Tyre Safety Guide UK 2026 | How to Check Your Tyres

Q: What is the legal minimum tyre tread depth in the UK?

The legal minimum tyre tread depth in the UK is 1.6mm across the central three-quarters of the tyre tread, around its entire circumference. Driving with tyres below this limit carries a fine of up to £2,500 and 3 penalty points per tyre.

Q: How often should I check my tyre pressure?

You should check tyre pressure at least once a month and before any long journey. Always check when tyres are cold (the car has been stationary for at least 2 hours). Incorrect tyre pressure can increase stopping distances, cause uneven wear, and reduce fuel efficiency.

Q: How do I check tyre tread depth?

Use a tread depth gauge for accurate measurement, or use the 20p coin test as a quick check. Insert a 20p coin into the main tread groove. If the outer band of the coin is hidden, your tread is above the legal limit. If you can see the band, your tyres may be illegal and should be checked by a professional.

Q: When should I replace my tyres?

Replace tyres when tread depth reaches 1.6mm (legal minimum) or preferably at 3mm for safety. Also replace if you notice bulges, cracks, cuts to the sidewall, or significant damage. Many manufacturers recommend replacing tyres over 5-6 years old regardless of tread depth.

The Basics

Why Tyre Safety Is Critical

Your tyres are the only point of contact between your vehicle and the road. In poor condition, they become a serious danger to you and everyone around you.

1 in 5

Road accidents involve tyre issues

According to road safety research, tyre-related problems contribute to approximately one in five serious road accidents in the UK each year. Worn, under-inflated or damaged tyres dramatically increase stopping distances and reduce your ability to steer out of danger.

£2,500

Fine per illegal tyre

Each tyre found to be below the legal minimum tread depth of 1.6mm can result in a fine of up to £2,500 and 3 penalty points on your licence. A car with four illegal tyres could therefore mean fines totalling £10,000 and 12 points — an automatic ban.

8m+

Extra stopping distance

A tyre worn to the legal minimum of 1.6mm can add more than 8 metres to your stopping distance in wet conditions compared to a tyre with 3mm of tread. At 70mph, that difference can be the gap between a near-miss and a serious collision.

Tyres degrade naturally over time through use, exposure to sunlight, and temperature changes. Even a vehicle used infrequently can develop dangerous tyres simply through age. Regular checks — which take no more than five minutes — can identify problems before they become emergencies.

This guide covers everything you need to know to keep your tyres safe, legal, and performing well. We recommend checking your tyres at least once a month and before any long journey. If you're ever unsure, Apex Mobile Tyres offers expert advice and a mobile tyre service across Coventry and the West Midlands — call 07593 103323 any time.

Legal Requirement

How to Check Tyre Tread Depth

Tread depth is the single most important indicator of a tyre's ability to grip wet roads safely. Here's how to measure yours.

Tread Depth Safety Guide

8mm+

New tyre — full performance

Excellent

4–8mm

Good condition — monitor regularly

Good

3mm

Recommended replacement threshold

Replace Soon

2mm

Significantly reduced wet grip

Urgent

1.6mm

Legal minimum — replace immediately

Illegal Below

1 The 20p Coin Test

The 20p coin test is a quick, everyday method any driver can use without any special tools. Here's how to do it correctly:

Take a 20p coin and insert it into the main tread groove of your tyre.
Look at the outer band of the coin — this rim is approximately 2mm wide.
If the band is hidden by the tread, your tyre is above the legal limit.
If the band is visible, your tyre may be at or below the legal limit — seek professional advice immediately.

Check multiple points around the tyre and across its width — wear can be uneven.

2 Using a Tread Depth Gauge

A dedicated tread depth gauge gives you an accurate reading in millimetres. These small, inexpensive tools are available at most motor factors and petrol stations.

Insert the probe into the tread groove, perpendicular to the tyre surface.
Press the gauge flat against the tread surface and read the measurement.
Measure in three places — both shoulders and the centre — for each tyre.
Record the lowest reading — that's the effective tread depth you should act on.

Most modern tyres include moulded wear indicators — small raised sections in the tread grooves at 1.6mm. When the tread is flush with these, the tyre is at the legal limit.

Monthly Check

Checking and Setting Tyre Pressure

Correct tyre pressure is essential for safe handling, fuel efficiency, and maximising tyre life. Over- or under-inflation both carry significant risks.

