The invention concerns a method for assessing the range of a motor vehicle run-flat system comprising at least for each wheel a tire casing, a deflation alarm and means supporting the running tread of the tire casing when the casing is deflated, which method, from the instant the deflation alarm has detected a predetermined deflating threshold, includes the steps of: periodically measuring the distance covered and a parameter C(t) characteristic of the running conditions; determining on the basis of C(t) and the measured distance over &Dgr;t a quantity characteristic of potential elementary damage of the system during the elapsed time &Dgr;t; calculating an estimate of the global damage by combining the calculated elementary damage levels since the start of flat running; and transmitting to the vehicle driver a quantity related to that estimate of the flat running system global damage.