Tyre Tread Depth: UK Legal Limits and How to Check Yours
Driving on tyres below the legal tread limit carries a fine of up to £2,500 per tyre and three penalty points. Here's how to stay legal and safe.
In the UK, the legal minimum tyre tread depth is 1.6mm across the central three-quarters of the tread width, around the entire circumference of the tyre. Driving on tyres below this limit is a serious offence: you can face a fine of up to £2,500 and three penalty points per illegal tyre — potentially 12 points and £10,000 if all four tyres are below the limit.
The easiest way to check your tread depth is the 20p coin test. Insert a 20p coin into the main tread grooves. If you can see the outer band of the coin — approximately 2mm wide — your tread may be approaching or below the legal minimum and you should have your tyres checked professionally. A dedicated tread depth gauge (available from any motor factors for under £5) gives you a more accurate reading.
Most safety organisations, including TyreSafe and the IAM (Institute of Advanced Motorists), recommend replacing tyres at 3mm rather than waiting for the 1.6mm legal limit. Tests show that wet braking distances increase significantly between 3mm and 1.6mm — at 60mph in wet conditions, a car with 1.6mm tread takes an additional 8 metres to stop compared to 3mm tread.
New tyres start at around 7-8mm of tread. A useful tip: use your tyre's built-in wear indicators — small raised ridges moulded into the bottom of the tread grooves. When the tread surface is flush with these indicators, you're at 1.6mm and must replace immediately. Book with Trident Mobile Tyres for fast, convenient same-day fitting.
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