| 摘要 |
PURPOSE:To contrive to improve the straight running property and wear proof by an arrangement wherein the mean value of and difference between the respective angles of reinforcement cords forming carcass cord layers laminated into two layers or an upper and a lower layer toward the peripheral direction of the tyre are made specified angles. CONSTITUTION:If the mean value beta of the angle alpha1 of the reinforcement cords of a lower carcass cord layer 4d and the angle alpha2 of the reinforcement cords of an upper carcass cord layer 4u is smaller than 92 deg., plys-tear is not made better than its conventional level, while if the value beta is larger than 102 deg., the plys-tear is improved further, however load durability gets worse than that of the conventional radial tyre. Even under the condition that the mean value beta of the angles alpha1 and alpha2 lies in the range of 92-102 deg., if the difference alpha2-alpha1 between the angles alpha2 and alpha1 is smaller than 5 deg., the plys-tear is not made better than that of the conventional radial tyre, while the difference alpha2-alpha1 is larger than 30 deg., the plys-tear is improved, however the load durability gets worse than that of the radial tyre. Consequently, the difference alpha2-alpha1 must be kept in the range of 5- 30 deg.. |
