JP2020152165A - Pneumatic tire - Google Patents

Abstract

To attain weight saving and improvement in steering stability performance, while improving durability performance in a high-temperature region.SOLUTION: In a pneumatic tire 100, a ratio L1/L2 is 0.25-0.90 of a protrusion amount L1 toward a bead part side of a tire rubber layer with respect to a perpendicular P drawn from the outermost end in a tire width direction of a belt layer toward an inner liner layer, relative to a periphery length L2 along the tire inner surface from an intersection point A of the perpendicular P and a tire inner surface to a tip point B of a bead toe. Further, in the pneumatic tire, a ratio Fh/SH is 0.20-0.45 of a height Fh of a bead filler from the inside in a tire radial direction to the outside in the tire radial direction, relative to a tire cross section height SH. Furthermore, in the pneumatic tire, a ratio Fmw/Fbw is 0.4-0.8 of a width Fmw of the bead filler in a tire width direction at a height position in the middle of the height Fh of the bead filler in the tire radial direction, relative to a width Fbw in the tire width direction at an innermost position of the bead filler in the tire radial direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire.

Conventionally, pneumatic tires that maintain low tire weight and rolling resistance while improving steering stability on dry road surfaces have been known (for example, Patent Document 1).

JP-A-2018-2008620

By the way, in a pneumatic tire, depending on the thickness of the inner liner, the air in the lumen may permeate the inner liner. When the air that has passed through the inner liner reaches the belt layer, moisture in the air may cause rust on the metal parts of the belt layer. When the metal portion of the belt layer is rusted, separation is likely to occur between the members constituting the belt layer, and the durability performance is deteriorated. Before such separation occurs, the wear of the tread portion becomes large, and it is often the time to replace the tire.

However, in hot regions where the temperature is relatively high, there is less wear on the tread than in regions where the temperature is relatively low, so the above separation may occur before it is time to replace the tires. is there. Increasing the thickness of the inner liner reduces the possibility of air in the lumen penetrating the inner liner. However, if the thickness of the inner liner is large, there arises a problem that the weight of the pneumatic tire becomes large. Further, it is not preferable to reduce the steering stability performance.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of achieving weight reduction and improvement of steering stability performance while improving durability performance in a high temperature area.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to an embodiment of the present invention has a tread portion extending in the tire circumferential direction to form an annular shape and a pair arranged on both sides of the tread portion. Side wall portions, a pair of bead portions arranged inside the pair of sidewall portions in the tire radial direction, a carcass layer mounted between the pair of bead portions, and each bead core of the pair of bead portions. In the space formed by folding the carcass layer outward in the tire width direction at the position of, the bead filler arranged on the tire radial outer side of each bead core and the bead filler arranged on the outer peripheral side of the carcass layer in the tread portion. The belt layer, the inner liner layer arranged on the inner surface of the tire along the carcass layer, and the area between the carcass layer and the inner liner layer excluding the tip of the bead portion. In a pneumatic tire having a tie rubber layer, the amount of protrusion L1 of the tie rubber layer toward the bead portion with respect to a vertical line P drawn from the outermost end portion of the belt layer in the tire width direction toward the inner liner layer. The ratio L1 / L2 to the periferi length L2 along the inner surface of the tire from the intersection A of the vertical line P and the inner surface of the tire to the tip point B of the bead toe is 0.25 or more and 0.90 or less, and the tire cross-sectional height. The ratio Fh / SH of the height Fh from the inner side of the bead filler in the tire radial direction to the outer side in the tire radial direction with respect to SH is 0.20 or more and 0.45 or less, and the innermost position of the bead filler in the tire radial direction. The ratio Fmw / Fbw of the width Fmw in the tire width direction of the bead filler at a position intermediate to the height Fh in the tire radial direction of the bead filler with respect to the width Fbw in the tire width direction is 0.4 or more. It is 8 or less.

The total gauge TGa, which is the sum of the thickness of the inner liner layer and the thickness of the tie rubber layer, is preferably 0.6 mm or more and 1.3 mm or less.

The ratio D / SH of the distance D between the innermost end of the tie rubber layer in the tire radial direction and the outermost end of the bead filler in the tire radial direction to the tire cross-sectional height SH is −0.2 or more. It is preferably 2 or less.

