Over two in five motorists drive with tyres so worn they are no longer road legal, a new survey shows.
Garage network HiQ says drivers using illegal tyres are a danger on the roads and they risk penalties that could send their car and van insurance premiums soaring.
The poll found that 42% of motorists drive their cars on tyres which have a tread depth under the legal minimum of 1.6mm across the width.
Potential dangers of worn out tyres include low grip on wet roads and longer braking distance than regular tyres.
In wet conditions a car with tyre tread depth of 3mm may take 31.3 metres to come to a halt while one with 1.6mm may take 39.5 metres to stop, tests by the Motor Industry Research Association (MIRA) show.
It is much too long a distance, with studies showing that even eight metres is dangerously long if a motorist is trying to avoid hitting a pedestrian or another vehicle.
Cars with all four tyres below legal tread depth can earn a motorist a straight ban with 12 penalty points on their licence and fines of up to £10,000.
© Press Association 2011