JP2014094644A - Tire for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a tire for a motor cycle in which rolling resistance is suppressed while maintaining driving stability.SOLUTION: In a tire for a motor cycle which is provided with a crown part, a pair of side wall parts connecting to both sides of the crown part, and a carcass extending as a toroidal shape over bead parts connecting each side wall part, the carcass includes a first carcass ply made of a first cord and a second carcass ply made of a second cord, the elastic modulus E1 of the first cord is lower than the elastic modulus E2 of the second cord, and the first carcass ply extends over the crown part, each side wall part, and each bead part, terminating with being folded back around the bead core buried in the bead parts while the second carcass ply extends over at least the crown part, terminating without being folded back around the bead core.

Description

  The present invention relates to a motorcycle tire.

  2. Description of the Related Art In recent years, motorcycle tires (for example, Patent Document 1) have been required to have low fuel consumption from the viewpoint of environmental considerations and economy, as well as responding to higher speeds and higher horsepower of vehicles. In other words, as one response to higher speed and higher horsepower of the vehicle, improvement of tire handling stability by the placement of a high-grip tread rubber on the crown and the placement of the tire by the placement of a high-rigidity belt. For example, securing high-speed durability. One means for reducing the fuel consumption of tires is to reduce the rolling resistance of tires, and in particular, to reduce energy loss caused by tire deformation during vehicle travel, which is said to account for about 90% of rolling resistance. (For example, Patent Document 2).

JP 2000-158920 A JP 2011-173510 A

  Here, the arrangement of the belt having a high rigidity on the crown portion can improve the rigidity of the crown portion and suppress the deformation of the crown portion, but the contact area to the road surface of the tire is reduced. Although rolling resistance is reduced, there is a fear that grip performance and steering stability may be lowered. On the other hand, the high-grip tread rubber disposed on the crown portion has a large energy loss (hysteresis loss) due to repeated deformation of the tread rubber itself when the vehicle is running, leading to an increase in tire rolling resistance. Therefore, it has been a trade-off to reduce the rolling resistance of the tire while responding to the higher speed and higher horsepower of the vehicle.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a motorcycle tire with reduced rolling resistance while maintaining steering stability.

  The inventors diligently studied how to reduce the deformation of a motorcycle tire and reduce the rolling resistance of the tire that occur when the vehicle travels. As a result, in conventional tires, it has been found that suppressing the deformation of the crown where the tread rubber with high grip and large energy loss (hysteresis loss) is effective in reducing rolling resistance. Obtained. Furthermore, as a way to suppress deformation of the crown portion, the inventors have reduced the rigidity other than the crown portion, that is, the rigidity of the carcass ply and deformed the low energy loss portion other than the crown portion. Although it is effective in reducing rolling resistance, on the other hand, if the rigidity of the carcass ply is reduced too much, the lateral rigidity of the tire may be reduced, for example, there is a risk that steering stability may deteriorate during turning. Also got. Therefore, the inventors have adjusted the rigidity of the carcass ply so that the vehicle load is applied to the low energy loss part other than the crown part while maintaining the steering stability while the vehicle is running, and the crown part is deformed. As a result, the present inventors have completed the present invention.

That is, the motorcycle tire of the present invention is for a motorcycle including a crown portion, a pair of sidewall portions that are continuous on both sides of the crown portion, and a carcass that extends in a toroidal shape across bead portions that are continuous to the sidewall portions. The carcass includes a first carcass ply formed from a first cord and a second carcass ply formed from a second cord, and the elastic modulus E1 of the first cord is the second carcass ply. Lower than the elastic modulus E2 of the cord, the first carcass ply extends over the crown portion, the sidewall portions, and the bead portions, and is folded back around a bead core embedded in the bead portion. The second carcass ply extends at least the crown portion and terminates without being folded around the bead core. The features.
According to the motorcycle tire of the present invention, while ensuring the lateral rigidity of the sidewall portion and the bead portion and maintaining the steering stability, the rigidity of the sidewall portion and the bead portion, particularly the bead portion, is appropriately reduced. Rolling resistance can be reduced.

