Method for estimating the level of overall wear of a tyre of an assembly mounted under running conditions on a vehicle, the tyre having a crown which is extended by two sidewalls that end in two beads, exhibiting revolution about a natural axis of rotation, the crown comprising a tread situated radially on the outside of the tyre with respect to the natural axis of rotation, said tread having a mean thickness E, the mounted assembly comprising components, namely a wheel and the tyre, delimiting an internal cavity, comprising the following steps: - acquiring a transfer function F of the mounted assembly between a longitudinal stiffness K XX ref on a reference ground and influencing factors, as the product of a first function F1 having as influencing factors at least the inflation pressure P, the temperature T and the load Z experienced, and a second, bijective function F2 having at least as influencing factor the thickness E of the tread; - acquiring a passage function β of the mounted assembly, which depends from influencing parameters associated with use of mounted assembly such as the inflation pressure P, the temperature T and the load Z experienced, said passage function being defined for a section of road as the ratio of the longitudinal stiffnesses Kxx of the mounted assembly for the same influencing factors, the numerator stiffness being evaluated on ground equivalent to the section of road and the denominator stiffness being evaluated on a reference ground, the said longitudinal stiffnesses Kxx are determined by way of a characterization campaign comprising numerical simulations and/or experimental measurements; in one measurement cycle, that is to say the mounted assembly is under the same conditions of use for the parameters such as the inflation pressure P, the temperature T and the load Z experienced: - determining at least one force Fx experienced by the mounted assembly and at least one rate of slip g% at the wheel centre of the mounted assembly, or acquiring parameters Q1 of the vehicle allowing said determinations thereof, when the vehicle is running in a straight line involving variations in acceleration on said section of road, the latter being dry; - determining a load Z1, or acquiring parameters Q2 of the vehicle allowing said determination, experienced by the assembly mounted under running conditions; - determining a temperature T1 of the assembly mounted under running conditions; - determining an inflation pressure P1 of the internal cavity of the assembly mounted under running conditions, and characterized in that it comprises the acquisition of a first longitudinal stiffness K XX act of the mounted assembly on actual ground with the aid of a first relationship between the forces Fx, the rates of slip g% or the parameters Q1, in that it comprises the acquisition of a second longitudinal stiffness on the reference ground K XX ref, said second longitudinal stiffness being evaluated with the aid of the transfer function F supplied with at least the influencing factors T1, P1, Z1 or the parameters Q2 and at least one characteristic thickness E0 of the tread, in that it comprises the acquisition of a scalar β 1 defined with the aid of the passage function β supplied with at least the influencing factors T1, P1, Z1, and in that the thickness E of the tread is determined by a relationship between the scalar β 1, the first longitudinal stiffness K XX act and the second longitudinal stiffness K XX ref as follows: E = F 2 − 1 F 2 E 0 ∗ K xx act β 1 ∗ K xx ref - acquiring a transfer function F of the mounted assembly between a longitudinal stiffness K XX ref on a reference ground and influencing factors, as the product of a first function F1 having as influencing factors at least the inflation pressure P, the temperature T and the load Z experienced, and a second, bijective function F2 having at least as influencing factor the thickness E of the tread; - acquiring a passage function β of the mounted assembly, which depends from influencing parameters associated with use of mounted assembly such as the inflation pressure P, the temperature T and the load Z experienced, said passage function being defined for a section of road as the ratio of the longitudinal stiffnesses Kxx of the mounted assembly for the same influencing factors, the numerator stiffness being evaluated on ground equivalent to the section of road and the denominator stiffness being evaluated on a reference ground, the said longitudinal stiffnesses Kxx are determined by way of a characterization campaign comprising numerical simulations and/or experimental measurements; - determining at least one force Fx experienced by the mounted assembly and at least one rate of slip g% at the wheel centre of the mounted assembly, or acquiring parameters Q1 of the vehicle allowing said determinations thereof, when the vehicle is running in a straight line involving variations in acceleration on said section of road, the latter being dry; - determining a load Z1, or acquiring parameters Q2 of the vehicle allowing said determination, experienced by the assembly mounted under running conditions; - determining a temperature T1 of the assembly mounted under running conditions; - determining an inflation pressure P1 of the internal cavity of the assembly mounted under running conditions, and