Pneumatic radial tires for passenger cars

Abstract

To provide a pneumatic radial tire for a passenger vehicle making both low-fuel consumption and cut-resistance compactible.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 an end of a carcass of a half part on one side in a tire width direction which is positioned inside when mounted on the vehicle (an end of a folded-back part of the carcass when the carcass has the carcass folded-back part) is positioned closer to inside in a tire radial direction than the end of a carcass folded-back part of a half part on the other side in the tire width direction which is positioned outside when mounted on the vehicle.SELECTED DRAWING: Figure 2

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 that improves 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). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2011 / 135774 brochure [Overview of the project] [Problems that the invention aims to solve]

[0004] As described above, narrow-width, large-diameter pneumatic radial tires for passenger cars are designed for low fuel consumption, and therefore, it is desirable to simplify their structure to further improve fuel efficiency through weight reduction. Furthermore, such narrow-width, large-diameter pneumatic radial tires for passenger cars are often used at high internal pressures. While high internal pressures reduce rolling resistance, there are concerns that they may worsen ride comfort, and from this perspective as well, it is desirable to simplify the structure to reduce the longitudinal spring coefficient.

[0005] However, simplifying the structure reduces its resistance to cuts, such as those caused by curbs. On the other hand, adding components to improve cut resistance increases weight and worsens fuel efficiency. Thus, achieving both low fuel consumption and cut resistance has generally been difficult.

[0006] Therefore, the present invention aims to provide a pneumatic radial tire for passenger cars that achieves both low fuel consumption and cut resistance. [Means for solving the problem]

[0007] The gist of the present invention is as follows: (1) A pair of bead sections, A carcass consisting of one or more carcass plies that toroidally span between a pair of bead sections, The carcass comprises a belt consisting of one or more belt layers, which is positioned on the radially outer side of the crown portion of the tire. The carcass consists of a carcass body portion that spans a pair of bead portions in a toroidal manner, and a carcass folded portion that is folded back from the carcass body portion around the bead core embedded in the bead portion. The tire's cross-sectional width SW is less than 165 mm, and 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 is 165 mm or more, and the tire's cross-sectional width SW and outer diameter OD satisfy the relationship OD(mm)≧2.135×SW(mm)+282.3(mm), or the tire's cross-sectional width SW(mm) and outer diameter OD(mm) satisfy the relationship OD(mm)≧-0.0187×SW(mm). 2 Satisfying +9.15 × SW(mm) - 380(mm), A pneumatic radial tire for passenger cars, characterized in that the end of the folded portion of the carcass in one half of the tire width direction that is on the inside when mounted on a vehicle is located radially inward from the end of the folded portion of the carcass in the other half of the tire width direction that is on the outside when mounted on a vehicle.

[0008] 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.

[0009] (2) A pair of bead sections, A carcass consisting of one or more carcass plies that toroidally span between a pair of bead sections, The carcass comprises a belt consisting of one or more belt layers, which is positioned on the radially outer side of the crown portion of the tire. The tire's cross-sectional width SW is less than 165 mm, and 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 is 165 mm or more, and the tire's cross-sectional width SW and outer diameter OD satisfy the relationship OD(mm)≧2.135×SW(mm)+282.3(mm), or the tire's cross-sectional width SW(mm) and outer diameter OD(mm) satisfy the relationship OD(mm)≧-0.0187×SW(mm). 2 Satisfying +9.15 × SW(mm) - 380(mm), In one half of the tire in the width direction that faces inward when mounted on a vehicle, the carcass is wrapped around the bead core embedded in the bead portion and terminated therein. In the other half of the tire width that faces outward when mounted on a vehicle, the carcass consists of a carcass body portion that straddles a pair of bead portions in a toroidal manner, and a carcass folded portion that is folded back from the carcass body portion around the bead core embedded in the bead portion. A pneumatic radial tire for passenger cars, characterized in that the end of the carcass in one half of the tire width direction that is on the inside when mounted on a vehicle is located radially inward from the end of the folded portion of the carcass in the other half of the tire width direction that is on the outside when mounted on a vehicle.

