JP2016215746A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire that can further improve durability of a bead part.SOLUTION: The tire, when a distance from a tire maximum width position Wto an intersection with a straight line Y1 on the straight line X2 is set as a distance D1, and when a distance from the tire maximum width position Wto an intersection with a straight line X1 on the straight line Y2 is set as a distance D2, satisfies a relation of D1/D2≥0.28, and when an area of a first bead filler 20 positioned outside in a tire width direction is set as Sout and an area of the bead filler 20 positioned inside in the tire width direction is set as Sin, with the straight line Y1 as a reference, satisfies a relation of Sout/(Sin+Sout)≥0.25.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a tire including a bead portion reinforced to enhance durability.

  Since a large load is applied to the bead portion in contact with the wheel rim, the bead portion is required to have high durability. The durability of the bead portion is greatly reduced when separation (separation) occurs between the carcass and the rubber member in contact with the outer side in the tire width direction of the carcass. Therefore, a reinforcement member is provided on the outer side in the tire width direction of the carcass to suppress separation. Structure is used. For example, a structure in which a rubber chafer covering the bead heel is provided or a bead filler (second bead filler) separate from a bead filler (first bead filler) integrated with a bead core is widely used.

  In addition, in order to more reliably suppress separation in the bead portion, a structure that takes into account the positional relationship of the members constituting the bead portion is also known (for example, Patent Document 1). Specifically, in a cross-sectional view of the tire along the tire width direction, the second bead filler covers an end portion on the outer side in the tire radial direction of the first bead filler, and an end portion on the inner side in the tire radial direction of the second bead filler. The second bead filler is disposed so that is positioned on the outer side in the tire radial direction than the bead core. The rubber chafer is disposed so as to cover the second bead filler.

  According to the tire having such a bead portion, the stress acting from the sidewall side and the bead core side toward the end portion of the first bead filler in the tire radial direction is stepwise by the rubber chafer and the second bead filler. Therefore, the concentration of stress on the first bead filler is alleviated, and separation starting from the vicinity of the outer end of the first bead filler in the tire radial direction can be effectively suppressed.

International Publication No. 2012/018106 (Pages 8-11, Fig. 2)

  The tire with the bead portion reinforced as described above may be used under extremely severe conditions such as a large load and a high wheel load, and high durability of the bead portion has been demanded.

  Therefore, the present invention has been made in view of such a situation, and an object thereof is to provide a tire that can further improve the durability of the bead portion.

The present invention is characterized in that a bead core (bead core 10), a first bead filler (first bead filler 20) disposed on the outer side in the tire radial direction of the bead core, a tire so as to entrain the bead core and the first bead filler. A first carcass (first carcass 31) bent outward in the width direction, a second carcass (second carcass 32) disposed on the outer side in the tire width direction of the first carcass, and a tire width larger than the second carcass A tire (tire 1) including a second bead filler (second bead filler 40) disposed on the outer side in the tire direction, and the inner end in the tire radial direction of the bead core in a sectional view of the tire along the tire width direction A straight line passing through the end 10a and parallel to the tire width direction is defined as a straight line X1, and the maximum width position where the tire width of the tire is maximum (tire maximum width position W _MAX ) A straight line passing through and parallel to the tire width direction is a straight line X2, a straight line passing through the outer end of the bead core in the tire width direction and perpendicular to the tire width direction is a straight line Y1, and the maximum width at which the tire width of the tire is maximum A straight line passing through the position and orthogonal to the tire width direction is defined as a straight line Y2, and on the straight line X2, the distance from the maximum width position to the intersection with the straight line Y1 is defined as a distance D1, and the straight line Y2 When the distance from the significant position to the intersection with the straight line X1 is the distance D2, the first bead filler that satisfies the relationship D1 / D2 ≧ 0.28 and is located on the outer side in the tire width direction with respect to the straight line Y1 When the area of the first bead filler located on the inner side in the tire width direction is Sin, the gist is that the relationship of Sout / (Sin + Sout) ≧ 0.25 is satisfied.

