JP6623716B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a foamed rubber is used for a sidewall portion, and more particularly, to a pneumatic tire capable of reducing a tire weight while maintaining trauma resistance.

  2. Description of the Related Art Conventionally, in pneumatic tires, from the viewpoint of resource saving and energy saving, the weight of tires has been reduced in order to reduce the amount of materials used in the tires and to reduce fuel consumption. As a method of reducing the weight of such a tire, for example, it has been proposed to use foamed rubber as the rubber constituting the sidewall portion (for example, see Patent Document 1).

  However, since foamed rubber has lower strength than non-foamed rubber, for example, there is a tendency for external damage to occur due to rubbing of a sidewall portion against a curb, a wall surface, or the like during traveling. That is, there is a problem that the resistance to trauma to friction is reduced. Therefore, when adopting a foamed rubber layer in the sidewall portion to reduce the weight of the tire, there is a demand for a measure for preventing a reduction in the trauma resistance without impairing the effect of weight reduction.

JP 07-101 211 A

  An object of the present invention is to provide a pneumatic tire in which foamed rubber is used for a sidewall portion, which is capable of reducing tire weight while maintaining trauma resistance. .

In order to achieve the above object, a pneumatic tire of the present invention includes a ring-shaped tread extending in the tire circumferential direction, a pair of sidewalls disposed on both sides of the tread, and a sidewall. A pair of bead portions disposed radially inward of the tire, and a pneumatic tire in which a carcass layer is mounted between the pair of bead portions, the side wall portion of the carcass layer on the outside in the tire width direction. The rubber layer is made of foamed rubber, and the tire cross-section height is defined as h, and a region included between the tire maximum width position and a position apart from the tire radial direction by 0.1 times the tire cross-section height h is defined as an area. The center area is included between the position 0.7 times the tire cross-sectional height h outward from the rim baseline in the tire radial direction and the position 0.1 mm away from the rim baseline in the tire radial direction by 0.1 times the tire cross-sectional height h. When a region has an outer region, wherein the specific gravity d _OUT in the outer region of the foamed rubber is less than the specific gravity d _C in the central region of the foamed rubber.

In the present invention, in order to reduce the weight of the tire by forming the rubber layer on the side of the carcass layer in the tire width direction outside of the sidewall portion to reduce the weight of the tire, the specific gravity of the foamed rubber is set as described above, and in the outer region. since the specific gravity d _OUT is less than the specific gravity d _C of the central region, the strength of the central region of easily foamed rubber in contact with the curb or a wall or the like during running to maintain sufficiently the highly the external damage resistance The tire weight can be sufficiently reduced while maintaining the tire weight.

In the present invention, it is included between a position 0.2 times the tire cross-sectional height h outward from the rim baseline in the tire radial direction and a position 0.1 mm away from the rim baseline inward and outward in the tire radial direction by 0.1 times the tire cross-sectional height h. When the region is the inner region, it is preferable that the specific gravity d _{IN in} the inner region of the foamed rubber is smaller than the specific gravity d _C in the central region of the foamed rubber. By setting the specific gravity of the foam rubber constituting the sidewall portion in this manner, the strength of the central region of the foam rubber which is easily brought into contact with a curb or a wall surface during traveling can be sufficiently maintained, while the bead portion side of the sidewall portion is maintained. However, it is possible to reduce the weight due to the low specific gravity of the foamed rubber, which is advantageous for reducing the tire weight while maintaining the trauma resistance.

In the present invention, the specific gravity d _{C in} the central region of the foamed rubber is preferably 0.6 to 1.0. By setting the specific gravity d _C in the central region in an appropriate range in this way, it is possible to achieve both excellent trauma resistance and a light weight tire effect in a well-balanced manner.

  In the present invention, the cells contained in the foamed rubber are preferably closed cells. By using a foamed rubber containing closed cells in this way, it is possible to obtain a higher breaking strength than a foamed rubber composed of open cells having the same specific gravity, and to provide excellent trauma resistance and an effect of reducing the weight of the tire. It is advantageous to achieve both.

