| 摘要 |
PURPOSE:To prevent a tyre from fatigue due to heat generation and from deterioration due to wet heat in running by selecting specific materials respectively for a cord of belt plies and its coating rubber. CONSTITUTION:Laminated belt ply layer 2 is built up by coating a belt cord 3 with belt cord rubber 4 and disposed between the outer face of the crown of carcass ply layer 5 and a cap tread rubber 1. A volumetric percentage alpha of cord in a unit belt layer (a) ranges under 40% while another volumetric percentage beta of cord in the arranged cord layer (b) of a unit belt ranges from 45% to 60%. With regard to the composition of the belt cord coating rubber, its loss factor is selected in a range of 0.10 or less and its modulus of potential elasticity is selected in a range of 20kg/cm<2> or more. |