[0010] (3) Equipped with a pair of sidewall sections, When the aforementioned passenger car pneumatic radial tire is mounted on a rim, filled to an internal pressure of 30 kPa, and unloaded, a cross-sectional view of the tire in the width direction is observed. The pneumatic radial tire for passenger cars according to claim 1 or 2, wherein the radius of curvature of the sidewall portion of one half in the tire width direction that is on the inside when mounted on a vehicle is smaller than the radius of curvature of the sidewall portion of the other half in the tire width direction that is on the outside when mounted on a vehicle. Here, "radius of curvature of the sidewall" refers to the radius of the circular arc obtained by approximating the outer contour line of the sidewall with a circular arc using the least squares method in a cross-sectional view of the tire in the width direction of the above condition. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a pneumatic radial tire for a passenger car that achieves both low fuel consumption and cut resistance.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic view showing the sectional width SW and outer diameter OD of the tire. [Figure 2] 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 3] It is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger car according to another embodiment of the present invention. [Figure 4] It is a diagram for explaining the arrangement of RFID. [Figure 5] It is a diagram for explaining the WIND bead. [Figure 6] It is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger car of a modified example.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be exemplified and described in detail with reference to the drawings.

[0014] FIG. 1 is a schematic view showing the sectional width SW and outer diameter OD of the tire. In a pneumatic radial tire for a passenger car (hereinafter, also simply referred to as a tire) according to an embodiment of the present invention, when the sectional width SW of the tire is less than 165 (mm), the ratio SW / OD of the sectional width SW to the outer diameter OD of the tire is 0.26 or less. When the sectional width SW of the tire is 165 (mm) or more, the sectional width SW (mm) and outer diameter OD (mm) of the tire are OD(mm)≧2.135×SW(mm)+282.3(mm) (hereinafter, referred to as "Relational Expression (1)") preferably satisfy. By satisfying the above ratio SW / OD or relation (1), the tire's cross-sectional width SW becomes relatively smaller than the tire's outer diameter OD, reducing air resistance. Furthermore, the narrower cross-sectional width allows for more space on the vehicle, and in particular, provides space for installing drive components near the inside of the tire when mounted on the vehicle. Furthermore, by satisfying the above ratio SW / OD or relation (1), the outer diameter OD of the tire becomes relatively larger relative to the cross-sectional width SW of the tire, reducing rolling resistance. In addition, the larger diameter of the tire raises the wheel axle, expanding the space under the floor, thus securing space for the vehicle's trunk and other components. As described above, by satisfying the ratio SW / OD or relation (1), it is possible to achieve low fuel consumption with respect to the supplied electrical energy, and also to secure a large vehicle space. Furthermore, the tire's section width SW (mm) and outer diameter OD (mm) are as follows: OD(mm)≧-0.0187×SW(mm) 2 +9.15 × SW (mm) - 380 (mm) (Hereafter referred to as "Relational Equation (2)") It is preferable that the following conditions be met. By satisfying the above relation (2), the tire's cross-sectional width SW becomes relatively smaller than the tire's outer diameter OD, reducing air resistance. Furthermore, the narrower cross-sectional width allows for more space on the vehicle, and in particular, space can be secured for the installation of drive components near the inside of the tire when mounted on the vehicle. Furthermore, by satisfying the above relation (2), the outer diameter OD of the tire becomes relatively larger with respect to the cross-sectional width SW of the tire, reducing rolling resistance. In addition, the larger diameter of the tire raises the wheel axle, expanding the space under the floor, thus securing space for the vehicle's trunk and other components. As described above, by satisfying relation (2) above, it is possible to achieve low fuel consumption with respect to the supplied electrical energy, and also to secure a large vehicle space. In each of the above examples, it is preferable that the tire satisfies the above ratio SW / OD and / or relation (2), or that it satisfies the above relation (1) and / or relation (2).

