JP2020104752A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can enhance rigidity.SOLUTION: The pneumatic tire comprises: a bead 2a arranged inside a bead part 2; a rim strip rubber 2b constituting an outer surface of the bead part; a tread rubber 4a constituting an outer surface of a tread part 4; and a side wall rubber 3a constituting an outer surface of a side wall part 3 and is connected to the rim strip rubber and the tread rubber respectively. The bead part comprises a bead core 2c annularly formed and a bead filler 2d arranged outside in a tire radial direction of the bead core. Rubber materials of the side wall rubber are the same as rubber materials of the rim strip rubber, and a modulus of the side wall rubber and of the rim strip rubber is equal to 25% of a modulus of the bead filler or more.SELECTED DRAWING: Figure 2

Description

The present invention relates to a pneumatic tire.

Conventionally, for example, a pneumatic tire includes a rim strip rubber that constitutes an outer surface of a bead portion, a tread rubber that constitutes an outer surface of a tread portion, and a sidewall rubber that constitutes an outer surface of a sidewall portion. (For example, Patent Document 1). By the way, for example, in applications such as racing, there is a demand for pneumatic tires having increased rigidity.

JP, 2008-108751, A

Then, a subject is to provide a pneumatic tire which can raise rigidity.

The pneumatic tire comprises a bead arranged inside a bead portion, a rim strip rubber constituting an outer surface of the bead portion, a tread rubber constituting an outer surface of a tread portion, and an outer surface of a sidewall portion. The rim strip rubber and the sidewall rubber that are respectively connected to the tread rubber, and the bead, the bead core formed in an annular shape, and a bead filler arranged on the outer side in the tire radial direction of the bead core. The rubber material of the sidewall rubber is the same as the rubber material of the rim strip rubber, and the modulus of the sidewall rubber and the rim strip rubber is 25% or more of the modulus of the bead filler. ..

Further, the pneumatic tire further comprises a carcass ply bridged between a pair of the beads, the carcass ply comprises a hoisting portion that is hoisted from the inner side to the outer side in the tire width direction around the bead, The outer end in the tire radial direction of the roll-up portion may be arranged outside the maximum width position where the dimension of the pneumatic tire in the tire width direction is maximum in the tire radial direction.

In addition, the pneumatic tire may further include a plurality of carcass plies bridged between the pair of beads.

FIG. 1 is a cross-sectional view of a main part of a pneumatic tire according to an embodiment in a tire meridian plane. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is an enlarged view of the area III in FIG.

Hereinafter, one embodiment of a pneumatic tire will be described with reference to FIGS. 1 to 3. In each drawing, the dimensional ratios of the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios of the drawings do not necessarily match.

In each drawing, a first direction D1 is a tire width direction D1 that is parallel to a tire rotation axis that is a rotation center of a pneumatic tire (hereinafter, also simply referred to as “tire”) 1, and a second direction D2 is The tire radial direction D2 that is the diameter direction of the tire 1, and the third direction D3 (not shown) is the tire circumferential direction D3 around the tire rotation axis.

In the tire width direction D1, the inner side is the side closer to the tire equatorial plane S1, the outer side is the side far from the tire equatorial plane S1, and the inner side is the side closer to the tire rotation axis in the tire radial direction D2, and the outer side. Is on the side far from the tire rotation axis. Further, the tire equatorial plane S1 is a plane that is orthogonal to the tire rotation axis and that is located at the center of the tire 1 in the tire width direction D1, and the tire meridian plane is a plane that includes the tire rotation axis and It is a plane orthogonal to the tire equatorial plane S1.

As shown in FIG. 1, a tire 1 according to this embodiment includes a pair of bead portions 2 each having a bead 2a, a sidewall portion 3 extending from each bead portion 2 to the outside in the tire radial direction D2, and a pair of sidewalls. The tread portion 4 is connected to the outer end portion of the portion 3 in the tire radial direction D2, and the outer surface in the tire radial direction D2 is in contact with the road surface. In the present embodiment, the tire 1 is a pneumatic tire 1 into which air is put and is mounted on the rim 10.

The position where the dimension (tire width) W1 of the tire 1 in the tire width direction D1 has the maximum value, that is, the maximum width position 1a exists in the sidewall portion 3. In the present embodiment, the maximum value of the tire width W1 is larger than the maximum value of the tire section height W2. The maximum value of the tire cross-section height W2 is the distance in the tire radial direction D2 from the inner end of the bead portion 2 in the tire radial direction D2 to the outer end of the tread portion 4 in the tire radial direction D2.

