Martin Rowlands, chairman...

Martin Rowlands, chairman of the National Tyre Distributors" Association (NTDA), said: "I am absolutely astonished. People aren"t having their wheels fitted properly, and that"s appalling." He is calling for improvements after we revealed that 85 per cent of technicians we visited didn"t tighten wheel nuts correctly. Rowlands warned the results could have frightening consequences. "People shouldn"t be in our profession if they can"t understand that this is a safety issue," he added.

We went undercover at 20 tyre fitters in London and Birmingham, ranging from big name chains to small independent operators. Each was asked to balance an alloy wheel on our test car, and afterwards it was checked to see if the technician had tightened the wheel nuts to the correct torque settings. We found that 17 of the 20 hadn"t. In extreme circumstances, the effect of incorrectly adjusted wheel nuts can result in the wheel coming loose, or even falling off completely.

Auto Express photographers caught a still-secret Porsche Cayenne losing one of its wheels while testing at the Nнѓбјrburgring in Germany back in issue 662.

The NTDA claims that a tyre fitter should ensure all wheel nuts are tightened to the correct setting, as laid out by the vehicle manufacturer, by using a torque wrench. However, on our test 65 per cent of the technicians didn"t appear to use a wrench to check their settings at all, and even where one was used, mistakes were still made.

"There"s no excuse for not using a torque wrench and not finding the correct settings for each car," added Rowlands. "It"s the responsibility of each tyre outlet to make sure their staff are doing their jobs properly."

The NTDA is planning to send a bulletin to all its members to alert them to our findings. Rowlands concluded: "Something needs to be done to help improve the situation within the industry."