  In the features of the present invention, the first carcass passes through the folded end portion (folded end portion 31a) of the first carcass bent outward in the tire width direction, and a straight line parallel to the tire width direction is defined as a straight line X3. A straight line passing through the outer end in the tire radial direction of the first bead filler and parallel to the tire width direction is defined as a straight line X4. On the straight line X3, a distance from the folded end to the intersection with the straight line Y1 is defined as a distance D3. On the straight line X4, when the distance from the outer end in the tire radial direction of the first bead filler to the intersection with the straight line Y1 is a distance D4, the relationship of D3 / D4 ≧ 1.55 may be satisfied.

  In the feature of the present invention, a straight line passing through the folded end and orthogonal to the tire width direction is defined as a straight line Y3.On the straight line Y3, a distance from the folded end to the intersection with the straight line X1 is a distance D5. In this case, the relationship D3 / D5 ≧ 0.26 may be satisfied.

  In the feature of the present invention, the 100% modulus value of the second bead filler may be 1.0 MPa or more and 5.0 MPa or less.

  In the features of the present invention, the second bead filler covers an end portion (end portion 20a) on the outer side in the tire radial direction of the first bead filler, and an end portion (end portion) on the inner side in the tire radial direction of the second bead filler. 40a) may be located outside the bead core in the tire radial direction, and the rubber chafer may cover the second bead filler.

  According to the characteristics of the present invention, a tire that can further improve the durability of the bead portion can be provided.

1 is a partial schematic perspective view of a tire 1 according to an embodiment of the present invention. It is a sectional view taken along the tire radial direction D _R, and the tire width direction D _T of the tire 1 according to the embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of a bead portion 5 shown in FIG. 2. 3 is an enlarged cross-sectional view of the bead part 5 for explaining the shape and positional relationship of the components of the bead part 5. FIG. 5 is an enlarged cross-sectional view of a bead portion of a tire according to Comparative Example 1. FIG. FIG. 4 is a view showing a displacement amount of a bead portion 5 of a tire according to an embodiment of the present invention.

  Next, an embodiment of a tire according to the present invention will be described with reference to the drawings.

(1) Schematic Configuration of Tire FIG. 1 is a partial schematic perspective view of a tire 1 according to this embodiment. As shown in FIG. 1, the tire 1 includes a tread portion 3 in which a predetermined tread pattern is formed by a circumferential groove (not shown) and the like and is in contact with the road surface. The tire 1 is a pneumatic tire and includes a bead portion 5 that is in contact with a wheel rim 100 (not shown in FIG. 1, refer to FIG. 4A). Further, a sidewall portion 7 is provided between the tread portion 3 and the bead portion 5.

  The tread pattern formed on the tread portion 3 is an example, and a different tread pattern may be used. As will be described later, the tire 1 includes a reinforced bead portion 5 in order to ensure durability against a high load, and can be suitably used for, for example, a pickup type truck. Further, the tire 1 may be filled with an inert gas such as nitrogen gas instead of air.

FIG. 2 is a cross-sectional view along the tire radial direction D _R and the tire width direction D _T of the tire 1 according to the present embodiment. Note that in FIG. 2, hatching is not shown in some components.

  As shown in FIG. 2, the inside of the tire 1 is fixed to a belt layer 4 and a wheel rim 100 (see FIG. 4A) having a function of mitigating the radial growth of the tire 1 and the impact from the road surface. The bead portion 5 and the carcass layer 30 forming the skeleton of the tire 1 are provided.

Belt layer 4 is disposed in the tire radial direction D _R inside of the tread portion 3, a bead part 5 is arranged in the tire radial direction D _R inside of the side wall portion 7. The carcass layer 30 is disposed from the tread portion 3 to the bead portion 5. The carcass layer 30 includes a first carcass 31 and a second carcass 32.

  The bead portion 5 of the tire 1 includes a bead core 10, a first bead filler 20, a second bead filler 40, a rubber chafer 50, a nylon cord layer 70, and a chafer 80.

  The bead core 10 is constituted by a bead wire (not shown), and provides a function of fixing the tire 1 to the wheel rim 100 (see FIG. 4A).

The first bead filler 20 is adjacent in the tire radial direction D _R outside of the bead core 10, so that the first carcass 31 fills a space formed by being folded in the tire radial direction D _R outwards as involving bead cores 10 Provided. The first bead filler 20, in a cross-sectional view as in FIG. 2, has a narrowing shape taken to go to the outer side in the tire radial direction D _R.

