JP2009045998A - Pneumatic tire for all-terrain vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire 2 for all-terrain vehicle having excellent steering stability. <P>SOLUTION: This tire 2 is provided with a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, and an intervention layer 14. The carcass 10 is provided with a first ply 26, and a second ply 28 located outside the first ply 26. The belt 12 is provided with a belt ply. The intervention layer 14 is located between the first ply 26 and the second ply 28. The first ply 26 is provided with a first cord made of organic fibers. The second ply 28 is provided with a second cord made of organic fibers. A ratio of the modulus of the second cord to the modulus of the first cord is ≥3.8. A ratio of the Young's modulus of the second cord to the Young's modulus of the first cord is ≥3.6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire mounted on an all-terrain vehicle.

  All Terrain Vehicle (hereinafter ATV) travels mainly on bad roads such as rocky land, sandy land, and muddy ground. This ATV is required to have a tire that absorbs road disturbances and has excellent ride comfort. In order for this ATV to travel stably on this rough road in the speed range of 40 km / h to 120 km / h, this ATV is required to have a tire that is excellent in straight running stability, turning stability and maneuverability.

  A tire having a high rigidity is excellent in handling stability but inferior in disturbance absorption. On the other hand, a tire having low rigidity is excellent in disturbance absorption but poor in steering stability. It is difficult to achieve both handling stability and disturbance absorption.

Japanese Patent Application Laid-Open No. 11-32217 discloses a pneumatic tire capable of maintaining durability and steering stability while achieving weight reduction. This tire includes a carcass composed of two low end plies and one high end ply. This tire is configured such that the number of cords per 5 cm width of the high end ply is five or more than that of the low end ply.
Japanese Patent Laid-Open No. 11-32217

  In order to obtain a tire having excellent steering stability for ATV, the rigidity is optimized. For this optimization, the thickness of the code included in the carcass ply may be adjusted. A tire in which a thick cord is used for the carcass ply has high rigidity. A highly rigid tire has excellent handling stability. On the other hand, this adjustment gives the tire a large mass. A tire having a large mass affects the fuel consumption of the ATV.

  In order to optimize the rigidity, the angle formed by the carcass ply cord with respect to the equator plane is adjusted. Adjustment of this angle affects the tire dimensions.

  The tread thickness is adjusted to optimize the stiffness. A tire having a tread having a large thickness has high rigidity. A highly rigid tire has excellent handling stability. On the other hand, this adjustment gives the tire a large mass. A tire having a large mass affects the fuel consumption of the ATV.

  In order to optimize the rigidity, the hardness of the crosslinked rubber constituting the tread is adjusted. This adjustment of hardness affects the wear resistance and crack resistance.

  Stiffness optimization affects performance such as mass, dimensions, wear resistance, crack resistance, and the like. It is difficult to obtain a tire having excellent steering stability without increasing its mass.

  An object of the present invention is to provide a pneumatic tire excellent in handling stability for all-terrain vehicles.

  A pneumatic tire for an all-terrain vehicle according to the present invention includes a tread whose outer surface forms a tread surface, a pair of sidewalls extending substantially inward in the radial direction from the end of the tread, and a radial direction substantially closer to the sidewall. A pair of beads located on the inside, a carcass spanned between both beads along the inside of the tread and the sidewall, a belt laminated with the carcass on the radially inner side of the tread, and an intervening layer ing. The carcass includes a first ply and a second ply located outside the first ply on the radially inner side of the tread. This belt includes a belt ply. The intervening layer is located between the first ply and the second ply on the radially inner side of the tread. The first ply includes a first cord made of an organic fiber. The second ply includes a second cord made of an organic fiber. The belt ply includes a belt cord made of organic fibers. The ratio of the modulus of the second chord to the modulus of the first chord is 3.8 or greater. The ratio of the Young's modulus of the second cord to the Young's modulus of the first cord is 3.6 or more.

  Preferably, in the tire, the intervening layer is along the inside of the tread and the sidewall.

  Preferably, in this tire, the hardness of the intervening layer is 40 or more and 90 or less. The thickness of this intervening layer is 0.3 mm or more and 0.5 mm or more.

