Abstract: There is disclosed a brake wear indicator which is suited for the retrofit installation on vehicle pneumatic brakes. The wear indicator comprises a sleeve that loosely fits over the push rod of the pneumatic actuator. The sleeve has an outside diameter permitting it to be received in the aperture of the actuator housing which slidably receives the push rod and is frictionally engaged within this aperture. When the vehicle brakes are applied during normal operation, the sleeve is extended from the actuator by the diaphragm member assembly which subdivides the actuator housing into the air pressure chamber and the ambient chamber which receives the push rod. Indicia are calibrated on the exterior surface of the sleeve whereby one can directly observe the degree of sleeve travel which corresponds to the push rod travel in the brake system. A continuous reading is thus obtainable on the degree of wear of the brake system.