The inner liner layer is provided at a position 5 mm inward in the tire radial direction from the innermost end in the tire radial direction of the tie rubber layer with respect to the total thickness K1 of the sidewall portion at the maximum tire width position. The ratio K2 / K1 of the thickness K2 of the constituent butyl rubber is preferably 0.05 or more and 0.30 or less.

The hardness of the cap rubber used for the tread portion is preferably 60 or more and 75 or less.

The belt layer includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the inclination angle of the reinforcing cords with respect to the tire circumferential direction is preferably 24 degrees or more and 32 degrees or less.

The rubber compound used in the tread portion preferably contains 1 part by weight or more of an antiaging agent.

The pneumatic tire according to the present invention can realize weight reduction and improvement in steering stability performance while improving durability in a high temperature area.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged view of a part of FIG. FIG. 3 is an enlarged view of a part of FIG. FIG. 4 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to a modified example of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of each embodiment, the same or equivalent components as those of the other embodiments are designated by the same reference numerals, and the description thereof will be simplified or omitted. The present invention is not limited to each embodiment. In addition, the components of each embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. The plurality of modifications described in this embodiment can be arbitrarily combined within the range of those skilled in the art. In addition, the configuration may be omitted, replaced or changed without departing from the gist of the invention.

[Pneumatic tires]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 1 shows a cross-sectional view of a one-sided region in the tire radial direction. Further, FIG. 1 shows a radial tire for a passenger car as an example of a pneumatic tire.

The cross section in the tire meridian direction is a cross section when the tire is cut on a plane including the tire rotation axis (not shown). Further, the reference numeral CL is a tire equatorial plane, and refers to a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. The tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 100, the inner side in the tire radial direction is the side toward the rotation axis in the tire radial direction, and the outer side in the tire radial direction is the tire radial direction. Refers to the side away from the axis of rotation. Further, the tire circumferential direction refers to a circumferential direction centered on the rotation axis. Further, the tire width direction means a direction parallel to the rotation axis. The inside in the tire width direction means the side toward the tire equatorial plane CL in the tire width direction, and the outside in the tire width direction means the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 100 and passes through the center of the tire width of the pneumatic tire 100. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line is a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 100. In the present embodiment, the tire equatorial line is designated by the same code "CL" as the tire equatorial plane.

As shown in FIG. 1, the pneumatic tire 100 of the present embodiment has a tread portion 1 extending in the tire circumferential direction to form an annular shape, and a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3 and 3 arranged inside the sidewall portion 2 in the tire radial direction.

A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction. The carcass layer 4 is folded back from the inside to the outside in the tire width direction around the bead cores 5 arranged in each bead portion 3. That is, the end portion of the carcass layer 4 reaches the bead portion 3 from the tread portion 1 via the sidewall portion 2, and is folded back outward in the tire width direction at the bead portion 3.

A bead filler 6 is arranged on the outer circumference of the bead core 5 of the bead portion 3. The bead filler 6 is arranged on the outer side of each bead core 5 in the tire radial direction. The bead filler 6 is made of a rubber composition having a substantially triangular cross section. The bead filler 6 is arranged in a space formed by folding the carcass layer 4 outward in the tire width direction at the position of the bead core 5. A rim cushion rubber (not shown) is arranged on the outside of the bead filler 6 in the tire width direction. The rim cushion rubber constitutes the contact surface of the bead portion 3 with respect to the rim flange (not shown).

A plurality of layers (two layers in the example of FIG. 1) of 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 that are inclined with respect to the tire circumferential direction. A steel cord is preferably used as the reinforcing cord of the belt layer 7.

On the outer peripheral side of the belt layer 7, at least one layer of the belt cover layer 8 formed by arranging the reinforcing cords at an angle of, for example, 5 degrees or less with respect to the tire circumferential direction is arranged for the purpose of improving high-speed durability. There is. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

An inner liner layer 9 is provided on the inner surface of the tire along the carcass layer 4. The inner liner layer 9 is composed of a rubber composition mainly composed of butyl rubber having an air permeation preventing property, and prevents the air filled in the tire from permeating to the outside of the tire. The total gauge TGa, which is the sum of the thickness of the inner liner layer 9 and the thickness of the tie rubber layer 10, is preferably 0.6 mm or more and 1.3 mm or less. If the total gauge TGa is less than 0.6 mm, the effect of preventing air from permeating out of the tire is reduced, which is not preferable. If the total gauge TGa exceeds 1.3 mm, it hinders the weight reduction of the tire, which is not preferable. The total gauge TGa is more preferably 0.6 mm or more and 1.0 mm or less.