The second bead filler 40 is provided adjacent to the outer side of the carcass layer 30 in the tire width direction _DT . The second bead filler 40 has a shape in which the central portion in the longitudinal direction is thick in a cross-sectional view as shown in FIG. 2 and becomes thinner toward both ends.

The rubber chafer 50 is provided adjacent to the outer side of the second bead filler 40 in the tire width direction _DT . Rubber chafer 50 is in contact with the wheel rim 100, are provided across the end portion in the tire radial direction D _R inner side rubber layer 60 forming the side wall portion 7 in the tire radial direction D _R inner of the bead core 10.

Nylon cord layer 70 is provided so as to cover the side surface and the lower surface of the bead core 10 (the tire radial direction D _R inner surface). The first carcass 31 is folded in the tire radial direction D _R outwards as involving bead core 10 including a nylon cord layers 70.

Chafer 80 is provided so as to cover the side surface and the lower surface of the bead core 10 containing nylon cord layer 70 (the tire radial direction D _R inner surface). The chafer 80 is particularly provided to prevent damage to the toe portion of the bead portion 5.

(2) Configuration of Bead Part Next, the configuration of the bead unit 5 will be described more specifically. FIG. 3 is an enlarged cross-sectional view of the bead portion 5 shown in FIG. As described above, the carcass layer 30 includes the first carcass 31 and the second carcass 32.

The first carcass 31 is bent outward in the tire width direction D _T so as to entrain the bead core 10 and the first bead filler 20. The first carcass 31 has turnup ends 31a of the first carcass 31 which is bent outward in the tire width direction D _T is located above the second bead filler 40 (the tire radial direction D _R outside). Further, in the present embodiment, the position of the folded end portion 31a in the tire radial direction D _R, the position of the boundary between rubber chafer 50 and side rubber layer 60 in the tire radial direction D _R, specifically, the tire radial direction of the rubber chafer 50 D _R outer end portion 50a and is substantially the same.

The second carcass 32 is disposed outside the first carcass 31 in the tire width direction _DT . The second carcass 32 is also called a down ply, and is arranged from the tread portion 3 to the bead portion 5 through the sidewall portion 7 (see FIG. 2). The tire radial direction D _R inner end 32a of the second carcass 32 is located in the tire width direction D _T outside of the bead core 10.

The first bead filler 20 is arranged in the tire radial direction D _R outside of the bead core 10. The second bead filler 40 is disposed outside the second carcass 32 in the tire width direction _DT . In the cross-sectional view as shown in FIG. 3, that is, the cross-sectional view of the tire along the tire width direction D _T (and the tire radial direction D _R ), the second bead filler 40 is the tire radial direction D _R of the first bead filler 20. The outer end 20a is covered. Also, the tire radial direction D _R inner end 40a of the second bead filler 40 is located in the tire radial direction D _R outward from the bead core 10.

  The second bead filler 40 is softer than the first bead filler 20. The 100% modulus value of the second bead filler 40 is 1.0 MPa or more and 5.0 MPa or less. The 100% modulus value of the second bead filler 40 is preferably 1.0 MPa or more and 4.0 MPa or less.

The rubber chafer 50 is disposed on the outer side in the tire width direction D _T than the second bead filler 40. The rubber chafer 50 covers the second bead filler 40. Further, a part of the rubber chafer 50 is exposed to the outside in the tire width direction D _T (on the side of the side wall portion 7), and the wheel rim 100 of the bead portion 5 (see FIG. A rim line 150 is formed as a mounting mark for a).

The rim line 150 serves as a mark as to whether or not the bead portion 5 is correctly attached to the wheel rim 100. If the tire 1 is set to normal internal pressure, the flange portion of the wheel rim 100, a tire radial direction D _R about several mm than the inner end of the rim line 150, located on the inner side in the tire radial direction. Incidentally, rim line 150 is not one, may be provided two or more, but most tire radial direction D width along the tire radial direction D _R of the _R inner rim line 150 may be any of about 2 mm.

  The normal internal pressure is the air pressure corresponding to the maximum load capacity of the JATMA (Japan Automobile Tire Association) YearBook. The regular wheel rim 100 refers to a standard rim in an applicable size defined in JATMA YearBook. Also, instead of JATMA, overseas corresponding standards may be used.

