Bead of a tire for a heavy vehicle of construction plant type

A tire for a heavy vehicle of construction plant type comprising two beads intended to come into contact with a rim a carcass reinforcement comprising at least one carcass reinforcement layer made of a metal reinforcing elements, the carcass reinforcing layer comprising a main part wrapped, within each bead, from the inside towards the outside of the tire around a bead wire to form a turn-up, the distance (d) between the turn-up and the main part decreasing continuously, radially towards the outside, from the bead wire, as far as a minimum distance (d1), then increasing continuously as far as a maximum distance (d2), each bead comprising a filling element extending the bead wire radially towards the outside, the filling element being formed of at least two polymer filling materials, a first polymer filling material being radially furthest towards the inside and in contact with the bead wire, a second polymer filling material being radially on the outside of the first polymer filling material and having an elastic modulus at 10% elongation that is lower than the elastic modulus at 10% elongation of the first polymer filling material, wherein a transition element, made of a polymer transition material, is in contact, via its radially inner face, with the first polymer filling material and in contact, via its radially outer face, with the second polymer filling material, and wherein the elastic modulus at 10% elongation of the polymer transition material is somewhere between the respective elastic moduluses at 10% elongation of the first and second polymer filling materials.