| 摘要 |
PROBLEM TO BE SOLVED: To provide a pneumatic radial tire having improved belt durability and a lighter weight in spite of using steel cords in a simple structure for a belt layer reinforcing material. SOLUTION: This pneumatic radial tire comprises a carcass layer extending from a tread portion through sidewall portions to bead portions where it is turned around bead cores and a steel cord belt layer for reinforcement between the carcass layer and a tread portion belt layer. Steel cords constituting the belt layers are 1×N structured steel cords consisting of three or four filaments having sizes of 0.25 mm to 0.31 mm. The cross section of the steel cords in the belt layer is oblate with a minor diameter in the tire radial direction. A value for P/d is 52-82 where d is the diameter of the filament and P is a twist pitch.
|