Further, the tire 1 is disposed inside the carcass layer 5 and a carcass layer 5 that is bridged between the pair of beads 2a and 2a, and is an inner liner that is disposed inside the carcass layer 5 and that has an excellent function of blocking gas permeation in order to retain air pressure. And layer 6. The carcass layer 5 and the inner liner layer 6 are arranged along the tire inner circumference over the bead portion 2, the sidewall portion 3, and the tread portion 4.

As shown in FIGS. 1 and 2, the carcass layer 5 includes carcass plies 5a and 5b bridged between a pair of beads 2a and 2a. The carcass plies 5a and 5b are folded back around the bead 2a so as to wind the bead 2a. As a result, the carcass plies 5a and 5b include ply body portions 5c and 5d extending between the pair of beads 2a and 2a, and winding portions 5e and 5f that are wound around the beads 2a from inside to outside in the tire width direction D1. Equipped with.

The carcass plies 5a and 5b include a plurality of cords arranged in a direction orthogonal to the tire circumferential direction D3 and a topping rubber that covers the cords. The material of the cords of the carcass plies 5a and 5b is not particularly limited, but, for example, organic fibers such as polyester, rayon, nylon and aramid, or metal such as steel is suitable.

The bead 2 a is formed in an annular shape and is arranged inside the bead portion 2. The bead portion 2 is provided with a rim strip rubber 2b that constitutes the outer surface of the bead portion 2. The rim strip rubber 2b contacts the rim 10 when the tire 1 is mounted on the rim 10. That is, the rim strip rubber 2b is arranged at least in a portion in contact with the rim 10.

The bead 2a includes a bead core 2c formed in an annular shape, and a bead filler 2d arranged outside the bead core 2c in the tire radial direction D2. In the cross section of the tire meridian surface, the bead core 2c is formed in a polygonal shape or a circular shape, and the bead filler 2d is formed so as to have a tapered shape with a narrow width toward the outside in the tire radial direction D2. ..

The bead core 2c includes, for example, a laminated metal wire (for example, a bronze-plated steel wire) and a topping rubber that covers the wire. The bead filler 2d is made of hard rubber, for example.

The tread portion 4 includes a tread rubber 4 a that forms an outer surface of the tread portion 4 and a belt layer 4 b that is arranged inside the tread portion 4. Then, the tread rubber 4a contacts the road surface. The belt layer 4b is arranged between the tread rubber 4a and the carcass layer 5.

The belt layer 4b includes a plurality of belt plies 4c and 4d. The number of belt plies 4c and 4d is not particularly limited. In the present embodiment, the first belt ply 4c and the second belt ply 4d are provided from the outer side in the tire radial direction D2.

The belt plies 4c and 4d include a plurality of cords arranged at a predetermined inclination angle (for example, 15° to 35°) with respect to the tire circumferential direction D3, and a topping rubber covering the cords. The material of the cords of the belt plies 4c and 4d is not particularly limited, but for example, organic fibers such as polyester, rayon, nylon and aramid, or metal such as steel is suitable.

The belt layer 4b may include a belt reinforcing portion 4e arranged outside the belt plies 4c and 4d in the tire radial direction D2. In the belt reinforcing portion 4e, at least one cord covered with topping rubber is spirally wound along the tire circumferential direction D3 (inclination angle with respect to the tire circumferential direction D3 is 0 to 5°), Has been formed. The cord of the belt reinforcing portion 4e is preferably made of an organic fiber such as polyester, rayon, nylon or aramid.

The sidewall portion 3 includes a sidewall rubber 3 a that forms an outer surface of the sidewall portion 3. The inner side surface of the sidewall rubber 3a in the tire width direction D1 is connected to the outer side surface of the carcass layer 5 in the tire width direction D1.

The sidewall rubber 3a is connected to the rim strip rubber 2b and the tread rubber 4a, respectively. Specifically, the inner end 3b of the sidewall rubber 3a in the tire radial direction D2 is connected to the outer end 2e of the rim strip rubber 2b in the tire radial direction D2, and the outside of the sidewall rubber 3a in the tire radial direction D2. The end 3c is connected to the outer end 4f of the tread rubber 4a in the tire width direction D1.

Here, the tire 1 according to the present embodiment employs a configuration that enhances the rigidity of the tire 1, and each configuration will be described below. First, a configuration in which the rigidity of the tire 1 is increased by the rubber material of the sidewall rubber 3a will be described.

