Boy racers in Bradford could be driving around in illegally and dangerously modified cars, experts have warned.

Roadside rescue organisation the RAC today said cars fitted with eye-catching body kits or other modifications could be breaking the law.

On one occasion a motorist had fitted extra-large wheels which then rubbed away the wheel arches so they became rusting and dangerous, a spokesman said.

The warning has been echoed by the Bradford-based West Yorkshire Casualty Reduction Partnership.

RAC inspector Ron Waldock said: “Car modification offers people an easy way to make their car stand out. When done well, they are done very well, but when done badly, they are illegal and dangerous.”

He warned car buyers in Bradford to be wary when buying customised cars and to get independent inspectors to check body parts have been properly fitted and the tuning has been done by a professional.

Insurance companies may also refuse to cover cars fitted with unsafe or illegal body kits, he said, or refuse to pay out if they are not notified of modifications.

Mr Waldock said: “One man had spent £3,500 having a body kit fitted to a Vauxhall Corsa. There were four six-inch diameter exhausts. When I asked what engine the vehicle had, it still had the 1,000cc three cylinder engine – it must have struggled to move.

“Another time a Peugeot 106 had been lowered so far the extra-large wheels were rubbing against the wheel arches and had rubbed away the inner liner and paint on the inner wings, so they were rusting.”

The West Yorkshire Casualty Reduction Partnership ran an event called the Great Yorkshire Cruise earlier in the year for car enthusiasts to show off their modified vehicles.

About 2,000 people visited the rally in Leeds and many were given advice by police officers about how roadworthy their cars were.

Philip Gwynne, a spokesman for the partnership, said: “Our view was car enthusiasts love their cars and want to have something distinctive and special.

“They are not out to flout the law but in some instances they are doing things to their cars which they don’t appreciate may breach the law.

“One of the main purposes of the Great Yorkshire Cruise was to provide the car enthusiasts with the opportunity not only to show off their cars but to get some advice from the police.”