PURPOSE: To improve the eccentric abrasion resistance by suppressing the reduction of the crown R due to traveling, maintaining the bead durability of a pneumatic radial tire for heavy load.

CONSTITUTION: In the filled state with the internal pressure of 10% of a prescribed internal pressure through the rim assembly, if the radius of curvature of carcass line is set to R2 directly under the belt edge part having the max. width, R3 at the carcass max. width position, and R4 at the position in 70% of the height at the max. width position from the innermost position in the tire radial direction of the carcass ply, 1>R3/R2>0.55, R4>R3. As for the carcass line in the case when the regular internal pressure is filled, the carcass max. width position R3 is recessed to the inside in the tire width direction, and the vicinity of the tread edge part having the radius of curvature of R3 larger than R2 is projected towards the tire outside, and the shape of a crown is made flat, and the difference of the radius on the shoulder side of the tread and the radius on the equator plane becomes small, and the part on the shoulder side of the tread is prevented from being dragged for a road surface, and the generation of the eccentric abrasion is suppressed.