Nearly 10 million motorists in the UK could find themselves driving a vehicle fitted with an illegal tyre in 2016, according to new research.
The survey, conducted by TyreSafe in partnership with Highways England, surveyed more than 340,000 replaced tyres at 819 retail outlets, revealing that more than 27% of tyres were already illegal when they were replaced.
This means that possibly more than one in four of the 37 million cars and light commercial vehicles (LCVs) on the UK's roads being driven with a tyre could cost its driver a £2,500 fine and three penalty points, an MoT failure or even an accident.
TyreSafe chairman Stuart Jackson said: "The tread depth survey results are a concern. Figures from the Department for Transport show that dangerous tyres are the largest single contributory factor in accidents resulting in casualties of any vehicle defect - including breaks.
"If the number of casualties from tyre-related incidents is to be reduced on our roads, the UK's motorists need to change their attitude to this primary safety feature and carry out regular checks to ensure their vehicle's tyres are roadworthy."
Tread depth must be at least the minimum legal limit of 1.6mm which is vital as it has a decisive impact on the amount of distance a vehicle takes to stop during wet conditions.
Studies in the past have shown that the braking distance of a vehicle with tread of 1.6mm is nearly 12m further than a vehicle with new tyres when braking in the wet from 50mph.
Jackson said: "The concern comes not just from the number of illegal tyres at the point of replacement, but also the proportion which were below 2mm - those with just 0.4mm left (half the thickness of a bank card) before reaching the 1.6mm legal minimum."
Jackson mentioned that research by TyreSafe revealed that 20 per cent of drivers have never checked their tyres and the majority of remaining motorists do not do so regularly.
He said: "The obvious conclusion is that while one-in-four tyres are illegal at the point of replacement, a further 43 per cent are changed before reaching 1.6mm more by good luck than good judgment.
"TyreSafe urges drivers to check their tyres regularly before their luck runs out."
70.4 per cent of tyres in the UK were illegal or below 2mm of tread depth at the point of replacement. Last year's tread depth survey revealed this figure was 66 per cent.
There is concern for TyreSafe that if this trend continues, there will be even more dangerous and illegal tyres on our roads next year.