[0015] Figure 2 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 2 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 2, this tire 1 has a carcass 3 made of radially arranged cord plies that spans toroidally between a pair of bead portions 2. In addition, this tire 1 has a belt 4 consisting of two belt layers 4a and 4b in the illustrated example and a tread 5 in order on the radially outer side of the carcass 3.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] In the example shown in Figure 2, 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, in the example shown in Figure 2, the carcass 3 has a carcass body portion 3a that toroidally straddles a pair of bead portions 2, and a folded portion 3b that is folded back from the carcass body portion 3a around the bead core 2a. In this embodiment, the end 3c of the carcass folded portion of one half (right side in the illustration) in the tire width direction is located radially inward of the end 3c of the carcass folded portion 3b of the other half (left side in the illustration) in the tire width direction. In this example, the end 3c of the carcass folded portion 3b is located radially outward from the radially outer end of the bead filler 2b and radially inward from the tire's maximum width position, both in one half and the other half in the tire width direction. This makes it possible to reduce the weight of the tire while ensuring the rigidity of the sidewall portion. 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 it may be located radially outward from the tire's maximum width position. Alternatively, the end 3c of the carcass folded portion 3b may be located inward in the tire width direction from the end of the belt 4 (for example, the end of the belt layer 4b) so as to be located between the carcass body 2a and the belt 4 in the tire radial direction, thus forming an envelope structure. Furthermore, for example, in one half in the tire width direction, the end 3c of the carcass folded portion 3b may be 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, while in the other half in the tire width direction, it may be located radially outward from the tire's maximum width position. Moreover, if the carcass 3 is composed of multiple carcass plies, the position of the end 3c of the carcass folded portion 3b (for example, the tire radial position) may be the same or different between the carcass plies. There are no particular limitations on the number of cords used in Carcass 3, but for example, it can range from 20 to 60 cords per 50mm. Furthermore, various structures can be employed for the carcass lines.For example, in the radial direction of the tire, the position of the maximum width of the carcass can be brought closer to the bead portion 2 side or closer to the tread 5 side. For example, the position of the maximum width 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.

[0020] The tire of this embodiment preferably has one or more inclined belt layers made of rubberized cords that extend inclined with respect to the circumferential direction of the tire, and it is most preferable to have two layers in order to balance weight reduction and suppression of distortion of the contact surface shape. However, from the viewpoint of weight reduction, the belt layer can be one layer, and from the viewpoint of suppressing distortion of the contact surface shape, it is also possible to have three or more layers. In the example shown in Figure 2, of the two belt layers 4a and 4b, the width in the tire width direction of the outer belt layer 4b in the tire radial direction is smaller than the width in the tire width direction of the inner belt layer 4a in the tire radial direction. On the other hand, the width in the tire width direction of the outer belt layer 4b in the tire radial direction can be larger than the width in the tire width direction of the inner belt layer 4a in the tire radial direction, or they can be the same. The width in the tire width direction of the belt layer with the largest width in the tire width direction (belt layer 4a in the illustrated example) is preferably 90 to 115% of the contact width, and particularly preferably 100 to 105% of the contact width. Note that "contact width" refers to the distance in the tire width direction between the contact ends E. "Contact point" refers to both ends of the tire's contact surface in the tire's width direction 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 belt layers 4a and 4b, 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 belt layers 4a and 4b. 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 of belt layers 4a and 4b 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 of belt layers 4a and 4b be a high angle, specifically 20° or more with respect to the tire circumferential direction, preferably 35° or more, and particularly in the range of 55° to 85° with respect to the tire circumferential direction. This is because setting the inclination angle to 20° or more (preferably 35° or more) increases the rigidity in the tire width direction, which can improve handling stability performance, especially during cornering. It is also because it can reduce shear deformation of the interlayer rubber and reduce rolling resistance.

[0021] 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.

[0022] The tire 1 of this embodiment has an inner liner 8 on the inner surface 7 of the tire (also simply referred to as the inner surface 7 of the tire). The thickness of the inner liner 8 is preferably about 1.5 mm to 2.8 mm, 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 8 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).

