JP4486200B2 - Pneumatic tire - Google Patents

Description

【００８３】
試験の結果、本発明の適用された実施例１、２のタイヤは、比較例１〜４及び従来例のタイヤに比較して制動距離が大幅に短縮されており、制動性能が向上していることが分かる。
【００８４】
【発明の効果】
以上説明したように、本発明の空気入りタイヤによれば、車両のＡＢＳを効果的に利用することが可能となり、制動性能を向上できる、という優れた効果を有する。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に係る空気入りタイヤのベルト及びカーカスの平面図である。
【図２】本発明の第１の実施形態に係る空気入りタイヤの回転軸に沿った断面図である。
【図３】本発明の第１の実施形態に係る空気入りタイヤのトレッドの平面図である。
【図４】本発明の第２の実施形態に係る空気入りタイヤのベルト及びカーカスの平面図である。
【図５】比較例１の空気入りタイヤのベルト及びカーカスの平面図である。
【図６】比較例２の空気入りタイヤの回転軸に沿った断面図である。
【図７】比較例３の空気入りタイヤの回転軸に沿った断面図である。
【図８】比較例４の空気入りタイヤのベルト及びカーカスの平面図である。
【図９】従来例の空気入りタイヤのベルト及びカーカスの平面図である。
【図１０】（Ａ）は従来の空気入りタイヤの接地しているブロックの変形状態を示す説明図であり、（Ｂ）は本発明の空気入りタイヤの接地しているブロックの変形状態を示す説明図であり、（Ｃ）は変形していないブロックの断面図であり、（Ｄ）はブレーキング時のタイヤの接地面付近の状態を説明する説明図である。
【符号の説明】
１０ 空気入りタイヤ
１４ カーカス
１６ カーカスプライ
２２ ベルト
２４ ベルトプライ
２６ ベルトプライ
２８ コード
３０ トレッド
３２ 周方向溝[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire with improved braking performance.
[0002]
[Prior art]
In recent years, an increasing number of vehicles are equipped with ABS (anti-lock brake system) in order to prevent tire locking during braking.
[0003]
For pneumatic tires, especially tread rubber with a high μ (friction coefficient) to improve braking performance when wet, or tread design to increase block rigidity to improve grounding Has been taken.
[0004]
[Problems to be solved by the invention]
However, changing to a tread rubber with a high μ (friction coefficient) or changing the tread design to increase block rigidity often has the disadvantage of increasing rolling resistance and deteriorating hydroplaning. .
[0005]
In addition, even though the peak μ can be increased by the above method, since it is often not possible to effectively increase μ in a slip ratio region higher than the peak μ, the frequency of occurrence of control mistakes during ABS operation is high. Therefore, there are many cases where the braking distance cannot always be shortened.
[0006]
In view of the above facts, the present invention has an object to provide a pneumatic tire in which such problems of the prior art are solved and braking performance is improved.
[0007]
[Means for Solving the Problems]
S-μ characteristics (relationship between slip ratio and friction coefficient) are often used as characteristics that describe braking performance.
[0008]
As a result of detailed analysis by the inventor of the situation in which a control error is likely to occur during ABS operation using this S-μ characteristic, in the slip ratio region higher than the slip ratio (about 10%) that generates the peak μ, It was found that there were many control errors in tires with a large decrease.
[0009]
In this slip ratio region, it was found that the tread surface of the tread portion on the ground contact surface was hardly sticking to the road surface and slipped in the traveling direction (opposite to the tire rotation direction).
[0010]
This is because the slip rate causes a relative displacement between the tread base (substantially equivalent to the belt outer layer) and the tread surface to generate a shear force (tire circumferential direction), which exceeds the maximum static friction coefficient and is displaced relatively. This is because the tread is going to return to the position of the tread base corresponding to the deformation before the deformation.
[0011]
At this time, if the tensile rigidity of the belt in the tire circumferential direction is high, the tread base behaves almost like a rigid ring and the expansion and contraction can be ignored. This leads to a decrease in braking force.