The bead portion 5 including the bead core 10, the first bead filler 20, the second bead filler 40, and the rubber chafer 50 is curved toward the direction away from the tire equator line CL (FIG. 1). In other words, the bead portion 5 has a shape in which the second carcass 32 is laid down in the tire width direction D _{T as} will be described later.

Further, in a cross-sectional view as in FIG. 3, the second carcass 32, in the region of the bead portion 5, passing through the tire radial direction D _R inner rim line 150, the thickness of the bead portion 5 (rubber gauge) direction parallel the tire radial direction D _R portion to the outer end portion 50a of the rubber chafer 50 from the intersection P1 between the straight line L1 is inclined in most tire width direction D _T outside. Further, on the straight line L1, the thickness of the tire width direction D _T outer surface (the position of the rim line 150) to the tire width direction D _T outer surface of the second carcass 32, tire width direction D _T out of the second carcass 32 It is thicker than the thickness from the side surface to the inner side surface of the first carcass 31 in the tire width direction _DT .

In the present embodiment, in a cross-sectional view as in FIG. 3, and the horizontal line HL that extends from the tire radial direction D _R inner end of the bead portion 5, extended from the end portion in the tire width direction D _T outside of the bead portion 5 When the intersection point where the perpendicular line VL intersects is P2, it is preferable that the back angle θ formed by the straight line L2 passing through the rim line 150 and the intersection point P2 with the horizontal line HL is 60 degrees or more and 80 degrees or less.

The tire radial direction D _R inner end of the bead portion 5, a tire radial direction D _R inner end 50b of the rubber chafer 50. Further, perpendicular VL passes through the height position of the half of the tire radial direction D _R of the bead core 10, as well as perpendicular to the horizontal line HL is parallel to the straight line (not shown), the tire width direction D _T outer surface of the rubber chafer 50 pass. In other words, the end portion of the bead portion 5 outside the tire width direction _DT is a portion where such a perpendicular line VL contacts the outer surface of the rubber chafer 50 in the tire width direction _DT .

  4 is an enlarged cross-sectional view of the bead portion 5 as in FIG. However, in FIG. 4, the hatching display of the cross section is omitted. Hereinafter, the shape and positional relationship of the components of the bead portion 5 will be described more specifically with reference to FIG.

As shown in FIG. 4, the straight line X1 passes through the tire radial direction D _R inner end of the bead core 10 (the end 10a), it is a straight line parallel to the tire width direction D _T. The straight line X2 is a straight line that passes through the tire maximum width position W _MAX (see also FIG. 2) where the tire width of the tire 1 is maximum and is parallel to the tire width direction D _T.

Straight X3 is first carcass 31 passes the folded end portion 31a of the first carcass 31 which is bent outward in the tire width direction D _T, is a straight line parallel to the tire width direction D _T. Straight X4 passes the tire radial direction D _R outer end of the first bead filler 20 (the end portion 20a), a straight line parallel with the tire widthwise direction D _T.

Further, the straight line Y1 passes through the tire width direction D _T outer end of the bead core 10 is a straight line orthogonal to the tire widthwise direction D _T. The straight line Y2 is a straight line that passes through the tire maximum width position W _MAX and is orthogonal to the tire width direction _DT . The straight line Y3 is a straight line that passes through the folded end portion 31a and is orthogonal to the tire width direction _DT .

  In the present embodiment, the distance from the maximum width position to the intersection with the straight line Y1 is the distance D1 on the straight line X2, and the distance from the maximum width position to the intersection with the straight line X1 is the distance D2 on the straight line Y2. Satisfy the following relationship.

D1 / D2 ≧ 0.28
The value D1 / D2 is preferably 0.30 or more and 0.35 or less.

When the area of the first bead filler 20 located outside the tire width direction _DT is Sout and the area of the first bead filler 20 located inside the tire width direction _DT is Sin with the straight line Y1 as a reference, The following relationship is satisfied.

Sout / (Sin + Sout) ≧ 0.25
The value of Sout / (Sin + Sout) is preferably 0.27 or more and 0.32 or less.

