The invention relates to a tire with radial carcass reinforcement, made up of at least one layer of metal reinforcing elements, the said tire comprising a crown reinforcement, itself radially capped by a tread, the said tread being connected to two beads via two side walls, the said tire comprising a first layer of polymer compound radially between the carcass reinforcement and the radially innermost layer of reinforcing elements of the crown reinforcement. According to the invention, the said first layer of polymer compound constitutes a buffer zone designed to trap oxygen on the outside of the said first layer, the axial width of the said first layer being at least equal to 70% of the width of the radially innermost layer of reinforcing elements of the crown reinforcement.