JP2004083001A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire capable of effectively restraining transmission of projection input to a cord of a carcass ply in the case when there is a partly large projection input against a tread part and excellent in durability. <P>SOLUTION: The pneumatic radial tire 1 is furnished with the carcass 2 made of at least one piece of ply extending in a toroidal form and a main belt 4 made of at least a piece of belt layer positioned on the outer peripheral side of made by applying rubber on the cord. A reinforcing belt 5 actually radially arranged and made of at least one cord layer constituted by applying rubber on a reinforcing element initial elongation of which is 0.2% or more is arranged between the carcass 2 and the main belt 4. <P>COPYRIGHT: (C)2004,JPO

Description

【００４６】
【表２】

【００４７】
【表３】

【００４８】
【表４】

【００４９】
【表５】

【００５０】
表１〜５に示す結果から、実施例１〜４のタイヤは比較例１〜４のタイヤより、実施例５〜８のタイヤは比較例５のタイヤより、実施例９のタイヤは比較例６のタイヤより、実施例１０及び１１のタイヤは比較例７〜１１のタイヤより、実施例１２のタイヤは比較例１２のタイヤより、それぞれ走行耐久性は維持しながら突起入力耐久性に優れている。また、実施例１０及び１１のタイヤは比較例８のタイヤより、突起入力耐久性では劣るものの、走行耐久性には優れており、総合的な耐久性に優れているといえる。
【００５１】
【発明の効果】
この発明により、例えば小石や釘等のような突起物をトレッド部踏面で踏みしめることによってトレッド部に対し部分的に大きな突起入力があった場合にも、かかる突起入力がカーカスプライのコードに伝達するのを有効に抑制することができ、耐久性に優れた空気入りタイヤ、特に偏平率が７０％以下であり、トラックやバス、運送車両等の重荷重車両に装着される重荷重用ラジアルタイヤを提供することが可能となった。
【図面の簡単な説明】
【図１】この発明に従う空気入りタイヤの要部の幅方向断面図である。
【図２】プランジャー性能を表す、押込み力−ストローク線図である。
【図３】この発明に従う他の空気入りタイヤの要部の幅方向断面図である。
【図４】主ベルト及び補助ベルトのコードの配設状態を示す図である。
【図５】主ベルト及び補助ベルトのコードの配設状態を示す図である。
【図６】主ベルト及び補助ベルトのコードの配設状態を示す図である。
【図７】主ベルト及び補助ベルトのコードの配設状態を示す図である。
【図８】主ベルトのコードの配設状態を示す図である。
【符号の説明】
１　　タイヤ
２　　カーカス
３　　クラウン部
４　　主ベルト
５　　補強ベルト
６　　トレッド部
７、７ａ、７ｂ　　周方向ベルト層
８ａ、８ｂ　　傾斜ベルト層
Ｓ　　タイヤ赤道面
Ｗｂ　　主ベルトの最大幅
Ｗｒ　　補強ベルト幅
Ｗｔ　　トレッド幅[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is effective in transmitting a large projection input to the carcass ply cord even when a large projection input such as a stone is made on the tread portion by treading on the tread portion. The present invention relates to a pneumatic tire having excellent durability, particularly a radial tire for heavy loads having an aspect ratio of 70% or less and mounted on heavy vehicles such as trucks, buses, and transportation vehicles.
[0002]
[Prior art]
In a pneumatic tire, for example, a heavy load radial tire, a cord of a belt disposed on an outer peripheral side of a crown portion of a carcass extends at an angle of 10 to 30 ° with respect to a tire equatorial plane, and mutually intersects the tire equatorial plane. An intersecting belt composed of at least two belt layers laminated so as to intersect, and one intersecting belt located between the intersecting belt and the carcass and extending at an angle of 40 to 70 ° with respect to the tire equatorial plane. The inclined belt layer, located outside the cross belt in the tire radial direction, the cord extends at an angle of 10 to 30 ° with respect to the tire equatorial plane, and the extending direction of the cord of the outer belt layer constituting the cross belt. It is known that the belt is constituted by a total of four belt layers of one inclined belt layer extending in the same direction.
[0003]
Further, in recent years, heavy load tires tend to be flattened in accordance with increasing demands for lowering the floor of a vehicle and using a single-wheel drive shaft or trailer shaft, which has conventionally been a double wheel.
[0004]
By the way, in recent years, the market has been demanded to improve the transport efficiency, so that the vehicle is required to have a higher speed and an increased load, and as a result, the durability of the carcass has become a problem especially in the tire.
[0005]
In order to improve the durability of the belt, for example, Patent Literature 1 discloses a tire having an additional ply in which a non-extensible metal reinforcing element is substantially radially arranged between belt layers. However, in this tire, the reinforcing effect of the carcass was insufficient because the reinforcing belt was disposed between the belts. Patent Document 2 discloses a split structure in which the innermost belt layer in the tire radial direction among the belt layers is divided and arranged except for a tread central region, and a reinforcing layer formed by embedding a cord in a radial direction. Are described along a carcass inside the belt layer in the tire radial direction. However, in this tire, durability was insufficient because reinforcement near the equatorial plane of the tire where deformation was most severe at the time of projection input was not performed. Patent Document 3 discloses a tire in which a width direction reinforcing layer made of a cord extending at an angle of 50 to 90 ° with respect to the tire circumferential direction is provided between a shoulder portion and a tire equatorial plane between a carcass and a belt. Is described. However, the purpose of this tire was not to improve durability, but to improve steering stability, and durability was insufficient because reinforcement near the equatorial plane of the tire where deformation was most severe at the time of projection input was not performed. .
