Legal Tyre Tread Depth in the UK: The 1.6mm Rule Explained

The legal tyre tread depth in the UK is 1.6mm for cars. That minimum applies across the central three-quarters of the tread and around the entire circumference of the tyre. If a tyre falls below it, you could be fined up to £2,500 and get 3 penalty points for each illegal tyre, and RoSPA recommends replacing tyres long before then, ideally at 3mm.

What is the legal tyre tread depth in the UK?

The minimum tread depth for cars, light vans and light trailers is 1.6mm. It's measured in the main grooves, the ones that contain the tread wear indicators, across the central three-quarters of the tyre's width and all the way round.

Three things catch drivers out:

• One worn patch is enough. The 1.6mm has to be there around the whole circumference, so a bald spot from a skid or a locked wheel can make the tyre illegal even if the rest looks fine.
• Uneven wear counts. If the inner edge is wearing faster, measure the inner part of the central three-quarters, not just the middle of the tyre.
• Damage matters as well as depth. Cuts deep enough to reach the cords, lumps, bulges and exposed cords will fail an MOT however much tread is left.

Fines and penalty points for illegal tyres

Driving on a tyre below the minimum tread depth can mean a fine of up to £2,500 and 3 penalty points per illegal tyre. With four illegal tyres, the fines alone could in theory reach £10,000.

The points matter too. The offence code for defective tyres (CU30) stays on your driving record for four years from the date of the offence. Building up 12 or more points within three years can lead to a driving ban, and new drivers have their licence cancelled if they get 6 or more points within two years of passing.

At the MOT, tread below the legal limit is a dangerous defect. The car fails and can't be driven away until the tyre is replaced.

Why replace tyres at 3mm, not 1.6mm?

Tread grooves move water out from under the tyre so the rubber can grip the road. As the tread wears, they clear less water, and stopping distances in the wet get longer.

RoSPA's tyre safety factsheet recommends replacing worn tyres well before the 1.6mm limit, ideally as soon as they reach 3mm. TyreSafe says 3mm is the minimum commonly advised by tyre and safety experts, and cites MIRA tests in which cars with 1.6mm of tread had up to 44% longer braking distances in the wet than cars with 3mm.

So when is the right time to replace tyres? Treat 3mm as your planning point and 1.6mm as the absolute limit. That gives you time to compare prices instead of buying in a hurry.

How to check tyre tread depth: 3 ways

How to do the 20p test

1. Park on level ground. Turning the steering to full lock makes the front tyres easier to see.
2. Push a 20p coin into one of the main grooves.
3. Look at the coin's outer band. If it's hidden, the tread is above 1.6mm at that point.
4. Repeat at several points around the tyre and across its width, then do the same on every tyre.
5. If you can see the band anywhere, check with a gauge or ask a tyre fitter.

The 20p test only tells you about the legal limit. It can't show when you've reached 3mm, so a tread depth gauge is worth keeping in the car.

When to replace tyres: the warning signs

Replace a tyre, or have it checked straight away, if you notice any of these:

• tread at or approaching 3mm
• tread level with the wear indicator bars
• cuts, lumps or bulges in the sidewall
• exposed cords or wire
• cracking in the sidewall, which can be a sign of age
• one edge wearing much faster than the other, which can point to tracking or suspension problems
• a tyre that keeps losing pressure

Where you can, replace tyres in pairs on the same axle. At the MOT, tyres of different sizes or construction on the same axle are a major defect.

How old is too old? Tyre age and the DOT date code

Every tyre has a date code on its sidewall, usually four digits at the end of the DOT number. The first two digits are the week of manufacture and the last two are the year, so 2423 means week 24 of 2023. A tyre with only a three-digit code was made before 2000, so it's more than 10 years old.

You may have heard of a 10-year rule. Since 1 February 2021, tyres over 10 years old have been banned on the front steered axles of lorries, buses and coaches, and on all single-wheel fittings on minibuses with 9 to 16 passenger seats. It doesn't apply to private cars, and there's no law setting a maximum age for car tyres.

That doesn't mean age doesn't matter. RoSPA recommends asking your tyre manufacturer at what age they advise replacement, and checking regularly for signs of ageing: cracking or crazing on the sidewall, a distorted tread and a deformed tyre carcass. Cars that sit unused for long periods, and their spare tyres, need particular attention.

How to read a tyre size: 205/55 R16 91V

You'll need your tyre size to buy replacements. It's on the sidewall, in a format like this:

Your handbook lists the sizes approved for your car, and replacements should match the size and meet at least the load index and speed rating your car's manufacturer specifies.

Tyres at the MOT: what the tester checks

The tyre section of the MOT inspection manual covers:

• tread depth: below 1.6mm is a dangerous defect
• cuts deep enough to reach the cords (major), and lumps, bulges or tears (dangerous)
• matching size and construction on each axle (major if not)
• damaged valves and tyres not seated properly on the rim
• the tyre pressure monitoring system on cars first used from 1 January 2012 (major if it's malfunctioning)
• obviously under-inflated tyres (minor)

The spare tyre isn't inspected. Tyre faults were found on 6.23% of car and light van MOTs in DVSA's figures for April 2025 to March 2026, and 4.47% of all tests recorded a dangerous tyre defect. Our guide to the most common MOT failures has the full picture, and our MOT checklist covers the other 18 checks worth doing before you book your MOT.

Buying replacement tyres

1. Find your size. Read it from the sidewall or your handbook.
2. Choose your tyre. The tyre label rates wet grip, fuel efficiency and external noise, which helps you compare models at a similar price.
3. Compare prices. Tyres.net lets you search by tyre size, such as 205/55 R16, and tyre type, compare prices and brands across partner retailers, then buy from the retailer you choose. Fitting and delivery options depend on that retailer, so check them before you order. Start on our compare tyre prices page.
4. Think about the season. If you drive in a cold, rural or hilly area, all-season or winter tyres may suit you better. Our guide to winter vs all-season tyres in the UK explains the trade-offs.
5. Sort out uneven wear. If your old tyres wore unevenly, have the wheel alignment and suspension checked, for example at your next car service.

Your monthly tyre routine

A few minutes once a month keeps you legal and safer:

1. Check pressures with the tyres cold, using the figures in your handbook.
2. Do the 20p test, or use a gauge, on every tyre.
3. Look along each sidewall for cuts, bulges and cracks.
4. Make a note of the tread depth, so you can see how fast it's wearing and plan ahead.
5. Look up your car's MOT history for any tyre advisories from past tests.