[Tie rubber layer]
A tie rubber layer 10 is arranged between the inner liner layer 9 and the carcass layer 4. The tie rubber layer 10 is a layer for preventing the cord of the carcass layer 4 from biting into the inner liner layer 9 when inflating an unvulcanized pneumatic tire during tire manufacturing. The tie rubber layer 10 contributes to air permeation prevention and steering stability on a dry road surface in a tire after production. In the pneumatic tire 100 of this example, the tie rubber layer 10 is selectively provided not in the entire area between the carcass layer 4 and the inner liner layer 9, but in a region other than the tip end side of the bead portion 3. That is, as shown in FIG. 1, the tie rubber layers 10 are provided on both sides of the tire equatorial plane CL in the tire width direction from the center region of the tread portion 1 through the shoulder region to the region of the sidewall portion 2. In the pneumatic tire 100 of this example, the tie rubber layer 10 is not provided on the tip side of the bead portion 3, so that the tie rubber layer 10 is provided in the entire area between the carcass layer 4 and the inner liner layer 9. Compared to, the weight can be reduced.

In order to improve the durability in a high temperature area, the butyl rubber of the inner liner layer 9 may be made relatively thick. Even in that case, by selectively providing the tie rubber layer 10 in the region excluding the tip side of the bead portion 3, the tie rubber layer 10 is provided in the entire area between the carcass layer 4 and the inner liner layer 9. , Weight reduction can be realized. If the butyl rubber of the inner liner layer 9 is made thinner, the weight can be reduced. However, thinning the butyl rubber is not preferable because it causes a decrease in the air permeation prevention performance and a decrease in the durability of the tire particularly in a high temperature area.

[Placement area of tie rubber layer]
In FIG. 1, the amount of protrusion of the tie rubber layer 10 toward the bead portion 3 with respect to the perpendicular line P drawn from the outermost end portion of the belt layer 7 in the tire width direction toward the inner liner layer 9 is defined as L1. Further, the periferi length along the inner surface of the tire from the intersection A of the perpendicular line P and the inner surface of the tire to the tip point B of the bead toe is L2. At this time, the ratio L1 / L2 of the protrusion amount L1 to the length L2 is preferably 0.25 or more and 0.90 or less. If the ratio L1 / L2 is less than 0.25, it becomes difficult to maintain air permeability, which is not preferable. If the ratio L1 / L2 exceeds 0.90, the effect of reducing the weight of the tire is reduced, which is not preferable. The ratio L1 / L2 is more preferably 0.30 or more and 0.70 or less.

[Belt layer]
Each belt layer 7 is arranged so that the reinforcing cords intersect each other between the layers. The inclination angle of the reinforcing cord of the belt layer 7 with respect to the tire circumferential direction is preferably 24 degrees or more and 32 degrees or less. When the inclination angle of the reinforcing cord with respect to the tire circumferential direction is 24 degrees or more and 32 degrees or less, the steering stability performance is improved. Further, the inclination angle of the reinforcing cord of the belt layer 7 with respect to the tire circumferential direction is more preferably in the range of 26 degrees or more and 28 degrees or less, and most preferably 27 degrees.

[Bead part]
FIG. 2 is an enlarged view showing the vicinity of the bead portion 3 of the pneumatic tire of FIG. In FIG. 2, the height of the bead filler 6 from the inside in the tire radial direction to the outside in the tire radial direction is defined as Fh. At this time, the ratio Fh / SH of the height Fh to the tire cross-sectional height SH is preferably 0.20 or more and 0.45 or less. If the ratio Fh / SH is less than 0.20, the rigidity of the sidewall portion 2 is not sufficient, and if the ratio Fh / SH exceeds 0.45, the rigidity of the sidewall portion 2 becomes too large. However, it is not preferable from the viewpoint of improving the steering stability performance. The height Fh of the bead filler 6 is preferably 25 mm or more and 50 mm or less, for example.

