Patent ID: 7493928

Claim:
A heavy duty tire comprising: a tread portion; a pair of sidewall portions; a pair of bead portions each having a bead core therein, the bead core having an aspect ratio (HC 1 /WC) of the maximum thickness HC 1 to the maximum width WC of from 0.43 to 0.58, the bead core having an axially inner thickness HCi and axially outer thickness Hco at the positions which divide the maximum width of the bead core into equal three parts, the axially outer thickness Hco being the maximum thickness and thicker than the axially inner thickness Hci, the bead core formed by winding a bead wire to form a substantially hexagonal cross sectional shape having a radially inner surface, and the radially inner surface of the bead core consisting of an axially inner part extending at angle of from 10 to 17 degrees with respect to the axial direction of the tire, an axially outer part extending substantially in parallel with the inner part and located radially outside of the axially inner part, and a step part connecting between the axially inner part and outer part to form one step; and a carcass comprising a carcass ply of cords extending between the bead portions and turned up around the bead core in each bead portion from the inside to outside of the tire so as to form a pair of turnup portions and a main portion there between, the turnup portion comprising a turnup main-part extending along an axially inner surface, a radially inner surface and an axially outer surface of the bead core smoothly, and a turnup sub-part extending from the turnup main-part toward the main portion near the radially outer surface of the bead core.