Abstract: Annular mask designed to be applied to the flange of an automobile wheel rim between the flange and the base of the tire to protect. The mask being made of a strong material, preferably steel sheet, in the form of a split ring shaped like the frustum of a cone with a wide apex angle, and with its two ends overlapping one another in an overlap sector. A separating device is provided for opening the mask for the pruposes of installation and removal.