom of the circumferential main groove, etc. may also be made of a rubber layer different from the peripheral area. In addition, the tread rubber constituting the tread 5 may be formed by a plurality of rubber layers different in the tire width direction. The plurality of rubber layers may have different loss tangents, moduli, hardness, glass transition temperatures, materials, etc. In addition, the width ratio of the plurality of rubber layers in the tire width direction may vary in the tire radial direction, and only a limited area (such as only the area near the circumferential main groove, only the area near the ground contact end, only the shoulder land portion, or only the central land portion, etc.) may have a rubber layer different from the peripheral area.

[0062] The tire 1 of this embodiment has an inner liner 8 on the inner surface 7 of the tire (referred to as the inner surface 7 of the tire for short), and the thickness of the inner liner 8 is preferably about 1.5 mm to 2.8 mm. This is because it can effectively reduce the noise inside the vehicle between 80 and 100 Hz. The air permeability coefficient of the rubber composition constituting the inner liner 8 is preferably 1.0×10 -14 cc·cm / (cm 2 ·s·cmHg) or greater and 6.5×10 -10 cc·cm / (cm 2 ·s·cmHg) or less.

[0063] The effects of the pneumatic radial tire for passenger vehicles according to the present embodiment will be described below. The effects when "one tire widthwise half" is located inside when the tire is mounted on a vehicle (when "the other tire widthwise half" is located outside when the tire is mounted on a vehicle) will be described below.

[0064] The pneumatic radial tire for passenger vehicles in this embodiment is a tire whose cross-sectional width SW and outer diameter satisfy the above-mentioned relational expressions (1) and / or (2). According to this tire, air resistance can be particularly reduced, and rolling resistance can also be reduced, thereby improving the fuel efficiency of the tire.

[0065] Furthermore, the end 3c of the carcass folded portion 3b in one tire widthwise half located on the inner side when the tire is mounted on the vehicle is located on the tire radially inner side of the end 3c of the carcass folded portion 3b in the other tire widthwise half located on the outer side when the tire is mounted on the vehicle. In this case, since the end 3c of the carcass folded portion 3b is located relatively on the tire radially outer side when the tire is mounted on the vehicle and is located on the outer side where cutting is likely to occur due to damage from a curb or the like, the resistance to external damage can be improved. On the other hand, compared with the case where the tire radial position of the end 3c of the carcass folded portion 3b located on the inner side when the tire is mounted on the vehicle is set in the same manner (located on the outer side when the tire is mounted on the vehicle), the tire can be made lighter, the rolling resistance can be reduced, and the fuel efficiency can be improved.

[0066] As described above, according to the pneumatic radial tire for a passenger vehicle of the present embodiment, a pneumatic radial tire for a passenger vehicle that achieves both high fuel efficiency and cut resistance can be provided.

[0067] As a variation of the above embodiment, in one tire width direction half located on the inner side when the tire is installed on the vehicle, the carcass 3 is wound around the bead core 2a buried in the bead portion 2 and terminates therein, and in the other tire width direction half located on the outer side when the tire is installed on the vehicle, the carcass 3 is composed of a carcass main body portion 3a spanning the pair of bead portions 2 in a ring shape and a carcass return portion 3b folded back from the carcass main body portion 3a around the bead core 2a buried in the bead portion 2, and the end of the carcass 3 in one tire width direction half located on the inner side when the tire is installed on the vehicle is located on the radial inside of the tire with respect to the end 3c of the carcass return portion 3b in the other tire width direction half located on the outer side when the tire is installed on the vehicle.

[0068] Even if the tire widthwise half located on the inner side when the tire is mounted on the vehicle adopts the so-called "WIND bead" structure (see Figure 5 ), if the end of the carcass 3 in one half of the tire width direction located on the inner side when the tire is mounted on the vehicle is located on the tire radial inner side of the end 3c of the carcass folded portion 3b in the other half of the tire width direction located on the outer side when the tire is mounted on the vehicle, the end 3c of the carcass folded portion 3b located on the outer side where cutting is likely to occur due to damage from the curb when the tire is mounted on the vehicle is relatively located on the tire radial outer side, thereby improving the resistance to external damage. On the other hand, compared with the case where the tire radial position of the end 3c of the carcass folded portion 3b located on the inner side when the tire is mounted on the vehicle is set in the same manner (located on the outer side when the tire is mounted on the vehicle), the tire can be made lighter, the rolling resistance can be reduced, and the fuel efficiency can be improved.

