Heavy-duty pneumatic tires

Abstract

To provide a pneumatic tire 2 for heavy load which can suppress spot wear around a hole provided in a shoulder land part and can suppress occurrence of chipping and rib tear originating from the hole while achieving reduction of a vulcanization time.SOLUTION: A tire 2 comprises a plurality of holes in a shoulder land part 28s, the holes extending toward a belt 14 from an exterior surface of the shoulder land part. The tire includes many juxtaposed fiber cords, and the fiber cord includes a fiber-reinforced layer comprising nylon fibers. This fiber-reinforced layer 22 includes an inner fiber-reinforced layer 66, and an outer fiber-reinforced layer 68. The inner fiber-reinforced layer 66 covers an outer end of a steel reinforcement layer 20 from an outer side in an axial direction, and the outer fiber-reinforced layer 68 covers an outer end of the inner fiber-reinforced layer 66 from an outer side in an axial direction.SELECTED DRAWING: Figure 1

Claims

1. A pair of beads having a core that extends in the circumferential direction, A carcass comprising a main body that bridges one core and the other core, a pair of folded portions connected to the main body that are folded back axially from the inside to the outside around each core, and a carcass ply including a number of parallel carcass cords, The tread located radially outward of the main body, A belt located radially outward of the main body and radially inward of the tread, A steel reinforcing layer comprising a number of parallel steel cords, each having an inner end located inside the main body in the axial direction and an outer end located outside the folded portion in the axial direction, which are folded back around the core; A fiber-reinforced layer comprising numerous parallel fiber cords, The tread is provided with at least three circumferential grooves arranged in parallel in the axial direction, thereby forming at least four parallel land areas in the axial direction. Of these circumferential grooves, the outermost circumferential groove in the axial direction is the shoulder circumferential groove, and of these land areas, the outermost land area in the axial direction is the shoulder land area. The aforementioned shoulder circumferential groove is a zigzag circumferential groove that extends continuously in a zigzag pattern in the circumferential direction. The axial dimension of the shoulder land portion changes along the circumferential groove of the shoulder, The shoulder portion is provided with a plurality of holes extending from its outer surface toward the belt. The position where the hole is formed coincides with the portion indicating the maximum axial width of the shoulder land portion. The aforementioned fiber cord is made of nylon fibers, A heavy-duty pneumatic tire comprising a fiber reinforcement layer comprising an inner fiber reinforcement layer located on the innermost side in the axial direction and an outer fiber reinforcement layer located on the outermost side in the axial direction, wherein the inner fiber reinforcement layer covers the outer end of the steel reinforcement layer from the outside in the axial direction, and the outer fiber reinforcement layer covers the outer end of the inner fiber reinforcement layer from the outside in the axial direction.

2. The heavy-duty pneumatic tire according to claim 1, wherein the distance from the hole to the outer end of the shoulder land portion is 0.12 times or more and 0.88 times or less the maximum axial width of the shoulder land portion.

3. The pneumatic tire for heavy loads according to claim 1 or 2, wherein the depth of the hole is 1 / 3 or more and 1 or less the depth of the shoulder circumferential groove.

4. In the radial direction, the outer end of the outer fiber reinforcement layer is located outside the end of the folded portion. The heavy-duty pneumatic tire according to any one of claims 1 to 3, wherein the radial distance to the outer end of the outer fiber reinforcement layer is 1.4 times or more and 1.8 times or less the radial distance to the end of the folded portion.

5. In the radial direction, the outer end of the inner fiber reinforcement layer is located inward from the outer end of the outer fiber reinforcement layer. The heavy-duty pneumatic tire according to any one of claims 1 to 4, wherein the radial distance to the outer end of the inner fiber reinforcement layer is smaller than the radial distance to the outer end of the outer fiber reinforcement layer, and the difference is 10 mm or more and 15 mm or less.

6. The heavy-duty pneumatic tire according to any one of claims 1 to 5, wherein the number of fiber cords in the fiber reinforcement layer is 20 or more and 70 or less per 50 mm width of the fiber reinforcement layer.

7. In the inner fiber reinforcement layer, the fiber cords are inclined with respect to the carcass cords. In the outer fiber reinforcement layer, the fiber cords are inclined with respect to the carcass cords in the opposite direction to the fiber cords in the inner fiber reinforcement layer. The intersection angle between the fiber cords in the inner fiber reinforcement layer and the carcass cords is 40 degrees or more and 80 degrees or less. A heavy-duty pneumatic tire according to any one of claims 1 to 6, wherein the intersection angle between the fiber cords in the outer fiber reinforcement layer and the carcass cords is 40 degrees or more and 80 degrees or less.

8. In the inner fiber reinforcement layer, the fiber cords are inclined with respect to the carcass cords. In the outer fiber reinforcement layer, the fiber cords are inclined with respect to the carcass cords in the opposite direction to the fiber cords in the inner fiber reinforcement layer. A heavy-duty pneumatic tire according to any one of claims 1 to 7, wherein the intersection angle between the fiber cords in the inner fiber reinforcement layer and the fiber cords in the outer fiber reinforcement layer is 80 degrees or more and 160 degrees or less.

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