UK Tyre Tread Depth Laws:
What Every Driver Must Know

Worn tyres are one of the most common causes of MOT failures and roadside penalties in the UK. Yet many drivers don’t know the legal minimum — or how to check it. Here’s everything you need to know.

What is the Legal Minimum Tyre Tread Depth in the UK?

This applies to all cars, vans and light trailers. The law is set out in the Motor Vehicles (Construction and Use) Regulations 1986. Driving on tyres below this limit is a criminal offence.

What Are the Penalties for Illegal Tyres?

Each illegal tyre can result in:

• A fine of up to £2,500
• 3 penalty points on your licence — per tyre
• Possible vehicle prohibition if stopped by police
• Invalidated motor insurance (an insurer may refuse a claim if you’re found to have illegal tyres at the time of an accident)

How to Check Your Tyre Tread Depth

There are three easy ways:

1. The 20p Coin Test

Insert a 20p coin into the main tread grooves of your tyre. If the outer band of the coin is visible, your tread may be below the legal minimum and you should get your tyres checked immediately. This is a rough guide only — for an accurate measurement, use a tread depth gauge.

2. Tread Wear Indicators (TWIs)

All modern tyres have built-in tread wear indicators — small raised blocks in the base of the tread grooves. When your tread wears down to the level of these blocks, you are at the legal limit. The location of TWIs is usually marked by a small triangle symbol on the tyre sidewall.

3. Tread Depth Gauge

A tread depth gauge (available from any car accessory shop for around £2-3) gives an accurate measurement in millimetres. Check in at least three places across the width of the tyre and at multiple points around the circumference.

When Should You Replace Your Tyres?

The law sets a minimum, not a recommendation. Tyre safety organisations and manufacturers — including Michelin, Continental and Bridgestone — recommend replacing tyres when they reach 3mm. Here’s why:

• Stopping distances on wet roads increase dramatically below 3mm
• At 1.6mm (legal limit) in wet conditions, stopping distances can be up to 44% longer than at 3mm
• Aquaplaning risk increases significantly with low tread depth

Beyond tread depth, you should also replace tyres that show visible cracking, bulging, cuts on the sidewall, or any signs of uneven wear. Tyres over 6-10 years old should be inspected by a professional even if tread depth looks adequate, as rubber degrades over time.

Get Your Tyres Checked in Hayes

If you’re unsure about your tyre tread depth or want a free check, call AK Mobile Tyre Fitting on 07549 328819. We serve Hayes, Uxbridge, Hounslow, Ealing and all of West London. We stock budget to premium tyres and can fit them at your location the same day.