[0012]
That is, as shown in FIG. 10A, when a vehicle traveling in the direction of arrow F brakes, the tread surface (treading surface) 104A side of the tire 100 is the traveling direction from the base side due to friction with the road surface 102. Although the tread block 104 is deformed so as to be displaced in the reverse direction (the state of the solid line in the figure), when the block 104 slides with respect to the road surface 102, the tread surface 104A side attempts to return to the traveling direction side as indicated by an arrow f. (The shape of the block 104 goes to the state indicated by the broken line. Finally, the shape goes to the original rectangular state as shown in FIG. 10 (C), and the tire circumferential direction between the tread base 106 and the tread surface 104A. The relative displacement is reduced.
[0013]
However, when the tensile rigidity of the belt portion in the tire circumferential direction is low, the tread base 106 (not shown in FIG. 10D) is extended to just below the load as shown in FIG. Stretched in the region.) Until it kicks out, and until it kicks out (region b), the direction f ′ in which it tries to return as shown in FIG. Since it is the same as the direction f in which it tries to slip back, even if the block 104 starts to slide with respect to the road surface 102, the relative displacement in the tire circumferential direction between the tread base 106 and the tread surface 104A does not readily decrease, and the shearing force increases ( That is, the block 104 is strung without slipping), and a large braking force is obtained.
[0014]
Furthermore, during vehicle braking, the load on the front wheels increases with the movement of the load due to inertia, and bears most of the braking force.
[0015]
In the front wheel, it was found that the vertical deflection of the tire increases with an increase in load, and the contact pressure and contact length near the shoulder portion increase to increase the contribution of braking force generation.
[0016]
And as a result of repeating various experiments, the belt circumferential direction tensile rigidity is reduced near the shoulder portion where the contribution of braking force generation is high, and the slip region shear force is effectively increased near this shoulder portion, thereby increasing the greater It turns out that braking force can be obtained.
[0017]
As a result of various experiments, it has been found that the effect becomes small when the width of the narrow belt ply is set wider than 3/5 of the width of the wide belt ply.
[0018]
If the width of the wider belt ply is narrower than 3/4 of the tread width, or the width of the narrower belt ply is set to be smaller than 2/15 of the width of the wider belt ply. It has been found that there is a risk that the steering stability, durability, and trauma resistance during turning may be significantly reduced.
[0019]
The present invention has been made in view of the above-mentioned fact, and the invention according to claim 1 is a pneumatic in which a tread has a plurality of circumferential grooves extending substantially in parallel along the tire circumferential direction. A tire, a carcass made of a carcass ply in which a plurality of cords are arranged in parallel with each other and covered with rubber, and a width in which a plurality of cords are arranged in parallel with each other and covered with rubber, arranged on the outer side in the tire radial direction of the carcass WT> Ww ≧ (3/4) WT, where the width of the tread is WT, the width of the wide belt ply is Ww, and the width of the narrow belt ply is Wn. (3/5) A belt having a relationship of Ww ≧ Wn ≧ (2/15) Ww and a tire side portion composed of a main rubber are provided, and the tire side portion has a Young's modulus higher than that of the main rubber. High secondary rubber Secondary rubber layer formed Te, characterized in that it is disposed.
[0020]
The operation of the first aspect of the invention will be described.
[0021]
By making the width of one of the two belt plies, that is, the outer layer or the inner layer, smaller than the width of the other belt plies, the belt becomes a single layer in the vicinity of the shoulder portion, and the circumferential tensile rigidity is remarkably increased. Since it can reduce, the shear force in a sliding area | region can be earned effectively.
[0022]
By the way, making the width Ww of the wide belt ply narrower than 3/4 of the tread width WT causes a significant decrease in steering stability, durability, and trauma resistance during turning. Therefore, by making the width of the wide belt ply wider than 3/4 of the tread width, predetermined steering stability, durability, and damage resistance are secured.
[0023]
By setting the width Wn of the narrower belt ply to be smaller than 2/15 of the width Ww of the wider belt ply, the steering stability, durability and trauma resistance during turning can be significantly reduced. In some cases, Wn ≧ (2/15) Ww is preferable.