Here, the tire cross-sectional height SH is a distance of ½ of the difference between the tire outer diameter and the rim diameter, and is measured as a no-load state while the tire is mounted on the specified rim to apply the specified internal pressure. The specified rim means the "applicable rim" specified in JATTA, the "Design Rim" specified in TRA, or the "Measuring Rim" specified in ETRTO. The specified internal pressure means the "maximum air pressure" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or "INFLATION PRESSURES" specified in ETRTO. The specified load means the "maximum load capacity" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or the "LOAD CAPACITY" specified in ETRTO. However, in JATTA, in the case of a passenger car tire, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

In FIG. 2, the width of the bead filler 6 in the tire width direction at the innermost position in the tire radial direction is defined as Fbw. Further, the width of the bead filler 6 in the tire width direction at a height intermediate to the height Fh in the tire radial direction of the bead filler 6 is defined as Fmw. At this time, the ratio Fmw / Fbw of the width Fmw to the width Fbw is preferably 0.4 or more and 0.8 or less. When the ratio Fmw / Fbw is 0.4 or more and 0.8 or less, it means that the bead filler 6 has a cross-sectional shape extending elongated outward in the tire radial direction. When the bead filler 6 has such a cross-sectional shape, the rigidity of the sidewall portion 2 can be ensured and the steering stability performance is improved. The ratio Fmw / Fbw is more preferably 0.55 or more and 0.78 or less. The ratio Fmw / Fbw is more preferably 0.65 or more and 0.75 or less.

The innermost end of the tie rubber layer 10 in the tire radial direction is 10T1. Further, the outermost end of the bead filler 6 in the tire radial direction is 6T. Let D be the distance between the end 10T1 and the end 6T along the tire radial direction. The ratio D / SH of the distance D to the tire cross-sectional height SH is preferably −0.2 or more and 0.2 or less. When the ratio D / SH is a negative value, it means that a part of the tie rubber layer 10 and a part of the bead filler 6 overlap when viewed from the tire width direction. When the ratio D / SH is a positive value, it means that the position of the end 10T1 and the position of the end 6T are separated from each other when viewed from the tire width direction. When the ratio D / SH is zero, it means that the position of the end 10T1 and the position of the end 6T coincide with each other when viewed from the tire width direction.

If the ratio D / SH is less than −0.2, the weight of the tie rubber layer 10 is large, which is not preferable from the viewpoint of realizing weight reduction. If the ratio D / SH exceeds 0.2, the rigidity of the sidewall portion 2 decreases, which is not preferable. When the ratio D / SH is −0.2 or more and 0.2 or less, it means that the position of the end 10T1 and the position of the end 6T are very close to each other and are almost the same position. Since the position of the end 10T1 and the position of the end 6T are very close to each other, the rigidity of the sidewall portion 2 can be ensured while reducing the weight, and the steering stability performance can be improved.

The distance D is preferably, for example, −20 mm or more and 20 mm or less. When the distance D is a negative value, it means that a part of the tie rubber layer 10 and a part of the bead filler 6 overlap when viewed from the tire width direction. When the distance D is a positive value, it means that the position of the end 10T1 and the position of the end 6T are separated from each other when viewed from the tire width direction. If the distance D is less than −20 mm, the weight of the tie rubber layer 10 is large, which is not preferable from the viewpoint of realizing weight reduction. If the distance D exceeds 20 mm, the rigidity of the sidewall portion 2 decreases, which is not preferable.

[Sidewall part]
FIG. 3 is an enlarged view showing the vicinity of the sidewall portion 2 of the pneumatic tire of FIG. In FIG. 3, the total thickness of the sidewall portion 2 at the maximum tire width position C is K1. Let K2 be the thickness of the butyl rubber constituting the inner liner layer 9 located 5 mm inward in the tire radial direction from the innermost end 10T1 of the tie rubber layer 10 in the tire radial direction. At this time, the ratio K2 / K1 of the butyl rubber thickness K2 to the total thickness K1 is preferably 0.05 or more and 0.30 or less.

[Rubber on the tread]
The rubber compound used in the tread portion 1 preferably contains 1 part by weight or more of an antiaging agent. The pneumatic tire of this example can maintain durability in a high temperature area by containing 1 part by weight or more of an antiaging agent.

