PURPOSE: To prevent exposure failure of a carcass cord to an inner liner at vulcanization forming by inserting an organic fiber cord reinforced ply between the carcass ply and the inner liner ply from the tread part to the widest position of the tire and setting the end count of the organic fiber cord more than the end count of the carcass cord.

CONSTITUTION: A reinforced ply 4 comprising at least one organic fiber cord is so inserted between a cracass ply 2 and an inner liner ply 5 as to extend from the tread part 1 at least to the widest part of the tire and the end count of the organic fiber cord 4a of the reinforced ply 4 is set 1 or more times of the end count of the steel cord 2a of the carcass ply 2. This constitution prevents the steel cord 2a from moving to the inner liner ply 5 due to a large tensile force which is produced at vulcanization forming so as to prevent the possibility of exposure failure.