[0023] The following describes the effects and advantages of the passenger car pneumatic radial tire of this embodiment. In the following, the effects and advantages are described when "one half in the tire width direction" is positioned on the inside when mounted on the vehicle (and when "the other half in the tire width direction" is positioned on the outside when mounted on the vehicle).

[0024] The pneumatic radial tire for passenger cars of this embodiment satisfies the above-mentioned relationship between the tire's cross-sectional width SW and its outer diameter. Such a tire can reduce air resistance and rolling resistance, thereby improving the tire's fuel efficiency. Furthermore, the end 3c of the carcass fold portion 3b on one half of the tire width direction that is on the inside when mounted on the vehicle is located radially inward of the carcass fold portion 3b on the other half of the tire width direction that is on the outside when mounted on the vehicle. Therefore, on the outside when mounted on the vehicle, where cuts such as those caused by curbs are more likely to occur, the radial position of the end 3c of the carcass fold portion 3b is relatively outward, thus improving resistance to damage. On the other hand, even on the inside when mounted on the vehicle, compared to the case where the radial position of the end 3c of the carcass fold portion 3b is the same as on the outside when mounted on the vehicle, the tire can be made lighter, reducing rolling resistance and improving fuel efficiency. As described above, the pneumatic radial tire for passenger cars of this embodiment provides a pneumatic radial tire for passenger cars that achieves both low fuel consumption and cut resistance.

[0025] As a modification of the above embodiment, in one half of the tire width direction that is on the inside when mounted on a vehicle, the carcass 3 is wrapped around the bead core 2a embedded in the bead portion 2 and terminated, and in the other half of the tire width direction that is on the outside when mounted on a vehicle, the carcass 3 consists of a carcass body portion 3a that straddles the pair of bead portions 2 in a toroidal manner, and a carcass folded portion 3b that is folded back from the carcass body portion 3a around the bead core 2a embedded in the bead portion 2, and the end of the carcass 3 of the one half of the tire width direction that is on the inside when mounted on a vehicle may be located radially inward of the end 3c of the carcass folded portion 3b of the other half of the tire width direction that is on the outside when mounted on a vehicle. Even if a so-called WIND bead structure (see Figure 5) is adopted for one half of the tire width that is on the inside when mounted on the vehicle, if the end of the carcass 3 of the one half of the tire width that is on the inside when mounted on the vehicle is located radially inward from the end 3c of the folded portion 3b of the carcass of the other half of the tire width that is on the outside when mounted on the vehicle, then in the case of the outside when mounted on the vehicle, where cuts such as those caused by curbs are more likely to occur, the radial position of the end 3c of the folded portion 3b of the carcass is relatively outward, thus improving resistance to damage. On the other hand, even on the inside when mounted on the vehicle, compared to the case where the radial position of the end 3c of the folded portion 3b of the carcass is the same as on the outside when mounted on the vehicle, the tire can be made lighter, rolling resistance can be reduced, and fuel efficiency can be improved.