  At this time, the average diameter of the closed cells is preferably 10 μm to 100 μm. As described above, by reducing the average cell diameter of the closed cells, the distribution density of the closed cells in the foamed rubber is increased, and the crack propagation when a trauma occurs in the tire is dispersed, thereby improving the trauma resistance. it can. In the present invention, the average cell diameter of the closed cells is cut out of a block-shaped sample from the foamed rubber, the cross section of the sample is photographed with an optical microscope having a magnification of 100 to 400, and the cell diameter of each cell in the cross section is measured. This was obtained by calculating the average of the bubble diameters.

  In the present invention, the modulus at the time of 100% elongation of the foamed rubber is preferably 0.8 MPa or more. By using the foamed rubber having such characteristics, the influence of the side wall portion rubbing against a curb or a wall surface during traveling can be reduced, which is advantageous for enhancing the resistance to trauma. In the present invention, the modulus at the time of 100% elongation of the foamed rubber is a value measured in accordance with JIS K6251 using a No. 3 type dumbbell test piece at a tensile speed of 500 mm / min and a temperature of 23 ° C. It is.

  In the present invention, it is preferable that the minimum thickness of the rubber layer on the side of the carcass layer in the tire width direction in the sidewall portion is 1.0 mm to 2.5 mm. By setting the thickness of the rubber layer in this manner, it is advantageous to achieve both excellent scratch resistance and the effect of reducing the weight of the tire.

  In the present invention, it is preferable to have an outer surface layer made of a non-foamed rubber composition on the outer side in the tire width direction of the rubber layer outside the carcass layer in the side wall portion including at least the central region. By providing the outer surface layer in this manner, the scratch resistance can be enhanced, but at this time, the outer surface layer is provided only on the outer side of the rubber layer in the tire width direction of the carcass layer in the sidewall portion and in the outer side in the tire width direction. Therefore, the influence on the tire weight (lightening of the tire) can be suppressed.

  In the present invention, the "specific gravity" of the foamed rubber is the apparent specific gravity of the foamed rubber as a whole including the bubbles, and varies depending on the size and distribution density of the bubbles in the foamed rubber. As the numerical value, a value measured according to JIS K6268 is used.

  In the present invention, the “tire maximum width position” refers to a tire diameter at a point where the carcass layer most protrudes outward in the tire width direction in a no-load state in which the tire is assembled to a regular rim and filled with a regular internal pressure. The “rim base line” is a reference line indicating the rim diameter position of the regular rim on which the pneumatic tire is mounted. The “regular rim” is a rim defined for each tire in a standard system including the standard on which the tire is based. For example, a standard rim for JATMA, a “Design Rim” for TRA, Alternatively, in the case of ETRTO, it is “Measurement Rim”, and “normal internal pressure” is the air pressure that is defined for each tire in the standard system including the standard on which the tire is based. , TRA, the maximum value described in the table “TIRE ROAD LIMITS AT VARIOUS COLD INFRACTION PRESSURESRES”, and ETRTO, “INFLASION PRESSURE”, but 180 kPa when the tire is a passenger car.

BRIEF DESCRIPTION OF THE DRAWINGS It is a meridian half cross section of the pneumatic tire which consists of embodiment of this invention. It is a meridian half sectional view of the pneumatic tire which consists of another embodiment of this invention. It is a meridian half sectional view of the pneumatic tire which consists of another embodiment of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the pneumatic tire of the present invention includes a ring-shaped tread portion 1 extending in the tire circumferential direction, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, A pair of beads 3 arranged radially inward of the wall 2 in the tire radial direction. Although FIG. 1 shows only one side of the tire equator CL, the other side has the same structure with respect to the tire equator CL.

  A carcass layer 4 is mounted between the pair of right and left bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside to the outside of the vehicle around a bead core 5 arranged in each bead portion 3. Further, a bead filler 6 is arranged on the outer periphery of the bead core 5, and the bead filler 6 is wrapped around the main body and the folded portion of the carcass layer 4. On the other hand, a plurality of (two in FIG. 1) belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. Further, a belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7. The belt reinforcing layer 8 includes an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing layer 8, the angle of the organic fiber cord with respect to the tire circumferential direction is set to, for example, 0 ° to 5 °.

