| 摘要 |
A pneumatic tire comprises a carcass ply extending between bead portions and turned up around a bead core in each bead portion from the inside to the outside of the tire to form a pair of turned up portions and a main portion therebetween, and a bead reinforcing layer made of steel cords and disposed axially outside the turned up portion in each bead portion, wherein each of the steel cords is made of steel filaments gathered together to have a shape index in a range of from 0.35 to 0.70, the shape index is the total of squared filament diameter of all the steel filaments which total is divided by the product of L1 and L2, wherein, in a cross section at a right angle to the longitudinal direction of the cord, L1 is the dimension of largest measure which occurs in one direction, and L2 is the dimension measured perpendicularly to this direction.
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