In 2005, a flag-to-flag rule for MotoGP was introduced. Previously, if a race started dry and rain fell, officials could red-flag (stop) the race and either restart or resume on 'wet' tyres. Now, when rain falls, a white flag is shown, indicating that riders can pit to swap the motorcycle on which they started the race for an identical one, as long as the tyres are different (that is, intermediates or wets instead of slicks). Besides different tyres, the wet-weather bikes have steel brake rotors and different brake pads instead of the carbon discs and pads used on the 'dry' bikes. This is because the carbon brakes need to be very hot to function properly, and the water cools them too much. The suspension is also 'softened' up somewhat for the wet weather.