Radial ply pneumatic tire

A radial ply pneumatic tire having an axis of rotation, a tread having a pair of lateral edges, a pair of reinforcing belts located radially inward of the tread, a pair of sidewalls, one sidewall extending radially inwardly from each lateral edge, a maximum section width, and a tire carcass structure, the tire carcass structure comprises:

• a) a pair of bead portions, one bead portion extending radially inwardly from each sidewall, each portion including a substantially inextensible core wherein the bead core has a coil of annularly wound round metal wire filaments, which in the toroidially shaped tire prior to its vulcanization, has a polygonal cross-sectional area defined by imaginary line segments contacting the outer surfaces of the filaments of the coil, the polygonal cross-sectional area has a flat base surface having a pair of edges and a width "W" between the edges and an axially inner first surface, an axially outer second surface and a radially outward point or surface, each first and second surface extending radially outwardly from an opposite edge of the flat base surface toward the radially outward point or surface, each first and second surface being tangent to the bead core, the first surface and the flat base surface forming an acute included angle .alpha. and the second surface and the flat base surface forming an acute included angle .beta., where .alpha. is greater than or equal to .beta.;
• b) a carcass reinforcing structure radially inward of the reinforcing belts extending circumferentially about the tire from one bead portion to the other bead portion, the carcass reinforcing structure having a first ply and a second ply, each ply having a pair of turnup ends, one turnup end of each ply being wrapped about each bead core and extending axially and radially outwardly, the turnup end of at least one ply terminating radially in proximity to the radial location of the maximum section width of the tire;
• c) an inner liner radially inward of the first ply;
• d) a pair of first fillers, a pair of second fillers, the first fillers each being between the first ply and the innerliner, one first filler extending from each bead portion radially outward to beneath the reinforcing belt, the second fillers being between the first and second ply, one second filler extending from each bead portion radially outward to beneath the reinforcing belt;
• and
• e) a bead filler located above each bead core and between the second ply and the turnup ends of the first and second plies.