[0006]
However, the tire may travel on an unpaved road surface where large protrusions such as stones are scattered, and in such a case, the protrusion may be stepped on the tread surface. In such a case, a large projection input partially acts on the tread portion. When the tire is a heavy-duty tire having the above-described belt structure, the projection input is easily transmitted to the carcass, and the ply cord is easily broken.
[0007]
[Patent Document 1]
JP-T-2002-514538 [Patent Document 2]
JP-A-4-356203 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2002-192910
[Problems to be solved by the invention]
Therefore, an object of the present invention is to transmit a large projection such as a stone to the tread portion even when a large projection is partially input to the tread portion by stepping on the tread portion tread. Pneumatic tires having excellent durability and, in particular, having a flatness of 70% or less and being mounted on heavy-duty vehicles such as trucks, buses, and transportation vehicles. To provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a carcass comprising at least one ply extending in a toroidal shape, and at least one belt layer which is located on an outer peripheral side of a crown portion of the carcass and has a cord covered with rubber. A pneumatic tire comprising a main belt comprising: a main belt comprising: a reinforcing belt having at least one layer rubber-coated with a cord having an initial elongation of 0.2% or more and substantially radially arranged between the carcass and the main belt; It is a pneumatic tire characterized by disposing. Here, the “substantially radial arrangement” of the cord specifically means that the cord is arranged at an angle of 90 ° ± 20 ° with respect to the tire equatorial plane, and the “initial elongation” means that the reinforcing belt is The rubberized cord of the cord layer constituting the cord is taken out from the product tire, and the tensile load is obtained by performing a tensile test using the cord as a test piece. And the value of elongation at the point where the straight line passing through the 70% load point intersects the horizontal axis.
[0010]
Further, it is preferable that the width of the reinforcing belt is in a range not less than 35% of the tread width and not more than the maximum width of the main belt.
[0011]
Further, the maximum width of the main belt is preferably in the range of 50 to 95% of the cross-sectional width of the tire.
[0012]
Furthermore, it is preferable that the main belt has at least one circumferential belt layer in which a cord extending substantially along the circumferential direction is embedded.
[0013]
In addition, it is preferable that the cord of the circumferential belt layer extends in the tire circumferential direction while bending in a wavy or zigzag manner.
[0014]
Further, it is preferable that the main belt has at least one inclined belt layer in which a cord extending at an angle of 5 to 70 ° with respect to the tire equatorial plane is embedded.
[0015]
Further, the main belt has at least two inclined belt layers, and among these inclined belt layers, at least two adjacent inclined belt layers are cross belts whose cords cross each other across the tire equatorial plane. Preferably, there is.
[0016]
Furthermore, it is preferable that each of the inclined belt layers constituting the cross belt has a cord extending at an angle of 10 to 40 ° with respect to the tire equatorial plane.
[0017]
In addition, the cross-sectional width of the tire is preferably 300 mm or more.
[0018]
In addition, it is preferable that the flat tire has a flatness of 70% or less.
[0019]
Further, the reinforcing elements constituting the reinforcing belt are preferably organic fibers.
[0020]
Further, it is preferable that the reinforcing element constituting the reinforcing belt is steel.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a main part of a typical pneumatic tire (hereinafter, referred to as “tire”) according to the present invention.