The rubber material of the sidewall rubber 3a is the same as the rubber material of the rim strip rubber 2b. As a result, the rubber hardness of the sidewall rubber 3a is the same as that of the rim strip rubber 2b, and the modulus of the sidewall rubber 3a is also the same as that of the rim strip rubber 2b.

Moreover, the rubber hardness of the sidewall rubber 3a and the rim strip rubber 2b is higher than that of the tread rubber 4a. Thereby, the rigidity of the sidewall portion 3 can be increased, and thus the rigidity of the tire 1 can be increased. Therefore, for example, the responsiveness of steering (the speed of reaction of transmitting the steering of the rim 10 to the road surface via the tire 1) can be improved.

The rubber hardness of each rubber 2b, 3a, 4a is not particularly limited. The rubber hardness of the sidewall rubber 3a and the rim strip rubber 2b is, for example, preferably 60 to 80, and more preferably 65 to 75, for example. The rubber hardness of the tread rubber 4a is preferably 50 to 70, for example.

The rubber hardness of the sidewall rubber 3a and the rim strip rubber 2b is, for example, preferably 5 or more, and more preferably 10 or more, higher than that of the tread rubber 4a. The rubber hardness is JIS K6253-1-2012 3.2 durometer hardness, and is measured in a 23° C. atmosphere using a type A durometer for general rubber (medium hardness). ..

The modulus of each rubber 2b, 3a is not particularly limited. The modulus of the sidewall rubber 3a and the rim strip rubber 2b is, for example, preferably 25% or more of the modulus of the bead filler 2d, and more preferably 30% or more, for example.

As a result, the rigidity of the sidewall portion 3 can be increased, so that the rigidity of the tire 1 can be increased. Therefore, for example, the responsiveness of maneuvering can be improved. The modulus is 100% elongation tensile stress (hereinafter, may be referred to as _“ Se _” ) measured at 23° C. according to JIS K6251.

The modulus of the sidewall rubber 3a and the rim strip rubber 2b may be, for example, 60% or less, 50% or less, or 45% or less of the modulus of the bead filler 2d. It may be 40% or less.

Each rubber 2b, 3a is made of vulcanized rubber. The vulcanized rubber of each rubber 2b, 3a is obtained by vulcanizing an unvulcanized rubber composition.

The rubber material before vulcanization of each rubber 2b, 3a, that is, the rubber composition contains a rubber component. Examples of the rubber component include natural rubber, polyisoprene rubber, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), nitrile rubber, and chloroprene rubber. From these, one or any combination can be selected and used. Among them, a combination of natural rubber and polybutadiene rubber, a combination of polyisoprene rubber and polybutadiene rubber, a combination of natural rubber, a polyisoprene rubber and polybutadiene rubber, and a natural rubber alone are preferable. More preferred is a combination of natural rubber and polybutadiene rubber.

When the rubber composition contains natural rubber, the amount of natural rubber in 100% by mass of the rubber component may be, for example, 10% by mass or more, 20% by mass or more, and 30% by mass or more. May be present, may be 80% by mass or more, and may be 100% by mass. The amount of natural rubber in 100% by mass of the rubber component may be, for example, 80% by mass or less, 70% by mass or less, 60% by mass or less, and 50% by mass or less. It may be.

When the rubber composition contains polybutadiene rubber, the amount of polybutadiene rubber in 100% by mass of the rubber component may be, for example, 10% by mass or more, 20% by mass or more, and 30% by mass or more. It may be present, may be 40% by mass or more, and may be 50% by mass or more. The amount of polybutadiene rubber in 100% by mass of the rubber component may be, for example, 90% by mass or less, 80% by mass or less, or 70% by mass or less.

The polybutadiene rubber is not particularly limited. Examples of the polybutadiene rubber include high cis polybutadiene rubber and low cis polybutadiene rubber. From these, one or any combination can be selected and used.

The cis-1,4 content of the high cis polybutadiene rubber is preferably 90% or more, more preferably 93% or more, still more preferably 95% or more. The cis-1,4 content can be measured by an infrared absorption spectrum analysis method.

The cis-1,4 content of the low cis polybutadiene rubber is less than 90%, for example 70% or less, 60% or less, or 50% or less. The cis-1,4 content of the low cis polybutadiene rubber may be 20% or more, or 30% or more.