  The present invention defines the structure of the side rubber layer G (hatched portion in the figure) located outside the carcass layer 4 in the tire width direction in the sidewall portion 2 as described later. It is not limited to the structure.

  In the present invention, the side rubber layer G is made of foamed rubber. The foamed rubber is, for example, a rubber composition containing open cells or closed cells obtained by adding a foaming agent during molding and generating bubbles during vulcanization. Such a foamed rubber has a smaller specific gravity as compared with a normal non-foamed rubber. Therefore, by adopting the side rubber layer G, the weight of the tire can be reduced.

At this time, the specific gravity of the foamed rubber is not constant throughout the side rubber layer G, is set to be smaller in the tread portion 1 side from the maximum width position P _C tires. Specifically, the tire section height and h, the central region A _C a region comprised between a position away by 0.1 times the tire section height h from the maximum width position P _C tires in the tire radial direction inside and outside Included from the rim base line BL to a position radially outward in the tire radial direction 0.7 times the tire sectional height h and from a position P _OUT inwardly and outwardly from the rim baseline BL by a distance 0.1 times the tire sectional height h. Assuming that the region to be _covered is the outer region A _OUT , the specific gravity d _OUT in the outer region A _OUT of the foamed rubber is smaller than the specific gravity d _C in the central region _AC of the foamed rubber. Since the specific gravity of the foamed rubber is set, while maintaining the external damage resistance while maintaining the strength of the easy central region A _C contacts the curbstone or a wall or the like during running, little influence on the external damage resistance center the weight of the tire by the low density region a _C tread portion 1 side of the region than (outer region a _OUT) can be sufficiently achieved.

In this case, the difference between the specific gravity d _OUT at the outer region A _OUT of the foamed rubber and a specific gravity d _C of the central region A _C of the foamed rubber is extremely large, the sidewall portion 2 is strongly pressed against the curbstone or a wall surface or the like When the outer area A _OUT comes into contact with a curb or a wall surface, it is difficult to prevent the outer area A _OUT from being damaged. Therefore, the specific gravity ratio d _OUT / d _C is set to 0.5 or more and 0.99 or less. Is preferred.

Further, in the present invention, the specific gravity of the foamed rubber is preferably set to be smaller at the bead part 3 side than the maximum width position P _C tires. Specifically, a position at a position apart from the rim base line BL by 0.1 times the tire sectional height h inward and outward from the position P _{IN that} is 0.2 times the tire sectional height h outward in the tire radial direction from the position P _IN . when the region and inside region a _iN comprised between, it is preferable specific gravity d _iN of the inside region a _iN of the foamed rubber than the specific gravity d _C of the central region a _C of the foamed rubber is smaller. By thus setting the specific gravity of the foam rubber, while maintaining the external damage resistance while maintaining the strength of the easy central region A _C contacts the curbstone or a wall or the like during running, small central region of influence of the external damage resistance Even with a low specific gravity in the region (the inner region A _IN ) closer to the bead portion 3 than A _C, the weight of the tire can be sufficiently reduced.

In this case, the difference between the specific gravity d _IN of the inside region A _IN of the foamed rubber and a specific gravity d _C of the central region A _C of the foamed rubber is extremely large, the sidewall portion 2 is strongly pressed against the curbstone or a wall surface or the like When the inner area A _IN comes into contact with a curb or a wall surface, it is difficult to prevent the inner area A _IN from being damaged. Therefore, the specific gravity ratio d _IN / d _C is set to 0.5 or more and 0.99 or less. Is preferred.

Accordingly, in the present invention, looking at the entire side rubber layer G, and a specific gravity d _C of the central region A _C, a specific gravity d _OUT and the bead part 3 side of the inner area A in the outer region A _OUT of the tread portion 1 side it is preferable that each of the specific gravity d _iN at _iN is small. Thus when changing the specific gravity of the foamed rubber, for example may be the specifications gravity is gradually reduced toward the tire maximum width position P _C to the tread portion 1 side or bead part 3 side. Alternatively, as shown in FIG. 2, foam rubbers having different specific gravities may be combined in the tire radial direction to form the side rubber layer G, and the specific gravity may be changed stepwise. In the example of FIG. 2, two different types of foam rubber is used in specific gravity, a large foam rubber relatively specific gravity is located at a site including a central region A _C, a small separate foamed rubber having relatively specific gravity outside by being respectively arranged in the region containing the site and inside region a _iN including the area a _OUT, than the specific gravity d _C of the central region a _C of the specific gravity d _OUT and an inner region a _iN at the outer region a _OUT The specific gravity d _IN is small. When the specific gravity is changed stepwise as described above, it is preferable that the boundaries between the foamed rubbers having different specific gravities are inclined with respect to the tire width direction as shown in FIG. Incidentally, the tire maximum width position P _C (central region A _C) from the tread portion 1 side (the outer region A _OUT) density change in towards specifications and the bead part 3 side (inside region A _IN) changes in specific gravity toward the The specifications can be the same or different.

