Abstract: An apparatus for cutting circumferential grooves in the tread of a pneumatic tire comprising at least one assembly formed of a knife whose cutting edge has the shape of the radial profile of the grooves to be created and a support to which the knife is connected and which guides the knife with respect to the pneumatic tire to be treated, the support being connected to a frame for bearing the pneumatic tire, is improved by having the support furthermore comprise a feeler. The depth of cut of the knife is controlled by the feeler which is connected to the support and arranged at a short distance from the knife.