The amount of high-cis polybutadiene rubber in 100% by mass of polybutadiene rubber may be, for example, 10% by mass or more, 20% by mass or more, 30% by mass or more, and 40% by mass. It may be the above, 80% by mass or more, or 100% by mass. The amount of high-cis polybutadiene rubber in 100% by mass of polybutadiene rubber may be, for example, 80% by mass or less, 70% by mass or less, or 60% by mass or less.

When a high cis polybutadiene rubber and a low cis polybutadiene rubber are used as the polybutadiene rubber, the total amount of the high cis polybutadiene rubber and the low cis polybutadiene rubber is, for example, 70% by mass or more in 100% by mass of the polybutadiene rubber. May be 80% by mass or more, 90% by mass or more, and 100% by mass.

The rubber composition may further contain carbon black, silica, a silane coupling agent, oil, stearic acid, zinc oxide, an antioxidant, wax, sulfur, a vulcanization accelerator and the like. Of these, one or any combination may be included in the rubber composition.

As the carbon black, for example, furnace black such as SAF, ISAF, HAF, FEF and GPF, as well as conductive carbon black such as acetylene black and Ketjen black can be used. The carbon black may be a granulated carbon black granulated in consideration of its handling property or an ungranulated carbon black. One or more of these can be used.

The amount of carbon black is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 50 parts by mass or more, and further preferably 60 parts by mass or more with respect to 100 parts by mass of the rubber component. The amount of carbon black is preferably 90 parts by mass or less, more preferably 80 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of silica include wet silica and dry silica. Of these, wet silica is preferable. Wet silica may include precipitated silica.

The amount of oil is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, and further preferably 8 parts by mass or less with respect to 100 parts by mass of the rubber component. The amount of oil may be 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more with respect to 100 parts by mass of the rubber component.

As anti-aging agents, aromatic amine anti-aging agents, amine-ketone anti-aging agents, monophenol anti-aging agents, bisphenol anti-aging agents, polyphenol anti-aging agents, dithiocarbamate anti-aging agents, thiourea An antiaging agent etc. can be mentioned. As the antiaging agent, one or any combination can be selected from these and used. The amount of the antioxidant is preferably 0.5 parts by mass to 5 parts by mass, and more preferably 1 part by mass to 4 parts by mass with respect to 100 parts by mass of the rubber component.

The amount of stearic acid is, for example, 1 part by mass to 4 parts by mass with respect to 100 parts by mass of the rubber component. The amount of zinc oxide is, for example, 1 part by mass to 4 parts by mass with respect to 100 parts by mass of the rubber component. The amount of wax is, for example, 1 part by mass to 4 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of sulfur include powdered sulfur, precipitated sulfur, insoluble sulfur, and highly dispersible sulfur. Sulfur can be used by selecting one or any combination from these. The amount of sulfur is preferably 0.5 parts by mass to 5 parts by mass, and more preferably 1 part by mass to 4 parts by mass in terms of sulfur content based on 100 parts by mass of the rubber component.

Sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization accelerator, dithiocarbamate vulcanization accelerator as vulcanization accelerator Etc. can be mentioned. As the vulcanization accelerator, one or any combination can be selected and used from these. The amount of the vulcanization accelerator is preferably 0.1 parts by mass to 5 parts by mass, and more preferably 0.1 parts by mass to 2 parts by mass with respect to 100 parts by mass of the rubber component.

The pre-vulcanization rubber material (rubber composition) of each of the rubbers 2b and 3a has been described above in detail.

The description of the configuration for increasing the rigidity of the tire 1 by the rubber material of the sidewall rubber 3a will be finished here.

Next, a configuration for increasing the rigidity of the tire 1 by the carcass plies 5a and 5b will be described.

In the tire 1, the rigidity of the maximum width position 1a tends to be low. On the other hand, the outer end 5g of the winding portion 5e of the first carcass ply 5a in the tire radial direction D2 is arranged outside the maximum width position 1a in the tire radial direction D2. Accordingly, since the winding portion 5e of the first carcass ply 5a is arranged at the maximum width position 1a, it is possible to prevent the rigidity of the maximum width position 1a from being lowered.

The number of carcass plies 5a and 5b is not particularly limited, but in the present embodiment, a plurality of carcass plies 5a and 5b are provided. Specifically, two of the first carcass ply 5a and the second carcass ply 5b are provided. As a result, a plurality of carcass plies 5a and 5b are arranged in the sidewall portion 3, so that the rigidity of the sidewall portion 3 can be increased.

Next, a configuration in which the rigidity of the tire 1 is increased by the thickness of the sidewall rubber 3a will be described.

