Tire for medium and heavy carrier vehicles

Claim 1

A tire for medium and heavy carrier vehicles having a tread, a radial carcass reinforcement anchored to at least one bead ring in each bead and a tread reinforcement formed of at least two plies of wires or cables parallel in each ply and crossed from one ply to the next, forming acute angles with the longitudinal direction of the tire, the radial carcass reinforcement having, when the tire is mounted on a rim and inflated to its operating pressure but not under load, as seen in meridian cross section, a neutral fiber whose point of intersection with the trace of the equatorial plane of the tire is at a radial distance from the point of contact of the tire with the flange of the rim at most equal to 0.65 times the maximum axial width of the neutral fiber, the width of the rim being at least equal to 0.88 times the maximum axial width of the neutral fiber, characterized by the fact that the tire being mounted on the rim and inflated to its operating pressure but not under load, the length of the segment of the neutral fiber of the radial carcass reinforcement between, on the one hand, a radially inner extreme point located at a radial distance outward of the point of contact of the tire with the flange of the rim equal to 0.1 times said radial distance between said point of contact and said point of intersection and, on the other hand, a radially outer extreme point located axially outward of said point of intersection and at a radial distance inward of said point of intersection equal to 0.1 times said radial distance between said point of contact and said point of intersection, is less than 1.20 times the distance between the two extreme points of said segment of the neutral fiber of the radial carcass reinforcement, said point of contact being located radially and axially inward of the point of maximum radial height of the flange of the rim, by the fact that the beads of the tire being mounted on the rim in their operating position and the tire being not inflated and not under load, the neutral fiber of the radial carcass reinforcement passes through a point located, on the one hand, radially inward of the point of intersection of the neutral fiber of the radial carcass reinforcement with the trace of the equatorial plane at a distance at most equal to 0.075 times the maximum axial width of the neutral fiber of the radial carcass reinforcement when the tire is mounted and inflated but not under load and, on the other hand, axially outward of the trace of the equatorial plane at a distance equal to one-third of the maximum axial width of the neutral fiber of the radial carcass reinforcement of the tire when mounted and inflated, said neutral fiber of the radial carcass reinforcement being symmetrical with respect to the trace of the equatorial plane, and by the fact that the radial carcass reinforcement has, at least along said segment of its neutral fiber, a relative elongation of less than 2.5% under a force equal to 10% of its ultimate tensile strength, whereby the belting action of the tread reinforcement under the effect of inflation to operating pressure is reduced to a relatively narrow zone centered on the equatorial plane so as to avoid the generation of harmful stresses at the tread reinforcement edges.