Pneumatic radial tire

摘要

A pneumatic radial tire includes a pair of annular bead portions 2A, 2B, a tread portion 3 having a tread surface portion, a pair of sidewall portions 4A, 4B each connecting one of both end portions of tread portion 3 in tire-width directions and an outward end in the tire-radial direction of the corresponding one of the bead portions 2A, 2B, and a carcass layer 5 extending continuously across and through the bead portions 2A, 2B, the sidewall portions 3, and the tread portion 4A, 4B, the carcass layer 5 being configured to form a framework of the tire. Main grooves are formed respectively in a tire's equatorial portion including a center line in the tire-width directions of the tread portion and in a portion located closer to a vehicle-fitted inner side than the tire's equatorial portion is, each main groove extending continuously in a tire-circumferential direction of the tread portion, a land-portion block row in which a plurality of blocks are consecutively arranged in the tire-circumferential direction is formed in a portion of the tread portion located closer to a vehicle-fitted outer side than the tire's equatorial portion of the tire is, and in a section taken in the tire-width directions, a surface curvature radius of a case line of the carcass layer on the vehicle-fitted outer side is larger than a surface curvature radius of a case line of the carcass layer on the vehicle-fitted inner side while the tire is inflated with air.

主权项

1. A pneumatic radial tire comprising:
a pair of annular bead portions; a tread portion located at an external side, in a tire-radial direction, of the pair of bead portions, and including a tread surface portion; a pair of sidewall portions each connecting one of both end portions of the tread portion in tire-width directions and an outward end in the tire-radial direction of the corresponding one of the bead portions; and a carcass layer extending continuously across and through the bead portions, the sidewall portions, and the tread portion, the carcass layer being configured to form a framework of the tire, wherein main grooves are formed respectively in a tire's equatorial portion including a center line in the tire-width directions of the tread portion and in a portion located closer to a vehicle-fitted inner side than the tire's equatorial portion is, each main groove extending continuously in a tire-circumferential direction of the tread portion, a first shoulder land portion row and a second shoulder land portion row are formed in a portion of the tread located closer to a vehicle-fitted outer side than the tire's equatorial portion, the first shoulder land portion row has a plurality of blocks which are consecutively arranged in the tire-circumferential direction, a V shaped groove is extended in the tire-circumferential direction and is formed between the first shoulder land portion row and the second shoulder land portion row, and includes first sloping-surfaces as side walls provided at the first shoulder land portion row side and second sloping-surfaces as side walls provided at the second shoulder land portion row side, the first sloping-surfaces each is inclined inwardly in the tire-radial direction from the first shoulder land portion row toward the second shoulder land portion row, the second sloping-surfaces each is inclined inwardly in the tire-radial direction from the second shoulder land portion row toward the first shoulder land portion row, the first sloping-surfaces and the second sloping-surfaces are arranged alternately in the tire-circumferential direction, a depth of the V shaped groove varies from a first portion to a second portion in the tire-circumferential direction, in a section taken in the tire-width directions, a surface curvature radius of a case line of the carcass layer on the vehicle-fitted outer side is larger than a surface curvature radius of a case line of the carcass layer on the vehicle-fitted inner side while the tire is inflated with air, wherein an outside lateral groove is connected to the V-shaped groove and the outside lateral groove has a V-shape in the tire width direction such that an apex of the outside lateral groove is adjacent to the V-shaped groove.