The hardness of the cap rubber used for the tread portion 1 is preferably 60 or more and 75 or less. If the hardness of the cap rubber is within this range, the steering stability performance is improved. Further, the hardness of the tire cap rubber used for the tread portion 1 is more preferably 67 or more and 72 or less, and further preferably 68 or more and 70 or less. The hardness in the above is JIS-A hardness, which is a durometer hardness measured under the condition of a temperature of 20 ° C. using an A type durometer in accordance with JIS K-6253.

[Modification example]
The above-mentioned tire internal structure shows a typical example of a pneumatic tire, but is not limited thereto. FIG. 4 is a cross-sectional view in the tire meridian direction showing a modified example of the pneumatic tire according to the embodiment of the present invention. In FIG. 4, in the pneumatic tire of this example, butyl rubber is arranged in the vicinity of the shoulder portion. In the pneumatic tire of this example, butyl rubber is not arranged in the center region including the vicinity of the equatorial plane CL of the tread portion 1. Other parts of the pneumatic tire of this example are the same as the pneumatic tire described with reference to FIGS. 1 to 3. Since the butyl rubber is not arranged in the center region of the pneumatic tire of this example, it is possible to realize further weight reduction.

Further, the pneumatic tire 100 may have a mounting direction display unit (not shown) indicating a mounting direction with respect to the vehicle. The mounting direction display portion is composed of, for example, marks and irregularities attached to the sidewall portion of the tire. For example, ECEER30 (Article 30 of the European Economic Commission for Europe) requires that a mounting direction display unit be provided on a sidewall portion that is outside in the vehicle width direction when mounted on a vehicle.

The value of the above ratio L1 / L2 may be different between the side that is inside the vehicle and the side that is outside the vehicle when mounted on the vehicle. Similarly, the above-mentioned ratio Fh / SH value may be different between the side that is inside the vehicle and the side that is outside the vehicle when mounted on the vehicle. Similarly, the value of the above ratio Fmw / Fbw may be different between the side that is inside the vehicle and the side that is outside the vehicle when mounted on the vehicle. Similarly, the above-mentioned ratio D / SH value may be different between the side that is inside the vehicle and the side that is outside the vehicle when mounted on the vehicle. Similarly, the above-mentioned value of the ratio K2 / K1 may be different between the side that is inside the vehicle and the side that is outside the vehicle when mounted on the vehicle.

[Example]
Tables 1 to 5 are tables showing the results of performance tests of pneumatic tires according to the present invention. In this performance test, the durability, weight reduction, and steering stability performance (dry steering stability performance) were evaluated for different pneumatic tires, and in this embodiment, for a plurality of types of pneumatic tires under different conditions. .. In these performance tests, a pneumatic tire (test tire) having a tire size of 185 / 60R15 84H (tire cross-sectional height SH = 111 mm) was assembled on a regular rim of 15 x 6.0 J and filled with a regular internal pressure (240 kPa). ..

The durability performance was evaluated by a drum running test in a constant temperature bath and indoors. After leaving the evaluation tire in a constant temperature bath at 80 ° C. for one month, the load was set to be equivalent to two passengers, and the running time until the tire broke under the condition of a speed of 50 km / h was measured. It was expressed as an index based on the tire (100). The higher this index is, the better the durability performance is.

The weight reduction was evaluated by measuring the weight of the test tire assembled on the regular rim and expressing it as an index based on the weight of the pneumatic tire of Conventional Example 1 described later (100). The higher this index is, the more weight reduction can be achieved.

To evaluate the steering stability performance, the test tires are mounted on a small vehicle (test vehicle) of FF (Front Engine Front Drive) with a displacement of 1500 cc, and the test vehicle runs on a test course on a dry road surface for straightness and handling. Was evaluated by a sensory evaluation by one skilled test driver. This sensory evaluation was expressed by an index based on the pneumatic tire of Conventional Example 1 (100). The higher this index is, the better the steering stability performance is.

In the pneumatic tires of Examples 1 to 38, the tie rubber layer is arranged between the carcass layer and the inner liner layer in a region excluding the tip of the bead portion, and the ratio L1 / L2 is 0.25 or more and 0. A pneumatic tire having a ratio of .90 or less, a ratio of Fh / SH of 0.20 or more and 0.45 or less, and a ratio of Fmw / Fbw of 0.4 or more and 0.8 or less.