[0069] Figure 3 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to another embodiment of the present disclosure. Figure 3 The tires shown are Figure 2 The tire in the illustrated embodiment is different in that the shape of the outer contour line of the sidewall portion 8 of the tire is different between one tire width direction half and the other tire width direction half. In particular, in the tire width direction cross-sectional view of the pneumatic radial tire for a passenger car, when the tire is assembled on the rim, filled with an internal pressure of 30 kPa and without load, the curvature radius R1 of the sidewall portion 8 in one tire width direction half located on the inner side when the tire is mounted on the vehicle is smaller than the curvature radius R2 of the sidewall portion 8 on the other tire width direction half located on the outer side when the tire is mounted on the vehicle. (The curvature radius CR1 of the carcass in one tire width direction half located on the inner side when the tire is mounted on the vehicle is smaller than the curvature radius CR2 of the carcass on the other tire width direction half located on the outer side when the tire is mounted on the vehicle). This is because by making the curvature radius R2 of the sidewall portion 8 located on the outer side where cutting is likely to occur due to damage from the curb, etc. when the tire is mounted on the vehicle relatively large, the cutting resistance can be further improved. The "radius of curvature of the carcass" should mean the radius of an arc when the outer contour line of the carcass is approximated by an arc in the tire width direction cross section in the above state using the least square method.

[0070] In addition, when the distance in the tire radial direction between a straight line m1 passing through a point on the tread surface at the tire equatorial plane and parallel to the tire width direction and a straight line m2 passing through the ground contact end E and parallel to the tire width direction is defined as the drop height L CR When the tread width of the tire is defined as TW, the ratio L is preferably CR / TW is greater than 0.045. This allows the crown shape to be relatively round, and thereby the shape of the ground contact patch can be made rounder, with the ground contact length in the shoulder portion being shorter than the ground contact length in the center portion. This prevents the shape of the ground contact patch from becoming too narrow when the camber angle changes, and further controls the degradation of the shape of the ground contact patch. "Ground contact end" refers to the two ends of the ground contact patch (the portion in contact with the road surface) of the tire when the tire is mounted on the rim, filled with a specified internal pressure, and loaded with a maximum load. "Tread width" refers to the distance between the ground contact ends of the tire when the tire is mounted on the rim, filled with a specified internal pressure, and unloaded.

[0071] <Tire and rim assembly>

[0072] Here, a tire and rim assembly is formed by mounting the above-mentioned pneumatic radial tire for passenger vehicles on a rim. According to this tire and rim assembly, the same effects as those explained for the above-mentioned pneumatic radial tire for passenger vehicles can be obtained. At this time, the internal pressure of the tire and 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, by increasing the internal pressure, rolling resistance can be further reduced. On the other hand, the internal pressure of the tire and rim assembly is preferably 350 kPa or less because this improves ride comfort.

[0073] <How to use pneumatic radial tires for passenger cars>

[0074] The method for using the pneumatic radial tire for a passenger car uses the above-mentioned pneumatic radial tire for a passenger car. According to the method for using the pneumatic radial tire for a passenger car, the same effects as those described above for the pneumatic radial tire for a passenger car can be obtained. At this time, it is preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 200 kPa or more, and it is even more preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 220 kPa or more, and it is even more preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 280 kPa or more. This is because the rolling resistance can be further reduced by increasing the internal pressure. On the other hand, it is preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 350 kPa or less because this improves the ride comfort.

[0075] <Example of Communication Device>

[0076] Figure 4 A tire widthwise half including the layers is shown.

