Sumitomo Rubber Industries Limited

Tadao Kouno

Kazuo Kadomaru

Hiroyuki Noma

A radial tire for motorcycle, in which the steering stability at high running speed is improved and the ply separation at the breaker edges is lessened. The tire comprises: a radial carcass extending between bead portions of the tire; a tread disposed radially outside the carcass; and a breaker disposed between the carcass and the tread and having at least one ply of metallic cords coated with rubber; each metallic cord comprising a plurality of twisted strands; each strand consisting of at least three twisted filaments made of metal; the elongation of each metallic cord when loaded when 1.0 kgf/cord being in a range of 0.5 to 1.5%; the tangential modulus of elasticity of each metallic cord when loaded with 10 kgf/cord being in a range of 8,000 to 15,000 kgf.sq.mm.

Radial tire for motorcycle with improved metallic belt cord

A radial tire for a motorcycle comprising a carcass ply and a breaker disposed radially outside thereof and comprising a first ply lying on the carcass ply and a second ply lying radially outside the first ply, wherein the carcass ply is composed of cords arranged radially at an angle of 70 to 90 degrees to the tire equator and having an elastic modulus MC of 250 to 600 kgf/sq.mm; the first ply of the breaker being composed of cords arranged at an angle of 10 to 30 degrees to the tire equator and having a elastic modulus MB1 of 450 to 1100 kgf/sq.mm; the second ply of the breaker being composed of aromatic polyamide cords arranged at an angle of 10 to 30 degrees to the tire equator and having a elastic modulus MB2 of 650 to 1600 kgf/sq.mm; the elastic modulus MB2 of the second ply cords being larger than the elastic modulus MB1 of the first ply cords; the elastic modulus MB1 of the first ply cords being larger than the elastic modulus MC of the carcass ply cords; and the difference MB2-MB 1 and the difference MB1-MC are in the range of 200 to 500 kgf/sq.mm.

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Sakaishi, Japan

Tadao Kouno