[0026] Figure 3 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger car according to another embodiment of the present invention. The tire shown in Figure 3 differs from the embodiment shown in Figure 2 in that the shape of the outer contour of the sidewall portion 8 of the tire differs between one half in the tire width direction and the other half in the tire width direction. Specifically, in a cross-sectional view in the tire width direction when a pneumatic radial tire for a passenger car is mounted on a rim, filled with an internal pressure of 30 kPa, and unloaded, the radius of curvature R1 of the sidewall portion 8 of one half in the tire width direction that is on the inside when mounted on a vehicle is smaller than the radius of curvature R2 of the sidewall portion 8 of the other half in the tire width direction that is on the outside when mounted on a vehicle. (The radius of curvature CR1 of the carcass in one half of the tire width direction that is on the inside when mounted on a vehicle is smaller than the radius of curvature CR2 of the carcass in the other half of the tire width direction that is on the outside when mounted on a vehicle.) This is because, on the outside when mounted on a vehicle, where cuts such as those caused by curbs are more likely to occur, the radius of curvature R2 of the sidewall portion 8 can be made relatively larger, thereby further improving cut resistance. The "radius of curvature of the carcass" refers to the radius of the arc when the contour line of the carcass is approximated by the least squares method in a cross-sectional view in the width direction of the tire in the above state. Furthermore, as shown in Figure 6, 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 in the tire's radial direction between lines m1 and m2 is the drop height L.CR and when the tread width of the tire is TW, the ratio L CR / TW is preferably more than 0.045. As a result, a tire with a relatively round crown shape can be obtained, and the contact shape can be made into a round shape in which the contact length of the shoulder portion is shorter than that of the center portion. Thereby, it is possible to further suppress the deterioration of the contact shape by preventing the contact shape from becoming too elongated when the camber angle changes. The "contact end" refers to both ends in the tire width direction of the contact surface (the surface in contact with the road surface) when the tire is mounted on the rim, filled with the specified internal pressure, and loaded with the maximum load. The "tread width" refers to the distance in the tire width direction between the contact ends when the tire is mounted on the rim, filled with the specified internal pressure, and unloaded.

[0027] <Tire - Rim Assembly> The tire - rim assembly here is formed by incorporating the above - mentioned pneumatic radial tire for passenger cars into the rim. According to this tire - rim assembly, the same operational effects as those described for the above - mentioned pneumatic radial tire for passenger cars can be obtained. At this time, 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 the rolling resistance can be further reduced by setting a high internal pressure. On the other hand, the internal pressure of the tire - rim assembly is preferably 350 kPa or less. This is because the riding comfort can be improved.

[0028] <Method of Using a Pneumatic Radial Tire 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.

[0029] <Examples with communication devices> Figure 4 shows the widthwise half of the tire, which has a layered structure. As shown in Figure 4, the tire may be equipped with an RF tag as a communication device 50. 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.

[0030] 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.

[0031] 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.

[0032] The RF tag may be positioned, for example, on the tire tread, outside the belt, which includes one or more belt plies, in the radial direction of the tire. For example, the RF tag may be positioned outside the belt in the radial direction of the tire, in close contact with the belt. Another example is when a reinforcing belt layer is provided, the RF tag may be positioned outside the reinforcing belt layer in the radial direction of the tire, in close contact with the reinforcing belt layer. Yet another example is when the RF tag is embedded in the tread rubber, outside the belt in the radial direction of the tire. By positioning the RF tag outside the belt in the tire tread, communication with the RF tag from the outside of the tire in the 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 radial direction of the tire can be improved. Alternatively, the RF tag may be positioned inside the belt in the tire tread, for example. In this way, the outside of the RF tag in the radial direction of the tire 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. Furthermore, if the belt comprises multiple belt plies, the RF tag may be positioned between any two belt plies in the tire tread. In this manner, the outer radial side of the RF tag is covered by one or more belt plies, making the RF tag less susceptible to damage from impacts from the tread surface or nail punctures.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The RF tag may be positioned sandwiched between the wire chafer and another component adjacent to the wire chafer on the inner or outer side in the tire width direction. This arrangement makes it less likely for the RF tag's position to change during tire deformation. Therefore, the load on the RF tag during tire deformation can be reduced, thereby improving the durability of the RF tag. The other component adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a rubber component such as a rubber chafer. Alternatively, the other component adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a carcass.

[0037] A belt reinforcing layer may be further provided on the radially outer side of the belt. For example, the belt reinforcing layer may consist of a cord made of polyethylene terephthalate wound continuously in a spiral in the circumferential direction of the tire. Here, the cord is 6.9 × 10 -2 The belt is treated with adhesive under a tension of N / tex or higher, and its modulus of elasticity at a load of 29.4N measured at 160°C may be 2.5mN / dtex·% or higher. Furthermore, the belt reinforcement layer may be arranged to cover the entire belt or to cover only the ends of the belt. In addition, the winding density per unit width of the belt reinforcement layer may differ at different positions in the width direction. By doing so, road noise and flat spots can be reduced without reducing high-speed durability.

