A method of estimating the available grip margin of a tire of a vehicle rolling on a ground involves: estimating a quantity Rslip ca, i.e., the ratio of the slip contact area and the total contact area of the tire on the ground; determining, in a signal processing unit, the grip potential used Pμ,used and/or the available grip margin of the tire Pμ,avail from the quantity and pre-established data corresponding to the type of the tire, where Pμ,avail=1−Pμ,used; and recording in a memory the grip potential used and/or the available grip margin of the tire.