  In the present invention, the elastic modulus of the cord is the slope (s-s curve) when the cord single wire is stretched 0.5% in accordance with the standard number JIS L 1017: 2002 (chemical fiber tire cord test method). Per 1 cm width obtained by multiplying the elastic modulus (cN / dtex) of the cord single wire calculated from) by the thickness (dtex) of the cord single wire and further multiplying the number of cord single wires driven per 1 cm width of the cord arranged on the tire Cord elastic modulus (N / cm).

  Here, in the motorcycle tire of the present invention, the first carcass ply is disposed closer to the tire lumen than the second carcass ply, and the second carcass ply is formed by folding the bead core. It is preferable that the first carcass ply turn-up portion passes through the outer side in the tire width direction from the outer end in the tire radial direction and extends inward in the tire radial direction to be terminated. According to the above configuration, the lateral rigidity of the sidewall portion and the bead portion can be sufficiently secured, and the steering stability can be maintained better.

  Further, in the motorcycle tire according to the present invention, the motorcycle tire includes a bead filler disposed outward in the tire radial direction of the bead core, and a tire radial inner end of the second carcass ply is It is preferable that the bead core is located on the outer side in the tire radial direction from the outer end in the tire radial direction and located on the inner side in the tire radial direction from the outer end in the tire radial direction of the bead filler. According to the above configuration, the lateral stiffness of the sidewall portion and the bead portion is effectively reduced, and the lateral stiffness of the sidewall portion and the bead portion is sufficiently secured while effectively reducing the rolling resistance of the tire. Stability can be maintained more reliably.

  Furthermore, in the motorcycle tire according to the present invention, the motorcycle tire includes a belt disposed radially outward of the carcass in the crown portion, and the belt includes a belt cord around the tire circumference. It is preferable to be composed of a single belt layer formed by spirally winding in the direction. According to the said structure, rolling resistance can be reduced more effectively, maintaining steering stability further reliably.

  In the motorcycle tire of the present invention, it is preferable that the elastic modulus E1 of the first cord and the elastic modulus E2 of the second cord satisfy a relationship of 1.05 ≦ E2 / E1 ≦ 1.5. According to the above configuration, the lateral rigidity of the sidewall portion and the bead portion is further sufficiently reduced while sufficiently reducing the rolling resistance of the tire by effectively reducing the rigidity of the sidewall portion and the bead portion, particularly the bead portion. The steering stability can be reliably maintained.

  According to the present invention, it is possible to provide a motorcycle tire having reduced rolling resistance while maintaining steering stability.

FIG. 1A is a diagram showing a cross section in the tire width direction of a half of a typical motorcycle tire according to an embodiment of the present invention. FIG. 1B is a diagram showing a cross section in the tire width direction of a half of a motorcycle tire according to another example of the present invention.

  Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 (a) is a diagram showing a tire width direction cross section in a no-load state in which an example of a motorcycle tire according to the present invention is mounted on an applied rim R and a predetermined internal pressure is applied. Each positional relationship and the like is determined by “no-load state in which a tire is mounted on an applied rim and a predetermined internal pressure is applied”, where “applied rim” is used when the tire is produced and used. Industrial standards valid in the region: JATMA (Japan Automobile Tire Association) YEAR BOOK in Japan, ETRTO (European Tire and Rim Technical Organization) STANDARD MANUAL, TRA (THE TIRE and RIM ASOCIO in the United States). Etc., and refers to a standard rim (or “Applied Rim”, “Recommended Rim”) at an applicable size. In addition, “the tire is mounted on the applied rim and the predetermined internal pressure is applied” means that the tire is mounted on the above-mentioned applied rim and the single wheel in the applied size / ply rating described in JATMA or the like. The air pressure corresponding to the maximum load capacity (maximum air pressure) refers to the state where no load is applied to the tire.

