A method and an apparatus of determining geometrical dimensions of a motor vehicle wheel (rim/tire assembly) 1 by contact-less sensing, wherein the wheel is fixed on wheel receiving means 2 of a tire changer, that at least one light beam 21 is emitted on to the wheel or at least a part of the wheel, wherein the light beam reflected at the impingement area is detected, and wherein the directions of the emitted and reflected light beams are evaluated for determining the shape and/or position of the respective impingement area on the wheel.