In the example of FIG. 2, for example, small foam relatively specific gravity than foam rubber that is disposed in a portion containing the same foamed rubber (the central region A _C into a region containing the site and inside region A _IN includes an outer region A _OUT the rubber) is disposed, but is the same and the density d _iN of specific gravity d _OUT and an inner region a _iN at the outer region a _OUT, a specific gravity d _OUT inner area a in the outer region a _{OUT It} may be larger than the specific gravity d _{IN at IN} . That is, it is preferable that the specific gravities d _OUT and d _IN have a relation of d _OUT ≧ d _IN . More preferably, it is the ratio of these specific gravity d _OUT / d _IN is at _{1.0 ≦ d OUT / d IN <} 1.2. As described above, by increasing the specific gravity in the outer region A _OUT , since the tire components are not included as compared with the folded region of the carcass layer 4 and the inner region A _{IN including the} bead filler 6, the structural breaking characteristics are reduced. It is possible to reliably increase the trauma resistance of the outer region A _OUT where it is difficult to obtain the trajectory, and to improve the trauma resistance of the entire sidewall portion 2 in a well-balanced manner. Also in the case of specifications specific gravity of the foamed rubber is gradually reduced toward the tread portion 1 side or bead part 3 side from the maximum width position P _C tires, the specific gravity of the specific gravity d _OUT and an inner region A _IN at the outer region A _OUT Preferably, the relationship with d _IN is set as described above.

In the present invention, when setting the magnitude relationship of the specific gravity of the foamed rubber as described above, the specific gravity d _C in the central region A _C of the foamed rubber is preferably 0.6 to 1.0, more preferably 0.70 to 1.0. ０．９0.90, more preferably 0.75５0.85. By thus setting the specific gravity d _C of the central region A _C of the foamed rubber, it is possible to achieve both good balance and weight-reducing effects of excellent external damage resistance and the tire. At this time, the specific gravity d _C of the central region A _C of the foamed rubber is less than 0.6, rupture strength of the entire foam rubber (in particular the central region A _C) is lowered, it is possible to obtain a sufficient external damage resistance It becomes difficult. If the specific gravity d _C of the central region A _C of the foamed rubber is greater than 1.0, since the specific gravity of the whole foamed rubber is not sufficiently small, it becomes difficult to obtain a sufficient effect of weight reduction.

  As described above, the foamed rubber is a rubber composition containing open cells or closed cells.When the foamed rubber containing open cells and the foamed rubber containing closed cells are compared, when both have the same specific gravity. The foamed rubber composed of closed cells has a higher breaking strength than the foamed rubber composed of open cells. For this reason, in the present invention, it is preferable to use a foamed rubber composed of closed cells that can provide high breaking strength at the same specific gravity. This makes it possible to achieve a high level of both excellent resistance to trauma and the effect of reducing the weight of the tire.

  When the foamed rubber composed of closed cells is used as described above, the closed cells preferably have an average cell diameter of 10 μm to 100 μm. As described above, when the average cell diameter of the closed cells is small, the distribution density of the closed cells in the foamed rubber increases with the same specific gravity. Therefore, when a trauma occurs in the tire, it is possible to disperse the propagation of the crack starting from the trauma occurrence position, which is advantageous for enhancing the trauma resistance. At this time, if the average cell diameter of the closed cells is smaller than 10 μm, the cells become too small and substantially the same as non-foamed rubber, so that it is difficult to obtain a sufficient lightening effect. If the average cell diameter of the closed cells is larger than 100 μm, it becomes difficult to set the specific gravity of the foamed rubber in an appropriate range, and it becomes difficult to obtain sufficient damage resistance.

