PURPOSE: To improve the durability of each bead portion by reducing tensile force which acts on a tire axial direction inside part in the vicinity of each bead core of a carcass layer.

CONSTITUTION: A pneumatic radial tire 10 for heavy load is equipped with one sheet of a carcass layer 12 consisting of steel cords that spread radially between a pair of bead cores 14. The carcass layer 12 is turned up at each bead core 14 from the tire axial inside to the outside, and an inside portion 12A and a turned-up portion 12B are formed. The upper end portion 12C of the turned-up portion 12B of the carcass layer 12 is wound up to the vicinity of a tire maximum width position M. On the tire axial inside of the carcass layer 12, a bead reinforcement band 18 consisting of rubber-covered cords is arranged along the carcass layer 12. The upper end portion 18A of the bead reinforcement band 18 is positioned in a range that does not exceed 50% of tire maximum height H, and the lower end portion 18B there of extends to the lower portion of a bead core 14.