JP2001180233A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of simultaneously improving the rolling resistance, the steering stability, the comfort in riding and the R/N performance while keeping the light weight and the superior durability of a bead part of a conventional tire. SOLUTION: This pneumatic tire has a radial carcass having a folding part, the bead filler rubber having a triangular cross section, and at least one reinforcement cord layer formed on a side face area from a bead part to a side wall part, at least one of the reinforcement cord layers is a spirally wound cord layer formed around a tire axis of at least one rubber-coated cord, and the radial carcass folding part has a radial height within a range of 5-45% of a height of a tire cross section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic radial tire for use in relatively small vehicles such as passenger cars and similar vans and pickups. While maintaining light weight and maintaining durability that does not pose a problem in practical use, steering stability performance, ride comfort performance and road noise (hereinafter R
/ N) which relates to a pneumatic tire having improved performance and rolling resistance at the same time.

[0002]

2. Description of the Related Art Pneumatic tires for automobiles, particularly tires used in relatively small vehicles mentioned at the beginning, include steering stability performance, ride comfort performance, vehicle interior noise performance, especially R / N performance, fuel consumption performance (rolling resistance). (Performance), etc., and there is a demand for improving various performances in general.

With respect to this demand, means for individually improving each performance have been established as described below. (1) Means for improving steering stability performance: securing cornering power, improving tire stiffness, and reducing tread rubber hysteresis loss. (2) Means for improving ride comfort and R / N performance: reducing tire rigidity. (3) Means for reducing weight and improving rolling resistance performance: reducing tire rigidity and reducing hysteresis loss of tread rubber.

[0004]

As described above, it is possible to improve individual performance. However, for example, means for improving steering stability and means for improving ride comfort and R / N performance are completely contradictory. For this reason, at present, it is necessary to rely on the application of glue-like means such as adjusting the gauge of the tread rubber. Further, as is apparent from the above, the improvement direction of the steering stability performance and the low rolling resistance performance are opposite because one of the improvement means is to improve the tire rigidity and the other is to reduce the tire rigidity.

On the other hand, attention is paid to the rigidity of the side surface region from the bead portion to the end of the tread portion through the sidewall portion in the tire rigidity, and as a means for reducing the radial carcass rigidity in this region, a side region region or a region close thereto is used. The end position is high enough to cover the area, and high turn-up (Hi
It has been proposed that the carcass turn-up portion called “gh Turn-up” be a low turn-up portion called a so-called Low Turn-up. However, by lowering the folded end, stress / strain concentration occurs at this end, causing cracks to occur relatively early, and this crack becomes a starting point of failure, causing a problem that bead part durability is significantly reduced. .

Accordingly, the invention described in claims 1 to 15 of the present invention provides a tire having at least the current weight, a bead portion durability which does not matter in the market, and a rolling resistance performance. It is another object of the present invention to provide a pneumatic tire having improved driving stability performance, ride comfort performance, and R / N performance.

[0007]

According to a first aspect of the present invention, there is provided a tread portion having a pair of sidewall portions and a pair of bead portions connected to both sides of the tread portion. A radial carcass that reinforces each of these portions between bead cores embedded in the bead portion, the radial carcass has a folded portion that turns around each bead core from the inside of the tire to the outside, and the bead portion extends from the bead core to the end of the tread portion. A pneumatic tire comprising a bead filler rubber having a triangular cross section extending in a tapered shape, and having one or more reinforcing cord layers in a side surface region from a bead portion to a sidewall portion, wherein at least one of the reinforcing cord layers is provided. Consists of one or more rubber-coated cords, spirally wound cord layers around the tire axis,
The folded part of the radial carcass has a tire cross-section height of 5 to 5.
A pneumatic tire having a tire radial height within a range of 45%.

Here, the section height of the tire is defined as JATMA YE
In relation to the outer diameter of the tire described in AR BOOK (1999), among them, `` Attach the tire to the applicable rim, make it the specified air pressure, 1 /
2 ". Hereinafter, a straight line parallel to the tire axis passing through the rim diameter position is referred to as a rim diameter line.

