Patent ID: 7926531

Claim:
A pneumatic tire comprising a carcass having a carcass ply with carcass cords extending from a tread portion to a bead core of a bead portion through a sidewall portion, wherein: the carcass cords are made of high tenacity vinylon fiber or polyalylate fiber; viscoelasticity characteristics per one cord at 120° C. satisfy the following equations (1) to (3): B>0 (1) B≦ 0.0000437× A+ 0.042857 (2) B≦− 0.00003636× A+ 0.163636 (3) wherein “A” represents a product of complex modulus E*(N/cm 2 ) and cross-sectional area “S”(cm 2 ) of the cord, “A” is 340 to 1800 N, and “B” represents a loss tangent tanδ which is 0.02 or higher; the carcass cords have a two-ply twist structure, and the number of twists n of the cord is 30 to 70 per 10 cm; and a twist coefficient “T” of the cord defined in the following equation (5) is 0.45 to 0.75: T=n ×√{(0.125 ×D/ 2)×(1/ρ)}×10 −3 (5) wherein “n” represents the number of twists per 10 cm, “D” represents total fineness based on corrected mass (dtex) of the cord, and “ρ” represents specific gravity of fiber.