Tire/wheel assembly for an automobile

The present invention relates to a mounted assembly (i.e. tire/wheel assembly) for an automobile vehicle, comprising a rim, a safety support which is mounted on the rim and at least the radially outer face of which is formed of a material of very high modulus, a tire casing mounted on the rim around said support, said rim having on each of its two peripheral edges a rim seat on which is mounted a bead of said casing, and comprising between its two seats a bearing surface receiving said support; this mounted assembly is characterised in that: the material of very high modulus has a secant tensile modulus at 10% elongation, measured at 80° C. and denoted E10, which is greater than 50 MPa; the mounted assembly is provided with a lubricating composition having values of viscosity (denoted respectively eta1 and eta2), expressed in Pa.s and measured at 20° C., which satisfy the following relationships: at a shear rate of 0.3 s-1: 80