UK Tyre Tread Depth Legal Limit: What You Must Know
Driving on illegal tyres in the UK carries a fine of up to Call for a quote,500 and 3 penalty points — per tyre. That's potentially Call for a quote,000 and 12 points (an automatic ban) for four bald tyres. Here's what the law says and what you should actually do.
The Legal Minimum: 1.6mm
UK law (Road Vehicles (Construction and Use) Regulations 1986) requires that car tyres must have a minimum tread depth of 1.6mm across the central three-quarters of the tread width, around the entire circumference. This applies to all passenger cars, light vans, and trailers.
Motorcycles have different requirements (1mm), and heavy goods vehicles are also subject to specific rules. But for the average UK driver, 1.6mm is the number you need to know.
The Penalties Are Severe
Each illegal tyre carries:
- Call for a quote,500 fine (per tyre)
- 3 penalty points (per tyre)
Four illegal tyres = Call for a quote,000 and 12 points = automatic driving ban. Beyond the legal consequences, driving on bald tyres invalidates your insurance. If you're involved in an accident on illegal tyres, your insurer can refuse to pay out — and you could be held personally liable for all damages.
How to Check Your Tread Depth
The 20p test: Insert a 20p coin into the main tread grooves at several points across the tyre and around the circumference. If the outer band of the coin (about 2mm from the edge) is visible, your tread is below 2mm and you should replace the tyre soon. If the outer band is completely hidden, you have adequate tread remaining.
Tread wear indicators: All modern tyres have built-in tread wear indicators (TWIs) — small raised bars sitting at 1.6mm in the main tread grooves. When the tread surface wears level with these bars, the tyre has reached the legal minimum and must be replaced.
Digital gauge: For the most accurate reading, use a digital tread depth gauge (under Call for a quote from any motor factors). Check at least three points across the tread and at several positions around the circumference. Uneven wear patterns are common and may mean part of your tyre is below the limit even if other areas look fine.
Why 1.6mm Isn't Really Safe Enough
The 1.6mm legal limit was set decades ago and many tyre safety experts now consider it too low. Independent testing by organisations including MIRA, Continental, and the RAC Foundation consistently shows that tyre performance — particularly wet braking — degrades dramatically below 3mm.
At 1.6mm on a wet road at 50 mph, your braking distance can be up to 44% longer than at 3mm. That's a massive difference. Most European motoring organisations and the AA recommend replacing tyres at 3mm. We agree — and most of our technicians will flag any tyre below 3mm during a service.
Tread Depth and MOT
Tyres are one of the most common reasons for MOT failure in the UK. The tester will check tread depth, sidewall condition, tyre size and type, and general condition. A tyre at 1.7mm will pass the MOT but could easily drop below 1.6mm within weeks — leaving you driving illegally without realising it. If your MOT is coming up and your tyres are marginal, replace them first.