Abstract: Method of designing a tire for the steered axle of a heavy goods vehicle, having a nominal sidewall height F, having a tread in the new state having a maximum total width Lo for maximum contact with the ground and provided with at least four circumferential grooves each extending between the tread surface and a groove bottom, these grooves delimiting three intermediate ribs and two edge ribs axially bounding the tread, each edge rib having two lateral walls, one of which, known as the internal lateral wall, having a height PREp measured with respect to the bottom of the groove delimiting the edge rib, this internal lateral wall having, when viewed in section on a plane containing the axis of rotation, an inclination DEp, each edge rib having a width LEp greater than the width of each of the intermediate ribs, by iteratively determining values for the dimensions LEp, PREp and DEp that satisfy the following relationship: P(LEp, DEp, PREp)<1.105769231×F, with P(LEp, DEp, PREp)=?303.528?2.00675×LEp+10.

Abstract: Tire comprising at least one carcass-type reinforcing structure anchored on each side of said tire in a bead whose base is intended to be mounted on a rim seat, each of said beads extending generally radially outwardly in the form of sidewalls, the sidewalls being connected radially towards the outside to a tread, the carcass-type reinforcing structure extending circumferentially from the bead towards said sidewall, a crown reinforcing structure, each of the beads also comprising an anchoring region for holding the reinforcing structure in place, wherein said tread comprises an inner layer of substantially incompressible rubbery material and an outer layer of compressible rubbery foam wherein: the foam expansion ratio is greater than 50%; the thickness of the layer is greater than 2.0 mm and preferably greater than 4 mm; and the outer layer has a Shore A hardness of less than 30 and preferably of between 10 and 20 Shore A.