How to Find Your Correct Tyre Pressure

The correct tyre pressure for your vehicle is not the same for every car — it varies by make, model, load, and tyre size. Never rely on the maximum pressure printed on the tyre sidewall, as this is the maximum the tyre can handle, not the recommended operating pressure.

Where to find the correct pressure:

Door jamb sticker — open the driver's door and look for a sticker on the door frame or sill. It usually shows pressures for different load conditions.
Owner's handbook — the vehicle manual will list recommended pressures for normal and fully loaded conditions.
Fuel filler flap — on some vehicles, a pressure guide is also printed inside the fuel filler flap.

How to Check Tyre Pressure — Step by Step

Check when cold. Always measure tyre pressure before driving, or after the car has been parked for at least two hours. Heat from driving increases pressure and gives a false reading.
Remove the valve cap from the tyre valve stem and keep it safe.
Press the gauge firmly onto the valve. A hiss of escaping air means the gauge isn't seated correctly — re-apply.
Read the measurement (in PSI or bar) and compare it to the recommended level for your vehicle.
Inflate or deflate as needed, then recheck. Replace the valve cap securely when done.
Check all four tyres including the spare if your vehicle carries one.

Under-inflation risks

›Increased tyre wear on both shoulders
›Higher fuel consumption (up to 3%)
›Reduced handling and steering response
›Risk of tyre failure at high speed (blowout)

Over-inflation risks

›Accelerated wear in the centre of the tread
›Harsher ride and reduced comfort
›Less tyre contact with road — longer stopping distances
›Increased vulnerability to damage from potholes

When to check pressure

›At least once a month
›Before any long journey (100+ miles)
›After a significant temperature change
›If carrying a heavy load or towing

Visual Inspection

How to Spot Tyre Damage

Beyond tread depth and pressure, a regular visual inspection can identify damage that could cause a sudden blowout or tyre failure.

Sidewall Bulges or Bubbles

A bulge or bubble on the sidewall of a tyre is one of the most serious faults you can find. It indicates that the internal structure of the tyre — the cords or plies — has been damaged, usually from an impact with a pothole, kerb, or road debris.

Unlike tread damage, sidewall bulges cannot be repaired. A tyre with a sidewall bulge is at serious risk of sudden blowout, particularly at motorway speeds.

Action required: Stop driving and replace the tyre immediately.

Cuts and Cracks in the Sidewall

Small surface cracks in the rubber are common in older tyres and are often caused by UV exposure, ozone, or simply age. These are generally cosmetic if shallow. However, deep cuts or cracks that penetrate the carcass of the tyre are a serious safety concern.

Any cut on the sidewall that exposes the cords or fabric beneath the rubber — or that is deeper than around 6mm — means the tyre must be replaced without delay.

If in doubt, have a professional inspect the tyre before driving further.

Uneven Wear Patterns

Uneven wear across the tyre surface is a sign that something else is wrong with the vehicle — not just the tyres. Different wear patterns indicate different problems:

Centre wear: Over-inflation — too much pressure
Edge wear: Under-inflation — insufficient pressure
One-sided wear: Wheel alignment issue
Patchy/cupped wear: Worn shock absorbers or wheel balance

Replacing tyres without fixing the root cause will simply destroy the new tyres prematurely.

Age of Tyres

Rubber degrades over time regardless of how much a tyre has been used. Most manufacturers recommend replacing tyres after five to six years, and nearly all consider any tyre over ten years old to be unfit for use — even if the tread looks fine.

You can find the manufacture date using the DOT code on the sidewall. The last four digits indicate the week and year of manufacture — for example, "2422" means week 24 of 2022.

Check the DOT date code on your sidewall. If your tyres are over 6 years old, have them professionally inspected.

Replacement Guide

When to Replace Your Tyres

Knowing when to replace a tyre is as important as knowing how to check it. Here are the clear indicators that a replacement is needed:

Tread depth at or below 1.6mm — this is the legal minimum. At this point, your tyre is unsafe in wet conditions and could result in prosecution. Replace immediately.

Tread depth approaching 3mm — the safety-recommended threshold. While still legal, stopping distances increase noticeably below 3mm in wet weather. Start planning replacement.

