A pneumatic radial tire according to claim 2, wherein the aromatic polyamide fiber cord in said layer of aromatic polyamide fiber cords is formed by twisting an aromatic polyamide fiber which has properties including a tensile strength of not less than 150 kg/mm2 and a modulus of tensile elasticity of not less than 3000 kg/mm2, in a manner such that a value within a range of 1500???K???3500 is obt