Most UK drivers know the headline number. The part they often get wrong is how that number is applied in the real world, and why a tyre can still be a problem before it is technically illegal.
For most cars, light vans and light trailers in the UK, the legal minimum tyre tread depth is 1.6mm. That figure is confirmed in GOV.UK roadworthiness guidance, while the DVSA MOT inspection manual explains how testers apply it in practice.
This guide covers what 1.6mm actually means, how MOT testers judge tyre tread, what else can fail a tyre even if the tread looks passable, and when replacing a tyre before the legal limit is the smarter move.
Quick answer
For most cars in the UK, a tyre must have at least 1.6mm of tread depth across the central three-quarters of the tread and around the entire outer circumference. If it drops below that standard, it is illegal on the road and it is also in MOT fail territory.
What is the legal tyre tread depth in the UK?
GOV.UK says tread must be a certain depth depending on vehicle type. For cars, light vans and light trailers, that minimum is 1.6mm.
That is the part most people remember. The part many do not is that the legal rule is not based on the best-looking section of the tyre. The depth has to be there across the middle working section of the tread, and it has to be there all the way round.
If you want the official wording behind the MOT side of this, the DVSA manual says the primary grooves must be at least 1.6mm deep within the central three-quarters of the breadth of tread and around the entire outer circumference of the tyre for the relevant vehicles most private motorists drive.
What does central three-quarters actually mean?
This is where drivers often get caught out.
The law does not mean the whole tyre width must measure 1.6mm from shoulder to shoulder. It also does not mean you can measure one neat-looking strip in the middle and ignore the rest.
In practical terms, the tyre needs enough tread across the middle 75 percent of its width, and that standard must be met all the way around the tyre.
So a tyre can be illegal if:
- one section of the middle band dips below the limit
- wear is patchy around the circumference
- the centre is legal in one spot but not in another
- the inner edge is badly worn and the worn area reaches into the part of the tread that must still meet the legal limit
That is why a quick glance at the outer shoulder is not a proper check.
Will 2mm pass an MOT?
Usually, yes.
A tyre at 2mm is still above the 1.6mm legal minimum, so it can pass on tread depth alone if there are no other problems. But 2mm is not a big safety cushion. If you do regular motorway miles, cover a lot of wet-weather mileage or know the tyre is wearing unevenly, it makes sense to plan replacement rather than trying to stretch every last fraction of a millimetre.
Legal and sensible are not always the same thing.
How MOT testers actually judge tyre tread
The DVSA MOT inspection manual is clear that different vehicle classes have different tread-depth rules, but for the cars most readers care about the working figure is 1.6mm.
The same manual explains that a tyre can fail not just because of low tread depth, but because of condition. Testers are looking for obvious safety issues such as:
- tread depth not in accordance with the requirements
- cuts deep enough to reach the ply or cords
- cords exposed or damaged
- lumps, bulges or tears caused by structural failure
- tyres on the same axle that are different sizes
- tyres on the same axle of different structure
- a tyre fouling part of the vehicle
That matters because a tyre can be above 1.6mm and still fail the MOT for damage.
How to check tread depth properly
1. Use a tread depth gauge
This is the clearest option. Measure more than one point across the tyre and more than one point around its circumference. A single reading can miss the area that is actually wearing fastest.
2. Look for wear indicators, but do not rely on them alone
Wear indicators are useful, but they are not a shortcut around proper checking. The legal test is still about the measured tread depth across the relevant part of the tyre.
3. Check all four tyres, not just the ones you can see easily
Front tyres often get the attention first, especially on front-wheel-drive cars, but rear tyres can still be close to the limit or wearing unevenly.
4. Ask the garage to note tread depth in writing
If the car is already in for a service, MOT, brakes or alignment work, ask for the tyre depths to be written down. That gives you a clearer picture than being told they are fine for now.
If uneven wear is part of the problem, our guide to wheel alignment vs tracking explains why geometry problems can eat through tread faster than many drivers expect.
Can a tyre be legal but still not a good idea to keep using?
Yes. Quite often.
A tyre at 1.7mm may still be legal today, but that does not mean it is a smart tyre to keep trusting for weeks. Wet-weather grip drops away as tyres wear down, and a tyre that only just clears the legal limit can turn into a problem sooner than expected if you use the car daily.
It is sensible to start replacement plans if:
- the tyre is close to the legal limit
- wear is uneven across the tread
- there are visible cuts, cracks or bulges
- grip in heavy rain has clearly worsened
- recent garage notes show the tyre is wearing down quickly
The legal limit is the floor, not the target.
Why tyres wear unevenly
If one tyre is wearing much faster than the others, the cause may matter as much as the tyre itself. Common reasons include:
- incorrect tyre pressures
- poor wheel alignment or tracking
- worn suspension parts
- damaged steering components
- pothole or kerb impacts
Replacing the tyre without fixing the cause can be false economy. You can easily ruin the next one the same way.
If your MOT or service has already uncovered other wear-related issues, our guide to common MOT repair costs in the UK gives a realistic idea of the bills that often follow neglected tyre and suspension problems.
Are worn tyres only an MOT issue?
No. The MOT is just the point at which many drivers finally have the tread measured properly.
GOV.UK’s vehicle safety guidance treats tyres as a routine roadworthiness check, alongside basics such as lights, fluid levels and brakes. A worn or damaged tyre is not just a paperwork issue. It is a grip, braking and safety issue every time the car is used.
A simple UK tyre tread checklist
If you want the short version, use this:
- measure all four tyres, not just the fronts
- check more than one point on each tyre
- make sure tread is above 1.6mm across the central three-quarters and around the full circumference
- look for cuts, bulges, cracks and exposed cords
- compare inner, centre and outer wear for signs of alignment or suspension trouble
- do not leave borderline tyres until MOT week if you rely on the car daily
That last point saves hassle. Tyres rarely become a problem at a convenient moment.
Tyre tread depth in the UK: the bottom line
For most UK cars, the legal minimum tyre tread depth is 1.6mm, and that depth has to be present across the central three-quarters of the tread and around the entire outer circumference.
That same standard sits behind the DVSA MOT inspection rules for the vehicles most motorists drive. If the tread is below that level, the tyre is not just worn. It is likely to be both illegal and an MOT fail.
But tread depth is only part of the story. Cuts, exposed cords, bulges and other tyre defects can still fail a car even when the tread number itself looks acceptable.
If your tyres are close to the limit, treat that as a replacement job to plan now, not a challenge to squeeze through one more month.
Frequently asked questions
What is the legal tyre tread depth for cars in the UK?
It is 1.6mm for cars, light vans and light trailers, measured across the central three-quarters of the tread and around the entire outer circumference.
Will 2mm pass an MOT?
Usually yes, because it is still above the legal minimum. But it is close enough to the limit that replacement should already be on your radar.
Can a tyre fail an MOT even if the tread depth is legal?
Yes. Cuts, visible cords, bulges and other serious tyre defects can still trigger an MOT failure.
Does the whole tyre need 1.6mm of tread?
No. The requirement applies across the central three-quarters of the tread width and around the entire circumference, not necessarily the full shoulder-to-shoulder width.
Is inner-edge tyre wear an MOT issue?
It can be. If the worn area reaches into the part of the tread that must still meet the legal limit, or the tyre is otherwise damaged, it can fail. Inner-edge wear can also point to alignment or suspension problems that need sorting properly.
Sources: GOV.UK vehicle safety guidance; DVSA MOT inspection manual, tyres section.