[0022]
The tire 1 shown in FIG. 1 has at least one ply extending in a toroidal shape between at least one pair of bead cores (not shown), a carcass 2 composed of one ply in FIG. And a main belt 4 comprising at least one rubber-coated cord, in FIG. 1, four belt layers. The main feature of the structure of the present invention is that at least one layer of a cord, which is substantially radially arranged and has an initial elongation of 0.2% or more, is rubber-coated between the carcass 2 and the main belt 4. 1, that is, in FIG. 1, a reinforcing belt 5 composed of a single cord layer.
[0023]
Hereinafter, a description will be given of how the present invention adopts the above configuration together with its operation. In order to easily reproduce the deformation behavior when the tire 1 steps on the protrusion, the inventors push a plunger head having a hemispherical tip at a speed of 50 mm / min from the center in the width direction of the tread portion of the tire. As a result of earnestly studying the so-called plunger performance, which evaluates durability from the magnitude of the energy value calculated from the stroke and the pushing force when the tire breaks, a general-purpose size with an aspect ratio of 80 to 90% In the case of a flat tire having a flattening rate of 70% or less as compared with the above tire, the bending deformation in the tire width direction is larger than the bending deformation in the tire circumferential direction when the tread portion 6 receives an input by a protrusion. It has been found that the tendency is more remarkable in a tire having a wider tread width Wt. The reason for this is that, in a flat tire, the tire circumferential tension becomes larger than the tire width direction tension due to the action of the radial expansion force when the internal pressure is applied. It is considered that as a result of setting the rigidity higher than the tire width direction rigidity, when the tread portion 6 receives an input from the protrusion, the tread portion 6 is hard to bend in the tire circumferential direction and is easily bent in the tire width direction. In the case of a flat tire having a large tread width Wt, the width of the main belt 4 is also increased with the increase in the tread width Wt in order to suppress the growth of the tread portion 6 in the tire radial direction due to the application of the internal pressure and to make the contact pressure uniform. As the width of the main belt 4 increases, the out-of-plane bending stiffness in the tire width direction at the time of local projection input of the main belt 4 decreases, and the bending deformation in the tire width direction increases. Do you get it. In addition, the inventors presumed that in the deformation due to the projection input to the tread portion, the carcass 2 was the outermost part of the bending deformation in the tire width direction, and the deformation amount was maximum, so that it was easy to cause a failure such as breakage of the ply cord. . Therefore, as a result of further analysis, the fracture surface of the ply cord of the carcass 2 in which the failure occurred had a cup-and-cone shape, and a large tensile force was applied. We found that there was a positive correlation with plunger performance and verified that the above assumption was correct.
[0024]
Here, the plunger performance is quantified as energy, which is the area of a triangle surrounded by a pushing force-stroke diagram, as shown in FIG. Therefore, in order to improve the plunger performance, the area may be increased by increasing at least one of the maximum pushing force and the maximum stroke until the tire is broken.
[0025]
Considering the test for evaluating the plunger performance step by step, as the protrusion is pushed into the tread, the input is gradually added to the tire reinforcing layer consisting of the carcass and the belt, and the outermost carcass layer of the bend is the largest. It is presumed that when a tensile force is input and the cord of the carcass immediately below the protrusion reaches the breaking strength, the cord breaks and propagates to the outer tire reinforcing layer, leading to breakage of all layers.
[0026]
As a means for improving the plunger performance, for example, a method of improving the strength of the carcass ply by increasing the number of cords of the plies constituting the carcass 2 is useful. In addition to increasing the weight, the spacing between the cords is reduced, separation is likely to occur at the folded end position of the carcass 2, and the durability at the bead portion where the folded end is normally located is reduced, which is not preferable. .