  In this tire, in order to optimize the rigidity, the ratio of the modulus of the second cord to the modulus of the first cord and the ratio of the Young's modulus of the second cord to the Young's modulus of the first cord are appropriately adjusted. ing. By this adjustment, the tire is configured such that the second cord has higher elasticity than that of the first cord. A carcass having such a configuration can contribute to rigidity. This tire has high rigidity. In this tire, the rigidity can be easily adjusted. A tire having high rigidity is excellent in handling stability. In this tire, it is not necessary to provide a tread and sidewall having a large thickness in order to obtain high rigidity. In this tire, an increase in mass is suppressed. This tire does not need to adjust the hardness of the cross-linked rubber constituting the tread in order to optimize the rigidity, so that performances such as wear resistance and crack resistance can be maintained. In this tire, it is not necessary to adjust the angle formed by the cords included in the carcass ply such as the first cord and the second cord with respect to the equator plane in order to optimize the rigidity. This tire includes an intervening layer between the first ply and the second ply. This intervening layer prevents cord separation caused by deformation of the tire when traveling on a rough road. This tire is excellent in durability.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 is a cross-sectional view showing a part of a pneumatic tire 2 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a part of the tire 2 of FIG. 1 and 2, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The tire 2 has a substantially left-right symmetric shape centered on a one-dot chain line CL in FIG. This alternate long and short dash line CL represents the equator plane of the tire 2. The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, an intervening layer 14, and an inner liner 16. The tire 2 is a tubeless type. The tire 2 is attached to an all-terrain vehicle (hereinafter referred to as ATV). A solid line BBL in FIG. 1 represents a bead base line.

  The tread 4 is made of a crosslinked rubber having excellent wear resistance. The tread 4 has a shape protruding outward in the radial direction. The tread 4 includes a tread surface 18. The tread surface 18 is in contact with the road surface. A groove 20 is carved in the tread surface 18. The groove 20 forms a tread pattern.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The sidewall 6 is made of a crosslinked rubber. The sidewall 6 absorbs an impact from the road surface by bending. Furthermore, the sidewall 6 prevents the carcass 10 from being damaged.

  The bead 8 is located substantially inward of the sidewall 6 in the radial direction. The bead 8 includes a core 22 and an apex 24 that extends radially outward from the core 22. The core 22 has a ring shape. The core 22 includes a plurality of non-stretchable wires (typically steel wires). The apex 24 is tapered outward in the radial direction. The apex 24 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a first ply 26 and a second ply 28. The first ply 26 and the second ply 28 are spanned between the beads 8 on both sides, and extend along the inside of the tread 4 and the sidewall 6. The first ply 26 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, the first main portion 30 and the first folding portion 32 are formed in the first ply 26. The second ply 28 is located outside the first ply 26 on the inner side in the radial direction of the tread 4. The second ply 28 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, a second main portion 34 and a second folding portion 36 are formed on the second ply 28. In the tire 2, the second main portion 34 is located outside the first main portion 30. The first folded portion 32 is located outside the second folded portion 36 in the axial direction. The end 38 of the first folded portion 32 is located radially outside the end 40 of the second folded portion 36. Note that three or more plies may be used for the carcass 10.

  Although not shown, the first ply 26 is composed of a large number of first cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each first cord with respect to the equator plane is not less than 50 ° and not more than 90 °. The second ply 28 includes a large number of second cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each second cord with respect to the equator plane is not less than 50 ° and not more than 90 °. In the tire 2, when the absolute value of the angle formed by the first cord with respect to the equator plane is less than 90 °, and the absolute value of the angle formed by the second cord with respect to the equator plane is less than 90 °, the carcass 10 Is configured such that the inclination direction of the first cord and the inclination direction of the second cord are reversed. In this case, from the viewpoint of steering stability, it is preferable that the absolute value of the angle formed by the first cord with respect to the equator plane and the absolute value of the angle formed by the second cord with respect to the equator plane are the same. In the tire 2, the angle formed by the first cord with respect to the equator plane is 88 °, and the angle formed by the second cord with respect to the equator plane is −88 °.