In the pneumatic tire of the conventional example 1, the tie rubber layer is provided in the entire area between the carcass layer and the inner liner layer, and does not contain an antiaging agent. Further, in the pneumatic tire of the conventional example 2, the tie rubber layer is not provided in the center portion and the bead portion between the carcass layer and the inner liner layer, but is provided only in the shoulder portion, and does not contain an antiaging agent.

The durability, weight reduction and steering stability of these pneumatic tires were evaluated by the above evaluation methods, and the results are shown in Tables 1 to 5.

As shown in Tables 1 to 5, when the total gauge TGa, which is the sum of the thickness of the inner liner layer and the thickness of the tie rubber layer, is 0.6 mm or more and 1.3 mm or less, the ratio D / SH is −0. When it is 2 or more and 0.2 or less, the ratio K2 / K1 is 0.05 or more and 0.30 at a position 5 mm inward in the tire radial direction from the innermost end of the tire rubber layer in the tire radial direction. In the following cases, when the hardness of the cap rubber used for the tread portion is 60 or more and 75 or less, and when the inclination angle of the reinforcing cord of the belt layer with respect to the tire circumferential direction is 24 degrees or more and 32 degrees or less, the tread portion is used. Good results were obtained in terms of durability, weight reduction and steering stability when the rubber compound used contained 1 part by weight or more of the anti-aging agent.

1 Tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 6T end 7 belt layer 8 belt cover layer 9 inner liner layer 10 tie rubber layer 10T1 end CL tire equatorial surface

Claims (7)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the pair of sidewall portions in the tire radial direction. In the space formed by the carcass layer mounted between the pair of bead portions and the carcass layer folded outward in the tire width direction at the positions of the bead cores of the pair of bead portions, the bead cores A bead filler arranged on the outer side in the tire radial direction, a belt layer arranged on the outer peripheral side of the carcass layer in the tread portion, an inner liner layer arranged on the inner surface of the tire along the carcass layer, and the carcass. In a pneumatic tire having a tie rubber layer between the layer and the inner liner layer and arranged in a region excluding the tip of the bead portion.
The vertical line P and the inner surface of the tire of the protrusion amount L1 of the tie rubber layer toward the bead portion with respect to the vertical line P drawn from the outermost end portion of the belt layer in the tire width direction toward the inner liner layer. The ratio L1 / L2 to the periferi length L2 along the inner surface of the tire from the intersection point A to the tip point B of the bead toe is 0.25 or more and 0.90 or less.
The ratio Fh / SH of the height Fh of the bead filler from the inside in the tire radial direction to the outside in the tire radial direction with respect to the tire cross-sectional height SH is 0.20 or more and 0.45 or less.
The width Fmw in the tire width direction of the bead filler at a position intermediate to the height Fh in the tire radial direction of the bead filler with respect to the width Fbw in the tire width direction at the innermost position in the tire radial direction of the bead filler. Pneumatic tires with a ratio of Fmw / Fbw of 0.4 or more and 0.8 or less. The pneumatic tire according to claim 1, wherein the total gauge TGa, which is the sum of the thickness of the inner liner layer and the thickness of the tie rubber layer, is 0.6 mm or more and 1.3 mm or less. The ratio D / SH of the distance D between the innermost end of the tie rubber layer in the tire radial direction and the outermost end of the bead filler in the tire radial direction to the tire cross-sectional height SH is −0.2 or more. 2. The pneumatic tire according to claim 1 or 2, which is 2 or less. The inner liner layer is provided at a position 5 mm inward in the tire radial direction from the innermost end in the tire radial direction of the tie rubber layer with respect to the total thickness K1 of the sidewall portion at the maximum tire width position. The pneumatic tire according to any one of claims 1 to 3, wherein the ratio K2 / K1 of the thickness K2 of the constituent butyl rubber is 0.05 or more and 0.30 or less. The pneumatic tire according to any one of claims 1 to 4, wherein the hardness of the cap rubber used for the tread portion is 60 or more and 75 or less. Any of claims 1 to 5, wherein the belt layer includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the inclination angle of the reinforcing cords with respect to the tire circumferential direction is 24 degrees or more and 32 degrees or less. The pneumatic tire described in one. The pneumatic tire according to any one of claims 1 to 6, wherein the rubber compound used for the tread portion contains 1 part by weight or more of an antiaging agent.

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