Pneumatic radial tyre and method of making the same

摘要

The tyre comprises a carcass (6) comprising an outer carcass ply (11,21,31) made of cords having a first heat-shrinkage-percentage K1 and an inner carcass ply (10,20,30) of cords having a second heat-shrinkage-percentage K2 different from the first heat-shrinkage-percentage K1. The cord tension of the inner carcass ply is smaller than the cord tension of the outer carcass ply. The method comprises the steps of making the outer carcass ply of cords having a first heat-shrinkage-percentage K1, making the inner carcass ply of cords having a second heat-shrinkage-percentage K2, wherein the first heat-shrinkage-percentage K1 at 150 degrees C is 120 to 160% of the second heat-shrinkage-percentage K2 at 150 degrees C, and heating and vulcanising a raw tyre to heat-shrink the outer carcass ply cords in a larger degree than the inner carcass ply.