  A pneumatic tire 10 for a motorcycle according to an example of the present invention shown in FIG. 1A includes a crown portion 1 whose surface is curved in a convex arc shape, and a pair of sidewall portions 2 connected to both sides of the crown portion 1. And the bead part 3 connected to each sidewall part 2 is provided.

  Further, the tire 10 has a carcass 4 extending in a toroidal shape across the crown portion 1, the sidewall portion 2, and the bead portion 3 between the bead cores 31 embedded in each bead portion 3. The carcass 4 includes a first carcass ply 41 formed from the first cord and a second carcass ply 42 formed from the second cord. Further, the first carcass ply 41 extends over the crown portion 1, each sidewall portion 2, and each bead portion 3, and around the bead core 31 embedded in the bead portion 3 from the inner side in the tire width direction to the tire width direction. It wraps outward and ends. That is, the first carcass ply 41 is positioned on the outer side in the tire width direction of the first carcass ply main body portion 43 extending over the crown portion 1, each sidewall portion 2, and each bead portion 3, and the first carcass ply main body portion 43. And it has the 1st carcass ply turn-up part 44 extended from the 1st carcass ply main-body part 43 and the circumference | surroundings of the bead core 31 from the tire radial direction inner side toward the tire radial direction outer side. As shown in FIG. 1A, the first carcass ply turn-up portion 44 extends from the bead portion 3 outward in the tire radial direction and terminates at the sidewall portion 2.

  Further, the second carcass ply 42 extends at least in the crown portion 1 (in FIG. 1A, the second carcass ply 42 is formed in a toroidal shape over the crown portion 1, the sidewall portions 2, and the bead portions 3. Extended). The carcass 4 shown in FIG. 1 (a) is composed of two plies of the first and second carcass plies 41 and 42. In the motorcycle tire of the present invention, a carcass ply is added as necessary. be able to.

  Further, a belt 5 is disposed outside the carcass 4 of the crown portion 1 in the tire radial direction.

  Further, a tread rubber 11 is disposed outside the belt 5 in the tire radial direction, and a tread groove such as a circumferential groove extending in the tire circumferential direction is omitted on the surface of the tread rubber 11 although illustration is omitted. Is formed. FIG. 1A shows a case where the tread rubber 11 has a single layer structure. However, if necessary, the tread rubber 11 may have a laminated structure of two or more layers such as a cap-and-base structure. Can do.

  Further, on the outer side in the tire radial direction of the bead core 31 embedded in the bead part 3, the first carcass ply main body part 43 and the first carcass ply folding part located on the outer side in the tire width direction of the first carcass ply main body part 43. 44, a bead filler 6 having a substantially triangular cross-section is disposed along the first carcass ply 41 so that the thickness gradually decreases outward in the tire radial direction.

  Further, an inner liner 7 is disposed on the tire lumen side of the first carcass ply 41.

In the motorcycle tire of the present invention, the elastic modulus E1 of the first cord constituting the first carcass ply 41 is lower than the elastic modulus E2 of the second cord constituting the second carcass ply 42. Further, the first carcass ply 41 is folded around the bead core 31 and is terminated, whereas the second carcass ply 42 is terminated without being folded around the bead core 31.
Therefore, in this motorcycle tire, the elastic modulus E1 of the first cord constituting the first carcass ply 41 folded around the bead core 31 is set to be the second carcass ply 42 constituting the second carcass ply 42 not folded around the bead core 31. Since it is lower than the elastic modulus E2 of the two cords, the rigidity of the sidewall portion 2 and the bead portion 3, particularly the bead portion 3, can be reduced. Then, by reducing the rigidity of the sidewall portion 2 and the bead portion 3, the sidewall portion 2 and the bead portion 3 bear the vehicle load due to the bending deformation when the vehicle travels, and at the same time the vehicle of the crown portion 1 Since the load of the load is reduced, the deformation of the crown portion 1 can be suppressed. As a result, the sidewall portion 2 and the bead portion 3 have lower energy loss with respect to deformation than the crown portion 1 on which the tread rubber 11 is disposed, so that the rolling resistance of the tire 10 can be reduced.
Further, if the rigidity of the sidewall portion 2 is excessively reduced, the lateral rigidity (rigidity in the tire width direction) of the sidewall portion 2 is lowered and steering stability is deteriorated, but the second carcass ply 42 constituting the second carcass ply 42 is formed. Since the elastic modulus E2 of the cord is higher than the elastic modulus E1 of the first cord constituting the first carcass ply 41, the lateral rigidity of the sidewall portion 2 and the bead portion 3 is ensured and the steering stability is maintained. be able to.