[0077] like Figure 4As shown, the tire may include an RF tag as a communication device 50. The RF tag has an IC chip and an antenna. For example, the RF tag can be configured by being sandwiched between multiple components of the same type or different types constituting the tire. In this way, it is easier to attach the RF tag when producing the tire, and the productivity of the tire with the RF tag can be improved. In this example, the RF tag can be configured between, for example, a bead filler and other components adjacent to the bead filler. The RF tag can be buried in any component constituting the tire. In this way, compared with configuring the RF tag by being sandwiched between multiple components constituting the tire, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. In this example, the RF tag can be buried in rubber components such as tread rubber and sidewall rubber. It is preferred that the RF tag is not configured at a position that is a boundary between components having different levels of rigidity in the peripheral length direction, and the peripheral length direction is a direction along the outer surface of the tire when viewed in a tire width direction section. In this way, the RF tag is not configured at a position where the skew is likely to be concentrated based on the rigidity step difference. This reduces the load on the RF tag, thereby improving the durability of the RF tag. In this example, it is preferred that the RF tag is not arranged at a position that is a boundary between the edge of the carcass and a member adjacent to the carcass edge (e.g., sidewall rubber, etc.) when viewed in a cross section in the tire width direction, for example. The number of RF tags is not limited. The tire may have only one RF tag, or it may have two or more RF tags. Here, the RF tag is explained as an example of a communication device, but a communication device other than an RF tag may also be used.

[0078] The RF tag can be configured in, for example, the tread portion of the tire. In this way, the RF tag will not be damaged by the side cut of the tire. The RF tag can be configured in, for example, the center of the tread in the tire width direction. The center of the tread is a position in the tread portion where distortion is less likely to be concentrated. In this way, the load applied to the RF tag can be reduced, thereby improving the durability of the RF tag. This also makes it 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, in the tire width direction, the RF tag can be configured within, for example, 1 / 2 of the tread width centered on the tire equatorial plane. In the tire width direction, the RF tag can be configured at, for example, the end of the tread. If the position of the reader that communicates with the RF tag is predetermined, the RF tag can be configured at, for example, the end of the tread on a side close to the reader. In this example, for example, in the tire width direction, the RF tag can be configured within, for example, 1 / 4 of the tread width with the tread end as the outer end.

[0079] The RF tag can be configured on the tire inner cavity side of a carcass including, for example, one or more carcass plies spanning between the bead portions. In this way, the RF tag becomes less likely to be damaged by external impacts of the tire, or less likely to be damaged by, for example, side cuts or nail punctures. As an example, the RF tag can be configured to be in close contact with the surface of the carcass facing the tire inner cavity. As another example, when there is another component on the tire inner cavity side of the carcass, the RF tag can be configured between the carcass and the other component located on the tire inner cavity side of the carcass. The other component located on the tire inner cavity side of the carcass is, for example, an inner liner forming the inner surface of the tire. As another example, the RF tag can be attached to the inner surface of the tire facing the tire inner cavity. By attaching the RF tag to the inner surface of the tire, it is easy to attach the RF tag to the tire, and it is also easy to check and replace the RF tag. In other words, the convenience of attachment and maintenance of the RF tag can be improved. In addition, by attaching the RF tag to the inner surface of the tire, the RF tag can be prevented from becoming the core of the tire failure compared to the structure in which the RF tag is buried inside the tire. Furthermore, when the carcass has a plurality of carcass plies and there is a position where the plurality of carcass plies overlap, the RF tag may be arranged between the overlapping carcass plies.

[0080] For example, the RF tag can be configured in the tread portion of the tire on the radially outer side of the belt portion, the belt portion including one or more belt plies. As an example, the RF tag can be configured to be in close contact with the belt portion on the radially outer side of the tire relative to the belt portion. In addition, as another example, when a reinforcing belt layer is provided, the RF tag can be configured to be in close contact with the reinforcing belt layer on the radially outer side of the tire relative to the reinforcing belt layer. In addition, as another example, the RF tag can be buried in the tread rubber on the radially outer side of the belt portion. By arranging the RF tag on the outer side of the belt portion in the tread portion of the tire, the communication with the RF tag from the radially outer side of the tire of the tire is less likely to be interfered by the belt portion. Therefore, the communication with the RF tag from the radially outer side of the tire of the tire can be improved. In addition, the RF tag can be configured in the tread portion of the tire, for example, on the radially inner side of the belt portion. In this way, the radially outer side of the RF tag is covered by the belt portion, so the RF tag becomes less likely to be damaged by the impact from the tread surface or by nail puncture. As an example in this regard, the RF tag can be arranged in the tread portion of the tire between the belt portion and the carcass located radially inside the belt portion. In addition, when the belt portion has a plurality of belt plies, the RF tag can be arranged in the tread portion of the tire between any two belt plies. According to this configuration, the radially outer side of the RF tag is covered by one or more belt plies, so the RF tag becomes less likely to be damaged by impact or nail puncture from the tread surface.

