| 摘要 |
PROBLEM TO BE SOLVED: To enhance the durability of a bead portion by effectively avoiding the fatigue breakdown of layer wires in a second layer as counted from the outermost layer. SOLUTION: When a tire is run, a bead core 12 is repeatedly twisted and the layer wires 33 of adjacent layers 32 rub against one another and are locally recessed under pressure. When the number of winding pitches of the layer wires 33b of the second layer 32b is smaller than those of the layer wires 33c, 33d of the inner layers, the angles of intersection between the layer wires 33a, b, c become smaller and scratch stresses are reduced. Also, the radius of curvature of the layer wire 33b itself is increased and the radius of curvature at the bend of the recess is reduced (smoothened).
|