  In the tire 2, the first cord is made of an organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The second cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. In the tire 2, the first cord is made of nylon fiber. The second cord is made of aramid fiber. In the tire 2, the material of the first cord and the material of the second cord are different. The material of the first cord and the material of the second cord may be the same.

  The belt 12 is located on the radially outer side of the carcass 10. The belt 12 is laminated with the carcass 10 on the radially inner side of the tread 4. The belt 12 reinforces the carcass 10. The belt 12 includes a first belt ply 42 and a second belt ply 44. The belt 12 includes two belt plies 42 and 44. The belt 12 may be composed of a single belt ply.

  Although not shown, each of the first belt ply 42 and the second belt ply 44 includes a plurality of belt cords and topping rubbers arranged in parallel. The absolute value of the angle formed by each belt cord with respect to the equator plane is 0 ° or more and 40 ° or less. When the absolute value of this angle is larger than 0 °, the belt 12 has an inclination direction with respect to the equator plane of the belt cord of the first belt ply 42 and an inclination direction of the belt cord of the second belt ply 44 with respect to the equator plane. Are configured to be reversed. In this case, the first belt ply 42 and the second belt ply 44 constitute a so-called cross ply structure. When the belt cord extends substantially in the circumferential direction, this angle is 0 °. In this case, the belt 12 may be configured by winding a long belt cord covered with a topping rubber in a spiral shape in the circumferential direction. Such a belt 12 constitutes a so-called jointless structure. In the tire 2, the angle formed by the belt cord of the first belt ply 42 with respect to the equator plane is 32 °, and the angle formed by the belt cord of the second belt ply 44 with respect to the equator plane is −32. °. Therefore, the tire 2 includes a belt 12 having a cross-ply structure.

  In the tire 2, the belt cord is made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. In the tire 2, the belt cord is made of nylon fiber.

  The intervening layer 14 extends along the inside of the tread 4 and the sidewall 6. In other words, the intervening layer 14 is located on the inner side in the radial direction of the tread 4 and on the inner side in the axial direction of the sidewall 6. The intervening layer 14 is sandwiched between the first main portion 30 and the second main portion 34. In other words, the intervening layer 14 is located between the first ply 26 and the second ply 28.

  The inner liner 16 is joined to the inner peripheral surface of the carcass 10. The inner liner 16 is made of a crosslinked rubber. For the inner liner 16, rubber having excellent air shielding properties is used. The inner liner 16 serves to maintain the internal pressure of the tire 2.

  As will be described later, in the tire 2, in order to optimize the rigidity, the ratio of the modulus M2 of the second cord to the modulus M1 of the first cord and the Young's modulus Y2 of the second cord The ratio to Young's modulus Y1 is adjusted appropriately. The tire 2 is configured so that the second cord has higher elasticity than the first cord by this adjustment. In the tire 2, the characteristics of the first cord are different from the characteristics of the second cord. As described above, the second main portion 34 is located outside the first main portion 30. Thus, this second code effectively binds the first code. In other words, the second ply 28 effectively restrains the first ply 26. Such a carcass 10 including the first ply 26 and the second ply 28 can contribute to rigidity. The tire 2 has high rigidity. The tire 2 is excellent in handling stability.

  In the tire 2, the first cord and the second cord can be selected in consideration of the specification of the tire 2. By this selection, the balance between steering stability and disturbance absorption can be adjusted. In the tire 2, the rigidity can be easily adjusted.

  In the tire 2, it is not necessary to provide a tread and a sidewall having a large thickness in order to optimize the rigidity. In the tire 2, an increase in mass is suppressed. Since it is not necessary to adjust the hardness of the crosslinked rubber constituting the tread 4, performances such as wear resistance and crack resistance can be maintained. In the tire 2, it is not necessary to adjust the angle formed by the cords included in the carcass 10 such as the first cord and the second cord with respect to the equator plane in order to optimize the rigidity.

  In the tire 2, the intervening layer 14 is made of a crosslinked rubber that does not include a cord. As described above, the intervening layer 14 is located between the first main portion 30 and the second main portion 34. The intervening layer 14 prevents cord separation caused by deformation of the tire 2 when traveling on a rough road. The tire 2 provided with such an intervening layer 14 is excellent in durability. In the tire 2, the intervening layer 14 is formed from the same rubber composition as the topping rubber constituting the carcass 10.

