Steel wire bead for tyres

A bead reinforcement structure (10) has at least one steel wire which makes several windings which build several layers, amongst which a radially inner layer and a radially outer layer. Each of said layers are built of one or more of windings so as to form a polygonal cross-sectional from The wire has a leading end (23) and a trailing end. The leading end (23) and the trailing end are positioned in a winding different from the left (22) or right winding (20) of the radially most inner layer.