| 摘要 |
<p>A pneumatic tyre comprises a pair of axially spaced bead portions (4) adapted for a 15-degree-taper rim, a bead core (5) disposed in each bead portion (4), and a carcass (6) turned up around the bead core (5). The bead core (5) is made of a single bead wire wound into a substantially polygonal cross sectional shape so that windings of the bead wire form radially piled-up wire arrays (L) which are inclined at an angle alpha of from 5 to 25 degrees with respect to the tyre axial direction (BL). The number (n) of windings of each wire array (L) gradually increases from a radially innermost wire array (L1) to a maximum wire array (LX) of which the number of windings (n-max) is maximum so that the polygonal cross sectional shape has a substantially trapezoidal region as a radially inner part. The width (W1) of the radially innermost wire array (L1) is in a range of from 0.4 to 0.7 times the width (W2) of the maximum wire array. The height (H) of the wire arrays measured from the radially innermost wire array (L1) to a radially outermost wire array (Lm) is in a range of from 0.8 to 2.0 times the width (W1) of the radially innermost wire array (L1). <IMAGE></p> |