In the tire 2, the ratio of the modulus M2 to the modulus M1 is 3.8 or more. By setting this ratio to 3.8 or more, the second ply 28 effectively restrains the first ply 26. Such a carcass 10 including the first ply 26 and the second ply 28 can contribute to rigidity. The tire 2 is excellent in handling stability. From this viewpoint, the ratio is more preferably 5.0 or more. Excessive rigidity of the carcass 10 affects the disturbance absorption and riding comfort of the tire 2. If the modulus M2 is excessively larger than the modulus M1, code separation occurs due to deformation of the tire 2 when traveling on a rough road. In this respect, the ratio is preferably 5.8 or less, and more preferably 5.3 or less. The moduli M1 and M2 are measured according to JIS-L1017. The moduli M1 and M2 are equivalent to the initial tensile resistance described in Section 8.8 of JIS-L1017. The moduli M1 and M2 are measured by a material testing machine ("2005 model" manufactured by Intesco) under the conditions shown below. Average values of 10 tests are adopted as the moduli M1 and M2.
Test temperature: 20 ° C
Test humidity: 65%
Material grip interval: 250 mm
Tensile speed: 300 mm / min

  In the tire 2, the ratio of the Young's modulus Y2 to the Young's modulus Y1 is 3.6 or more. By setting this ratio to 3.6 or more, the second ply 28 effectively restrains the first ply 26. Such a carcass 10 including the first ply 26 and the second ply 28 can contribute to rigidity. The tire 2 is excellent in handling stability. From this viewpoint, the ratio is more preferably 6.3 or more. Excessive rigidity of the carcass 10 affects the disturbance absorption and riding comfort of the tire 2. If the Young's modulus Y2 is excessive as compared with the Young's modulus Y1, cord separation occurs due to deformation of the tire 2 when traveling on a rough road. In this respect, the ratio is preferably 7.4 or less, more preferably 6.7 or less, and particularly preferably 6.6 or less. The Young's modulus Y1 and Y2 are measured according to JIS-L1017. The Young's moduli Y1 and Y2 are apparent Young's moduli specified in JIS-L1017.

  In FIG. 1, a double arrow line H0 represents the height in the radial direction from the bead base line to the tire equatorial plane. This radial height H0 is the tire cross-section height. A double arrow line H1 represents the height in the radial direction from the bead base line to the end 46 of the intervening layer 14.

  In the tire 2, the ratio of the radial height H1 to the radial height H0 is preferably 0.6 or less. By setting this ratio to 0.6 or less, code separation can be effectively prevented. The tire 2 is excellent in durability. In this respect, the ratio is more preferably equal to or less than 0.5, and particularly preferably equal to or less than 0.4. The tire 2 arranged so that the intervening layer 14 reaches the cores 22 of both beads 8 reliably prevents this cord separation. From this viewpoint, this ratio is preferably 0.1 or less.

  In FIG. 2, a double arrow line TA represents the thickness of the intervening layer 14. In the tire 2, from the viewpoint that the intervening layer 14 can contribute to durability, the thickness TA of the intervening layer 14 is 0.3 mm or more. From the viewpoint that excessive rigidity can be prevented, the thickness TA is 0.5 mm or more. In the tire 2, the thickness TA is 0.3 mm.

  In the tire 2, the hardness of the intervening layer 14 is 40 or more and 90 or less. By setting the hardness to 40 or more, the intervening layer 14 can contribute to durability. From this viewpoint, the hardness is preferably 57 or more. By setting the hardness to 90 or less, excessive rigidity can be prevented. From this viewpoint, the hardness is preferably 72 or less. In the tire 2, this hardness is 61.

  In the present invention, the hardness is measured by a type A durometer according to JIS-K6253. This hardness is measured under conditions where the temperature is 23 ° C. In addition, the test piece formed by bridge | crosslinking a rubber composition is used for this measurement. This test piece is obtained by holding the rubber composition in a mold having a temperature of 160 ° C. for 10 minutes.

