Bearing of tumbling for a group support rotates of a vehicle, of the supplied type of means of centraggio for a respective element refraining mountable loyal to the external ring of the bearing rotates angularly and; the means of centraggio are defined from respective struck cylindrical of different diameter obtained laterally on the outside on an obtained muff like an independent and planted element axially of jolt and with interference in a frontal center of the external ring, so as to turn out connected angularly loyal and coaxial with the external ring; the muff door preferibilmente an element of cooperating estate with the inner ring of the bearing in order protect to held of fluid and powder the volventi bodies of the bearing. (Figure 1).