JP4705284B2 - Radial tire for ATV - Google Patents

Description

【００３６】
【表２】

【００３７】
表の如く、実施例のタイヤは、スライドコントロール性及び乗り心地性の双方に優れ、高い操縦安定性を確保しうるのが確認できる。
【００３８】
【発明の効果】
本発明は叙上の如く構成しているため、乗り心地性やギャップ吸収性、及び重量増加やグリップ感不足等の従来的な弊害を招くことなく、中〜高速域で旋回する際のスライドコントロール性を向上させることができ、高い操縦安定性を発揮しうる。
【図面の簡単な説明】
【図１】本発明のＡＴＶ用ラジアルタイヤの一実施例を示す断面図である。
【図２】そのトレッドパターンを例示する展開図である。
【図３】トレッドゴムのゴム厚さを示す断面図である。
【符号の説明】
２ トレッド部
２Ｇ トレッドゴム
３ サイドウォール部
４ ビード部
５ ビードコア
６ カーカス
７ ベルト層
７Ａ、７Ｂ ベルトプライ
Ｐａ タイヤ赤道
Ｐｂ 中間点
Ｐｃ トレッド接地端
Ｇ トレッド溝[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radial tire for ATV that has improved slide controllability in a medium to high speed range by defining a rubber thickness distribution of tread rubber.
[0002]
[Prior art]
ATV radial tires are used on rough roads such as muddy ground, grassland, and sand under low load. Therefore, unlike a tire for passenger cars, it is important to ensure ground contact and attach a levitation force. For this reason, a profile with a low flatness is adopted and a low internal pressure of about 30 kPa or less is filled. Further, the rubber thickness of the tread rubber is gradually reduced from the tire equator side toward the ground contact end side, and the reduction of the turning characteristics accompanying the flattening is suppressed.
[0003]
On the other hand, in the internal structure, a relatively low modulus organic fiber cord such as nylon is used for the carcass and the belt layer to give flexibility and ensure riding comfort and handling. The cord angle of the belt layer with respect to the tire circumferential direction is usually 15 to 30 degrees, and the tread rubber having a rubber hardness of 53 to 70 degrees is used.
[0004]
On the other hand, in recent years, high-performance ATV vehicles, such as those for competition and sports whose maximum speed exceeds 120 km / h, have appeared along with the enhancement of courses and facilities and the expansion of the competition population.
[0005]
However, there is a problem that the slide controllability is impaired when a conventional tire is used and a high-power ATV vehicle turns in the middle to high speed range. The medium to high speed region means a speed region of 50% or more of the maximum speed. For example, when the maximum speed is 120 km / h, 60 km / h or more is referred to as a medium to high speed region.
[0006]
For this purpose, for example, (a) increasing the belt stiffness by reducing the cord angle of the belt layer;
(B) Increase the rubber hardness and height of the bead apex rubber and reduce the roll feeling by increasing the tire side rigidity;
(C) increase the rubber hardness of the tread rubber and increase the tread rigidity;
Etc. are taken.
[0007]
[Problems to be solved by the invention]
However, both methods tend to impair ride comfort and gap absorption, and the method (b) leads to an increase in the tire weight, and the method (c) does not have a grip feeling and is controlled. There is also a negative effect of reducing stability.
[0008]
Therefore, the present invention is based on defining the rubber thickness distribution of the tread rubber, when turning in the middle to high speed range without causing adverse effects such as ride comfort, gap absorbability, weight increase and grip feeling deficiency. An object of the present invention is to provide a radial tire for ATV that can improve the slide controllability.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application is directed to a carcass extending from a tread portion having a tread groove recessed to a bead core of a bead portion through a side wall portion, inside the tread portion and outside the carcass. A pneumatic tire for ATV comprising a belt layer disposed on
While the rubber hardness (durometer A hardness) of the tread rubber forming the tread portion is 53 to 70 °,
The rubber thickness of the tread rubber on the tire equator is TA, the rubber thickness at the tread ground end is TC, the rubber thickness at the midpoint between the tire equator and the tread ground end is TB, and the minimum at the groove bottom of the tread groove is When the rubber thickness is TD, the following relationship is satisfied.
1.0 <TB / TA ≦ 1.10
0.48 ≦ TC / TA ≦ 0.61
TD> 2.0mm
0.1mm ≦ (TB-TA) ≦ 1.8mm
[0010]
According to a second aspect of the present invention, the belt layer has a maximum belt width BW of 0.3 to 1.0 times the tread ground contact width WT.
[0011]
In the invention of claim 3, the belt layer is composed of two belt plies, and the ply width of each belt ply is 0.3 to 0.65 times the tread grounding width WT.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a meridional section of a radial tire 1 for ATV of the present invention (hereinafter sometimes referred to as tire 1).
[0013]
In FIG. 1, a tire 1 according to the present embodiment is arranged on a carcass 6 that extends from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3, an inner side of the tread portion 2, and an outer side of the carcass 6. Belt layer 7.
[0014]
The carcass 6 is formed from one or more carcass plies 6A and 6B, in this example, in which carcass cords are arranged at an angle of 70 ° to 90 ° with respect to the tire circumferential direction. As the carcass cord, a relatively low modulus organic fiber cord such as nylon, polyester, rayon or the like is used.
[0015]
In addition, the carcass 6 has folded portions 6b on both sides of the body portion 6a straddling the bead cores 5 and 5 so that the periphery of the bead core 5 is folded back from the inside to the outside, and between the body portion 6a and the folded portion 6b. Is provided with a bead apex rubber 8 rising from the bead core 5 in a tapered shape. In this bead apex rubber 8, it is preferable to keep the height h1 from the bead base line BL at the radially outer end to 0.4 times or less of the tire height H1 in order to balance the overall tire rigidity. .
[0016]
The belt layer 7 is formed of one or more belt cords arranged at an angle of, for example, 15 ° to 30 ° with respect to the tire circumferential direction, in this example, two belt plies 7A and 7B. ing. The belt plies 7A and 7B are arranged with different inclination directions so that the cords cross each other between the plies.
[0017]
The belt layer 7 reinforces the tread portion 2 and plays an important role for securing puncture resistance, durability, and tire rigidity, as in a tire for a passenger car. Further, due to the tagging effect, the tire 1 is given a flat profile with a flatness ratio of 55% or less, in this example about 50%, and the levitation force in soft ground is increased. However, in this type of tire, the ride comfort and gap absorbability are also very important, especially for use on uneven road surfaces. For this reason, as with the carcass cord, nylon, A low modulus organic fiber cord such as polyester or rayon is preferably used.