[0081] The RF tag can be configured at a position such as in the sidewall portion or bead portion of the tire. For example, the RF tag can be configured on the sidewall portion or bead portion, for example, close to a 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 can be configured between the carcass and the sidewall rubber or between the tread rubber and the sidewall rubber. The RF tag can be configured in the tire radial direction, for example, between the tire maximum width position and the tread surface position. According to this configuration, compared with the configuration in which the RF tag is configured on the tire radial inner side of the tire maximum width position, the communication with the RF tag from the tire radial outer side of the tire can be improved. The RF tag can be configured on the tire radial inner side of the tire maximum width position, for example. According to this configuration, the RF tag is configured near the bead portion with 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 can be configured at a position adjacent to the bead core in the tire radial direction or the tire width direction. Skew is less likely to be concentrated near the bead core, which reduces the load on the RF tag, thereby improving the durability of the RF tag. In particular, it is preferred that the RF tag is disposed radially inward of the tire at the maximum width position of the tire and radially outward of the bead core of the bead portion. According to this configuration, the durability of the RF tag can be improved, and the communication between the RF tag and the reader is less likely to be interfered by the bead core, thereby improving the communication performance of the RF tag. In addition, when the sidewall rubber is composed of a plurality of rubber members of the same or different types adjacent to each other in the tire radial direction, the RF tag can be configured to be sandwiched between the plurality of rubber members constituting the sidewall rubber.

[0082] The RF tag can be configured to be sandwiched between the bead filler and the member adjacent to the filling filler, for example. According to this configuration, the RF tag can be placed at a position where strain is less likely to be concentrated due to the disposal of the bead filler. This reduces the load applied to the RF tag, thereby improving the durability of the RF tag. The RF tag can be configured between the bead filler and the carcass, for example. The part of the carcass that sandwiches the RF tag between the carcass and the bead filler can be located outside the tire width direction relative to the bead filler, or inside the tire width direction relative to the bead filler. If the part of the carcass that sandwiches the RF tag between the carcass and the bead filler is located outside the tire width direction relative to the bead filler, the load applied to the RF tag due to the impact or damage from the tire width direction outside of the tire can be even more reduced, thereby improving the durability of the RF tag. In addition, the bead filler can have a portion adjacent to the sidewall rubber configuration. In this case, the RF tag can be configured to be sandwiched between the bead filler and the sidewall rubber. In addition, the bead filler can also have a portion adjacent to the rubber bead chafer configuration. In this case, the RF tag can be configured to be sandwiched between the bead filler and the rubber bead chafer.

[0083] The RF tag can be configured to be, for example, sandwiched between the rubber bead packer and the sidewall rubber. According to this construction, the RF tag can be placed at a position where strain is less likely to concentrate due to the placement of the rubber bead packer. This reduces the load applied to the RF tag, thereby improving the durability of the RF tag. The RF tag can be configured to be, for example, sandwiched between the rubber bead packer and the carcass. According to this construction, the load applied to the RF tag due to impact and damage from the rim can be reduced. Therefore, the durability of the RF tag can be improved.

[0084] The RF tag can be configured to be, for example, sandwiched between a wire bead filler and another member adjacent to the wire bead filler on the outside or inside of the wire bead filler in the tire width direction. According to this configuration, the position of the RF tag is less likely to change when the tire is deformed. This reduces the load applied to the RF tag when the tire is deformed, thereby improving the durability of the RF tag. Another member adjacent to the wire bead filler on the inside or outside of the tire width direction may be a rubber member, such as a rubber bead filler. In addition, another member adjacent to the wire bead filler on the inside or outside of the tire width direction may be a carcass.

