Patent ID: 7575031

Claim:
A heavy duty radial tire comprising a carcass which extends from a tread portion to each of bead cores in a pair of bead portions through a pair of sidewall portions, and a belt layer disposed radially outward of the carcass in the tread portion, wherein: said belt layer comprises at least three plies of belt cords in which disposed on the radially innermost side is a first belt ply of belt cords arranged at an angle of 10 to 45° with respect to the tire circumferential direction, a third belt ply is disposed radially outward of said first belt ply, the belt cords of said third belt ply being arranged at an angle of 10 to 45° with respect to the tire circumferential direction in the slanting direction reverse to that of said first belt ply, and between said first and third belt plies is disposed a second belt ply of belt cords spirally wound at an angle of at most 5° with respect to the tire circumferential direction, and in which the axial width W 1 of said first belt ply and the axial width W 3 of said third belt ply are at least 85% of a tread ground contact width Tw and the difference W 1 -W 3 is at least 14 mm, and the axial width W 2 of said second belt ply is at least 70% of the tread ground contact width Tw and is smaller than the widths W 1 and W 3 of said first and third belt plies, a pair of reinforcing rubber layers are disposed between said first and third belt plies so as to extend axially outwardly from each of the axially outer ends of said second belt ply, and each of said reinforcing rubber layers comprises an axially inner rubber portion which is continuous with the axially outer end of said second belt ply and which has a substantially constant thickness T 1 of 1.5 to 4.0 mm and a complex elastic modulus E*1 of 8.0 to 14.0 MPa, and an axially outer rubber portion which is continuous with said axially inner rubber portion and which has a thickness T 2 e of at least 2.0 mm at the axially outer end of said third belt ply and a complex elastic modulus E*2 of 6.0 to 12.0 MPa which is smaller than the complex elastic modulus E*1.