THE V6 C5 uses wider, lower-profile 215/55R16 tyres than the 195/65R15 rubber used on four-cylinder models. The V6 also has a sensor/transmitter located in each tyre valve that sends a signal to a receiver housed in the steering column. If the pressure drops below 0.3 bar below the recommended setting, a light and sound warning is activated. The C5 uses a full-size, cast alloy spare wheel.