Pneumatic tire bead portion structure

A pneumatic tire for heavy duty use comprising a radial carcass (1) and two bead regions (5) each reinforced by a bead core (2), whereby the carcass comprises two sets of at least two textile plies each, anchored around the bead core (2), the plies (3A,3B) of the first set (3) being wrapped around the bead core (2) from the inside towards the outside of the tire and the plies (4A,4B) of the second set (4) being wrapped around the bead core (2) from the outside towards the inside of the tire and whereby the bead regions (5) each comprise an axially inner (6) and an axially outer (7) textile reinforcing layer and a rubber apex strip (8) of a substantially triangular cross-section extending radially outwardly from the bead core (2), said axially inner (6) and outer (7) textile reinforcing layer being respectfully disposed axially inside and outside of said first and second sets of carcass plies along the radial extent of the rubber apex strip (8), said first and second sets of carcass plies being separated from one another only below a separation point at the apex of the rubber apex strip (8), characterized

• in that the height (h.sub.1) of the radially outermost end of the rubber apex strip (8) is located between 0.15 and 0.2 times the height (h.sub.0) of the tire cross-section;
• in that the ply endings (3A', 3B') of the first set of plies (3) are located at a height which is lower than the height (h.sub.1) of the radially outermost end of the rubber apex strip (8);
• and
• in that the height (h.sub.2) of the radially outermost edge of the axially inner textile reinforcing layer (6) is higher than the height (h.sub.3) of the radially outermost edge of the axially outer textile reinforcing layer (7), of the height (h.sub.2) of the radially outermost edge (13') of the axially inner textile reinforcing layer (6) being located between 0.25 and 0.45 times the height (h.sub.0) of the tire cross-section and the height (h.sub.3) of the radially outermost edge (10') of the axially outer textile reinforcing layer (7) being located between 0.2 and 0.35 times the height (h.sub.0) of the tire cross-section.