In Australia, it was impossible to tell which tyre a car was using

A rule change this season means that teams must use both of the two types of tyre supplied during a race.

The two types must be distinguishable but a first attempt failed because a small white spot painted on the tyre could not be seen when the car moved.

Following a re-think, the softer of the two types will now have a white line painted within one of the four grooves.

Bridgestone's head of track engineering operations, Kees van de Grint, said: "This has received a positive response from teams and onlookers.

"It is time consuming to apply to the tyres but is clearly visible on track."