  If the elastic modulus E1 of the first cord of the first carcass ply 41 is equal to or higher than the elastic modulus E2 of the second cord constituting the second carcass ply 42, the rigidity of the bead portion 3 is increased. It does not sufficiently decrease in relation to the rigidity of the portion 2, and the deformation of the crown portion 1 is not suppressed during traveling of the vehicle, and the rolling resistance of the tire 10 cannot be reduced.

  Here, in the pneumatic tire 10 for a motorcycle, the first carcass ply 41 is disposed closer to the tire lumen than the second carcass ply 42, and the second carcass ply 42 is disposed at the first carcass ply turn-up portion 44. It is preferable that the tire extends inward in the tire radial direction from the outer end in the tire radial direction (hereinafter also referred to as “first carcass ply folded end”) and ends in the tire radial direction. According to the above configuration, the first carcass ply 41 is disposed on the tire lumen side, and the second carcass ply 42 extends inward in the tire radial direction through the inner side in the tire width direction from the first carcass ply folded end. Compared to the first carcass ply main body portion 43 and the second carcass ply 42 in the tire width direction, the side wall portion 2 and the bead portion 3 are less likely to bend in the tire width direction. Sufficiently secured and steering stability is better maintained. When the second carcass ply 42 is disposed closer to the tire lumen than the first carcass ply main body 43, distortion tends to occur at the tire radial inner end of the second carcass ply 42 during vehicle travel. As a result, there is a possibility that separation is likely to occur.

  Further, the inner end in the tire radial direction of the second carcass ply 42 is located on the outer side in the tire radial direction from the outer end in the tire radial direction of the bead core 31, and the inner end in the tire radial direction from the outer end in the tire radial direction of the bead filler 6. It is preferable to be located at. According to the above configuration, the lateral rigidity of the sidewall part 2 and the bead part 3 can be more sufficiently ensured while effectively reducing the rigidity of the bead part 3 in relation to the rigidity of the sidewall part 2. . When the inner end in the tire radial direction of the second carcass ply 42 is positioned more inward in the tire radial direction than the outer end in the tire radial direction of the bead core 31, the rigidity of the bead part 3 is related to the rigidity of the sidewall part 2. There exists a tendency not to fall effectively, and there exists a possibility that the rolling resistance of the tire 10 cannot be reduced. In addition, when the inner end in the tire radial direction of the second carcass ply 42 is positioned outward in the tire radial direction from the outer end in the tire radial direction of the bead filler 6, the lateral rigidity of the sidewall portion 2 and the bead portion 3 during vehicle travel. There is a tendency that it cannot be sufficiently secured, and the steering stability may be reduced.