[0027]
Then, the inventors considered that the configuration of the carcass should be left as it is, and that a width-direction belt for increasing the width-direction rigidity should be disposed between the carcass 2 and the main belt 4. Further, it has been found that when the width direction belt is formed by the cord having the initial elongation, the stroke becomes larger than that when the belt is formed by the ordinary non-stretchable cord. Therefore, in the present invention, it has been conceived that the maximum stroke is increased by configuring the widthwise belt using a cord having an initial elongation of 0.2% or more, and as a result, the plunger performance is improved. Was completed.
[0028]
The initial elongation of the cord of the reinforcing belt needs to be 0.2% or more. If the initial elongation of the cord of the reinforcing belt is less than 0.2%, the reinforcing belt cannot be sufficiently bent and deformed in the width direction so as to enclose the protrusions, the maximum stroke cannot be sufficiently increased, and the plunger performance is not improved. This is because no improvement can be obtained. When it is necessary to further suppress the breakage of the carcass ply cord due to the projection input, the initial elongation of the cord of the reinforcing belt is preferably 0.7% or more. This is because the use of a cord having a large initial elongation increases the maximum stroke and can improve the plunger performance. The means for imparting the initial elongation to the reinforcing element is not particularly limited, and examples thereof include a method of arranging the reinforcing element while bending it in a wavy or zigzag manner, a method of changing a twist structure of a cord, and the like. The reinforcing element of the reinforcing belt includes a monofilament in addition to the cord.
[0029]
Further, it is preferable that the width Wr of the reinforcing belt 5 is in the range of 35% or more of the tread width Wt and the maximum width Wb of the main belt 4 or less. If the width Wr of the reinforcing belt 5 is less than 35% of the tread width Wt, the reinforcement near the equatorial plane of the tire, which is most severely deformed at the time of the projection input, is insufficient and the breakage of the ply cord cannot be suppressed effectively. If the maximum width Wb of the belt 4 is exceeded, the reinforcing effect becomes substantially constant and only the tire weight increases.
[0030]
Further, it is preferable that the maximum width Wb of the main belt 4 is in the range of 50 to 90% of the sectional width Ws of the tire. If the maximum width Wb of the main belt 4 is less than 50% of the cross-sectional width Ws of the tire, the effect of suppressing the radial expansion deformation of the tire at the time of tire air pressure load becomes insufficient. When the protrusion is input, the tread rubber is extruded outward in the tire width direction and deformed, and the tread rubber near the widthwise end of the main belt 4 is pulled along the tire radially outward, thereby resulting in the tire width of the main belt 4. This is because separation occurs between the directional end and the tread rubber.
[0031]
Furthermore, it is preferable that the main belt 4 includes at least one (two in FIG. 1) circumferential belt layers 7a and 7b in which cords extending substantially along the circumferential direction are embedded. By embedding the cord substantially along the circumferential direction, the radial growth of the tread portion 6 outward in the tire radial direction caused by the application of the internal pressure is suppressed, and the running durability of the main belt 4 is improved.
[0032]
In addition, it is preferable that the cords of the circumferential belt layers 7a and 7b extend along the tire circumferential direction while bending in a wavy or zigzag manner. This is because, by bending in a wavy or zigzag shape, elongation during vulcanization can be easily obtained, which is advantageous in production.
[0033]
In addition, it is preferable that the main belt 4 includes at least one, in FIG. 1, two inclined belt layers 8a and 8b in which cords extending at an angle of 5 to 70 ° with respect to the tire equatorial plane S are embedded. The tire performs cornering by generating a lateral force. In order to obtain the lateral force, it is necessary to secure in-plane shear rigidity. This is because the main belt 4 includes the inclined belts 8a and 8b in which the cords extending at an angle of 5 to 70 ° with respect to the tire equatorial plane S are embedded, so that the in-plane shear rigidity can be secured.
