How a Formula One steering wheel works

When a session starts dry but then starts to rain, the team will switch tyres but the driver has to change a setting on the bottom right-hand corner of the steering wheel for the new tyres.

Wet tyres have a bigger diameter to raise the ride height slightly and reduce the risk of aquaplaning.

The driver has to select the type of tyre on the steering wheel so that the onboard computers can understand the gearing and keep the telemetry and displays accurate.

http://getcartech.co.uk/in-car-technology/2011/10/12/how-a-formula-one-steering-wheel-works