Further, the elastic modulus E1 of the first cord constituting the first carcass ply 41 and the elastic modulus E2 of the second cord constituting the second carcass ply 42 satisfy the relationship of 1.05 ≦ E2 / E1 ≦ 1.5. It is preferable to satisfy. According to the above configuration, the lateral rigidity of the sidewall part 2 and the bead part 3 is more effectively reduced and the lateral rigidity of the sidewall part 2 and the bead part 3 is further sufficiently ensured and the steering stability is improved. Can be reliably maintained. When the relationship between the elastic moduli becomes 1.5 <E2 / E1, the lateral rigidity of the sidewall portion 2 and the bead portion 3, particularly the bead portion 3, tends to be reduced, and the steering stability becomes insufficient. There is a fear that the rigidity of the sidewall portion 2 tends to be high, and the deformation of the crown portion 1 may not be suppressed when the vehicle travels. Further, when the relationship between the respective elastic moduli becomes E2 / E1 <1.05, the rigidity of the sidewall portion 2 and the bead portion 3, particularly the bead portion 3, tends not to be sufficiently lowered. 2 and the deformation of the crown portion 1 due to the bending deformation of the bead portion 3 and the effective reduction of the rolling resistance of the tire 10 may not be achieved, or the sidewall portion 2 and the bead portion 3 Lateral rigidity tends to decrease, and steering stability may be insufficient.
From the viewpoint of improving safety, it is more preferable that the elastic modulus E1 of the first cord and the elastic modulus E2 of the second cord satisfy a relationship of 1.05 ≦ E2 / E1 ≦ 1.3.

  Although not limited, for example, in the front wheel tire, the elastic modulus E1 of the first cord constituting the first carcass ply 41 is 17000 to 23000 (N / cm), and the second carcass ply 42 is The elastic modulus E2 of the second cord to be configured is preferably 15000 to 21000 (N / cm). According to the above configuration, the rigidity of the sidewall portion 2 and the bead portion 3 is further effectively reduced while the lateral rigidity of the sidewall portion 2 and the bead portion 3 is further sufficiently secured and the steering stability is more effectively maintained. The rolling resistance of the tire 10 can be reduced more effectively.

  The first cord of the first carcass ply 41 and the second cord of the second carcass ply 42 are not limited. For example, aliphatic polyamide (nylon), polyester (polyethylene naphthalate, polyethylene terephthalate), rayon, It is preferably made of an organic fiber cord such as aromatic polyamide (aramid), among which the first cord is preferably made of nylon, polyethylene naphthalate or polyethylene terephthalate, and the second cord is made of rayon. This is because the above configuration of the first cord and the second cord is suitable for realizing the above relationship between the elastic modulus E1 of the first cord and the elastic modulus E2 of the second cord.

Here, it is preferable that the belt 5 is composed of one belt layer, and the belt layer is formed by winding the belt cord in a spiral shape in the tire circumferential direction. According to the above configuration, since the belt 5 has a monospiral belt structure, compared with the case where the belt 5 has an intersecting belt layer structure, the ground contact area can be increased and the steering stability can be improved, and the tire weight can be increased. This can reduce fuel consumption.
The crossing belt layer structure means that the belt 5 is composed of two belt layers, the belt cords of each belt layer are arranged inclined with respect to the tire circumferential direction, and each belt cord of the belt 5 is The belt structure is arranged and formed so as to cross each other across the tire equator line CL.
Further, FIG. 1A shows a case where the belt 5 is composed of one belt layer, but the number of belt layers of the belt 5 can be any number as required. For example, in order to reinforce the carcass 4 between the carcass 4 and the belt 5, a two-layer belt layer formed by rubber coating a plurality of belt cords arranged in parallel to each other can be disposed. .

  The belt cord of the belt 5 is not limited, but is made of, for example, a steel cord or an organic fiber cord such as aliphatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon, aromatic polyamide (such as aramid). Of these, it is preferable to use a steel cord or an organic fiber cord made of aramid, particularly a steel cord. Since the belt cord of the belt 5 is made of a steel cord, the rigidity of the crown portion 1 can be more effectively ensured and high-speed durability can be improved.

Next, another example of a motorcycle tire according to the present invention will be described with reference to FIG. In FIG. 1B, elements similar to those of the tire 10 shown in FIG. 1A are denoted by the same reference numerals, and description thereof is omitted.
In the pneumatic tire 20 for a motorcycle of this example, the first carcass ply 41 is disposed closer to the tire lumen than the second carcass ply 42, and the second carcass ply 42 is tire width from the first carcass ply folding end. It extends inward in the tire radial direction through the inner side in the tire direction and the inner side in the tire width direction of the bead filler 6. According to the above configuration, the rolling resistance can be further reduced.