  In the tire 2, the complex elastic modulus (E *) of the intervening layer 14 is preferably 3.4 MPa or more and 11.7 MPa or less. By setting the complex elastic modulus to 3.4 MPa or more, the intervening layer 14 can contribute to the durability of the tire 2. From this viewpoint, the complex elastic modulus is more preferably 4.0 MPa or more. By setting this complex elastic modulus to 11.7 MPa or less, excessive rigidity of the tire 2 can be suppressed. The tire 2 can maintain disturbance absorption and riding comfort. From this viewpoint, the complex elastic modulus is preferably 8.0 MPa or less. In the tire 2, the complex elastic modulus of the intervening layer 14 is 4.5 MPa.

  In the tire 2, the loss coefficient (tan δ) of the intervening layer 14 is preferably 0.05 or more and 0.12 or less. By setting the loss factor to be 0.05 or more, the intervening layer 14 can contribute to the durability of the tire 2. In this respect, the loss factor is more preferably 0.06 or more. By setting the loss coefficient to be 0.12 or less, heat generation of the intervening layer 14 due to deformation of the tire 2 when traveling on a rough road is suppressed. In this respect, the loss factor is more preferably 0.11 or less.

In the present invention, the complex elastic modulus and loss factor of the intervening layer 14 are based on viscoelasticity spectrometer (“VA-200 type” manufactured by Shimadzu Corporation) under the conditions shown below in accordance with the provisions of “JIS-K 6394”. )).
Initial strain: 10%
Amplitude: ± 2%
Frequency: 10Hz
Deformation mode: Tensile
Measurement temperature: 70 ° C

  The test piece used for the measurement by a viscoelastic spectrometer is plate shape, the length is 45 mm, the width is 4 mm, and the thickness is 2 mm. Measurement is performed by chucking both ends of the test piece. The length of the displacement part of the test piece is 30 mm. This test piece is obtained by holding the rubber composition in a mold having a temperature of 160 ° C. for 10 minutes.

  In the tire 2, the density of the first cord is preferably 30 or more and 80 or less. By setting the density to 30 or more, the first ply 26 can contribute to the rigidity. The tire 2 is excellent in handling stability. In this respect, the density is more preferably equal to or greater than 40, and particularly preferably equal to or greater than 45. By setting the density to 80 or less, excessive rigidity of the tire 2 can be suppressed. In the tire 2, disturbance absorbability and riding comfort can be maintained. In this respect, the density is more preferably equal to or less than 70, and particularly preferably equal to or less than 60. In the tire 2, the density of the first cord is 50. This density is obtained by measuring the number of first cords existing per 5 cm width of the first ply 26 in a cross section perpendicular to the longitudinal direction of the first cords. The density of the second code described later is also measured in the same manner.

  In the tire 2, the density of the second cord is preferably 30 or more and 80 or less. By setting the density to 30 or more, the second ply 28 can contribute to rigidity. The tire 2 is excellent in handling stability. In this respect, the density is more preferably equal to or greater than 40, and particularly preferably equal to or greater than 45. By setting the density to 80 or less, excessive rigidity of the tire 2 can be suppressed. In the tire 2, disturbance absorbability and riding comfort can be maintained. In this respect, the density is more preferably equal to or less than 70, and particularly preferably equal to or less than 60. In the tire 2, the density of the second cord is 50.

  In the present invention, the size and angle of each member of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and the tire 2 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 2. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 2 relies. “Maximum air pressure” in the JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “INFLATION PRESSURE” in the ETRTO standard are normal internal pressures.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
The basic configuration shown in FIG. 1 is used, and the specification includes the specification shown in Table 3 below, using the code B shown in Table 1 as the first code and the code G as the second code. A pneumatic tire for ATV of Example 1 was obtained. The size of this tire is “AT20 × 10R9 KT355”. In this tire, the ratio (M2 / M1) of the modulus M2 of the second cord to the modulus M1 of the first cord is 5.3. The ratio (Y2 / Y1) of the Young's modulus Y2 of the second cord to the Young's modulus Y1 of the first cord is 6.6. The thickness TA of the intervening layer of the tire is 0.3 mm. The hardness (durometer A hardness) of this intervening layer measured under conditions where the temperature is 25 ° C. is 61.