[0024]
Further, by setting the width Wn of the narrower belt ply to be smaller than 3/5 of the width Ww of the wider belt ply ((3/5) Ww ≧ Wn), the belt circumference near the shoulder portion is set. The directional tensile rigidity can be further reduced, and the sliding region shear force can be more effectively obtained.
[0025]
In addition, it is a well-known fact that the in-plane rotational rigidity of the tire side portion increases by providing a sub rubber layer made of a sub rubber having a higher Young's modulus than the main rubber constituting the tire side portion. By suppressing side rotation and shear deformation during braking, a difference in displacement occurs between the tire side and the tread base, so the tread base returns before the tread base (belt) kicks out from directly under the load. The tendency to try can be made remarkable.
[0026]
By combining such a carcass structure and the belt structure, it is possible to effectively obtain shear force in the slip region, and can suppress the decrease in μ in the high slip rate region, and effectively use the ABS of the vehicle. It becomes possible to do.
[0027]
The invention according to claim 2 is a pneumatic tire having a plurality of circumferential grooves extending substantially parallel to the tire circumferential direction on the tread, wherein the plurality of cords are arranged in parallel to each other and covered with rubber. Carcass ply and two belt plies arranged on the outer side in the tire radial direction of the carcass and having different widths in which a plurality of cords are arranged parallel to each other and covered with rubber. When the width of the wide belt ply is Ww and the width of the narrow belt ply is Wn, WS> Ww ≧ (3/4) WS, (3/5) Ww ≧ Wn ≧ (2/15) Ww And a tire side portion composed of a main rubber, and the tire side portion is provided with a sub rubber layer formed of a sub rubber having a higher Young's modulus than the main rubber. That features To.
[0028]
The operation of the second aspect of the invention will be described.
[0029]
Similarly to the pneumatic tire according to claim 1, the pneumatic tire according to claim 2 can effectively obtain a shearing force in a slip region, and can suppress a decrease in μ in a high slip rate region. The ABS of the vehicle can be used effectively.
[0030]
The difference between the pneumatic tire according to claim 2 and the pneumatic tire according to claim 1 is only in the method of defining the width Ww of the wide belt ply and the width Wn of the narrow belt ply.
[0031]
When the shoulder shape is a square shoulder shape (angular shape), the tread width WT can be measured, but when the shoulder shape is a round shoulder shape (substantially arc shape), the position of the tread edge is unclear and the tread width WT is In the case of a round shoulder-shaped pneumatic tire, it is more convenient to specify the width Ww of the wide belt ply and the width Wn of the narrow belt ply on the basis of the ground contact width WS because it cannot be measured accurately. It is.
[0032]
Here, the contact width is measured with the following load, internal pressure, and load.
[0033]
The load is the maximum load (maximum load capacity) of a single wheel at the applicable size (ply rating) described in the following standard, and the internal pressure is the maximum single wheel at the applicable size described in the following standard. The air pressure corresponding to the load (maximum load capacity), and the rim is a standard rim (or “Approved Rim” or “Recommended Rim”) in the applicable size described in the following standards.
[0034]
The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States it is “The Tire and Rim Association Inc. Year Book”, in Europe it is “The European Tire and Rim Technical Organization Standards Manual”, and in Japan it is the Japan Automobile Tire Association “JATMA Year Book”. It is prescribed.
[0035]
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the length along the carcass line from the ply return end to the ground end is L, and the length along the carcass line of the auxiliary rubber layer is Assuming that Ls is established, a relationship of Ls <0.5 × L is established.
[0036]
The operation of the third aspect of the invention will be described.
[0037]
If the length L along the carcass line of the auxiliary rubber layer is 0.5 times or more of the length Ls along the carcass line from the ground contact end to the ply turn-up end, the in-plane rigidity of the tire side portion will increase too much and It causes a decrease in comfort. Therefore, a predetermined riding comfort can be ensured by setting Ls <0.5 × L.