First, as shown in FIGS. 2 and 3, the tire 1 includes a side ply 7 arranged inside the bead portion 2 and the sidewall portion 3. The side ply 7 is arranged between the carcass layer 5 and the bead 2a. Specifically, the side ply 7 is arranged between the winding portions 5e and 5f of the carcass plies 5a and 5b and the bead filler 2d.

Thereby, the rigidity of the sidewall portion 3 (in particular, the inner portion in the tire radial direction D2) and the bead portion 2 can be increased. The number of side plies 7 is not particularly limited. In the present embodiment, one sidewall ply 7 is provided for each sidewall 3 and bead 2. Further, for example, the number of side plies 7 for one sidewall part 3 and one bead part 2 is preferably smaller than the number of belt plies 4c and 4d.

The side ply 7 includes a plurality of cords arranged in a direction inclined with respect to the tire circumferential direction D3, and a topping rubber covering the cords. The material of the cord of the side ply 7 is not particularly limited, but for example, organic fibers such as polyester, rayon, nylon, and aramid, or metal such as steel is suitable.

In the present embodiment, the cords of the belt plies 4c and 4d and the side ply 7 are made of metal, and the cords of the belt reinforcing portion 4e and the carcass plies 5a and 5b are made of non-metal (for example, organic fiber). Thus, the tire 1 includes the metalless region 1b between the belt plies 4c and 4d and the side plies 7. The rigidity of the metalless region 1b tends to be lower than the rigidity of the region (metal region) having the belt plies 4c and 4d and the side plies 7.

By the way, in the cross section of the tire meridian surface in the unloaded state in which the tire 1 is mounted on the regular rim 10 and filled with the regular internal pressure, as shown in FIG. 3, the metalless region 1b has a plurality of inner surfaces having different radii of curvature. Areas 1c to 1e. The boundary line between the regions 1c to 1e (indicated by a broken line in FIG. 3) is a normal line to the inner surface of the tire 1.

The plurality of regions 1c to 1e include a minimum region 1c having the smallest inner surface radius of curvature, a first region 1d arranged between the minimum region 1c and the belt plies 4c and 4d, and a minimum region 1c and a side. The second region 1e disposed between the ply 7 and the ply 7 is included. In addition, the number of the plurality of regions 1c to 1e is not particularly limited.

Then, when the tire 1 is elastically deformed during traveling, stress is likely to be concentrated in the minimum area 1c of the metalless area 1b. On the other hand, the minimum region 1c includes the maximum thickness position 3d where the thickness W3 of the sidewall rubber 3a is maximum in the metalless region 1b. As a result, the rigidity of the minimum area 1c can be increased. The thickness W3 of the sidewall rubber 3a is the dimension of the inner surface of the tire 1 in the normal direction.

The rigidity of the belt plies 4c and 4d is higher than that of the side ply 7. For example, since the cord diameters of the plies 4c, 4d, and 7 are different and the number of cord ends (the number of cords per unit width) is different, the total cord mass of the belt plies 4c and 4d per unit width is It is larger than the total cord mass per unit width of No. 7.

On the other hand, the distance W4 between the minimum area 1c and the belt ply 4d is smaller than the distance W5 between the minimum area 1c and the side ply 7. As a result, the minimum area 1c approaches the belt plies 4c and 4d having high rigidity, so that the rigidity of the minimum area 1c can be increased.

The distances W4 and W5 between the minimum area 1c and the plies 4d and 7 are distances along the inner surface of the tire 1. The distance W4 between the minimum region 1c and the belt ply 4d is the outermost end in the tire width direction D1 of the end portions of the belt plies 4c and 4d (in the present embodiment, the end of the second belt ply 4d). The distance W4 between the portion 4g) and the minimum area 1c.

The minimum region 1c includes an outer region 1g arranged outside the center 1f of the minimum region 1c in the tire radial direction D2, and an inner region 1h arranged inside of the center 1f of the minimum region 1c in the tire radial direction D2. Equipped with. Further, since the inner region 1h is separated from the belt plies 4c and 4d having high rigidity, the inner region 1h tends to have low rigidity.

On the other hand, the inner region 1h includes the maximum thickness position 3d of the sidewall rubber 3a having high rubber hardness. Moreover, the average thickness W3 of the sidewall rubber 3a in the inner region 1h is larger than the average thickness W3 of the sidewall rubber 3a in the outer region 1g. As a result, the rigidity of the inner area 1h can be increased.

