| 摘要 |
PURPOSE: A pneumatic radial tire and a carcass profile decision method are provided to improve the endurance of the belt edge and abrasion resistance in the portion contacted to the road surface by forming the carcass profile with five arcs considering the diameter of the tire, the maximum width of a section and the width of the tread section. CONSTITUTION: The maximum diameter of a tire, the maximum width of the tire section and the width of the tread section are set, and an arc of a bead part and a fixed point of the bead part are placed according to the width of a rim, the shape of a rim flange and the area of the bead part. The profile of a carcass from the carcass central point to the fixed point of the bead part is made of five arcs(A,B,C,D,E). The position of a point(Ps) is decided on a Y-axis according to height(H) from the fixed point of the bead part to the carcass central point and height from the point to the carcass central point. The position of the point on an X-axis is decided to be equal to the maximum width of a section. Radii of curvature of arcs and contact points(P1,P2,P3) between arcs are positioned according to the maximum diameter of the tire and the width of the tread section. Arcs are connected at contact points, and the fourth arc and the fifth arc are connected at the contact point. The endurance of the tire and abrasion resistance are improved with forming the carcass profile with five arcs.
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