[0038]
The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein one end of the auxiliary rubber layer on the bead side is located closer to the ground plane than the ply turn-up end on the ground plane. It is characterized by.
[0039]
The operation of the fourth aspect of the invention will be described.
[0040]
Conventionally, the rubber layer for improving the in-plane rigidity of the tire side surface portion is usually disposed in the vicinity of the ply folding end. However, in the case of the present invention, since the shear rigidity in the region close to the road surface is improved and the displacement difference between the tire side portion and the tread base is increased, the tread base attempts to return while kicking from directly under the load. The phenomenon can be effectively extracted.
[0041]
The invention according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, one end of the auxiliary rubber layer on the grounding surface side is located on the bead side with respect to the grounding end.
[0042]
The operation of the invention described in claim 5 will be described.
[0043]
If the auxiliary rubber layer is disposed on the inner side (equatorial plane side) than the ground contact end, the durability of the tire is lowered, which is not preferable. Therefore, the durability of the tire is ensured by disposing one end of the auxiliary rubber layer on the ground contact surface side on the bead side with respect to the ground contact end.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the pneumatic tire of the present invention will be described with reference to FIGS.
[0045]
As shown in FIG. 2, the pneumatic tire 10 of the present embodiment includes a pair of bead cores 12 and a carcass 14 straddling the pair of bead cores 12 in a toroidal shape.
[0046]
The carcass 14 is composed of a single carcass ply 16 in the present embodiment. The carcass ply 16 includes a plurality of cords arranged in parallel to each other, and has a normal structure in which the plurality of cords are embedded in a coating rubber (not shown).
[0047]
A belt 22 is disposed outside the carcass 14 in the tire radial direction.
[0048]
The belt 22 includes two belt plies 24 and a belt ply 26.
[0049]
Each of the belt ply 24 and the belt ply 26 includes a cord 28 made of a plurality of metal fibers arranged in parallel with each other, and the plurality of cords 28 are embedded in a coating rubber (not shown). Of structure.
[0050]
As shown in FIG. 1, the belt ply 24 arranged on the inner side in the tire radial direction (arrow IN direction side) has an angle θ <b> 1 (22 ° in the present embodiment) with the cord 28 rising leftward with respect to the tire equatorial plane CL. Inclined.
[0051]
On the other hand, in the belt ply 26 arranged on the outer side in the tire radial direction, the cord 28 is inclined to the right with respect to the tire equatorial plane CL at an angle θ2 (22 ° in the present embodiment).
[0052]
The belt ply 26 is formed to be narrower than the belt ply 24. The width P1 of the belt ply 24 is set to 150 mm, and the width W2 of the belt ply 26 is set to 75 mm. That is, it is set so that the relationship of W2 = 0.5 × W1 is established.
[0053]
As shown in FIGS. 2 and 3, a tread 30 having a tread width WT (same as the ground contact width WS in the present embodiment) made of thick rubber is disposed on the outer side in the tire radial direction of the belt 22. . Note that the tread width WT of the tread 30 of the present embodiment is 160 mm.
[0054]
The tread 30 has a plurality of (four in this embodiment) circumferential grooves 32 extending along the tire circumferential direction (arrow A direction and arrow B direction) and a tire width direction (arrow L direction and arrow R direction). A rectangular block-shaped land portion 36 that is partitioned by a plurality of lateral grooves 34 extending in the direction is provided.
[0055]
Further, the tire side surface portion 38 includes a rubber (hereinafter referred to as a secondary rubber) having different physical properties from the main rubber constituting the tire side surface portion 38 between the ply turn-back end 40 and the ground contact end 42 of the tread 30 along the carcass line. The secondary rubber layer 44 is provided. Here, if the Young's modulus Es of the secondary rubber and the Young's modulus E of the main rubber are established, the relationship of Es = 1.7 × E is established. Further, if the distance from the ply folding end 40 to the grounding end 42 along the carcass line is L, and the length of the sub rubber layer 44 along the carcass line is Ls, Ls = 0.4 × L. The rubber layer 44 has a thickness of 0.5 mm.