As described above, in the pneumatic tire 1 according to the present embodiment, the bead 2a arranged inside the bead portion 2, the rim strip rubber 2b constituting the outer surface of the bead portion 2, and the outer surface of the tread portion 4 are provided. The tread rubber 4a and the sidewall rubber 3a, which constitutes the outer surface of the sidewall portion 3 and is connected to the rim strip rubber 2b and the tread rubber 4a, are provided, and the bead 2a is formed in an annular shape. And a bead filler 2d arranged outside the bead core 2c in the tire radial direction D2. The rubber material of the sidewall rubber 3a is the same as the rubber material of the rim strip rubber 2b. The modulus of the sidewall rubber 3a and the rim strip rubber 2b is 25% or more of the modulus of the bead filler 2d.

According to this structure, since the rubber material of the sidewall rubber 3a is the same as the rubber material of the rim strip rubber 2b, the rigidity of the sidewall portion 3 can be increased. As a result, the rigidity of the pneumatic tire 1 can be increased.

Moreover, since the modulus of the sidewall rubber 3a and the rim strip rubber 2b is 25% or more of the modulus of the bead filler 2d, the rigidity of the sidewall portion 3 can be further increased. As a result, the rigidity of the pneumatic tire 1 can be further increased.

The pneumatic tire 1 according to the present embodiment further includes a carcass ply 5a bridged between the pair of beads 2a, 2a, and the carcass ply 5a is arranged around the bead 2a in the tire width direction. A winding portion 5e that is wound from the inside to the outside of D1 is provided, and an outer end 5g of the winding portion 5e in the tire radial direction D2 has a maximum width position 1a at which the dimension W1 of the pneumatic tire 1 in the tire width direction D1 is maximum. Rather, it is arranged outside the tire radial direction D2.

According to such a configuration, the rigidity of the maximum width position 1a tends to be low, whereas the outer end 5g of the winding portion 5e in the tire radial direction D2 is located outside the maximum width position 1a in the tire radial direction D2. It is arranged. Accordingly, since the winding portion 5e is arranged at the maximum width position 1a, it is possible to prevent the rigidity of the maximum width position 1a from being lowered.

Moreover, the pneumatic tire 1 according to the present embodiment is configured to further include a plurality of carcass plies 5a and 5b bridged between the pair of beads 2a and 2a.

According to this structure, since the plurality of carcass plies 5a and 5b are arranged in the sidewall portion 3, the rigidity of the sidewall portion 3 can be further increased. As a result, the rigidity of the pneumatic tire 1 can be further increased.

The pneumatic tire 1 is not limited to the configuration of the above-described embodiment, and is not limited to the above-described operational effects. Needless to say, the pneumatic tire 1 can be variously modified without departing from the scope of the present invention. For example, it is needless to say that one or a plurality of configurations and methods according to various modifications described below may be arbitrarily selected and applied to the configurations and methods according to the above-described embodiments.

(1) In the pneumatic tire 1 according to the above embodiment, the inner region 1h is configured to include the maximum thickness position 3d. However, although the pneumatic tire 1 preferably has such a configuration, it is not limited to such a configuration. For example, the outer region 1g may include the maximum thickness position 3d.

(2) Further, in the pneumatic tire 1 according to the above embodiment, the average of the thickness W3 of the sidewall rubber 3a in the inner region 1h is larger than the average of the thickness W3 of the sidewall rubber 3a in the outer region 1g. It is thick. However, although the pneumatic tire 1 preferably has such a configuration, it is not limited to such a configuration. For example, the average thickness W3 of the sidewall rubber 3a in the inner region 1h may be equal to or less than the average thickness W3 of the sidewall rubber 3a in the outer region 1g.

(3) In the pneumatic tire 1 according to the above embodiment, the distance W4 between the minimum area 1c and the belt ply 4c is smaller than the distance W5 between the minimum area 1c and the side ply 7. .. However, although the pneumatic tire 1 preferably has such a configuration, it is not limited to such a configuration. For example, the distance W4 between the minimum area 1c and the belt ply 4c may be equal to or more than the distance W5 between the minimum area 1c and the side ply 7.

(4) Further, in the pneumatic tire 1 according to the above embodiment, the outer end 5g in the tire radial direction D2 of the winding portion 5e of one carcass ply 5a among the plurality of carcass plies 5a and 5b has the maximum width position. It is configured to be arranged on the outer side in the tire radial direction D2 with respect to 1a. However, the pneumatic tire 1 is not limited to such a configuration.