[0034]
The main belt 4 has at least two, in FIG. 1, two inclined belt layers 8a and 8b, and among these inclined belt layers 8a and 8b, at least two adjacent inclined belt layers 8a and 8b. Are preferably crossed belts whose cords cross each other across the tire equatorial plane S. In particular, the inclined belt layers 8a and 8b constituting the crossed belt each have an angle of 10 to 40 ° with respect to the tire equatorial plane S. It is preferable to have a cord extending at By crossing the cords of the inclined belt layers 8a and 8b across the tire equatorial plane S in this way, the in-plane shear rigidity is further improved. By setting the inclination angle to 10 to 40 °, both in-plane shear rigidity and suppression of radial growth can be achieved.
[0035]
Further, the present invention can be suitably used for a tire having a cross-sectional width Ws of 300 mm or more. In the tire having such a cross-sectional width, the distance between the sidewalls is long and the projection input is supported only by the tread portion 6 having a flat shape, so that the carcass 2 is particularly greatly deformed at the crown portion 3 and the carcass 2 is easily broken. However, by adopting the above structure, such deformation can be suppressed and plunger performance can be improved.
[0036]
Further, it is preferable that the tire is a heavy duty radial tire having an aspect ratio of 70% or less. This is because the lower the flatness, the more remarkably the plunger performance decreases.
[0037]
Further, the material of the reinforcing element may be any material that can be bonded to rubber by dipping treatment of organic fiber such as aramid fiber, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or steel. . In particular, when the durability of the belt is further required, as in the case of a retread tire that is recapped a plurality of times, it is preferable to use organic fibers having high strength and low bending rigidity. If an organic fiber is used, the rigidity step at the end of the reinforcing element is reduced, and the deformation at the time of applying a load is easily followed, so that separation from the end is less likely to occur. Further, when it is necessary to particularly increase the bending rigidity, it is preferable to use steel.
[0038]
The above description is only an example of the embodiment of the present invention, and various changes can be made within the scope of the claims. For example, in FIG. 1, the arrangement order of the belt layers constituting the main belt 4 is such that the circumferential belt layers 7 a and 7 b and the inclined belt layers 8 a and 8 b are arranged in this order when viewed from the tire radial inner side. The arrangement order is not limited to this. For example, the inclined belts 8a and 8b may be arranged inside the circumferential belt layers 7a and 7b in the tire radial direction. Further, as shown in FIG. 3, one circumferential belt layer may be disposed between the inclined belt layers 8a and 8b constituting the cross belt. Further, the width of the circumferential belt 7 may be smaller than the width of the inclined belt layers 8a and 8b.
[0039]
【Example】
Next, a pneumatic tire according to the present invention was prototyped and its performance was evaluated, and will be described below.
[0040]
The tires of Examples 1 to 4 have a tire size of 275 / 70R22.5, the tires of Examples 5 to 11 have a tire size of 435 / 45R22.5, and the tire of Example 12 has a tire size of 285 / 60R22.5, and has the data shown in Tables 1 to 5, respectively. In the table, "1B" is the innermost belt layer in the tire radial direction, and "2B" to "4B" mean the belt layers located in the tire radial outer side of "1B" in order. “R” and “L” mean that the inclination angle of the reinforcing element constituting the belt layer with respect to the tire equatorial plane rises to the right and to the left as viewed in FIG. Means that.
[0041]
