Drivers could lose their licences and face a £10,000 fine for a simple 20p mistake — failing to ensure their car's tyre tread depth meets the legal minimum. The law requires a tread depth of at least 1.6mm across three-quarters of the tyre. Motorists caught with a tyre below this threshold face three penalty points and a £2,500 fine per tyre. If all four tyres are under the limit, the penalty rises to 12 points and a £10,000 fine, enough to trigger a driving ban.
Why tyre tread matters
Tyre tread is essential for grip, especially in wet conditions. The grooves remove water, helping the vehicle brake, steer, and accelerate. A study by MIRA found that cars with 1.6mm tread had up to 44% longer braking distances in the wet compared to those with 3mm tread.
How to check with a 20p coin
The RAC recommends the 20p coin test: insert a 20p coin into the tread grooves. If you cannot see the outer band, your tyres are above the legal limit. If the band is visible, the tyres may be unsafe and need professional inspection. The RAC advises checking every two weeks and before long journeys. For accuracy, a tread depth gauge can be used, and some modern cars have built-in wear indicators.