[0056]
(Function)
In the pneumatic tire 10 of the present embodiment, by making the width W2 of the outer layer belt ply 26 smaller than the width W1 of the inner layer belt ply 24, the belt 22 becomes a single layer near the shoulder portion, and the circumferential tensile rigidity is increased. Since it can be significantly reduced, it is possible to effectively earn a shearing force acting on the block 36 in the slipping region during braking.
[0057]
Further, since the secondary rubber layer 44 made of the secondary rubber having a higher Young's modulus than the main rubber constituting the tire side portion 38 is disposed inside the tire side portion 38, the tire side portion 38 has high in-plane rotational rigidity. can get.
[0058]
Accordingly, the rotation and shear deformation of the tire side portion 38 during braking can be suppressed, and a displacement difference is generated between the tire side portion 38 and the belt 22, so that the belt 22 is kicked from directly under the load. The tendency for the base 22 to return can be made remarkable.
[0059]
In the pneumatic tire 10 of the present embodiment, since the above-described carcass structure and the belt portion structure are combined, it is possible to effectively obtain a shearing force in a slipping region during braking, and μ in a high slip rate region. The decrease can be suppressed, and the ABS of the vehicle can be used effectively.
[0060]
Further, since the belt 22 of the present embodiment has a narrow upper belt ply 26 and a lower belt ply 24, the shoulder belt outermost layer becomes a lower belt, and the tread base extends. The effect can be greater than that obtained by reversing the vertical relationship.
[0061]
The length Ls along the carcass line of the auxiliary rubber layer 44 is longer than 0.5 times the length L along the carcass line from the tread end portion 42 to the ply folding end (Ls> 0.5 × L). ), The in-plane rotational rigidity of the tire side portion 38 is excessively increased and the ride comfort is reduced. Therefore, by setting Ls ≦ 0.5 × L, it is possible to ensure a predetermined riding comfort while improving the braking performance.
[0062]
Alternatively, if the width W2 of the narrow belt ply 26 is larger than 3/5 of the width W1 of the wide belt ply 24, the circumferential tensile rigidity of the belt 22 cannot be significantly reduced in the vicinity of the shoulder portion.
[0063]
Therefore, by setting Wn ≦ (3/5) × Ww, the circumferential tensile rigidity can be significantly reduced.
[0064]
Further, if the width W1 of the wide belt ply 24 is set to be smaller than 3/4 of the tread width WT, or the width W2 of the narrow belt ply 26 is set to be smaller than 2/15 of the width W1 of the wide belt ply 24, the rotation is reduced. There is a risk that steering stability, durability, and trauma resistance during rudder will be significantly reduced.
[0065]
Therefore, predetermined steering stability, durability, and the like are ensured by setting Ww ≧ (3/4) × WT and Wn ≧ (2/15) × Ww.
[Second Embodiment]
Next, 2nd Embodiment of the pneumatic tire of this embodiment is described according to FIG. In addition, the same code | symbol is attached | subjected about the same structure as 1st Embodiment, and the detailed description is abbreviate | omitted.
[0066]
As shown in FIG. 4, the belt 22 of the present embodiment has an upper belt ply 26 that is wide and a lower belt ply 24 that is narrow. The width W1 of the narrow belt ply 24 is 75 mm, The width W2 of the wide belt ply 26 is set to 150 mm.
[0067]
In the belt 22 of the present embodiment, the upper belt ply 26 is widened and the lower belt ply 24 is narrowed, so that the effect is slightly reduced because the elongation of the tread base is reduced as compared with the first embodiment. However, almost the same effect can be obtained.
[0068]
Other operations and effects are the same as those in the first embodiment.
(Other embodiments)
In the above embodiment, the wide belt ply 24 (or the belt ply 26) and the narrow belt ply 26 (or the belt ply 24) are combined, and the tread width WT (or ground contact width WS), the width W1 of the belt ply 24, and By defining the relationship of the width W2 of the belt ply 26, both end portions in the width direction are compared with the tensile rigidity in the tire circumferential direction of the central portion in the width direction of the belt 22 (the two-layer portion of the belt ply 24 and the belt ply 26). Although the tensile rigidity in the tire circumferential direction of the belt ply 24 or the belt ply 26 is substantially reduced (about 1/2), the present invention is not limited to this, for example, the wider one The belt ply driving may be sparse and the narrower belt driving may be combined densely.
