Tyre Tread Depth: UK Legal Requirements Explained

Tyre tread depth isn’t just about grip or comfort — it’s a matter of safety and legality.
In the UK, thousands of vehicles fail MOT tests each year because of worn tyres, and driving below the legal tread limit can lead to hefty fines and penalty points.

Here’s everything UK drivers need to know about legal tyre tread depth, how to measure it, and why it matters more than most people realise.

What Is the Legal Tyre Tread Depth in the UK?

According to UK law (The Motor Vehicles (Construction and Use) Regulations 1986) and DVSA standards, your car tyres must have:

A minimum tread depth of 1.6mm across the central three-quarters of the tyre, around its entire circumference.

That means:

• The outer edges can have slightly less tread,
• But the main contact area — the middle three-quarters — must stay above 1.6mm at all times.

What Happens If Your Tyres Are Below the Legal Limit?

Driving with illegal tyres can result in:

• A fine of up to £2,500 per tyre
• 3 penalty points per tyre
• Potential MOT failure

In extreme cases, especially after an accident, driving with illegal tyres can also invalidate your insurance.

New Tyre Tread Depth (and When to Replace)

New car tyres typically have a tread depth of around 8mm. 

While the legal limit is 1.6mm, both the DVSA and tyre manufacturers recommend replacing tyres once they reach 3mm.

Why?

• Braking distance on wet roads increases dramatically below 3mm.
• At 1.6mm, stopping distance can be double that of a new tyre.

Want to know what typically affects tyre lifespan? Read our guide on how long tyres last and what shortens it 

How to Check Your Tyre Tread Depth

You can measure tread depth in a few simple ways:

1. The 20p Test

• Insert a 20p coin into your tyre’s tread groove.
• If you can see the outer rim of the coin, your tread is likely below 1.6mm — and not road legal.

(The raised border of a 20p coin measures roughly 2.7mm — a simple and accurate home test.)

For a full step-by-step walkthrough, see our 20p tyre test guide. 

2. Tread Depth Gauge

A digital or manual gauge gives an exact reading in millimetres and costs less than £10.

3. Built-in Tread Wear Indicators

Most tyres have small raised rubber bars inside the tread grooves. 

Once these sit level with the tread, it’s time to replace your tyres.

Tyre Tread Depth for Different Vehicle Types

Why Tyre Tread Depth Matters for Safety

• Wet Grip: Deeper tread channels more water away, reducing aquaplaning risk.
• Shorter Braking Distances: Every millimetre lost increases stopping time.
• Better Fuel Efficiency: Proper tread reduces rolling resistance.
• MOT Compliance: Low tread is a common reason for MOT failure.

Tyre Tread Depth – Quick Facts

• Legal Minimum: 1.6mm (central three-quarters) 
• New Tyres: Around 8mm 
• Replace By: 3mm for best safety 
• Penalty: £2,500 + 3 points per tyre 
• Best Check: The 20p test or a tread gauge.

Final Word

Your tyres are your car’s only contact with the road — just four patches of rubber keeping you safe at every speed. 

Checking tread depth regularly can prevent accidents, MOT failures, and costly fines.

Book a free tyre tread check near you through Tyre Savings’ trusted UK fitting partners — or order new tyres online with fitting included.

FAQs: Tyre Tread Depth in the UK

Q1: What is the legal minimum tread depth in the UK? 

1.6mm across the central three-quarters of the tyre’s tread around the full circumference.

Q2: Will low tread cause MOT failure? 

Yes. If tyres are below 1.6mm, your vehicle will fail its MOT.

Q3: When should I replace my tyres? 

The DVSA and tyre experts recommend replacing tyres when tread reaches 3mm for safe braking and wet grip.

Q4: How often should I check tyre tread depth? 

Every 2–4 weeks or before long journeys.

Q5: Can I check the tread depth myself? 

Yes — the 20p coin test or a tread gauge both work effectively