According to the invention described in claim 1, claim 2 is provided.
As described above, the spirally wound cord layer is disposed outside the tire of the radial carcass body except for the turn-back portion, and the spiral wound cord layer is related to this arrangement, as in the invention described in claim 3. The layer is arranged along the outer side of the tire at the radial carcass turnover, or as in the invention described in claim 4, the spirally wound cord layer is arranged along the inside of the radial carcass turnup.

[0010] According to the invention described in claims 1 to 4, as in the invention described in claim 5, the spirally wound cord layer has a height exceeding the radial height of the end of the radial carcass folded portion in the tire direction. Actually, as in the invention described in claim 6, the spirally wound cord layer has a tire sectional height of 20 to 6 mm.
It has a tire radial height in the range of 0%.

According to the invention described in claims 1 to 6, as in the invention described in claim 7, the cord of the spirally wound cord layer is selected from nylon cord, polyester cord, rayon cord, Kevlar cord and steel cord. It is a kind of code to choose.

Further, according to the invention described in claims 1 to 7, as in the invention described in claim 8, the spirally wound cord layer has a number of cords in a range of 15 to 60/5 cm. .

[0013] Further, according to the invention described in claims 1 to 8, as in the invention described in claim 9, the bead filler rubber has a JIS hardness at 30 ° C within the range of 65 to 83.

According to the invention described in the first to ninth aspects, as a modification, as in the invention described in the tenth aspect, the reinforcing cord layer has a separate reinforcing cord layer in addition to the spirally wound cord layer. In this regard, in this case, the separate reinforcing cord layer is a separating cord layer composed of a multiplicity of rubber-coated cord arrays having both ends separated in the cord axis direction.

[0015] With regard to the invention described in claims 10 and 11,
As in the invention described in claim 12, the cord of the separation cord layer is a kind of cord selected from a nylon cord, a polyester cord, a rayon cord, a Kevlar cord, and a steel cord.
As in the invention described in claim 13, each cord of the separation cord layer has an inclination angle within a range of 0 to 75 ° with respect to the tire radial direction.

According to the invention described in the first to thirteenth aspects, as another modified example different from the above, as in the invention described in the fourteenth aspect, the bead filler rubber is in contact with the tapered tip portion and at the end of the tread portion. A separate reinforcing rubber sheet extending toward the sheet rubber, the sheet rubber having a uniform thickness of 2 mm or less,
In this regard, as in the invention described in claim 15, the reinforcing sheet rubber has a tire radial height within a range of 30 to 75% of the tire cross-sectional height.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a pneumatic tire of the present invention, FIG. 2 is a transparent side view of a spirally wound cord layer of the present invention, and FIGS. 3 and 4 are main parts of the tire shown in FIG. 5 and 6 are enlarged cross-sectional views.
It is a principal part expanded sectional view of the modification of the tire shown in FIG.3 and FIG.4.

The tire 1 shown in FIG. 1 is a pneumatic radial tire for use in a relatively small vehicle described at the beginning, and the tire 1 has a pair of bead portions 2, a pair of sidewall portions 3, And a tread portion 4 connected thereto. Each of these portions 2 to 4 is reinforced by a radial carcass 6 of one or more ply extending between the bead cores 5 embedded in the bead portion 2, in the illustrated example, one ply. Further, the tread portion 4 is reinforced by a belt 7 disposed on the outer periphery of the radial carcass 6. The tread portion 4 has a tread rubber 8 on the outer peripheral side of the belt 7.

The radial carcass 6 has at least one
The ply has a folded portion 6t that folds around each bead core 5 from the inside of the tire 1 to the outside. As a ply cord of the radial carcass 6, an organic fiber cord such as a nylon cord, a polyester cord, a rayon cord, a Kevlar cord or an inorganic fiber such as a carbon fiber cord or a steel cord is applied. Further, the bead portion 2 includes a bead filler rubber 9 extending from the bead core 5 to the end of the tread portion 4 in a tapered shape.
It has a triangular cross section.