[0069]
The cord angle of the belt ply may be a small angle with respect to the tire circumferential direction at the center portion in the belt width direction, and may be a large angle with respect to the tire circumferential direction at both ends in the belt width direction.
[0070]
Furthermore, the belt 22 of the present embodiment is composed of two belt plies, but may be composed of three or more belt plies.
[0071]
The cord 28 of the present embodiment is a metal fiber cord, but may be a cord of another material.
(Test example)
In order to confirm the effect of the present invention, one type of tire of a conventional example, four types of tires of comparative examples, and three types of tires of examples to which the present invention was applied were prepared and subjected to a braking test.
[0072]
The braking test was performed by assembling a test tire on a 5.5 J rim at an internal pressure of 200 KPa and mounting it on an actual vehicle. The test conditions are as follows.
Tire size: 195 / 65R14
Vehicle: FF passenger car (ABS equipped car)
Installation position: 4 wheel front wheel load: 4.01 kN
Rear wheel load: 3.14kN
Road surface: Asphalt water depth: 2mm
Initial speed: 80km / h
The ABS operation test tire is as follows. In addition, description is only described about a different point on the basis of Example 1 (pneumatic tire of 1st Embodiment).
[0073]
Example 1: The pneumatic tire according to the first embodiment described above.
[0074]
Example 2: A pneumatic tire according to the second embodiment described above.
[0075]
Comparative Example 1: Although the structure conforms to the first embodiment described above, as shown in FIG. 5, the tire has a belt ply 24 having a width W1 of 150 mm and a belt ply 26 having a width W2 of 135 mm. Incidentally, W2 = 0.9 × W1.
[0076]
Comparative Example 2: Although the structure conforms to the first embodiment described above, as shown in FIG. 6, the tire has a structure in which the auxiliary rubber layer 44 is not provided in the tire side portion 38.
[0077]
Comparative Example 3: Although the structure conforms to the first embodiment described above, as shown in FIG. 7, the end portion of the secondary rubber layer 44 on the bead portion 12 side is 10 mm along the carcass line from the ply folding end 40. Is also located below.
[0078]
Comparative Example 4: Although the structure conforms to the first embodiment described above, as shown in FIG. 8, both the belt ply 24 and the belt ply 26 have a narrow width, and the width of the inner layer belt ply 24 is the outer layer helt ply. The tire is slightly wider than 26. The width P1 of the belt ply 24 is set to 80 mm, and the width W2 of the belt ply 26 is set to 75 mm. Incidentally, W1 = 0.5 × WT.
[0079]
Conventional Example: A structure according to the first embodiment described above, but as shown in FIG. 9, a tire in which the width W1 of the belt ply 24 is set to 150 mm and the width W2 of the belt ply 26 is set to 141 mm. Incidentally, W2 = 0.94 × W1.
[0080]
Here, the ratio (Ms / Mc) of the tensile rigidity Ms on the shoulder side of the belt layer of each tire and the tensile rigidity Mc of the center was measured. Here, the shoulder side of the belt layer refers to a belt layer having a width of 10% centered on a position of 90% of the ground contact width from one end of the ground contact width in the tire width direction when a predetermined load is applied. The center of the belt layer refers to a belt layer having a width of 10% around the equator plane. In Comparative Example 4, since the belt layer does not exist on the shoulder side of the belt layer, the value of Ms / Mc was set to 0.0.
[0081]
In the comparative evaluation, the braking distance (the distance traveled from the start to the stop of the braking) performed under the above-described conditions was indicated as an index with the conventional tire as 100. The numerical value indicates that the smaller the distance for convenience, the shorter and better the braking distance. The results are shown in Table 1 below.
