It's a strong lesson for South African drivers thinking of skimping on tyre replacement. One in England has made a point of telling how he was paralysed after buying cheap, worn rubber for his MPV. Keith Johnston from Tyne & Wear in north-east England suffered life-changing injuries in a crash earlier in 2012 and is now permanently paralysed from the top of his chest down. He can only move his arms and neck.CHEAP PROVED COSTLYApart from the severe physical injuries, he also experienced emotional scars relating to the February 8 crash when he was driving his Renault Scenic in below-freezing temperatures and lost control on a curve. The car rolled into a ditch; his four passengers, fortunately, were not hurt. All the tyres on the Scenic had recently been bought in a used condition and were blamed as a major factor in the incident by a police investigation. The rear tyres had less than the legal tread depth.Johnston, however, admitted he had always bought worn tyres, unaware of the risks associated with them. He said: “I thought I was saving money with part-worn tyres but I’ve paid a terrible price. Unfortunately for me it’s too late but I would urge other drivers to steer clear of worn tyres - always opt for brand-new ones.”ONGOING INVESTIGATIONJohnston’s plight is the focus of a UK tyre safety campaign led by TyreSafe, a tyre safety organisation. It recently revealed the findings of an ongoing investigation carried out with Auto Express magazine into worn tyres.An independent tyre expert bought 50 used tyres and found 98% of them were sold illegally. A third of them had potentially dangerous damage; other serious safety issues included dangerous repairs, exposed cords and evidence of run-flat damage. One was described as "having the potential to kill". Stuart Jackson, TyreSafe's chairman, said: “It’s impossible to know the history of used tyres and the true extent of any damage which may have occurred inside the tyre. All tyres suffer from wear over time but TyreSafe always advocates the fitting of new one as the safest option.”Have you bought used tyres? They're sold freely at roadside stalls - perhaps its time for a government clampdown on such outlets. Tell us what you think in the Readers' Comments section below.