Any sidewall bulge or bubble — no repair is possible. A bulge means the internal structure is compromised and blowout risk is high. Do not drive on this tyre.

Deep cuts, gashes or exposed cords — any damage that penetrates the tyre's carcass means the tyre must be replaced, not repaired.

Tyre is over 6 years old — rubber degrades with age. If you don't know how old your tyres are, check the DOT date code on the sidewall and have them inspected if they're approaching six years.

After a significant impact — if you've hit a pothole, kerb, or road debris hard, have the tyre inspected even if it looks undamaged. Internal damage may not be visible.

Need new tyres fitted in Coventry or the West Midlands?

Apex Mobile Tyres comes to you — at home, at work, or at the roadside. Available 24/7 with Fast, professional service.

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Expert Answers

Frequently Asked Questions About Tyre Safety

Common questions about UK tyre safety, answered by our mobile tyre specialists.

What is the legal minimum tyre tread depth in the UK?

The legal minimum tyre tread depth in the UK is 1.6mm across the central three-quarters of the tyre tread, around its entire circumference. This applies to cars, vans, and light trailers under 3,500kg. Driving with tyres below this limit carries a fine of up to £2,500 and 3 penalty points per tyre — meaning four illegal tyres could mean up to £10,000 in fines and 12 points, resulting in an automatic driving ban.

While 1.6mm is the legal minimum, most tyre manufacturers and safety organisations recommend replacing tyres at 3mm, as grip in wet conditions deteriorates noticeably below this level.

How often should I check my tyre pressure?

You should check tyre pressure at least once a month and before any long journey. Always check when tyres are cold — that means the car has been stationary for at least two hours and has covered no more than a couple of miles at low speed since. Heat from driving causes air inside the tyre to expand, giving a falsely high reading.

Incorrect tyre pressure can increase stopping distances, cause uneven wear, reduce fuel efficiency, and in severe cases lead to tyre failure. The correct pressure for your vehicle is found in the owner's manual or on a sticker inside the driver's door frame.

How do I check tyre tread depth at home?

Use a tread depth gauge for an accurate measurement in millimetres — these cost only a few pounds at most motor factors. Alternatively, use the 20p coin test as a quick check: insert a 20p coin into the main tread groove. If the outer band of the coin is hidden by the tread, you are above the legal limit. If the band is visible, your tyres may be at or below 1.6mm and should be checked by a professional immediately.

Always check multiple points across the tyre width and around the circumference, as wear can be uneven. Also check for the tyre wear indicator bars — small raised sections moulded into the tread grooves at 1.6mm that become flush with the tread surface when the legal limit is reached.

When should I replace my tyres?

Replace tyres when tread depth reaches 1.6mm (the legal minimum), or ideally at 3mm for improved safety margins. You should also replace tyres immediately if you notice any bulges, cracks, or cuts to the sidewall, or if significant tread damage is present.

Regardless of tread depth, many manufacturers recommend replacing tyres that are over five to six years old. Rubber compounds degrade with age, UV exposure, and temperature cycling — a tyre can become unsafe even if it looks fine on the surface. Always check the DOT date code to determine how old your tyres are.

Can I repair a punctured tyre or does it need replacing?

A tyre can often be safely repaired if the puncture is in the central three-quarters of the tread area and the hole is no larger than 6mm in diameter. Repairs must be carried out from the inside of the tyre using a combination patch-plug repair, following British Standard BS AU 159. A simple plug inserted from the outside only — a common roadside bodge — is not considered a permanent or safe repair.

Tyres with sidewall damage, run-flat damage (driven on while flat), or punctures outside the central tread area cannot be safely repaired and must be replaced. If you're unsure, always ask a qualified tyre technician to assess the damage.

What does a tyre safety check involve?

A professional tyre safety check covers all four tyres (and the spare if applicable) and includes: measuring tread depth across the full width of each tyre, checking tyre pressure against the vehicle manufacturer's specification, visual inspection of both sidewalls for bulges, cuts, cracks or embedded objects, checking the valve stems and caps, and inspecting for any signs of uneven wear that might indicate wheel alignment or suspension problems.

Apex Mobile Tyres provides professional tyre checks at your location across Coventry and the West Midlands. Call 07593 103323 to arrange a visit.

UK Tyre Safety Guide 2026