Further, on the straight line X3, the folded end portion 31a and the distance to the intersection of the straight line Y1 and the distance D3, on the straight line X4, to the intersection of the straight line Y1 from the tire radial direction D _R outer end of the first bead filler 20 When the distance is D4, the following relationship is satisfied.

D3 / D4 ≧ 1.55
The value of D3 / D4 is preferably 1.60 or more and 1.70 or less.

  Further, on the straight line Y3, when the distance from the folded end 31a to the intersection with the straight line X1 is a distance D5, the following relationship is satisfied.

D3 / D5 ≧ 0.26
Note that the value of D3 / D5 is preferably 0.3 or more and 0.35 or less.

(4) Comparative Evaluation Table 1 shows tires according to Examples (Examples 1 to 4) having the characteristics of the tire 1 described above, and tires according to Comparative Examples (Comparative Examples 1 to 4) not having the characteristics. The running test results are shown.

  Specifically, tires according to Examples and Comparative Examples were continuously run (rotated) under the following conditions using a drum testing machine.

・ Set speed: 60km / h
・ Set internal pressure: 600kPa
・ Set load: 2,200kg
・ Tire size: 205R14C (or 195 / 85R16 (Comparative Example 3))
-Use rim shape: 6.5J
The tires according to Examples 1 to 4 satisfy the relationships of D1 / D2 ≧ 0.28, Sout / (Sin + Sout) ≧ 0.25, D3 / D4 ≧ 1.55, and D3 / D5 ≧ 0.26. Further, in the tires according to Examples 1 to 4, the 100% modulus value of the second bead filler satisfies the relationship of 1.0 to 5.0 MPa. On the other hand, the tire according to Comparative Example 1 does not satisfy the above-described D1 / D2 relationship (the underlined numerical values in Table 1 indicate that the relationship is not satisfied, the same applies hereinafter). The tire according to Comparative Example 2 does not satisfy the relationship of Sout / (Sin + Sout). Further, the tires according to Comparative Examples 3 and 4 do not satisfy the relationship of D1 / D2, Sout / (Sin + Sout), D3 / D4, and D3 / D5. Further, in the tires according to Comparative Examples 3 and 4, the 100% modulus value of the second bead filler does not satisfy the relationship of 1.0 to 5.0 MPa.

  FIG. 5 is an enlarged cross-sectional view of a bead portion of a tire 1A according to Comparative Example 4. Similar to the tire 1, the tire 1A includes a bead portion including a first bead filler, a second bead filler, a rubber chafer, and the like. In the tire 1A, the first bead filler is composed of two layers (hard / soft). The Sout / (Sin + Sout) value of the tire according to Comparative Example 4 was calculated based on the area of the hard layer.

  As shown in Table 1, the tires according to Examples 1 to 4 have improved durability as compared with the tires according to Comparative Examples 1 to 4. “Test result (durability)” shown in Table 1 indicates the distance that can be continuously traveled using the drum tester under the above-described conditions. Specifically, the value of the distance that the tire according to the first embodiment can continuously travel is set to “100”, and the distances of the other tires are displayed as indexes.

(5) Action / Effect According to the tire 1 described above, the relationship of D1 / D2 ≧ 0.28 and Sout / (Sin + Sout) ≧ 0.25 is satisfied. Therefore, in the initial state (DEF) before the carcass layer 30 in the bead portion 5, specifically, the second carcass 32 (down ply) is set to the normal internal pressure, compared to a conventional tire such as a comparative example. The shape is “laid down”. In other words, the back angle θ of the second carcass 32 is smaller than that of the conventional tire.

Specifically, since a D1 / D2 ≧ 0.28, the tire maximum width position W _MAX, along located more tire radial direction D _R inward, relative to the tire width direction D _T outer end of the bead core 10, more tire Located outside the width direction _DT . As a result, the second carcass 32 is laid down.

Further, since Sout / (Sin + Sout) ≧ 0.25, the first bead filler 20 falls to the outside in the tire width direction _DT , and as a result, the second carcass 32 is laid down.

  Therefore, in the initial state (DEF) before being assembled to the rim wheel, the state set to the normal internal pressure (INF), and the load state mounted on the vehicle (LOAD), the displacement amount of the bead portion 5 is accurately the second. The amount of displacement of the carcass 32 can be reduced. Here, FIGS. 6A and 6B show the displacement amount of the bead portion 5 analyzed using the FEM model.

