| 摘要 |
PURPOSE:To ensure durability of a bead and reduce the weight of a tyre, by a method wherein a bead core is formed by two different wires rolled in a spiral, and break tenacity per a unit cross section area of a wire at a radially internal portion is increased over that of an external portion. CONSTITUTION:In a bead part 1, a carcass layer 2 is folded back around a bead core 3 from the inner side toward the outer side of a tyre. A bead sheet part 6 of a rim 5 is inclined at an angle of about 15 deg. with a tyre rotary shaft, and the base port of the bead core 3 is also inclined approximately at the same angle as that of the bead sheet part 6. In the above tyre, the bead core 3 is formed by two spirally-wound different wires A and B. Break tenacity per a unit cross section area of the wire B at a radially inner side part is increased over that of the wire A at a radially outer side part. This constitution enables increase of break tenacity of a bead, ensurance of durability of a bead, and reduction of the weight of a tyre.
|
