Tyre Tread Depth Guide (UK) — Legal Limit, Safety & How to Check

Tyre tread depth is one of the most important safety checks you can do.
Good tread helps your tyres grip the road, especially in wet conditions.

This guide explains:
✅ the UK legal limit
✅ recommended tread depth for safety
✅ how to check your tyres at home

What Is the UK Legal Tread Depth Limit?

In the UK, the legal minimum tread depth is:

✅ 1.6mm

Across the central ¾ of the tyre
Around the entire circumference

⚠️ If your tyres are below 1.6mm, they are illegal and unsafe.

What Tread Depth Is Recommended for Safety?

Even though 1.6mm is legal, most drivers replace tyres earlier for better grip.

Recommended tread depth:

  • ✅ 3.0mm for safer wet braking

  • ❄️ 4.0mm+ recommended for winter tyres performance

  • 🚐 Vans / heavy loads: often best replacing earlier for safety

Why Tread Depth Matters

Low tread depth increases:
❌ stopping distance
❌ risk of aquaplaning
❌ loss of grip in rain
❌ poor cornering stability

In wet UK weather, tread depth makes a big difference.

How to Check Tyre Tread Depth (3 Easy Methods)

✅ 1) Tread Depth Gauge (Best Method)

A cheap tread gauge gives the most accurate reading.

Steps:

  1. Put the gauge into the main tread grooves

  2. Press it down

  3. Read the number in mm

Check multiple points across the tyre.

✅ 2) 20p Coin Test (Quick Check)

This is a simple UK trick.

Steps:

  1. Put a 20p coin into the tread groove

  2. If you can see the outer rim of the coin clearly, your tread may be low

⚠️ This is not as accurate as a gauge, but it’s a good quick check.

✅ 3) Tread Wear Indicators (Built into the tyre)

Most tyres have wear bars inside the tread grooves.

When the tread is level with the wear bar:
⚠️ you’re near the legal limit (around 1.6mm)

Uneven Tyre Wear (What It Means)

If your tread is wearing unevenly, it usually means there’s a problem.

Wear on both outer edges

Possible causes:

  • underinflation

  • hard cornering

Wear in the centre of the tyre

Possible causes:

  • overinflation

Wear on inside edge only

Possible causes:

  • wheel alignment issues

  • suspension wear

If you notice uneven wear, it’s best to get it checked.

What Is Aquaplaning?

Aquaplaning happens when a tyre can’t clear water fast enough, so it rides on top of the water instead of gripping the road.

Low tread depth makes aquaplaning more likely, especially:

  • at higher speeds

  • in heavy rain

  • on worn tyres

Can You Get Fined for Low Tread?

Yes ⚠️

Driving on illegal tyres can lead to:
❌ fines
❌ points on your licence
❌ MOT failure
❌ invalid insurance in an accident

It’s not worth the risk.

When Should You Replace Your Tyres?

You should consider replacing tyres if:

✅ tread is close to 2mm–3mm
✅ tyre is worn unevenly
✅ cracking / ageing is visible
✅ bulges or cuts are present
✅ you feel vibration or poor grip

Even if tread is legal, old or damaged tyres can still be unsafe.

Quick Tyre Tread FAQ

Is 1.6mm safe?

It’s legal, but not ideal in wet conditions.
Most people replace tyres at around 3mm for better safety.

Do I need to replace tyres in pairs?

Recommended: Yes ✅
Replacing in pairs gives balanced grip and safer handling.

Can one tyre be replaced on its own?

It’s possible, but not always recommended.
It depends on wear levels and the condition of the other tyres.

Need New Tyres?

If your tread is getting low, it’s best to replace early to stay safe.

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