Pneumatic radial tire for heavy load vehicles including improved bead portion reinforcing construction

摘要

A pneumatic radial tire for heavy load vehicles including an improved bead portion reinforcing construction constructed such that the cords of a reinforcing layer along the outside of a carcass ply are inclined on a circle formed by the upper end of a turn-up region of the carcass ply at an angle of 50 DEG to 70 DEG with respect to the radial plane of the tire and have an air gap ratio delta of 38% to 60% measured at a region where the cords of the reinforcing layer cross with a line tangent to a curved surface of a rim flange and extending in parallel with the rotary axis of the tire and given by the following formula <IMAGE> where b is a distance between two midlines of two adjacent cords, measured perpendicular to the cords, and c is a cord diameter.