The tire 1 is provided with one or more reinforcing cord layers 10 in the pair of side surface regions from the bead portion 2 to the sidewall portion 3, in the illustrated example, one layer. Here, as shown in FIG.
At least one layer is composed of one or more, in the illustrated example, one continuous rubber-coated cord 10HWC, which is a cord layer 10HW that is spirally wound around one axis X of the tire. In FIG. 2, for convenience of explanation, adjacent rubber-coated cords 10HWC from the winding start end 10HWs to the winding end 10HWe are shown separated from each other, but at least the adjacent rubber-coated cords 10HWC in the tire 1 are joined to each other, The spirally wound cord layer 10HW has a complete layer shape.

The folded back portion 6t of the radial carcass 6
Is the height H from the rim diameter line (defined above, the same applies hereinafter) RL, that is, the height H (hereinafter the same) in the radial direction (hereinafter referred to as the radial direction) of the tire 1 is the cross-sectional height ( SH is in the range of 5 to 45% of SH as defined above. That is, the folded portion 6t has a low turn-up configuration.

First, when the ride comfort and R / N performance are grasped from the viewpoint of the tire mechanism, (1) the tire 1 which rolls under a load is transferred from the uneven portion of the running road surface to the ground tread portion 4. The impact force is input, (2) the impact force is transmitted to the belt 7 via the tread rubber 8, and the belt 7 vibrates. (3) The vibration of the belt 7 is
And transmitted from the bead portion 4 to the rim (indicated by a two-dot chain line in FIG. 1), and (4) the vibration of the rim causes the vehicle to vibrate. Leads to poor / good ride comfort and R / N performance. Therefore, reducing the radial rigidity of the tire 1 of the sidewall portion 3 is effective in improving ride comfort performance and R / N performance.

Next, the steering stability performance does not depend on the degree of the overall rigidity of the tire which is largely determined, but rather the rigidity of the side surface region from the bead portion 2 to the sidewall portion 3 and the rigidity of the tread portion 4. Is determined by the degree of rigidity of each of them. Above all, the stiffness of the side surface area plays an important role in the steering stability, and the stiffness is also determined by the lateral stiffness substantially orthogonal to the traveling direction of the tire 1 and the stiffness in the traveling direction, that is, the longitudinal stability. Good or bad. Steering stability can be improved by increasing the lateral rigidity and the longitudinal rigidity.

Finally, the rolling resistance is determined by the viscoelastic material,
It is mainly caused by the hysteresis loss of the rubber, and thus of the organic fiber cord, which is converted to heat. The outer rubber of the side wall portion 3 has physical properties of low hysteresis loss, and the organic fiber cord or the inorganic fiber cord has much more physical properties of low hysteresis loss. Therefore, the lower the radial rigidity of the side wall portion 3, the lower the rolling resistance.

Here, the spirally wound cord layer 10 described above is used.
By applying the HW and the turn-up portion 6t of the low turn-up, the following effects (1) to (4) can be obtained. That is, (1) One or more spirally wound cord layers 10HW provided in a pair of side surface regions cooperate with the low turn-up folded portions 6t to vertically move the respective side surface regions in the load contact ground region. The rigidity (in the radial direction) can be made lower than the rigidity in the vertical direction of each side surface region using the conventional high turn-up folded portion and the high hardness reinforcing rubber layer.

Therefore, each side surface region to which the spirally wound cord layer 10HW and the low turn-up folded portion 6t are applied,
As compared with the above-described conventional side surface regions, the degree of bending is further increased, and as a result, the damping effect of vibration acceleration is improved, and the ability to absorb the vibration brought from the belt 7 is further improved, and the bead portion is improved. Vibration transmissibility can be reduced, and vibration ride comfort and R / N performance are greatly improved.
Note that R / N is represented by the overall decibel (A) value.

