Patent ID: 7677287

Claim:
A heavy load radial tire comprising a carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion, and a belt layer disposed radially outward of the carcass and in the tread portion, wherein the belt layer includes a first belt ply disposed on the radially innermost side of the belt layer and radially outward of the carcass, in which belt cords are arranged at an angle θ 1 of 45 to 75° with respect to a circumferential direction of the tire, a second belt ply disposed radially outward of the first belt ply, in which belt cords are arranged at an angle θ 2 of 10 to 45° with respect to the circumferential direction of the tire, and the belt cord angle θ 1 of the first belt ply is greater than the angle θ 2 , a third belt ply disposed radially outward of the second belt ply, in which belt cords are arranged at an angle θ 3 of 10 to 45° with respect to the circumferential direction of the tire and an inclining direction of the belt cords of the third belt ply is opposite from that of the belt cords of the second belt ply, and a fourth belt ply comprising a pair of plies which is disposed radially outward of the third belt ply and at a distance from each other on both sides of a tire equator, in which a belt cord is spirally wound at an angle θ 4 of not more than 5° with respect to the circumferential direction of the tire in each of the fourth belt plies, wherein ply widths W 2 and W 3 of the second and third belt plies in an axial direction of the tire are not less than 85% of a tread ground-contact width Tw, a ply width W 4 of the fourth belt ply in the axial direction of the tire is not less than 40 mm, an axial distance K between an outer end of the fourth belt ply and the tire equator is in a range of 35% to 40% of the tread ground-contact width Tw, a difference W 2 −W 3 of the ply widths W 2 and W 3 of the second and third belt plies in the axial direction of the tire is not less than 14 mm, a reinforcing rubber layer is disposed between outer ends of the second and third belt plies in the axial direction of the tire, a maximum thickness T 1 of the reinforcing rubber layer is not less than 3.0 mm, and a complex elastic modulus E*1 of the reinforcing rubber layer is in a range of 6.0 to 12.0 MPa.