MORE than 8,000 cars have failed the NCT so far this year because their tyres were fitted the wrong way around.
Untrained and 'unscrupulous' fitters are being blamed for the dangerous mix-up.
Large numbers of modern tyres have treads with special grooves for better grip in wet and slippery conditions, to reduce stopping distances and avert accidents.
These are called 'directional' tyres and have arrows on the side showing the way they should be fitted – but more than 8,000 had the arrows facing in the opposite, incorrect direction when NCT tested, new research reveals.
Those 'backways' tyres heighten the risk of an accident because they have substantially less grip on wet roads so incorrectly fitted tyres automatically invokes a re-test.
Tyres are the second most common reason for failing the NCT, after problems with front suspension.
Now, for the first time, tyre outlets are being licensed as safety concerns grow, not just for 'backways' fittings but over the numbers of part-worn tyres being sold.
All staff of licensed retailers will now be independently assessed and accredited.
The clampdown also means the licensed retailers will not sell part-worn tyres – they describe them as "potentially dangerous products".
It is the first time standards have been introduced in the industry and follows a mandate from members of the Irish Tyre Industry Association (ITIA). So far, 35 outlets have been licensed.
A survey by the ITIA last year found that more than 50pc of second-hand or part-worn tyres sold here were dangerous or 'not fit for purpose' because of tread depth, condition or age.
ITIA president Kevin Farrell says the new self-regulation system should reduce the numbers having to get their cars retested due to tyre issues.
His association's analysis of the NCT's statistics is the first of its kind.
"Both from anecdotal evidence from our members and from the NCT statistics, the incorrect fitting of tyres by untrained fitters is clearly widespread, and is endangering road users," he said.