For comparison, the tire size was the same as in Examples 1 to 4 and had the specifications shown in Table 1. Although the inclination angle of the reinforcing belt with respect to the tire equator was 80 °, the initial elongation of the reinforcing element was zero. A tire (Comparative Example 1) has the same tire size as those of Examples 1 to 4, has the specifications shown in Table 1, and has an initial elongation of the reinforcing element of 0.2%. The tire having a tilt angle of 60 ° (Comparative Example 2), the tire size, the main belt, and the reinforcing belt are the same as those in Example 1 and have the specifications shown in Table 1, but the arrangement position of the reinforcing belt is 4B. (Comparative Example 3), the tire size, the main belt, and the reinforcing belt are the same as those in Example 1 and have the specifications shown in Table 1, but the arrangement position of the reinforcing belt is mainly Of the belt layers that make up the belt, the innermost in the tire radial direction (Comparative Example 4) between the side belt layer (1B) and the adjacent belt layer (2B), the tire size is the same as in Examples 5 to 8, and has the specifications shown in Table 2. Although the inclination angle of the reinforcing belt with respect to the tire equator is 80 °, the tire having the initial elongation of the reinforcing element of zero (Comparative Example 5), the tire size is the same as that of Example 9, and the specifications shown in Table 3 were obtained. Although the tire has an inclination angle of 80 ° with respect to the tire equator of the reinforcing belt, but the initial elongation of the reinforcing element is zero (Comparative Example 6), the tire size is the same as Examples 10 and 11, and Table 4 A tire having the specifications shown but not having a reinforcing belt (Comparative Example 7), the tire size was the same as in Examples 10 and 11, having the specifications shown in Table 4, and the inclination angle of the reinforcing belt with respect to the tire equator. Is 90 °, but the first reinforcement element Tire having zero elongation (Comparative Example 8), tire size being the same as that of Example 10, having the specifications shown in Table 4, and having an initial elongation of the reinforcing element of 0.7, but a reinforcing belt tire The tire having an inclination angle of 60 ° with respect to the equator (Comparative Example 9), the tire size, the main belt, and the reinforcing belt are the same as those in Example 10, and have the specifications shown in Table 4, but the arrangement position of the reinforcing belt. Is the outer diameter in the tire radial direction of 4B (Comparative Example 10), the tire size, the main belt, and the reinforcement belt are the same as those in Example 10 and have the specifications shown in Table 4, but the arrangement position of the reinforcement belt Is a tire (Comparative Example 11) in which the tire layer is located between the second belt layer (2B) and the third belt layer (3B) counted from the inside in the tire radial direction among the belt layers constituting the main belt (Comparative Example 11). Same as 12 and shown in Table 5 A prototype tire (Comparative Example 12) having various specifications but having an initial elongation of the reinforcing element of zero was also produced.
[0042]
(Projection input durability)
The protrusion input durability was determined by assembling each of the test tires into a standard rim defined by JATMA to form a tire wheel, applying an air pressure of 900 kPa (relative pressure), and applying a semicircular protrusion of φ38 mm at a speed of 50 mm / min. 2. Measure the stroke and the pressing force required for breaking by pressing against the crown portion of the tire tread, and calculate the energy, which is the area of a triangle surrounded by the pressing force-stroke diagram, as shown in FIG. Was evaluated by. The evaluation results are shown in Tables 1 to 5.
[0043]
(Running durability)
The running durability was determined by assembling each of the test tires on a standard rim defined by JATMA to form a tire wheel, leaving the tire under a pressure of 900 kPa (relative pressure) for one month, and then applying a tire load shown in Tables 1 to 5, The vehicle traveled on a drum tester under the conditions of a traveling speed of 60 km / h, and a traveling distance until a belt failure occurred was measured. The evaluation results are shown in Tables 1 to 5.
[0044]
The evaluation results in Table 1 show the evaluation results of Comparative Example 1, the evaluation results in Table 2 show the evaluation results of Comparative Example 5, the evaluation results in Table 3 show the evaluation results of Comparative Example 6, and the evaluation results in Table 4 show Are the evaluation results of Comparative Example 7, and the evaluation results in Table 5 are the index ratios when the evaluation result of Comparative Example 12 is 100. The larger the value, the better.
[0045]
[Table 1]

