摘要 |
PROBLEM TO BE SOLVED: To provide a lightweight pneumatic radial tire without reducing durability and high-speed durability.SOLUTION: A pneumatic radial tire includes a belt formed of at least two belt layers. Each of the first and second belt layers of the belt is obtained by embedding steel cords 10 each comprising a core formed by arranging in parallel two core filaments 11 without twisting and N(2≤N≤4) sheath filaments 12 twisted around the core in coating rubber along a belt width direction in parallel. When a diameter of the core filament 11 is d1, and a diameter of the sheath filament 12 is d2, d1>d2 is satisfied. When a longitudinal diameter of a circumscribed rectangle of the steel cord 10 is L1, a short diameter is L2, and the total cross sectional area of all the filaments constituting the steel cord is S, a steel filling rate &eegr;(%) defined by &eegr;(%)=S/(L1×L2)×100 is always >43.7 and ≤78.5. |