Method for ascertaining the deformation of a tyre casing subjected to a load when mounted on a wheel so as to constitute a pneumatic mounted assembly in rolling state with rotation speed W, said tyre casing having a crown, intended to be in contact with the ground, and in revolution about a natural rotational axis, comprising the following steps: - Fastening at least one sensor to the tyre casing at the crown of the tyre casing so as to generate at least one output signal sensitive to the acceleration, in the direction normal to the crown, applied to said sensor in the tyre casing; - Acquiring at least one first temporal signal Sig comprising at least the amplitude of the at least one output signal while rolling; - Delimiting the first signal Sig over a number N TdR of wheel turns so as to construct a wheel-turn signal Sig TdR, N TdR being greater than 1; - Determining at least one reference speed W reference associated with at least one portion of the wheel-turn signal Sig TdR; the method being characterized by the following steps: - Normalizing the at least one portion of the wheel-turn signal Sig TdR; by a variable which is a function F proportional to the square of the reference speed W reference, over a number of wheel turns N' TdR, N' TdR being greater than or equal to 1; - Angularly resampling the at least one portion of the wheel-turn signal Sig TdR; - Defining at least one first energy density S from the at least one portion of the angularly resampled normalized wheel-turn signal Sig TdR, named S + when the at least one portion of the angularly resampled normalized wheel-turn signal Sig TdR; is greater than a threshold A, or named S - when the at least one portion of the angularly resampled normalized wheel-turn signal Sig TdR; is less than or equal to said threshold A; - Identifying the deformation Def% of the tyre casing as a function G of the at least one first energy density S. - Fastening at least one sensor to the tyre casing at the crown of the tyre casing so as to generate at least one output signal sensitive to the acceleration, in the direction normal to the crown, applied to said sensor in the tyre casing; - Acquiring at least one first temporal signal Sig comprising at least the amplitude of the at least one output signal while rolling; - Delimiting the first signal Sig over a number N TdR of wheel turns so as to construct a wheel-turn signal Sig TdR, N TdR being greater than 1; - Determining at least one reference speed W reference associated with at least one portion of the wheel-turn signal Sig TdR; - Normalizing the at least one portion of the wheel-turn signal Sig TdR; by a variable which is a function F proportional to the square of the reference speed W reference, over a number of wheel turns N' TdR, N' TdR being greater than or equal to 1; - Angularly resampling the at least one portion of the wheel-turn signal Sig TdR; - Defining at least one first energy density S from the at least one portion of the angularly resampled normalized wheel-turn signal Sig TdR, named S + when the at least one portion of the angularly resampled normalized wheel-turn signal Sig TdR; is greater than a threshold A, or named S - when the at least one portion of the angularly resampled normalized wheel-turn signal Sig TdR; is less than or equal to said threshold A; - Identifying the deformation Def% of the tyre casing as a function G of the at least one first energy density S.