Is my tyre tread legal?

In Great Britain, a car first used from 3 January 1933 needs at least 1.6 mm of tread across the central three quarters of the tread breadth and around the entire circumference. That figure is on GOV.UK's vehicle safety page, in Highway Code Annex 6, and in the DVSA MOT inspection manual for cars and passenger vehicles, all checked in 2026. The law behind the manuals is regulation 27 of the Road Vehicles (Construction and Use) Regulations 1986.

The 1.6 mm line is a minimum, not a target. A tyre at 1.6 mm is legal for the depth test and has no spare tread left. Wet grip falls as the grooves shallow, and Highway Code rule 227 says stopping distances in wet weather will be at least double those on dry roads because the tyres have less grip. The legal test does not measure that extra risk. It only asks whether the remaining primary grooves still meet 1.6 mm in the right place.

The MOT manual is precise. A tread pattern is the combination of plain surfaces and grooves around the tyre. Grooves that contain tread wear indicators, or grooves cut as deep as those when new, are the primary grooves. Shallower sipes are secondary grooves and are not used for the depth test. The breadth of tread is the part of the tyre that can contact the road under normal use, measured at 90 degrees to the peripheral line of the tread.

The primary grooves must be at least 1.6 mm deep within the central three quarters of that breadth, and around the entire outer circumference. Either side of the central three quarters can be devoid of tread. Measuring the outer shoulder, where a tyre often looks healthier, is how people convince themselves a bald centre is still legal. It is not the test. Measure the lowest point in the legal band, then check that band all the way round, because a flat spot or a worn patch on one sector fails the circumference rule.

National Highways states that, for the vehicle classes this checker supports, a driver can face a fine of up to £2,500 and 3 penalty points per illegal tyre. DVLA lists the endorsement as CU30, using a vehicle with defective tyres, at 3 points, staying on the record for 4 years from the date of the offence. GOV.UK's vehicle safety page also states the wider dangerous condition figures: a fine of up to £2,500, a ban, and 3 penalty points.

The Sentencing Council guideline for defective tyres, used in England and Wales, treats the fine as per tyre. It says one set of points will normally cover offences on the same occasion, so four illegal tyres can mean four fines and one set of 3 points rather than 12 points. New drivers still need to watch the 6 point revocation in the first 2 years, because 3 points on a fresh licence is halfway to losing it. A totting disqualification at 12 points in 3 years is the other clock.

Insufficient tread depth is a dangerous defect in the DVSA manual for cars and passenger vehicles. A dangerous defect is a fail, and you should not drive the vehicle except in the narrow circumstances GOV.UK allows after a fail, which are a pre-booked test and a journey for repairs. The tester only inspects the tyres on the road wheels. A defect on a spare is advice, not a fail, until you fit that spare and use it on the road.

Depth is only one tyre fail. The same section of the manual fails a cut more than 25 mm or 10 per cent of the section width that reaches the cords, a lump, bulge or tear from structural failure, mixed structures such as radial and cross-ply on the same axle, different sizes on the same axle, a load or speed rating below the minimum, and a tyre fouling the vehicle. Obviously under-inflated is a minor defect. A tyre pressure monitoring system that is malfunctioning on an M1 car first used on or after 1 January 2012 is a major defect.

Use a proper tread depth gauge, not a 20 pence coin as a substitute for a number. Take several readings around the tyre in the central three quarters and keep the lowest. Check every tyre, including the inner twin on a van if there is one. Do this when you check pressures, which Annex 6 says should be weekly, and when the tyres are cold, because a hot tyre can mislead a pressure reading even though it does not change the tread depth.

Look as well as measure. A bulge, a cut that shows cord, a flap of tread lifting, or a valve that is cracked are illegal or unsafe even when the grooves still read 3 mm. Mixed brands are not themselves a fail. Mixed structures on the same axle are. If you are not sure of the structure, read the sidewall: radial is the usual passenger car construction, and mixing that with a cross-ply on the same axle is the MOT fail.

Motorcycles over 50 cc, large vehicles and passenger-carrying vehicles need at least 1 mm, across three quarters and in a continuous band around the circumference. Mopeds only need visible tread. Vehicles first used before 3 January 1933 also sit on the 1 mm rule in the MOT manual, as do passenger vehicles with more than 8 passenger seats. Zero-emission goods vehicles over 3,500 kg but not over 4,250 kg gross are in the 1.6 mm group with cars.

Light vans up to 3.5 tonnes and light trailers in the same first-use group use 1.6 mm. DVSA's towing safety guidance repeats that both the car and the trailer need at least 1.6 mm across the central three quarters and around the entire circumference. A trailer tyre is as much a legal tyre as a car tyre. Recut tyres are only permitted on specified heavier vehicles in the MOT manual, not on an ordinary car.

The 1.6 mm car figure is a Great Britain Construction and Use rule, applied in England, Scotland and Wales, and it is the figure the GB MOT manual uses. Wales has no separate tread depth. Northern Ireland runs its own MOT through the DVA and has its own construction and use regulations. Treat 1.6 mm on this page as the GB legal minimum for the vehicle classes the checker supports.

Enforcement still happens at the roadside in every UK nation. A GB car driven in Northern Ireland still has to be roadworthy. If you need the NI wording, use nidirect rather than assuming the GB manual is the NI manual.

It does not become legal again at the next MOT. Using it is the offence. A burst in motion is the version of that offence that also writes the car off. Annex 6 says if a tyre bursts, grip the wheel, let the car roll to a stop, and only change it if you can do so without putting yourself or others at risk. A worn tyre is also the defect most likely to turn a wet roundabout into a police report, and illegal tyres on a claim file are the sort of fact an insurer will read twice.

If you have already been stopped, the points are per the published rules above. If the MOT has already failed the car as dangerous for tread, do not drive it home except for the GOV.UK repair and retest journeys. Replace the tyre, keep the invoice, and only then treat the car as usable.

The 20 pence test is not the legal test. A coin can hint that the grooves are getting low. It cannot tell you 1.5 mm from 1.7 mm, and it cannot check the whole circumference. Another myth is that 1.6 mm is only an MOT fail, not a roadside offence. The Construction and Use rule applies whenever the vehicle is used. Another is that a part-worn tyre is allowed to be shallower. It is not. Once it is on the car, it has to meet the same 1.6 mm rule.

People also treat the spare as a free pass, mix winter and summer depths, and assume a van on a car licence uses a different number. Light vans up to 3.5 tonnes in the post-1933 group use 1.6 mm. Company cars and hire cars use 1.6 mm. Foreign cars used in Great Britain use 1.6 mm. The only published exceptions in the sources above are the 1 mm classes, mopeds with visible tread, and the extra bus and goods-vehicle age rules.