The removal of timy bits of elastomeric material caused by the seal material repeatedly extruding through a small opening (extrusion gap or gap between a back-up ring and the metal surface) under pressure fluctuations, vibration or other relative movement. The rubber material can also be "pinched off" due to side loads increasing and decreasing the extrusion gaps.

The jerking action which occurs in a vehicle, due to the distortion within some tires as they are forced to traverse pavement ridges at a slight angle.