The invention concerns a tyre P comprising at least two beads B assembled to a running tread (7) via two sidewalls (5), at least the first bead B having a seat (12B) sloping outwards, and a carcass reinforcement (1), formed with at least a belt (1A, 1B), anchored in said first bead B to at least an annular anchoring element (2), and whereof the meridian profile has a constant curvature direction in the first bead B and the sidewall (5) extending it radially, and a tangent TT' forming with the axis of rotation an angle phi 2 opening outwards not more than 70 DEG . The invention is characterised in that said sidewall (5) comprises an additional inextensible sidewall ring (4) located axially inside at least a carcass belt (1A), called axially outer belt, an extruded profile (6) of rubber mixture being radially located between the annular bead anchoring element (2) and the additional sidewall ring (4), and axially located inside the axially outer belt (1A).