(2) On the other hand, in the contact area of the tire 1 filled with internal pressure, the cord 10HWC of the spirally wound cord layer 10HW
As a result, the rigidity of the cord 10HWC itself is increased, and as a result, the longitudinal rigidity of each side surface area along the cord 10HWC arrangement direction is increased, and the lateral rigidity of the both areas is increased. The cornering power of the tire 1 is improved by compensating for the disadvantage of the folded portion 6t. Thereby, the steering stability performance is improved. At this time, it is effective to locate the radially inner end 10HWie of the spirally wound cord layer 10HW as radially inward as possible within a range satisfying the above conditions. It is preferred to be located more radially inward.

(3) The rigidity in the vertical direction of each side surface region having the spirally wound cord layer 10HW and the turn-up folded portion 6t is more than the rigidity of each side surface region of the conventional high hardness reinforcing rubber layer application. As compared with the conventional tread portion 4, the side surface region has a larger amount of overhang deformation to the outside of the tire 1 than in the prior art, in other words, absorbs the ground deformation in the low hysteresis loss region. As a result, the rolling resistance is at least lower than that of the conventional tire described above. As described above, the simultaneous improvement of the steering stability performance, the riding comfort performance, the R / N performance, and the rolling resistance performance can be achieved.

(4) By using the spirally wound cord layer 10HW, the stress at the radial end of the folded portion 6t is reduced.
Since the strain is reduced, the durability of the bead portion 2 can be improved as compared with a conventional tire having a low turn-up turn-back portion. When an organic fiber cord is used for the spirally wound cord layer 10HW, the organic fiber cord has a specific gravity smaller than the specific gravity of rubber, so that the weight of the tire 1 is suppressed to a weight equal to or less than that of the conventional tire. can do. If the height H in the radial direction of the folded portion 6t is less than 5% of the cross-sectional height SH of the tire 1, it becomes difficult to form and vulcanize the tire while producing it while maintaining the radial carcass tension. %, The ride comfort performance, the R / N performance, and the rolling resistance performance cannot be improved.

As described above, the provision of the spirally wound cord layer 10HW in each side surface region of the tire 1 is anisotropic, which cannot be obtained with the high hardness bead filler rubber 9 or the high hardness sheet rubber. That is, the tire 1 utilizes the property of high rigidity in the front-rear direction and low rigidity in the radial direction. By combining this with the low-turn-up folded portion 6t, the riding comfort and performance that had to be sacrificed in the past were obtained. R / N performance is greatly improved, rolling resistance is improved, steering stability is maintained at least as high as that of conventional tires, and durability of bead portion 2 of folded portion 6t has no practical problem. Can be held.

Hereinafter, the spirally wound cord layer 10HW and the bead filler rubber 9 will be described in detail. First, as shown in FIGS. 1 and 3 to 5, the spirally wound cord layer 10HW
The radial carcass 6 is disposed outside the tire 1 on the main body 6b of the radial carcass 6 excluding the folded portion 6t. More specifically, FIG.
As shown in FIGS. 3 and 5, the spirally wound cord layer 10HW is arranged along the tire outer side of the folded portion 6t, and as shown in the right half of FIG. 1 and FIG. Both the case where the round cord layer 10HW is arranged along the tire inner side of the folded portion 6t are allowed. For convenience of explanation, FIG.
Exemplifies the combination of these, but in addition to the mixture, includes a case where only the outside of the folded portion 6t is used and a case where only the inside of the folded portion 6t is used. Thereby, the spirally wound cord layer 10
The HW is useful for reducing the stress and strain at the turn end of the turn portion 6t.

Next, the spirally wound cord layer 10HW has a radial height h10HW exceeding the height H of the folded portion 6t.
That is, h10HW> H. If h10HW ≦ H, since the end of the folded portion 6t does not overlap with the spirally wound cord layer 10HW, stress / strain concentrates on the end of the folded portion 6t, failure occurs from this end, and the durability of the bead portion 2 is improved. Occurs. The actual radial height h10HW of the spirally wound cord layer 10HW is in the range of 20 to 60% of the sectional height SH of the tire 1. If it is less than 20%, the desired steering stability cannot be obtained, and if it exceeds 60%, the effect saturates and the weight increases.