  As described above, the embodiment of the present invention has been described with reference to the drawings, but the motorcycle tire of the present invention is not limited to the above example and other examples, and the motorcycle tire of the present invention includes: Changes can be made as appropriate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all.

(Examples 1-7)
A motorcycle tire for a front wheel (tire size: MCR120 / 70ZR17) having a configuration as shown in FIGS. 1A and 1B is made as a prototype with the specifications shown in Table 1, and each tire is shown in Example 1. It was set to ~ 7.
Specifically, in the front wheel tires of Examples 1 to 5 and 7, the first carcass ply disposed on the tire lumen side is folded around the bead core, and the first carcass ply folded end is the sidewall portion. Is located. Further, the inner end in the tire radial direction of the second carcass ply is located between the outer end in the tire radial direction of the bead core and the outer end in the tire radial direction of the bead filler, and outside the first carcass ply folded portion in the tire width direction. doing. Furthermore, the belt forms a monospiral structure. The distances from the bead base line to the first carcass ply turn-up end, the second carcass ply tire inner end in the tire radial direction, and the bead filler outer end in the tire radial direction are 29 mm, 10 mm, and 17 mm, respectively.
And the front wheel tire of Example 6 has a structure in which the inner end in the tire radial direction of the second carcass ply extends inward in the tire radial direction through the inner side in the tire width direction of the bead filler, It has the same structure as Examples 1-5 and 7.
(Comparative Examples 1-2)
For Comparative Example 1, the magnitude relationship between the elastic moduli E1 and E2 was changed, and the second carcass ply was also folded around the bead core from the inner side in the tire width direction to the outer side in the tire width direction like the first carcass ply. Except for this, a front wheel tire having the same configuration as in Example 1 was prototyped, and the tire was referred to as Comparative Example 1.
In Comparative Example 2, a front wheel tire having the same configuration as that of Example 1 was manufactured except that the magnitude relationship between the elastic moduli E1 and E2 was changed, and the tire was used as Comparative Example 2.
Each tire of Examples 1-7 and Comparative Examples 1-2 was evaluated by the following method.

<Rolling resistance>
Using the indoor drum tester, the tires of Examples 1 to 7 and Comparative Examples 1 and 2 were run, and the rolling resistance was measured. Specifically, the tire (size: 120 / 70ZR17M / C) was assembled to a rim having a size of MT3.5 × 17, and the tire internal pressure was set to 250 kPa.
Then, using an indoor drum tester, a load of 2.31 kN was applied to each tire, and then the tire was run at a drum surface speed of 80 km / h to measure rolling resistance. Table 1 shows the results of index evaluation with the rolling resistance of the tire of Comparative Example 1 as 100. The smaller the value, the lower (improved) the rolling resistance of the tire.
<Steering stability>
Each of the front wheel tires of Examples 1 to 7 and Comparative Examples 1 and 2 (tire size: MCR120 / 70ZR17) is assembled to a rim of size MT3.5 × 17 so that the tire internal pressure is 250 kPa. The rear wheel tire having the structure (tire size: MCR180 / 55ZR17) was assembled to a rim of size MT5.5 × 17, the tire internal pressure was set to 290 kPa, and the respective front wheel tire and rear wheel tire were mounted on the motorcycle. The test rider then traveled on the test course and performed a sensory evaluation on the handling stability. Table 1 shows the results of the index evaluation with Comparative Example 1 as 100. The larger the value, the better the steering stability. In addition, if the numerical value of the index evaluation is within the range of 100 ± 5, it can be said that it is equivalent to the steering stability of the tire of the index evaluation 100.