  The foamed rubber preferably has not only the above specific gravity but also a high modulus. Specifically, the modulus at 100% elongation is preferably at least 0.8 MPa, more preferably at least 1.1 MPa. By using the foamed rubber having such characteristics, the influence of the side wall portion rubbing against a curb or a wall surface during traveling can be reduced, which is advantageous for enhancing the resistance to trauma.

  In addition to the above-described configuration, by reducing the thickness of the side rubber layer G, it is possible to further reduce the weight of the tire. However, when the rubber layer G is extremely thin, it is difficult to obtain sufficient cut resistance. Therefore, the minimum thickness of the rubber layer G is preferably set to 1.0 mm to 2.5 mm, more preferably 1.2 mm to 2.0 mm. At this time, if the minimum thickness of the rubber layer G is smaller than 1.0 mm, it is difficult to obtain sufficient damage resistance. If the minimum thickness of the rubber layer G is larger than 2.5 mm, sufficient weight reduction cannot be expected.

It is preferable that the portion where the thickness of the rubber layer G is minimized avoids a portion that is likely to come into contact with a curb or a wall surface during traveling (that is, the central region A _C ). More preferably, the rubber layer in the tire radial direction inner region than 0.6 times the position P _OUT of the tire section height h from the outer side in the tire radial direction and the rim base line BL than the central region A _C on the outer side in the tire radial direction Preferably, there is a portion where the thickness of G is minimized.

  In the present invention, as shown in FIG. 3, an outer surface layer g made of a non-foamed rubber composition portion may be provided on the side wall layer 2 outside the carcass layer 4 in the tire width direction on the side wall portion 2. preferable. By providing the outer surface layer g in this manner, the foamed rubber is not exposed on the outer surface of the tire, and the side rubber layer G is covered with a non-foamed rubber composition having a higher strength than the foamed rubber. Can be enhanced. At this time, the outer surface layer g is limitedly provided on the outer side in the tire width direction of the side rubber layer G, so that the influence on the tire weight (lightening of the tire) can be suppressed.

The outer surface layer g may when positioned so as to include at least the central region A _C, may be provided on the entire sidewall portion 2. However, from the viewpoint of suppressing the influence of the tire weight, it is preferable to limit arranged only in the tire width direction outermost contributions largest central region A _C to external damage resistance. In order to suppress the influence on the tire weight, the average thickness of the outer surface layer g may be, for example, 0.1 mm to 0.5 mm.

  The type of the non-foamed rubber composition constituting the outer surface layer g is not particularly limited, but a rubber composition having the same composition as the rubber portion of the foamed rubber may be used. Further, in order to further improve the scratch resistance, a rubber composition having a higher modulus than the foamed rubber may be used.

The tire size is 205 / 55R16, which has the basic structure shown in FIG. 1, and the side rubber layer G is composed of a material (foamed rubber or non-foamed rubber), and the type of foam when foamed rubber is used (closed cell or open cell) specific gravity d _iN), modulus at 100% elongation, the minimum thickness of the specific gravity d _C, a specific gravity d _OUT at the outer region a _OUT, inner area a _iN of bubbles), average cell diameter, the specific gravity (center region a _C The 18 types of pneumatic pneumatic tires of Conventional Example 1, Comparative Examples 1 and 2, and Examples 1 to 15 in which the presence or absence of an outer surface layer provided on the outer side in the tire width direction of the side rubber layer G are set as shown in Tables 1 and 2, respectively. A tire was manufactured.

In these examples, parts the thickness of the side rubber layer G is minimized, both the outer side in the tire radial direction from the outer side in the tire radial direction and the rim base line BL than the central region A _C of the tire section height h 0 It exists in a region radially inward of the position P _{OUT of} .6 times in the tire radial direction. In Example 15 comprises an outer surface layer, this outer surface layer is made from a rubber composition having the same composition as the rubber portion of the foamed rubber, limitedly provided only in the central region A _C, its average thickness It is set to 0.3 mm.