Next, the cord 1 of the spirally wound cord layer 10HW
0HWC is a type of cord selected from nylon cord, polyester cord, rayon cord, Kevlar cord and steel cord. Which code is selected depends on the setting of the required steering stability performance, ride comfort performance, R / N performance, and rolling resistance performance.

Next, the code 1 of the spirally wound code layer 10HW
The number of shots of 0HWC is 15 to 60 pieces / 5 cm. Here, the number of hits is a unit length measured in a direction orthogonal to the cord axis, here, the number of cords 10HWC per 5 cm. The number of shots is set in accordance with the type of the code 10HWC in which the performance is entangled.

Next, the bead filler rubber 9 has a JIS hardness at 30 ° C. within the range of 65 to 83, preferably 7
Within the range of 0 to 80. Outside this range, simultaneous improvement of ride comfort, R / N performance and rolling resistance performance is impeded. The radial height h9 of the bead filler rubber 9
Is within the range of 10 to 70% of the tire section height SH,
Both high and low are acceptable.

Hereinafter, two modified examples will be described. First, as shown in FIG. 5, the reinforcing cord layer 10 has a separate reinforcing cord layer in addition to the spirally wound cord layer 10HW. The separate reinforcing cord layer is a separating cord layer 10AR composed of a multiplicity of rubber-coated cord arrangements having both ends separated in the cord axis direction.

The cord of the separation cord layer 10AR is selected from nylon cord, polyester cord, rayon cord, Kevlar cord and steel cord. Also, the separation code layer 10AR
Each cord has an inclination angle in the range of 0 to 75 °, preferably in the range of 40 to 70 ° with respect to the radial direction of the tire 1.

As shown in FIG. 5, the separation cord layer 10AR is disposed outside the spirally wound cord layer 10HW or inside (not shown). Further, the radial height h10AR of the separation cord layer 10AR is the spirally wound cord layer 1
Both the height (illustrated example) and the height (illustration omitted) higher than the height h10HW of 0HW are allowed.

Since the addition of the separation cord layer 10AR contributes to the improvement of the steering stability, the selection of the cord and the inclination angle are determined by the required steering stability, ride comfort and R. / N performance and rolling resistance performance. If the height h10AR of the separation cord layer 10AR is higher than the height h10HW of the spirally wound code layer 10HW, and the separation code layer 10AR is arranged outside the spirally wound code layer 10HW, the spirally wound code layer can be formed. 10
It has an effect of suppressing the occurrence of cracks in the radially outer end 10HWoe of the HW.

Next, as shown in FIG. 6, the bead filler rubber 9 is separately provided with a reinforcing sheet rubber 11 extending toward the end of the tread portion 4 in contact with the tip including the tapered tip 9p. The sheet rubber 11 is 2 mm or less, preferably 0.1 mm.
It has a uniform thickness in the range of 3 to 1.0 mm. The height h11 of the radially outer end 11oe of the reinforcing sheet rubber 11
Is within the range of 30 to 75% of the sectional height SH of the tire 1,
Preferably, it is in the range of 45 to 60%. This configuration,
It is suitable to give priority to steering stability performance over ride comfort performance and R / N performance.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A radial ply tire 1 for a passenger car, having a size of 195 / 65R15, having a basic configuration according to FIG.
A main part was prepared according to the tire of Example 1 according to FIG. 3 and a main part was prepared according to FIG. 4 except that the heights h9 of the bead filler rubbers 9 were different from those of Examples 2 and 3. The tires of Examples 1 to 3 have the same essential configuration on both sides of the tire equatorial plane E, and a nylon cord is applied to the cord 10HWC of the spirally wound cord layer 10HW. The number of cords to be inserted is 50/5 cm. The sectional height SH of the tire 1 is 125 mm.

