Pneumatic tire with locked bead construction

The present invention relates to the bead portion of a pneumatic tire, and more specifically of a tire for heavy duty use, comprising a bead core with a round or polygonal shape, an apex, a carcass comprising three reinforcing structures, comprising each at least one reinforcing ply. A tire () has three carcass reinforcing structures (). The second carcass reinforcing structure () is folded radially outwardly around each bead core 16 (), so that the edges () of the second carcass reinforcing structure () are each located between an apex () and the neighboring bead core. The third carcass reinforcing structure () has its turndown portions () folded radially inwardly around the turnup portion of the second carcass reinforcing structure () and the bead core, so that the edges () of the plies of the third carcass reinforcing structure are located at the radially inner side of the bead cores (). The first carcass reinforcing structure () has its turnup portions () folded radially outwardly around each bead core, the turnupportion of the second carcass reinforcing A structure () and the turndown portion of the third carcass reinforcing structure () so that the edges () of the plies of the first carcass reinforcing structure are located near the radially outer portion of the apex ().