[0018]
Also, in this example, the ply width W1 of the inner belt ply 7A is wider than the ply width W2 of the outer belt ply 7B, thereby relaxing the rigidity step at the outer end of the belt and peeling due to stress concentration. Damage is suppressed. Therefore, it is preferable to provide a ply width difference W1-W2 of about 20 mm or more.
[0019]
The maximum belt width BW, which is the maximum ply width W1, is in the range of 0.3 to 1.0 times the tread ground contact width WT. In this example, in order to optimize the rigidity balance of the entire tire, The case where both the ply widths W1 and W2 are 0.3 to 0.65 times the tread ground contact width WT is illustrated. If it exceeds 0.65 times, the wandering performance is deteriorated, and the steering stability tends to be lowered due to the unevenness of the road surface.
[0020]
Here, the “tread contact width WT” means the width in the tire axial direction of the tread surface that can be grounded when a normal load is applied to a normal internal pressure tire that is assembled with a normal rim and filled with a normal internal pressure. To do. The “regular rim” is a rim defined by the standard in the standard system including the standard on which the tire is based. For example, it is a standard rim for JATMA, “Design Rim” for TRA, or ETRTO. Means "Measuring Rim". The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum air pressure in the case of JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, If it is ETRTO, it is "INFLATION PRESSURE". The “regular load” is a load defined by the standard for each tire. The maximum load capacity in the case of JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, If it is ETRTO, it is "LOAD CAPACITY".
[0021]
Next, as shown in FIG. 2, for example, a tread groove G is formed in the tread portion 2 to form a block pattern in which a plurality of blocks 11 are spaced in a convex shape. At this time, in order to improve traction, in this example, the block 11 is horizontally long, and the land area LA that is the total surface area of the block 11 and the sea area SA that is the total area of the tread groove G The ratio SA / LA is set in the range of 5.7 to 3.0.
[0022]
Further, as the tread rubber 2G forming the tread portion 2, a conventional rubber tread rubber 2G having a hardness (durometer A hardness) of 53 to 70 ° is used, and the distribution of the rubber thickness T of the tread rubber 2G is as follows. Stipulated as follows.
[0023]
That is, as shown in FIG. 3, the rubber thickness of the tread rubber 2G on the tire equator Pa is TA, the rubber thickness at the tread grounding end Pc is TC, and the intermediate point Pb between the tire equator Pa and the tread grounding end Pc. When the rubber thickness is TB and the minimum rubber thickness TD at the groove bottom of the tread groove G is satisfied, the following relationship is satisfied.
1.0 <TB / TA ≦ 1.10 --- (1)
0.48 ≦ TC / TA ≦ 0.61 (2)
TD> 2.0mm --- (3)
0.1 mm ≦ (TB−TA) ≦ 1.8 mm −−− (4)
[0024]
The “rubber thickness T” means the rubber thickness between the tread surface 2S and the radially outer surface of the cord reinforcing layer closest to the tread surface 2S. Therefore, for example, in the region where the belt layer 7 is present, the rubber thickness is between the outer surface of the belt layer 7 and the tread surface 2S, and in the region where the belt layer 7 is not present, the thickness is between the outer surface of the carcass 6 and the tread surface 2S. Means the rubber thickness.
[0025]
In this way, the relationship (1) to (4) is satisfied, and the rubber thickness distribution is
TB>TA> TC
By doing so, it is possible to improve the slide control performance when turning in the middle to high speed range without impairing the ride comfort and the gap absorbability. The conventional rubber thickness distribution has a relationship of TA>TB> TC.
[0026]
Here, when the ratio TB / TA is larger than 1.10, the rigidity difference between the blocks becomes excessive, and both slide controllability and riding comfort are deteriorated. Also, when the ratio TB / TA is 1.0 or less, the slide controllability is not linear, and similarly, the slide controllability and ride comfort are lowered.
[0027]
On the other hand, when the ratio TC / TA is less than 0.48, the tire rigidity is lowered and the tire tends to become low, and the slide control performance and the ride comfort are deteriorated. On the other hand, when the ratio TC / TA exceeds 0.61, the tire rigidity is increased, so that the gap absorbability is deteriorated. Similarly, the slide control property and the ride comfort are deteriorated.
[0028]
If the difference in rubber thickness TB-TA is less than 0.1 mm, the effect of improving the slide control and ride comfort will not be sufficiently exerted. Conversely, if it exceeds 1.8 mm, the slide control will deteriorate. To do .
[0029]
In order to exert the effect, it is indispensable that the tire does not bend and deform unevenly at the groove bottom of the tread groove G. For this reason, in the present embodiment, the minimum rubber thickness TD at the groove bottom. Is 2.0 mm or more.
[0030]
As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.
[0031]
【Example】
The ATV tire with the tire size of AT20 × 10R9, which has the internal structure shown in FIG. 1, was prototyped with the specifications shown in Table 1, and the overall performance of each sample tire in terms of slide control, ride comfort, and steering stability The results are shown in Table 1.
Specifications other than those in Table 1 are substantially the same for each tire as shown in Table 2.
[0032]
(1) Slide controllability;
A sample tire was mounted on the rear wheel of an ATV car (660CC) with a rim (8.0 AT) and internal pressure (28 kPa), ran on an ATV competition course, and turned in a medium to high speed range (about 40 km / h). The slide controllability was evaluated by a three-point method of ○ (good), Δ (normal), and × (bad) by sensory evaluation of the driver.
[0033]
(2) Ride comfort;
Riding comfort (including gap absorption) when running on the competition course was evaluated by a three-point method of ○ (good), Δ (normal), and × (bad) based on the driver's sensory evaluation.
[0034]
(3) Overall performance of handling stability;
In addition to slide control and ride comfort when running on the competition course, the overall performance of handling stability including handling, rigidity, grip, etc. was evaluated by a five-point method based on the driver's sensory evaluation.
[0035]
[Table 1]