[Examples 2, 3 and 9]
Tires were obtained in the same manner as in Example 1 except that the first cords were as shown in Tables 2 and 3 below and the ratio (M2 / M1) and ratio (Y2 / Y1) were changed.

[Comparative Examples 3 to 7]
Tires were obtained in the same manner as in Example 1 except that the first cord and the second cord were as shown in Table 2 and the ratio (M2 / M1) and ratio (Y2 / Y1) were changed.

[Example 8]
A tire was obtained in the same manner as in Example 1 except that the thickness TA of the intervening layer was as shown in Table 3 below.

[Examples 4 to 7]
A tire was obtained in the same manner as in Example 1 except that the hardness of the intervening layer was as shown in Table 3 below.

[Comparative Example 1]
Tires were obtained in the same manner as in Example 1 except that the first cord and the second cord were as shown in Table 2 below, and the ratio (M2 / M1) and ratio (Y2 / Y1) were changed and no intervening layer was provided. . Comparative Example 1 is a conventional tire that is commercially available.

[Comparative Example 2]
A tire was obtained in the same manner as in Example 1 except that the second cord was as shown in Table 2 and the ratio (M2 / M1) and ratio (Y2 / Y1) were changed and no intervening layer was provided.

[Real car evaluation]
The prototype tire was incorporated into a “9 × 8.0 AT” rim, and the internal pressure of the tire was 25 kPa. This tire was mounted on an all-terrain vehicle having a displacement of 400 cc. This all-terrain vehicle was run on a dirt course in the range of 40 km / h to 100 km / h, and a sensory evaluation was performed by the driver. Stability was evaluated from the viewpoint of roll feeling and disturbance absorption during straight running and turning. Steering performance was evaluated from the viewpoint of handle weight and ground contact feeling during driving. The durability was evaluated by visually observing the degree of tire damage when the travel distance was 1000 km. Prior to this running test, the mass of the prototype tire was measured. These results are shown in Tables 2 and 3 as index values with Comparative Example 1 as 100. It is shown that the larger this value, the better. In the overall evaluation, Y is marked with a tire having passed a result that is better than Comparative Example 1 in all evaluations. Otherwise, it is written as N.

  As shown in Table 1, the tires of the examples were confirmed to be better than the comparative example in all items (stability, maneuverability, durability, and tire mass). From this evaluation result, the superiority of the present invention is clear.

  The pneumatic tire according to the present invention can be mounted on various vehicles.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a part of the tire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Tire 4 ... Tread 6 ... Side wall 8 ... Bead 10 ... Carcass 12 ... Belt 14 ... Intervening layer 16 ... Inner liner 18 ... Tread surface 20 ... Groove 22 ... Core 24 ... Apex 26 ... First ply 28 ... Second ply 30 ... First main part 32 ... First turn-up part 34 ... First Two main parts 36 ... second folded part 38, 40, 46 ... end 42 ... first belt ply 44 ... second belt ply

Claims (3)

A tread whose outer surface forms a tread surface, a pair of sidewalls extending substantially inward in the radial direction from the end of the tread, a pair of beads positioned substantially inward in the radial direction from the sidewall, and a tread and sidewalls A carcass stretched between the beads along the inside, a belt laminated with the carcass on the inner side in the radial direction of the tread, and an intervening layer;
The carcass includes a first ply and a second ply located outside the first ply on the radially inner side of the tread,
This belt is equipped with a belt ply,
The intervening layer is located between the first ply and the second ply on the radially inner side of the tread;
This first ply has a first cord made of organic fibers,
This second ply has a second cord made of organic fiber,
This belt ply has a belt cord made of organic fibers,
The ratio of the modulus of the second chord to the modulus of the first chord is 3.8 or greater;
A pneumatic tire for all-terrain vehicles, wherein the ratio of the Young's modulus of the second cord to the Young's modulus of the first cord is 3.6 or more.   The tire according to claim 1, wherein the intervening layer is along the inside of the tread and the sidewall. The intervening layer has a hardness of 40 or more and 90 or less,
The tire according to claim 1 or 2, wherein the thickness of the intervening layer is 0.3 mm or more and 0.5 mm or more.

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