  FIG. 6A shows the state of the second carcass 32 when the tire 1 according to this embodiment changes from the initial state (DEF) to the load state (LOAD). The solid line is the initial state (DEF), and the two-dot chain line is the load state (LOAD). FIG. 6B shows a displacement locus of the second carcass 32 including the region A shown in FIG. The solid line is the trajectory of the tire according to the comparative example, and the dotted line is the trajectory of the tire 1 according to the present embodiment. As shown in FIG. 6 (b), since the second carcass 32 (down ply) is also laid in the DEF state, even if the DEF state is changed to the INF state and further to the LOAD state, The displacement amount of the down ply of the tire 1 according to the embodiment is small.

  For this reason, even when shifting from the DEF state to the LOAD state, the down-ply deformation at the position facing the wheel rim 100 (near the region A), that is, near the rim line 150 is suppressed, so that separation occurs near the region A. Can be effectively suppressed.

In this embodiment, the relationship of D3 / D4 ≧ 1.55 is satisfied, and the relationship of D3 / D5 ≧ 0.26 is satisfied. Therefore, in the tire radial direction D _R outside portion of the end portion 20a of the first bead filler 20, a carcass layer 30, specifically, a first carcass 31 in the vicinity of the folded ends 31a, and the folded end portion 31a The portion of the second carcass 32 that is opposed falls down outside the tire width direction D _T , and as a result, the second carcass 32 is laid down.

  Therefore, it is easy to form the above-mentioned “sleeping” shape in the DEF state. For this reason, the deformation of the downply is further suppressed, and the occurrence of separation in the vicinity of the region A can be effectively suppressed.

In this embodiment, the second bead filler 40 covers the tire radial direction D _R outer end 20a of the first bead filler 20. Also, the tire radial direction D _R inner end 40a of the second bead filler 40 is located in the tire radial direction D _R outward from the bead core 10. Further, the rubber chafer 50 covers the second bead filler 40. Therefore, the stress acting from the sidewall portion 7 toward the end portion 20a of the first bead filler 20 and the stress acting from the bead portion 5 in contact with the wheel rim 100 toward the end portion 20a of the first bead filler 20 are It is reduced stepwise by the two bead filler 40 and the rubber chafer 50. Further, according to such a configuration, the carcass layer 30, particularly the second carcass 32, moves away from the rim line 150. Therefore, the concentration of stress on the end 20a of the first bead filler 20 is alleviated, and separation starting from the vicinity of the end 20a of the first bead filler 20 can be suppressed.

  As described above, the 100% modulus value of the second bead filler 40 is 1.0 MPa or more and 5.0 MPa or less, and preferably 1.0 MPa or more and 4.0 MPa or less. According to such a feature, it is possible to effectively alleviate the concentration of distortion due to the downply deformation at a position facing the wheel rim 100 (near the region A), that is, near the rim line 150. Compared to the case where the 100% modulus value of the second bead filler 40 is out of the above-described numerical range, for example, 5.270 MPa, the distortion due to the down-ply deformation is reduced by 16% in the tire 1 (second bead filler) Comparison when 40% 100% modulus value is set to 3.045MPa).

  If the modulus value is less than 1.0 MPa, the second bead filler 40 itself is excessively distorted, so that the second bead filler 40 tends to be a starting point of failure. When the modulus value exceeds 5.0 MPa, the carcass layer 30 (ply coating rubber) becomes softer than the second bead filler 40, and the effect of relaxing the distortion cannot be obtained.

(5) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. For example, the embodiments of the present invention can be modified as follows.

  For example, in the above-described embodiment, the relationship of D3 / D4 ≧ 1.55 is satisfied and the relationship of D3 / D5 ≧ 0.26 is satisfied. However, such a relationship may not necessarily be satisfied. That is, it is only necessary to satisfy the relationship of D1 / D2 ≧ 0.28 and Sout / (Sin + Sout) ≧ 0.25.

