a method and apparatus for sensing air pressure in pneumatic suspension units for a vehicle , such as a motorcycle , comprising : air pressure sensors capable of sensing air pressures in pneumatic suspension units to generate an output signal when the air pressures are below a predetermined level ; a vehicle speed sensor capable of sensing vehicle speed to generate an output signal when the vehicle speed exceeds a predetermined level ; a signal processor adapted to receive output signals from the pressure sensors and the vehicle speed sensor and generate an output when the air pressures in the pneumatic suspension units are below a predetermined level while the vehicle speed continues to be in excess of a predetermined level for more than a predetermined period of time . an indicating device produces an indicating signal when it receives an output signal from the signal processor .