  In the column of "Material" in Tables 1 and 2, "foamed" is shown when the material constituting the side rubber layer G is foamed rubber, and "non-foamed" when it is non-foamed rubber. In the column of "Type of air bubble" in Tables 1 and 2, "closed" is shown for closed cells and "open" for open cells.

  With respect to these 18 types of pneumatic tires, tire weight and trauma resistance were evaluated by the following evaluation methods, and the results are shown in Tables 1 and 2.

Tire weight The weight of each test tire was measured. The evaluation results are shown as indices with the reciprocal of the measured value of Conventional Example 1 being 100. The larger the index value, the smaller the tire weight.

Damage resistance Each test tire is mounted on a rim size 16 x 6.5 JJ wheel, mounted on a test vehicle (front wheel drive vehicle) with a displacement of 1600 cc at an air pressure of 230 kPa, and is almost parallel to the curb made of concrete with a height of 20 cm. I drove to enter. This running was repeated while changing the approach speed to the curb, and the speed at which surface damage of 1 mm or more in depth and 5 mm or more in length on the surface of the sidewall portion was measured. The evaluation results were indicated by an index with Conventional Example 1 being 100. The larger the index value, the higher the rate at which surface damage occurs, and the better the resistance to trauma to friction. If the index value is “98” or more, the conventional level of the resistance to trauma is maintained, and preferably, the index value is “99” or more.

  As is clear from Tables 1 and 2, Examples 1 to 15 all reduced tire weight as compared with Conventional Example 1 while maintaining a high level of trauma resistance. On the other hand, in Comparative Example 1, since the side rubber layer G was made of non-foamed rubber, it was excellent in trauma resistance, but the tire weight was significantly deteriorated. In Comparative Example 2, since the entire side rubber layer G was made of foamed rubber having a specific gravity (low specific gravity), the tire weight could be greatly reduced, but the trauma resistance was significantly deteriorated.

1 tread portion 2 sidewall portion 3 bead portion 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 belt reinforcing layer G side rubber layer g outer surface layer P _C maximum tire width position A _C central region A _OUT outer region A _IN inner region CL tire equator

Claims (8)

A ring-shaped tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed inside the sidewall portion in the tire radial direction. A pneumatic tire having a carcass layer mounted between the pair of bead portions,
The rubber layer of the carcass layer in the side wall portion on the outer side in the tire width direction is made of foamed rubber, and the tire cross-section height is defined as h. The region included between the positions separated by 1 times is defined as the central region, and the tire cross-sectional height h is set at a position 0.7 times the tire cross-sectional height h outward from the rim baseline in the tire radial direction and from the position 0.7 times the tire cross-sectional height h. When the area included between the positions separated by 0.1 times from each other is defined as the outer area, the specific gravity d _OUT of the foamed rubber in the outer area is smaller than the specific gravity d _C of the foamed rubber in the central area. A pneumatic tire, characterized in that: The region included between the position 0.2 times the tire cross-sectional height h outward from the rim baseline and the position 0.1 mm away from the rim baseline in the tire radial direction inside and outside the tire radial direction is inside the region. 2. The pneumatic tire according to claim 1, wherein a specific gravity d _IN of the foamed rubber in the inner region is smaller than a specific gravity d _C of the foamed rubber in the central region. The pneumatic tire according to claim 1, wherein a specific gravity d _C of the foamed rubber in the central region is 0.6 to 1.0.   The pneumatic tire according to any one of claims 1 to 3, wherein the bubbles contained in the foamed rubber are closed cells.   The pneumatic tire according to claim 4, wherein the closed cells have an average cell diameter of 10 µm to 100 µm.   The pneumatic tire according to any one of claims 1 to 5, wherein the foamed rubber has a modulus at 100% elongation of 0.8 MPa or more.   The pneumatic tire according to any one of claims 1 to 6, wherein a minimum thickness of a rubber layer of the carcass layer in the tire width direction outside of the sidewall portion is 1.0 mm to 2.5 mm.   An outer surface layer made of a non-foamed rubber composition portion is provided at least in the tire width direction outside of the carcass layer in the tire width direction in the sidewall portion including the central region. 7. The pneumatic tire according to any one of the above items 7.

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