[0046]
[Table 2]

[0047]
[Table 3]

[0048]
[Table 4]

[0049]
[Table 5]

[0050]
From the results shown in Tables 1 to 5, the tires of Examples 1 to 4 were better than the tires of Comparative Examples 1 to 4, the tires of Examples 5 to 8 were better than the tire of Comparative Example 5, and the tire of Example 9 was better than the tire of Comparative Example 6. The tires of Examples 10 and 11 are superior to the tires of Comparative Examples 7 to 11, and the tire of Example 12 is superior to the tire of Comparative Example 12 in the protrusion input durability while maintaining the running durability. . Further, the tires of Examples 10 and 11 are inferior to the tires of Comparative Example 8 in projection input durability, but are excellent in running durability and excellent in overall durability.
[0051]
【The invention's effect】
According to the present invention, for example, even when a large projection input is applied to the tread portion by stepping a projection such as a pebble or a nail on the tread portion tread, the projection input is transmitted to the carcass ply cord. Pneumatic tires having excellent durability, in particular, having a flatness of 70% or less, and being mounted on heavy-duty vehicles such as trucks, buses, and transportation vehicles. It became possible to do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in a width direction of a main part of a pneumatic tire according to the present invention.
FIG. 2 is a pushing force-stroke diagram showing plunger performance.
FIG. 3 is a cross-sectional view in a width direction of a main part of another pneumatic tire according to the present invention.
FIG. 4 is a diagram showing a state in which cords of a main belt and an auxiliary belt are arranged.
FIG. 5 is a diagram showing a state in which cords of a main belt and an auxiliary belt are arranged.
FIG. 6 is a diagram showing a state in which cords of a main belt and an auxiliary belt are arranged.
FIG. 7 is a diagram showing a state in which cords of a main belt and an auxiliary belt are provided.
FIG. 8 is a diagram showing a state in which cords of a main belt are arranged.
[Explanation of symbols]
Reference Signs List 1 tire 2 carcass 3 crown portion 4 main belt 5 reinforcing belt 6 tread portions 7, 7a, 7b circumferential belt layers 8a, 8b inclined belt layer S tire equatorial plane Wb maximum width Wr of main belt Wr reinforcing belt width Wt tread width

Claims (12)

A pneumatic tire comprising a carcass composed of at least one ply extending in a toroidal shape and a main belt located on the outer peripheral side of a crown portion of the carcass and composed of at least one belt layer covered with a rubber cord. ,
A reinforcing belt is provided between the carcass and the main belt, the reinforcing belt comprising at least one cord layer, which is substantially radially arranged and has a rubber coating of a reinforcing element having an initial elongation of 0.2% or more. Pneumatic tires. The pneumatic tire according to claim 1, wherein the width of the reinforcing belt is equal to or greater than 35% of the tread width and equal to or less than the maximum width of the main belt. 3. The pneumatic tire according to claim 1, wherein a maximum width of the main belt is in a range of 50 to 95% of a cross-sectional width of the tire. The pneumatic tire according to any one of claims 1 to 3, wherein the main belt has at least one circumferential belt layer in which a cord extending substantially along a circumferential direction is embedded. The pneumatic tire according to claim 4, wherein the cord of the circumferential belt layer extends along the tire circumferential direction while bending in a wavy or zigzag manner. The pneumatic tire according to any one of claims 1 to 5, wherein the main belt has at least one inclined belt layer in which a cord extending at an angle of 5 to 70 ° with respect to the tire equatorial plane is embedded. The main belt has at least two inclined belt layers, and among these inclined belt layers, at least two adjacent inclined belt layers are cross belts whose cords cross each other across the tire equatorial plane. The pneumatic tire according to claim 6. The pneumatic tire according to claim 7, wherein each of the inclined belt layers constituting the cross belt has a cord extending at an angle of 10 to 40 with respect to the tire equatorial plane. The pneumatic radial tire according to any one of claims 1 to 8, wherein a cross-sectional width of the tire is 300 mm or more. The pneumatic tire according to any one of claims 1 to 9, which is a heavy-load radial tire having an aspect ratio of 70% or less. The pneumatic tire according to any one of claims 1 to 10, wherein the reinforcing elements constituting the reinforcing belt are organic fibers. The pneumatic tire according to any one of claims 1 to 10, wherein the reinforcing element constituting the reinforcing belt is steel.

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