The law
For cars, light vans and light trailers, the tread must be at least 1.6mm deep across the central three-quarters of the width, around the entire circumference. The tyre must also be free of cuts over 25mm, bulges, tears and exposed cords, and be the right type and size for the vehicle.
Motorcycles over 50cc need at least 1mm across three-quarters of the width.
How to check: the 20p test
- Put a 20p coin into the main tread groove.
- If you cannot see the outer band of the coin, the tread is above 1.6mm.
- If you can see the band, the tyre may be illegal. Check it with a tread depth gauge or ask a tyre fitter.
- Repeat at three or four places around each tyre, and across the width, because tyres can wear unevenly.
Most tyres also have tread wear indicators: small raised bars inside the main grooves at 1.6mm. When the tread is level with the bars, the tyre is at the legal limit.
Why 3mm is a better limit
Tread clears water from under the tyre. As it wears, stopping distances on wet roads grow noticeably, and the risk of aquaplaning rises. Many tyre makers and road safety groups recommend changing tyres before they reach 3mm.
Fines and points
Driving on illegal tyres can mean a fine of up to £2,500 and 3 penalty points for each tyre. Four bad tyres could cost a driver their licence. Illegal tyres also fail the MOT.
Other tyre checks
- Pressure: check monthly, when the tyres are cold, against the figures in the handbook or door frame.
- Age: the four-digit DOT code shows the week and year of manufacture. Tyres older than about 6 years can harden and crack even with good tread.
- Size and ratings: use our tyre size calculator to decode the sidewall and compare sizes.
Sources
- GOV.UK: Tyres, vehicle safety
- TyreSafe: Understanding tyre markings
- GOV.UK: Penalty points and endorsement codes
Checked against official sources on 15 October 2026. Rules and prices change, so confirm anything important on GOV.UK. Spotted something out of date? Tell us.