[0038] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 12: Responsible Consumption and Production" and "No. 13: Climate Action," among others. [Explanation of symbols]

[0039] 1: Passenger car pneumatic radial tire (tire), 2: Bead section, 2a: Bead core, 2b: Bead filler, 3: Carcass, 4: Belt, 4a, 4b: Belt layer, 5: Tread 6: Inner surface of the tire, 7: Inner liner, 8: Sidewall section, 50: Communication equipment, CL: Tire equatorial plane

Claims

1. A pair of bead sections, A carcass consisting of one or more carcass plies that toroidally span between a pair of bead sections, The carcass comprises a belt consisting of one or more belt layers, which is positioned on the outer side in the radial direction of the crown portion of the tire. The carcass consists of a carcass body portion that spans a pair of bead portions in a toroidal manner, and a carcass folded portion that is folded back from the carcass body portion around the bead core embedded in the bead portion. The tire's cross-sectional width SW is less than 165 mm, and 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 is 165 mm or more, and the tire's cross-sectional width SW and outer diameter OD satisfy the relationship OD(mm) ≥ 2.135 × SW(mm) + 282.3(mm), or the tire's cross-sectional width SW(mm) and outer diameter OD(mm) satisfy the relationship OD(mm) ≥ -0.0187 × SW(mm) ２ Satisfying +9.15 × SW (mm) - 380 (mm), The end of the folded portion of the carcass in one half of the tire width direction that is on the inside when mounted on the vehicle is located radially inward of the end of the folded portion of the carcass in the other half of the tire width direction that is on the outside when mounted on the vehicle. Equipped with a pair of sidewall sections, When the aforementioned passenger car pneumatic radial tire is mounted on a rim, filled with an internal pressure of 30 kPa, and unloaded, a cross-sectional view of the tire in the width direction is observed. A pneumatic radial tire for passenger cars, characterized in that the radius of curvature of the sidewall portion of one half in the tire width direction that is on the inside when mounted on a vehicle is smaller than the radius of curvature of the sidewall portion of the other half in the tire width direction that is on the outside when mounted on a vehicle.

2. A pair of bead sections, A carcass consisting of one or more carcass plies that toroidally span between a pair of bead sections, The carcass comprises a belt consisting of one or more belt layers, which is positioned on the outer side in the radial direction of the crown portion of the tire. The tire's cross-sectional width SW is less than 165 mm, and 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 is 165 mm or more, and the tire's cross-sectional width SW and outer diameter OD satisfy the relationship OD(mm) ≥ 2.135 × SW(mm) + 282.3(mm), or the tire's cross-sectional width SW(mm) and outer diameter OD(mm) satisfy the relationship OD(mm) ≥ -0.0187 × SW(mm) ２ Satisfying +9.15 × SW (mm) - 380 (mm), In one half of the tire in the width direction that faces inward when mounted on a vehicle, the carcass is wrapped around the bead core embedded in the bead portion and terminated therein. In the other half of the tire width that faces outward when mounted on a vehicle, the carcass consists of a carcass body portion that straddles a pair of bead portions in a toroidal manner, and a carcass folded portion that is folded back from the carcass body portion around the bead core embedded in the bead portion. A pneumatic radial tire for passenger cars, characterized in that the end of the carcass in one half of the tire width direction that is on the inside when mounted on a vehicle is located radially inward from the end of the folded portion of the carcass in the other half of the tire width direction that is on the outside when mounted on a vehicle.

3. Equipped with a pair of sidewall sections, When the aforementioned passenger car pneumatic radial tire is mounted on a rim, filled with an internal pressure of 30 kPa, and unloaded, a cross-sectional view of the tire in the width direction is observed. The pneumatic radial tire for passenger cars according to claim 2, wherein the radius of curvature of the sidewall portion of one half in the tire width direction that is on the inside when mounted on a vehicle is smaller than the radius of curvature of the sidewall portion of the other half in the tire width direction that is on the outside when mounted on a vehicle.

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