How to Check Your Tyre Tread Depth

Your tyres are the only point of contact between your car and the road surface. The tread pattern is specifically designed to channel water away, maintain grip, and keep you safe — but as it wears down, your stopping distances increase dramatically. Knowing how to check your tread depth takes just a few seconds and could save your life.

What Is the Legal Minimum Tread Depth in the UK?

In the UK, the legal minimum tread depth is 1.6mm across the central three-quarters of the tyre, around the entire circumference. Driving with tyres below this limit is not only dangerous — it is also illegal and can result in a fine of up to £2,500 and three penalty points per tyre. That means four illegal tyres could land you a £10,000 fine and 12 penalty points, which is an automatic ban.

The 20p Test: Quick and Simple

The easiest way to check your tyre tread at home is the 20p test:

• Take a 20p coin and insert it into the main tread grooves of your tyre
• If the outer band of the coin is hidden by the tread, your tyre is above the legal limit
• If you can see the outer band, your tread is getting low and the tyre should be inspected or replaced

Repeat this test in several places across each tyre — both in the centre and near the edges — as wear is not always even.

Using a Tread Depth Gauge

For a more precise measurement, you can use a tread depth gauge, available from most motor factors for just a few pounds. Simply push the gauge into the tread groove and read the measurement. New tyres typically start with around 8mm of tread, so anything below 3mm is worth paying attention to, and at 1.6mm you must replace immediately.

Why 3mm Is the Recommended Replacement Point

While 1.6mm is the legal minimum, most tyre safety experts and motoring organisations recommend replacing tyres at 3mm. Research shows that stopping distances increase significantly below 3mm:

• At 3mm, stopping from 50mph on a wet road takes approximately 35 metres
• At 1.6mm, the same stop takes around 43 metres — that is an extra 8 metres, or roughly two car lengths

In wet conditions, those extra metres could be the difference between stopping safely and a collision.

Signs of Uneven Tyre Wear

When checking your tread, look for patterns that suggest other problems:

• Wear on both edges — the tyre is likely underinflated
• Wear in the centre — the tyre is likely overinflated
• Wear on one edge only — this often indicates a wheel alignment issue
• Patchy or cupped wear — could point to suspension problems or unbalanced wheels

If you spot uneven wear, it is worth having the cause investigated before fitting new tyres — otherwise the new ones will wear unevenly too.

How Often Should You Check?

A good rule of thumb is to check your tyre tread depth at least once a month and before any long journey. It only takes a couple of minutes and gives you peace of mind. If you are in Oxford or anywhere across Oxfordshire and are unsure about the state of your tyres, NN Mobile Tyres can inspect them at your location.

Frequently Asked Questions

Is it an MOT failure if my tread is below 1.6mm?

Yes. Any tyre with tread depth below the legal minimum of 1.6mm across the central three-quarters will result in an MOT failure. It is also a dangerous defect classification, which means the vehicle should not be driven until the tyre is replaced.

Can I be fined for worn tyres even if I have not been in an accident?

Absolutely. The police can issue a fixed penalty notice for illegal tyre tread during a routine stop or spot check. Each illegal tyre carries a potential fine and penalty points.

Does tyre age matter as well as tread depth?

Yes. Even if the tread looks fine, tyres older than five years should be inspected regularly, and most manufacturers recommend replacing them after ten years regardless of tread. Rubber deteriorates over time, becoming harder and less grippy.

Need help? Call NN Mobile Tyres on 07362 638978 or WhatsApp us — we are available 24/7 across Oxfordshire.