A quarter of company car drivers are driving their vehicles on illegal tyres and another 29% are waiting until they reach the minimum legal limit before getting tyres changed.

A survey of 1,800 tyres replaced between September and December 2007 revealed that 24.7% had worn below the legal limit of 1.6mm. A further 28.7% of tyres were replaced precisely on the legal limit of 1.6mm. 

This is despite advice that best practice is for tyres to be replaced when they reach 2mm of tread.

"Research shows that in wet weather it takes an extra car length to stop at 50mph if your tyres are at 1.6mm compared to 3mm,” said John Carlisle, head of operations at Sandicliffe Motor Contracts, which carried out the survey.