PURPOSE: To sufficiently reinforce the captioned tire and improve fatigue resistance by reinforcing at least one of a belt and a carcass ply arranged inside a tread part by making use of a cord yielded by subjecting a polyester fiber having prescribed characteristics to original and final twisting.

CONSTITUTION: In a pneumatic tire provided with a carcass ply layer 1 reinforced by a belt (braker layer) 4 arranged inside a tread 5, at least one of the belt 4 and the carcass ply layer 1 is reinforced by a specific polyester cord. For this cord, one obtained by subjecting a polyethylene fiber having the following characteristics to original and final twisting is used: intrinsic viscosity IV≥0.50, double refractive index in fiber cross section ΔnA-ΔnB<0, fiber double refractive index Δn≥180×10-3, fiber length period in small angle X-ray diffraction LP≥160 angstrome, specific gravity SG≥1.390, degree of shrinkage under a dry heat condition at 160°C, SHD≤15%, and single yarn denier dpf≤35.