| 摘要 |
PURPOSE:To improve the extent of steering stability, by specifying the ratio of a tire outer diameter to a mold outer diameter as well as the ratio of tire width to bead width at the time of filling normal internal pressure and a relationship between length of a bead apex and a tilt angle, respectively. CONSTITUTION:In case of a radial tire of 80 deg.-90 deg. in cord angles of carcass ply 3, a ratio Dt/Dm between a tire outer diameter Dt and a mold outer diameter Dm at the time of filling normal internal pressure should be set to a range of 1.0-1.05. Also, a ratio Wt/Wb between tier width Wt and bead width Wb should be set to a range of 1.2-1.4. In addition, length l of a bead apex 4 and angle theta made by a straight line passing through a bottom part B and an upper end E of the apex 4 and a line RL passing through the bottom part B and paralleling a tire rotation axis are constituted so as to satisfy the specified relation. With this constitution, steering stability is improvable.
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