Tyre Safety Laws UK: What You Need to Know to Stay Legal
Driving on illegal tyres in the UK carries a fine of up to £2,500 and three penalty points — per tyre. That means four illegal tyres could result in a £10,000 fine and 12 points, enough for a driving ban. This guide explains UK tyre law in plain English so you know exactly where you stand.
The Legal Minimum Tread Depth in the UK
The legal minimum tread depth for car tyres in the UK is 1.6mm across the central three-quarters of the tread, around the full circumference of the tyre. This applies to cars, light vans, and light trailers.
Many tyre safety experts and manufacturers recommend replacing tyres at 3mm, not 1.6mm. The reason: wet braking distances increase significantly as tread depth drops below 3mm. At 1.6mm your tyre is legal, but it is meaningfully less safe than it was at 3mm — particularly on wet UK roads.
How to Check Your Tread Depth
- 20p coin test — Insert a 20p coin into the tread groove. If the outer band of the coin is hidden, your tread is above 1.6mm. If you can see the outer band clearly, your tyres may be illegal.
- Tread wear indicators — All modern tyres have small rubber bars moulded into the tread grooves at 1.6mm depth. When your tread is level with these bars, the tyre is at the legal limit.
- Tread depth gauge — Available from any motor factors for under £5. The most accurate method.
What Counts as an Illegal Tyre in the UK?
Under the Road Vehicles (Construction and Use) Regulations 1986, a tyre is illegal if it:
- Has a tread depth below 1.6mm across the central three-quarters of the tread
- Has a cut in the sidewall that is deep enough to reach the ply or cord beneath
- Has a lump, bulge, or tear caused by partial failure of the structure
- Has exposed ply or cord
- Is not the type or size specified for the vehicle
- Is mixed with an incompatible type on the same axle (e.g. mixing radial and cross-ply)
Penalties for Illegal Tyres
The penalties are applied per tyre:
| Offence | Maximum Fine | Penalty Points |
|---|---|---|
| Illegal tread depth (per tyre) | £2,500 | 3 |
| Defective tyre — bulge, cut, exposed cord (per tyre) | £2,500 | 3 |
| Wrong tyre type/size for vehicle (per tyre) | £2,500 | 3 |
Accumulating 12 or more penalty points within 3 years results in a minimum 6-month driving ban. New drivers who passed their test within the past 2 years face licence revocation at just 6 points.
Tyre Age and the Law
There is currently no UK law specifying a maximum tyre age, but there is strong guidance. Most manufacturers recommend replacing tyres over 10 years old regardless of appearance, and the British Tyre Manufacturers’ Association advises that tyres over 5 years old be inspected annually by a specialist.
You can check the age of a tyre from its DOT code on the sidewall. The last four digits indicate the week and year of manufacture — for example, “2318” means the 23rd week of 2018.
Spare Tyres and the Law
Spare tyres must also meet the legal minimum tread depth when in use. A space-saver spare (the narrow “temporary” spare found in many cars) is only legal at the speed and distance limits printed on it — typically 50mph and 50 miles. Driving a space-saver at motorway speed or for extended distances is illegal and unsafe.
MOT and Tyre Checks
During an MOT, the tester checks:
- Tread depth (failure if below 1.6mm)
- Tyre condition — cuts, bulges, exposed cord
- Correct size and type for the vehicle
- Tyre pressure (advisory only, not a failure point)
- Matching types on the same axle
A tyre failure during an MOT means your vehicle fails the test. Given that a new tyre costs less than an MOT retest, it is always worth replacing borderline tyres before the test.
Frequently Asked Questions
What is the legal tyre tread depth in the UK?
The legal minimum is 1.6mm across the central three-quarters of the tread, around the full circumference. Most safety experts recommend replacing at 3mm for adequate wet weather performance on UK roads.
Can I drive on a tyre with a slow puncture?
A tyre with a slow puncture should be repaired or replaced as soon as possible. Driving on an underinflated tyre is dangerous — it affects handling and braking — and a tyre that is significantly underinflated may be considered defective. Have it inspected immediately.
Is it illegal to mix tyre brands?
Mixing brands is not illegal in the UK, provided all tyres are of the correct type and size for the vehicle. However, mixing radial and cross-ply tyres on the same axle is illegal. It is strongly recommended to fit tyres in matching pairs on the same axle for consistent handling.
How often should I check my tyre pressure?
At least once a month and before any long journey. Tyres lose pressure naturally over time — approximately 1 PSI per month — and temperature changes affect pressure significantly. Underinflation increases tyre wear, fuel consumption, and the risk of blowout.