[0036]
[Table 2]

[0037]
As shown in the table, it can be confirmed that the tires of the examples are excellent in both slide control and riding comfort and can ensure high steering stability.
[0038]
【The invention's effect】
Since the present invention is configured as described above, the slide control when turning in the middle to high speed range without incurring conventional adverse effects such as ride comfort, gap absorbability, weight increase and insufficient grip. Can be improved, and high steering stability can be exhibited.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a radial tire for ATV of the present invention.
FIG. 2 is a development view illustrating the tread pattern.
FIG. 3 is a cross-sectional view showing a rubber thickness of a tread rubber.
[Explanation of symbols]
2 Tread part 2G Tread rubber 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 7A, 7B Belt ply Pa Tire equator Pb Middle point Pc Tread grounding end G Tread groove

Claims (3)

A radial tire for ATV comprising a carcass extending from a tread having a recessed tread groove through a sidewall portion to a bead core of the bead portion, and a belt layer disposed inside the tread portion and outside the carcass. And
While the rubber hardness (durometer A hardness) of the tread rubber forming the tread portion is 53 to 70 °,
The rubber thickness of the tread rubber on the tire equator is TA, the rubber thickness at the tread ground end is TC, the rubber thickness at the midpoint between the tire equator and the tread ground end is TB, and the minimum at the groove bottom of the tread groove is A radial tire for ATV satisfying the following relationship when the rubber thickness TD is:
1.0 <TB / TA ≦ 1.10
0.48 ≦ TC / TA ≦ 0.61
TD> 2.0mm
0.1mm ≦ (TB-TA) ≦ 1.8mm The radial tire for an ATV according to claim 1, wherein the belt layer has a maximum belt width BW of 0.3 to 1.0 times the tread ground contact width WT. The belt layer is composed of two belt plies, and the ply width of each belt ply is 0.3 to 0.65 times the tread grounding width WT. Radial tire.

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