| 摘要 |
PROBLEM TO BE SOLVED: To keep the carcass cord fatigue resistance and increase the tire side rigidity by specifying the number of upper twists, the number of lower twists, the upper twist coefficient, and the lower twist coefficient. SOLUTION: The carcass cords of a tire are made of organic fibers, a lower twist is applied to organic fiber raw threads as specified by equations 1.3<=n2 /n1 <=2.0 and 0.45<N2 <0.68, then an upper twist is applied to multiple lower twist yarn in the opposite direction to the lower twist, where n1 is the number of lower twists (/10cm), N1 is the lower twist coefficient, n2 is the number of upper twists (/10cm), and N2 is the upper twist coefficient. This tire satisfies the equation H1 /H2 =0.2-0.8, where H1 is the height from bead lower carcass cords to a fold end, and H2 is the height from the bead lower carcass cords to center section carcass cords in the tire cross section. The double twist yarn satisfies the equations N1 =n1×(0.139×D1 /P)1/2×10<-3> and N2 =n2×(0.139×D2 /P)1/2×10<-3> , where P is the specific gravity of the organic fibers.
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