For example, among the plurality of carcass plies 5a and 5b, the outer ends 5g in the tire radial direction D2 of the hoisting portions 5e and 5f of all the carcass plies 5a and 5b are located outside the maximum width position 1a in the tire radial direction D2. It may be arranged. Note that, for example, the outer ends 5g in the tire radial direction D2 of the winding portions 5e and 5f of all the carcass plies 5a and 5b of the plurality of carcass plies 5a and 5b are located in the tire radial direction D2 rather than the maximum width position 1a. It may be configured to be arranged inside.

(5) In the pneumatic tire 1 according to the above embodiment, the rubber hardness of the sidewall rubber 3a and the rim strip rubber 2b is higher than that of the tread rubber 4a. However, although the pneumatic tire 1 preferably has such a configuration, it is not limited to such a configuration. For example, the rubber hardness of the sidewall rubber 3a and the rim strip rubber 2b may be less than or equal to the rubber hardness of the tread rubber 4a.

In order to specifically show the configuration and effects of the tire 1, examples of the tire 1 and comparative examples thereof will be described below.

Details of each component in Table 1 are as follows.
Natural rubber RSS#3
Polybutadiene rubber "BR150B" (polybutadiene rubber polymerized with a cobalt-based catalyst, cis-1,4 content = 96%, vinyl group content = 2%) Ube Industries carbon black "Cast 3" Tokai Carbon oil " Process NC-140" JX Nikko Nisseki Energy's stearic acid "Lunak S-20"Kao's zinc oxide "Zinc oxide 2" Mitsui Mining & Smelting Co., Ltd. Antioxidant "Nocrac 6C" Ouchi Shinko Chemical Co., Ltd. Wax "OZOACE-0355" Made by Nippon Seiro Co., Ltd. Vulcanization accelerator CZ "Sokshinol CZ" Made by Sumitomo Chemical Co., Ltd. Vulcanization accelerator NS "Noxceller NS-P" Made by Ouchi Shinko Chemical Co., Ltd. Sulfur "Powdered sulfur" Tsurumi Chemical Industry Company

Preparation of unvulcanized rubber of each compounding A compounding agent except sulfur and a vulcanization accelerator was added to the rubber according to Table 1 and kneaded with a Banbury mixer to obtain a rubber mixture. The rubber mixture, sulfur and vulcanization accelerator were kneaded with a Banbury mixer to obtain an unvulcanized rubber.

Tensile stress (modulus) at 100% elongation
The unvulcanized rubber was vulcanized at 150° C. for 30 minutes to obtain a vulcanized rubber. The 100% elongation tensile stress of the vulcanized rubber was determined according to JIS K-6251:2017. Specifically, first, vulcanized rubber was punched with a punching blade to obtain a No. 3 dumbbell-shaped test piece. Next, the tensile force when 100% elongation was given to the dumbbell-shaped test piece at 23° C. was measured. The 100% elongation tensile stress was obtained by dividing (dividing) the tensile force by the initial cross-sectional area of the dumbbell-shaped test piece.

Preparation of Pneumatic Tire in Example 1 An unvulcanized tire of Compound C was used as both a sidewall rubber and a rim strip rubber to prepare an unvulcanized tire, and the unvulcanized tire was vulcanized and molded. -The pneumatic tire which concerns on FIG. 3 was produced. The tire size of this pneumatic tire was 235/45R17.

Production of Pneumatic Tire in Example 2 A pneumatic tire was produced in the same manner as in Example 1 except that the unvulcanized rubber of the compound D was used as both the sidewall rubber and the rim strip rubber.

Manufacture of Pneumatic Tire in Comparative Example 1 In the same manner as in Example 1 except that the unvulcanized rubber of Compound A was used as the sidewall rubber and the unvulcanized rubber of Compound C was used as the rim strip rubber. A pneumatic tire was produced.

Preparation of Pneumatic Tire in Comparative Example 2 In the same manner as in Example 1 except that the unvulcanized rubber of the compound B was used as the sidewall rubber and the unvulcanized rubber of the compound C was used as the rim strip rubber. A pneumatic tire was produced.

Preparation of Pneumatic Tire in Comparative Example 3 In the same manner as in Example 1 except that the unvulcanized rubber of Compound A was used as the sidewall rubber and the unvulcanized rubber of Compound D was used as the rim strip rubber. A pneumatic tire was produced.

Preparation of Pneumatic Tire in Comparative Example 4 In the same manner as in Example 1 except that the unvulcanized rubber of the compound B was used as the sidewall rubber and the unvulcanized rubber of the compound D was used as the rim strip rubber. A pneumatic tire was produced.