＊「第二カーカスプライのビード部周辺構造」において、「折返しあり」とは、第二カーカスプライがビードコアの周りで折り返された構造を有していることを指す。
また、「折返しなし」とは、第二カーカスプライがビードコアの周りで折り返されていない構造を有していることを指し、さらに、第二カーカスプライのタイヤ径方向内端が第一カーカスプライ折返し部よりタイヤ幅方向外側に位置する構造（図１（ａ））を「折返しなし（外側）」と、第二カーカスプライのタイヤ径方向内端が第一カーカスプライ折返し部よりタイヤ幅方向内側に位置する構造（図１（ｂ））を「折返しなし（内側）」と表記する。

* In “the peripheral structure of the bead part of the second carcass ply”, “with folding” means that the second carcass ply has a structure folded around the bead core.
In addition, “no folding” means that the second carcass ply has a structure that is not folded around the bead core, and the inner end in the tire radial direction of the second carcass ply is the first carcass ply folding. The structure located on the outer side in the tire width direction from the portion (FIG. 1 (a)) is “no folding (outside)”, and the inner end in the tire radial direction of the second carcass ply is on the inner side in the tire width direction from the first carcass ply folding portion The positioned structure (FIG. 1B) is described as “no folding (inside)”.

  From the results shown in Table 1, the tires of Examples 1 to 7 are more stable than the tire of Comparative Example 1 in which the elastic modulus is E1 = E2 and the second carcass ply is folded around the bead core. It can be seen that the rolling resistance was reduced while maintaining the properties. Further, it can be seen that the rolling resistance of the tires of Examples 1 to 7 was reduced while maintaining steering stability as compared with the tire of Comparative Example 2 in which the elastic modulus was E1> E2. Furthermore, it can be seen that the steering stability of the tires of Examples 1 to 6 is sufficiently maintained as compared with the tire of Example 7 in which the elastic modulus is E2 / E1> 1.5.

  According to the present invention, it is possible to provide a motorcycle tire having reduced rolling resistance while maintaining steering stability.

DESCRIPTION OF SYMBOLS 1 Crown part 2 Side wall part 3 Bead part 4 Carcass 5 Belt 6 Bead filler 7 Inner liner 10 Pneumatic tire 11 for motorcycles Tread rubber 31 Bead core 41 First carcass ply 42 Second carcass ply 43 First carcass ply main exterior 44 First carcass ply turn-up part 20 Pneumatic tire for motorcycle E1 Elastic modulus of first cord E2 Elastic modulus of second cord

Claims (5)

A motorcycle tire comprising a crown portion, a pair of sidewall portions continuous on both sides of the crown portion, and a carcass extending in a toroid shape over a bead portion connected to each sidewall portion,
The carcass includes a first carcass ply formed from a first cord and a second carcass ply formed from a second cord,
The elastic modulus E1 of the first cord is lower than the elastic modulus E2 of the second cord,
The first carcass ply extends over the crown portion, the sidewall portions, and the bead portions, and is folded back around a bead core embedded in the bead portion, and ends.
The tire for a motorcycle according to claim 2, wherein the second carcass ply extends at least the crown portion and terminates without being folded around the bead core. The first carcass ply is disposed closer to the tire lumen than the second carcass ply;
The second carcass ply extends from the outer side in the tire radial direction of the first carcass ply folded portion formed by folding back the bead core and extends inward in the tire radial direction and terminates. 2. A motorcycle tire according to 1. The motorcycle tire comprises a bead filler disposed on the outer side of the bead core in the tire radial direction,
The inner end in the tire radial direction of the second carcass ply is located on the outer side in the tire radial direction from the outer end in the tire radial direction of the bead core, and is located on the inner side in the tire radial direction from the outer end in the tire radial direction of the bead filler. The motorcycle tire according to claim 1 or 2. The motorcycle tire includes a belt disposed outward in the tire radial direction of the carcass in the crown portion,
The motorcycle tire according to any one of claims 1 to 3, wherein the belt is formed of a single belt layer formed by winding a belt cord in a spiral shape in a tire circumferential direction. The elastic modulus E1 of the first cord and the elastic modulus E2 of the second cord are:
1.05 ≦ E2 / E1 ≦ 1.5
The tire for a motorcycle according to any one of claims 1 to 4, satisfying the relationship:

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