The humble 20 cent piece could save a life this long weekend.

Motorists are being urged to use the coin to check their tyre baldness before they drive away.

Jorn Scherzer of the Energy Efficiency and Conservation Authority says to place the coin into the tyre groove, base down.

He says if you can see the whole number '20', it's time to think about new tyres.

Jorn Scherzer says replacing with newer, more efficient tyres could make saving equal to 15 cents per litre.