[0085] A belt reinforcement layer may be provided on the tire radially outer side of the belt portion. For example, the belt reinforcement layer may be made by continuously spirally winding a cord made of polyethylene terephthalate around the tire in the tire circumferential direction. -2 N / tex or more tension applied adhesive treatment to make the cord, the elastic modulus under 29.4N load measured at 160°C can be 2.5mN / dtex% or more. In addition, the belt reinforcement layer can be configured to cover the entire belt portion, or it can be configured to cover only the two ends of the belt portion. In addition, the winding density per unit width of the belt reinforcement layer can be changed according to the position in the width direction. According to this configuration, road noise and flat spots can be reduced without reducing high-speed durability.

[0086] [Contribution to the Sustainable Development Goals (SDGs) led by the United Nations]

[0087] SDGs are proposed to realize a sustainable society. One embodiment of the present disclosure is considered to be a technology that can contribute to "No. 12_Ensuring sustainable consumption and production patterns" and "No. 13_Climate change and specific countermeasures".

[0088] Reference numerals list

[0089] 1 Pneumatic radial tires for passenger cars (tire)

[0090] 2 Bead section

[0091] 2a Bead core

[0092] 2b Bead filler

[0093] 3 Carcass

[0094] 4 Belt

[0095] 4a, 4b belt layer

[0096] 5 Tread

[0097] 6 Tire inner surface

[0098] 7 Lining

[0099] 8 Side wall

[0100] 50 communication devices

[0101] CL Tire equatorial plane

Claims

1. A pneumatic radial tire for a passenger vehicle, comprising: a pair of bead portions; a carcass composed of one or more carcass plies spanning in a toroidal manner between the pair of bead portions; and The belt portion is composed of one or more belt layers arranged on the outer side of the crown portion of the carcass in the radial direction of the tire, wherein: The carcass is composed of a carcass main body portion and a carcass folded portion, wherein the carcass main body portion is annularly spanned between the pair of bead portions, and the carcass folded portion is folded back from the carcass main body portion around a bead core buried in the bead portion. The cross-sectional width SW of the tire is less than 165 (mm), and the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD of the tire is 0.26 or less, or the cross-sectional width SW of the tire is 165 (mm) or more, and the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ 2.135 × SW (mm) + 282.3 (mm), or the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ -0.0187 × SW (mm) 2 +9.15×SW(mm)-380(mm), and An end of the carcass folded portion in one tire widthwise half located on the inner side when the tire is mounted on the vehicle is located radially inside of an end of the carcass folded portion in the other tire widthwise half located on the outer side when the tire is mounted on the vehicle.

2. A pneumatic radial tire for a passenger vehicle, comprising: a pair of bead portions; a carcass composed of one or more carcass plies spanning in a toroidal manner between the pair of bead portions; and The belt portion is composed of one or more belt layers arranged on the outer side of the crown portion of the carcass in the radial direction of the tire, wherein: The cross-sectional width SW of the tire is less than 165 (mm), and the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD of the tire is 0.26 or less, or the cross-sectional width SW of the tire is 165 (mm) or more, and the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ 2.135 × SW (mm) + 282.3 (mm), or the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relationship expression: OD (mm) ≥ -0.0187 × SW (mm) 2 +9.15×SW(mm)-380(mm), In one tire width direction half portion located on the inner side when the tire is mounted on a vehicle, the carcass is wound around a bead core buried in the bead portion and terminated therein, and, In the other tire widthwise half located on the outside when the tire is mounted on a vehicle, the carcass is composed of a carcass main body portion and a carcass folded back portion, the carcass main body portion spanning between the pair of bead portions in an annular shape, and the carcass folded back portion folded back from the carcass main body portion around a bead core buried in the bead portion, An end of the carcass in one tire widthwise half located inside when the tire is mounted on a vehicle is located radially inside of an end of the carcass folded portion in the other tire widthwise half located outside when the tire is mounted on a vehicle.

3. The pneumatic radial tire for a passenger vehicle according to claim 1 or 2, comprising a pair of sidewall portions, wherein: In a cross-sectional view in the tire width direction of the pneumatic radial tire for a passenger vehicle, when the tire is assembled on a rim, filled with an internal pressure of 30 kPa and without a load, The curvature radius of the sidewall portion in one tire width direction half located on the inner side when the tire is mounted on the vehicle is smaller than the curvature radius of the sidewall portion in the other tire width direction half located on the outer side when the tire is mounted on the vehicle.

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