| 摘要 |
PURPOSE: To provide a pneumatic radial tire which is lightweight and is excellent in high speed durability and is excellent in uniformity, maneuvering stability and comfort to ride in and can also be inexpensively manufactured without substantially increasing rolling resistance. CONSTITUTION: In this pneumatic radial tire, a steel cord belt layer 4 whose cord angle to the tire circumferential direction is less than 25 deg. to 45 deg. is arranged outside a carcass layer 2, and a tape 7 composed of an organic fiber cord is wound round the outer periphery of the steel cord belt layer 4 while bending it in a zigzag shape, and a cylindrical organic fiber cord belt layer 5 having a two-layer structure is formed. When a cord angle of the organic fiber cord belt layer 5 to the tire circumferential direction is denoted byθand a width is denoted by D and a cylinder radius is denoted by (r) and the number of zigzag bending times per tire one round of the tape 7 is denoted by (n), the relationship of (tanθ=n×D/2πr) is satisfied, and (8 deg.<θ<32 deg.) is also realized.
|