Average lap time A race car equipped with pneumatic tires was run by a professional driver on the circuit and the lap time was measured for four laps to obtain the average lap time. Table 2 shows the reciprocal of the average lap time of each example, which is an index with the reciprocal of the average lap time of Comparative Example 1 being 100. The larger the index, the shorter the average lap time. We asked the racing team to drive the circuit and measure the lap time.

Front and rear rigidity (Kx)
Using a stiffness tester manufactured by Yamato Seiko Co., Ltd., a pneumatic tire having an internal pressure of 220 kPa was loaded with a vertical load of 470 kgf and a longitudinal load of 141 kgf, and the longitudinal deflection was measured. Table 2 shows the reciprocal of the flexure of each example, which is an index with the reciprocal of the flexure of Comparative Example 1 being 100. The larger the index, the smaller the bending and the more excellent the front-rear rigidity.

Lateral rigidity (Ky)
Using a stiffness tester manufactured by Daiwa Seiko Co., Ltd., a pneumatic tire having an internal pressure of 220 kPa was loaded with a vertical load of 470 kgf and a lateral load of 141 kgf to measure lateral deflection. Table 2 shows the reciprocal of the flexure of each example, which is an index with the reciprocal of the flexure of Comparative Example 1 being 100. The larger the index, the smaller the bending and the better the lateral rigidity.

The rigidity (front-rear rigidity and lateral rigidity) of the pneumatic tire in Example 1 was higher than the rigidity of Comparative Example 1 and Comparative Example 2. Therefore, it can be said that the steering response of the pneumatic tire in Example 1 is higher than that of the pneumatic tires of Comparative Example 1 and Comparative Example 2. In support of that, the average lap time of the pneumatic tire in Example 1 was shorter than the average lap time of Comparative Example 1 and Comparative Example 2.

The rigidity (front-rear rigidity and lateral rigidity) of the pneumatic tire in Example 2 was higher than the rigidity of Comparative Example 3 and Comparative Example 4. Therefore, it can be said that the steering response of the pneumatic tires of Example 2 is higher than the steering responses of the pneumatic tires of Comparative Examples 3 and 4. In support of that, the average lap time of the pneumatic tire in Example 2 was shorter than the average lap time of Comparative Example 3 and Comparative Example 4.

1... Pneumatic tire, 1a... Maximum width position, 1b... Metalless area, 1c... Minimum area, 1d... First area, 1e... Second area, 1f... Center, 1g... Outer area, 1h... Inner area, 2 ...Bead portion, 2a...bead, 2b...rim strip rubber, 2c...bead core, 2d...bead filler, 2e...outer end portion, 3...sidewall portion, 3a...sidewall rubber, 3b...inner end portion, 3c...outer side End portions 3d... Maximum thickness position, 4... Tread portion, 4a... Tread rubber, 4b... Belt layer, 4c... First belt ply, 4d... Second belt ply, 4e... Belt reinforcing portion, 4f... Outer end portion, 4g...end part, 5...carcass layer, 5a...first carcass ply, 5b...second carcass ply, 5c,5d...ply body part, 5e,5f...winding part, 5g...outer end,6...inner liner layer, 7... Side ply, 10... Rim, D1... Tire width direction, D2... Tire radial direction, S1... Tire equatorial plane

Claims (3)

A bead placed inside the bead part,
A rim strip rubber forming the outer surface of the bead portion,
With a tread rubber that constitutes the outer surface of the tread portion,
A sidewall rubber that constitutes the outer surface of the sidewall portion and is connected to the rim strip rubber and the tread rubber, respectively,
Equipped with
The bead includes a bead core formed in an annular shape, and a bead filler arranged on the outer side in the tire radial direction of the bead core,
The rubber material of the sidewall rubber is the same as the rubber material of the rim strip rubber,
The pneumatic tire in which the modulus of the sidewall rubber and the rim strip rubber is 25% or more of the modulus of the bead filler. Further comprising a carcass ply bridged between a pair of the beads,
The carcass ply includes a winding portion that is wound around the bead from the inside in the tire width direction to the outside,
The pneumatic outside according to claim 1, wherein an outer end in the tire radial direction of the rolled-up portion is arranged outside in the tire radial direction with respect to a maximum width position where the dimension of the pneumatic tire in the tire width direction is maximum. tire. The pneumatic tire according to claim 1 or 2, further comprising a plurality of carcass plies bridged between a pair of the beads.

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