| 摘要 |
PURPOSE:To make the destruction pressure of a bead part and the fit pressure to a rim be over a standard, and realize weight reduction, by increasing tensil elasticity in a stage on a tread side higher than that in a stage on a rim side of the bead wire of a bead assembly composed of an organic fiber. CONSTITUTION:In a bead assembly Sb, a rubber coated organic fiber bead wire having the tensile elastic modulus E1 is wound to 6-1 to 7-1 at a first stage. Next, bead wires of second, third, and fourth stages having tensile elastic moduli E2, E3, and E4 are wound on from 6-2, 6-3, and 6-4 to 7-2, 7-3, and 7-4 respectively in order like, the first stage. The tensile moduli E1-E4 at every stage are determined by changing the number of strands to be E1<E2<E3<E4. Consequently the destruction pressure and bead expansion force of a tire is increased to satisfy fit pressure to a rim to reduce weight. |