The tires of Conventional Examples 1 to 3 without the spirally wound cord layer 10HW and the comparative tires having the same spirally wound cord layer 10HW as in Example 2 but having a high turn-up configuration were prepared. did. Table 1 shows the essential structures of the tires of Examples 1 to 3, the tires of Conventional Examples 1 to 3, and the comparative tire.
Shown in Table 1 of tires of Conventional Examples 1 to 3 and Comparative Example Tires
Except for the parts shown in Table 1, all tires of Examples 1 to 3 were used. In Table 1, the bead filler rubber 9 is abbreviated as BF rubber.

[0043]

[Table 1]

Each tire shown in Table 1 was used as a test tire.
An indoor test and an actual vehicle test were performed. In the indoor test, first, the tire weight was measured. The measurement results are shown in Conventional Example 1.
Of the tire weight of 100. The smaller the value, the better. Next, the radial stiffness is the longitudinal spring constant,
The lateral stiffness was represented by a lateral spring constant, and the longitudinal rigidity was represented by a longitudinal spring constant, and these constants were measured.
The measurement results were represented by an index with the spring constant of Conventional Example 1 being 100. The larger the value, the better.

Next, the rolling resistance was measured, and the resistance was divided by the applied load to obtain a rolling resistance coefficient. This rolling resistance coefficient was represented by an index with Conventional Example 1 being 100.
The larger the value, the better. Next, an indoor drum durability test was performed. The test conditions were as follows: the internal pressure was 300 kPa, the applied load was equivalent to twice the maximum load capacity described in the JATMA standard (1999), the drum surface speed was 60 km / h, and the bead failed. The vehicle was allowed to run until it occurred, and the running distance was measured. The measurement results are shown in Conventional Example 1.
The index is expressed as an index with the travel distance of the vehicle as 100. Table 1 shows these indices.

In the actual vehicle test, a skilled test driver runs on a predetermined course on a test course, and the steering stability performance and riding comfort performance are determined by feeling, and the tire of Conventional Example 1 is set as a reference point (zero). Additional points within the range of ± 5 points,
The deduction system was used. Of course, the larger the value of the additional point (plus point), the better. Also, the overall value of dB (A) is measured as the R / N performance using the in-vehicle noise when traveling on the R / N generating road surface. A) Value, less than minus dB
(A) was calculated. The larger the value of minus dB (A), the better. Table 1 shows the results.

From the results shown in Table 1, regarding the steering stability, the tires 1 of Examples 1 to 3 are equivalent to or slightly lower than the tires of Conventional Example 1, but at a level that does not cause any problem. Has improved significantly. On the other hand,
With respect to the rolling resistance performance, the riding comfort performance, and the R / N performance, the tires 1 of Examples 1 to 3 are significantly improved compared to the tire of Conventional Example 1, and the conventional examples 2 and 3 are significantly inferior in steering stability performance. It can be seen that this is the tire level. On the other hand, in the comparative example tire, although the steering stability performance is certainly improved, the ride comfort performance and the R / N performance are reduced,
The effectiveness of combining the low turn-up folded portion with the spirally wound cord layer 10HW is understood.

As shown in Table 1, the durability of the bead portion 2 in Examples 1 to 3 is reduced by lowering the turn-up portion 6t to a low turn-up compared with the tire of the conventional example 1 in the high turn-up turn-up portion. Although it is unavoidable to do so, it is at least superior to the bead durability of Conventional Examples 2 and 3, and if this level of bead 2 durability is attained, it is confirmed that no problem occurs in the market. ing. It can also be seen that the tire weights of Examples 1 to 3 are almost equal to the tire weights of Conventional Examples 1 to 3.

[0049]

According to the invention described in claims 1 to 15 of the present invention, the weight of a conventional lightweight tire is maintained, and
To provide a pneumatic tire capable of simultaneously improving rolling resistance performance, steering stability performance, ride comfort performance, and R / N performance while maintaining bead durability at a level that is not problematic in the market. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pneumatic tire according to the present invention.

FIG. 2 is a perspective side view of a spirally wound cord layer of the present invention.

