| 摘要 |
A pneumatic tyre (1) comprises a tread portion (2), a pair of sidewall portions (3), a pair of bead portions (4), and a carcass ply (6) of steel cords (10) extending between the bead portions (4) through the tread portion (2) and sidewall portions (3). Each of the carcass cords (10) comprises a number "n" of steel filaments (F) each having a diameter (d) of from 0.17 to 0.40 mm. The steel filaments (F) are twisted together to have a "1Xn" bundle-twist structure or an interlace-twist structure. In a vicinity of the maximum tyre section width point P of each of the sidewall portions, a sectional shape coefficient S of each carcass cord is set in a range of from 0.5 to 0.9, wherein the sectional shape coefficient S is (d<2> X n)/(L1 X L2), "n" is the number of the filaments, "d" is the average of the diameters of the filaments, "L1" is the largest measure of distance between two extremities of the cord which occurs in a direction in a cross section of the cord, and "L2" is the measure of distance between two extremities of the cord in a direction perpendicular to the above-mentioned direction. <IMAGE> |