In the embodiment described above, the second bead filler 40 covers the end portion 20 a on the outer side in the tire radial direction of the first bead filler 20, and the end portion 40 a on the inner side in the tire radial direction of the second bead filler 40 is more than the bead core 10. located in the tire radial direction D _R outer, rubber chafer 50 has been covered second bead filler 40, such a configuration is not essential.

  In the above-described embodiment, the 100% modulus value of the second bead filler 40 is 1.0 MPa or more and 5.0 MPa or less, but the 100% modulus value of the second bead filler 40 is not necessarily limited to such a range. .

In the above-described embodiment, the second carcass 32 is disposed from the tread portion 3 to the bead portion 5 through the sidewall portion 7 (see FIG. 2), but the second carcass 32 is not necessarily configured as such. Also good. That is, the second carcass 32 only needs to be disposed outside the first carcass 31 in the tire width direction _DT, and may be disposed, for example, below the bead portion 5 (bead base).

1, 1A tire
3 Tread part
4 Belt layer
5 Bead section
7 Side wall
10 Beadcore
10a end
20 First bead filler
20a end
30 carcass layers
31 First carcass
31a Folded end
32 Second carcass
32a end
40 2nd bead filler
40a end
50 Rubber chafer
50a, 50b end
60 side rubber layer
70 Nylon cord layer
80 Chefa
100 wheel rim
150 rim line

Claims (5)

A bead core,
A first bead filler disposed on the outer side of the bead core in the tire radial direction;
A first carcass bent outward in the tire width direction so as to involve the bead core and the first bead filler;
A second carcass disposed on the outer side in the tire width direction of the first carcass;
A tire comprising a second bead filler disposed on the outer side in the tire width direction than the second carcass,
In a cross-sectional view of the tire along the tire width direction,
A straight line passing through the inner end of the bead core in the tire radial direction and parallel to the tire width direction is a straight line X1,
Passing through the maximum width position where the tire width of the tire is maximum, a straight line parallel to the tire width direction is a straight line X2,
A straight line passing through the outer end of the bead core in the tire width direction and perpendicular to the tire width direction is a straight line Y1,
Passing through the maximum width position where the tire width of the tire is maximum, a straight line perpendicular to the tire width direction is a straight line Y2,
On the straight line X2, the distance from the maximum width position to the intersection with the straight line Y1 is the distance D1,
On the straight line Y2, when the distance from the maximum width position to the intersection with the straight line X1 is a distance D2,
D1 / D2 ≧ 0.28
And satisfying the relationship
When the area of the first bead filler located on the outer side in the tire width direction is Sout and the area of the first bead filler located on the inner side in the tire width direction is Sin with the straight line Y1 as a reference,
Sout / (Sin + Sout) ≧ 0.25
Tires that satisfy the relationship. The first carcass passes through the folded end of the first carcass bent outward in the tire width direction, and a straight line parallel to the tire width direction is defined as a straight line X3.
A straight line passing through the outer end in the tire radial direction of the first bead filler and parallel to the tire width direction is defined as a straight line X4.
On the straight line X3, the distance from the folded end to the intersection with the straight line Y1 is a distance D3,
On the straight line X4, when the distance from the outer end in the tire radial direction of the first bead filler to the intersection with the straight line Y1 is a distance D4,
D3 / D4 ≧ 1.55
The tire according to claim 1, satisfying the relationship: The first carcass passes through the folded end of the first carcass bent outward in the tire width direction, and a straight line parallel to the tire width direction is defined as a straight line X3.
A straight line passing through the folded end and orthogonal to the tire width direction is a straight line Y3,
On the straight line X3, the distance from the folded end to the intersection with the straight line Y1 is a distance D3,
When the distance from the folded end to the intersection with the straight line X1 is the distance D5 on the straight line Y3
D3 / D5 ≧ 0.26
The tire according to claim 1 or 2, satisfying the relationship:   The tire according to any one of claims 1 to 3, wherein a 100% modulus value of the second bead filler is 1.0 MPa or more and 5.0 MPa or less. A rubber chafer disposed on the outer side in the tread width direction than the second bead filler;
The second bead filler covers a tire radial direction outer end of the first bead filler,
An end of the second bead filler on the inner side in the tire radial direction is located on the outer side in the tire radial direction than the bead core,
The tire according to any one of claims 1 to 4, wherein the rubber chafer covers the second bead filler.

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