FIG. 3 is an enlarged sectional view of a main part of a left half of the tire shown in FIG. 1;

FIG. 4 is an enlarged sectional view of a right half of the tire shown in FIG. 1;

FIG. 5 is an enlarged sectional view of a main part of a modified example of the tire shown in FIG. 3;

FIG. 6 is an enlarged sectional view of a main part of another modification of the tire shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead part 3 Side wall part 4 Tread part 5 Bead core 6 Radial carcass 6b Radial carcass body 6t Turnback part 7 Belt 8 Tread rubber 9 Bead filler rubber 9p Bead filler rubber tip 10 Reinforcement cord layer 10HW spirally wound cord layer 10HWC spiral wound cord 10HWs spiral wound cord start end 10HWe spiral wound cord end 10AR separation cord layer 11 reinforcing sheet rubber E tire equatorial plane X tire axis RL rim diameter line SH tire cross section height H turnover height h9 bead filler rubber Height h10HW Spiral wound cord layer height h10AR Separated cord layer height h11 Reinforced sheet rubber height

Claims (15)

[Claims] 1. A radial carcass comprising a tread portion, a pair of sidewall portions and a pair of bead portions connected to both sides thereof, and a radial carcass for reinforcing each of these portions between bead cores embedded in the bead portions. Has a folded portion that folds around each bead core from the inside of the tire to the outside, and the bead portion includes a bead filler rubber having a triangular cross section extending from the bead core to the end of the tread portion, and from the bead portion to the sidewall portion. In a pneumatic tire having one or more reinforcing cord layers in the side surface region, at least one of the reinforcing cord layers is formed of a spirally wound cord layer of one or more rubber-coated cords around the tire axis, The folded part of the radial carcass has a tire cross-section height of 5 to 5.
A pneumatic tire having a tire radial height within a range of 45%. 2. The tire according to claim 1, wherein the spirally wound cord layer is disposed outside the tire of the radial carcass body excluding the folded portion. 3. The spirally wound cord layer is arranged along the radial carcass folded portion along the tire outer side.
Tire described in. 4. The tire according to claim 1, wherein the spirally wound cord layer is arranged along the inside of the radial carcass folded portion. 5. The tire according to claim 1, wherein the spirally wound cord layer has a height that exceeds a radial height of the end of the radial carcass folded portion. 6. The tire according to claim 1, wherein the spirally wound cord layer has a height in a tire radial direction within a range of 20 to 60% of a tire cross-sectional height. 7. The tire according to claim 1, wherein the cord of the spirally wound cord layer is a kind of cord selected from nylon cord, polyester cord, rayon cord, Kevlar cord and steel cord. . 8. The spirally wound cord layer has a length of 15 to 60 wires / 5.
The tire according to any one of claims 1 to 7, wherein the number of cords is in a range of cm. 9. The tire according to claim 1, wherein the bead filler rubber has a JIS hardness at 30 ° C. within a range of 65 to 83. 10. The tire according to claim 1, wherein the reinforcing cord layer has a separate reinforcing cord layer in addition to the spirally wound cord layer. 11. The tire according to claim 12, wherein the separate reinforcing cord layer is a separating cord layer comprising a number of rubber-coated cord arrays having both ends separated in the cord axis direction. 12. The tire according to claim 10, wherein the cord of the separation cord layer is a kind of cord selected from a nylon cord, a polyester cord, a rayon cord, a Kevlar cord, and a steel cord. 13. The tire according to claim 10, wherein each cord of the separation cord layer has an inclination angle in a range of 0 to 75 ° with respect to the tire radial direction. 14. The bead filler rubber further includes a reinforcing sheet rubber extending toward the end of the tread portion in contact with the tapered tip portion, and the sheet rubber has a uniform thickness of 2 mm or less. A tire according to any one of the preceding claims. 15. The tire according to claim 14, wherein the reinforcing sheet rubber has a height in a tire radial direction within a range of 30 to 75% of a tire sectional height.