A turbocharger shaft is supported for rotation about its axis in a bearing housing by a pair of floating ring bearings disposed between the shaft and the bearing housing. The floating ring bearings are penetrated in a substantially radial direction by a plurality of apertures to allow the passage of lubricating oil between inner and outer surfaces of the ring. The apertures are arranged at irregular angular intervals around the ring so as to prevent the generation of sub-synchronous vibrations that occur during rotation of the turbocharger shaft. This reduces turbocharger noise and increases life.