Drivers should never buy part worn tyres as they pose terrifying dangers to motorists and other road users, according to campaign group TyreSafe.
The firm carried out an investigation in which it purchased 50 part-worn tyres to test their quality. It found that more than a third had dangerous levels of damage or did not comply with regulations.
One tyre in particular had a metal object wedged 5cm through its tread, which was likely to cause "sudden and total tyre failure" in the future, with the potential to lead to a fatally devastating accident.
Other damage included exposed cords, bead damage, evidence that they had been driven flat or an indication of unsafe, dangerous repairs having been made to them.
Furthermore, 98 per cent of the tyres were sold illegally.
“Even if properly marked, it is impossible to know the history of a part worn tyre which makes it extremely difficult to be sure about its internal condition and safety credentials,” said chairman of TyreSafe, Stuart Jackson.
“With rigorous quality controls on all new tyres, fitting these as replacements is undoubtedly the safest option. What’s more, as our investigation showed, it’s often the best value too.”