The invention relates to a novel tire having beads of a specified structure. In particular, the tire, when viewed in meridian section, has a radial carcass reinforcement and a bead of specified structure. The bead features a reinforcement ring that is able to move axially. The tire also features structures that are responsive to axial movement of the reinforcement ring, which modify clamping of the bead on its rim causing the clamping to increase with increasing tension of the carcass reinforcement.