[0082]
[Table 1]

[0083]
As a result of the test, the tires of Examples 1 and 2 to which the present invention is applied have a significantly shortened braking distance as compared with the tires of Comparative Examples 1 to 4 and the conventional example, and the braking performance is improved. I understand that.
[0084]
【The invention's effect】
As described above, according to the pneumatic tire of the present invention, it is possible to effectively use the ABS of the vehicle, and there is an excellent effect that the braking performance can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view of a belt and a carcass of a pneumatic tire according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the rotation axis of the pneumatic tire according to the first embodiment of the present invention.
FIG. 3 is a plan view of the tread of the pneumatic tire according to the first embodiment of the present invention.
FIG. 4 is a plan view of a belt and a carcass of a pneumatic tire according to a second embodiment of the present invention.
5 is a plan view of a belt and a carcass of a pneumatic tire of Comparative Example 1. FIG.
6 is a cross-sectional view of the pneumatic tire of Comparative Example 2 along the rotation axis. FIG.
7 is a cross-sectional view of the pneumatic tire of Comparative Example 3 along the rotation axis. FIG.
8 is a plan view of a belt and a carcass of a pneumatic tire of Comparative Example 4. FIG.
FIG. 9 is a plan view of a belt and a carcass of a conventional pneumatic tire.
FIG. 10A is an explanatory view showing a deformed state of a grounded block of a conventional pneumatic tire, and FIG. 10B shows a deformed state of a grounded block of the pneumatic tire of the present invention. It is explanatory drawing, (C) is sectional drawing of the block which is not deform | transforming, (D) is explanatory drawing explaining the state of the contact surface vicinity of the tire at the time of braking.
[Explanation of symbols]
10 Pneumatic tire 14 Carcass 16 Carcass ply 22 Belt 24 Belt ply 26 Belt ply 28 Cord 30 Tread 32 Circumferential groove

Claims (5)

A pneumatic tire having a plurality of circumferential grooves extending substantially parallel to the tire circumferential direction on the tread,
A carcass made of a carcass ply in which a plurality of cords are arranged in parallel with each other and covered with rubber;
It is arranged on the outer side in the tire radial direction of the carcass, and is composed of two belt plies having different widths in which a plurality of cords are arranged in parallel with each other and covered with rubber, the tread width is WT, the width of the wide belt ply is Ww, When the width of the narrow belt ply is Wn, a belt satisfying the relationship of WT> Ww ≧ (3/4) WT, (3/5) Ww ≧ Wn ≧ (2/15) Ww,
Tire side parts composed of main rubber,
A pneumatic tire characterized in that a secondary rubber layer formed of a secondary rubber having a higher Young's modulus than the main rubber is disposed on the tire side portion. A pneumatic tire having a plurality of circumferential grooves extending substantially parallel to the tire circumferential direction on the tread,
A carcass made of a carcass ply in which a plurality of cords are arranged in parallel with each other and covered with rubber;
It is arranged on the outer side in the tire radial direction of the carcass, and is composed of two belt plies with different widths in which a plurality of cords are arranged in parallel to each other and covered with rubber, and the ground contact width of the tire is WS and the width of the wide belt ply is Ww, where the width of the narrow belt ply is Wn, and a belt satisfying the relationship WS> Ww ≧ (3/4) WS, (3/5) Ww ≧ Wn ≧ (2/15) Ww,
Tire side parts composed of main rubber,
A pneumatic tire characterized in that a secondary rubber layer formed of a secondary rubber having a higher Young's modulus than the main rubber is disposed on the tire side portion. When the length along the carcass line from the ply folded end to the ground end is L, and the length along the carcass line of the sub rubber layer is Ls,
Ls <0.5 × L
The pneumatic tire according to claim 1, wherein the relationship is established.   The pneumatic tire according to any one of claims 1 to 3, wherein one end of the secondary rubber layer on the bead side is located closer to the ground contact surface than a ply turn-up end closest to the ground contact surface.   5. The pneumatic tire according to claim 1, wherein one end of the auxiliary rubber layer on the ground contact surface side is located closer to the bead than the ground contact end.

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