It means the tyre is still legal and passed, but the tread is nearing the 1.6mm minimum. The tyre should be checked regularly and replaced before it drops below the legal limit.
Last reviewed: June 2026
What the close to the legal limit advisory signals
A tyre worn close to the legal limit advisory means the tread is approaching 1.6mm but has not yet failed. An MOT certificate that reads tyre worn close to the legal limit is giving an early warning rather than recording a fault. The tyre measured above the legal minimum on the day, so it passed, but the tread is shallow enough that the tester judged it worth flagging. This advisory is among the most common on UK MOT certificates because tread wears steadily with every mile and many tyres reach this point well within a year.
- The minimum legal car tyre tread is 1.6mm across the central three-quarters of the tread and around the entire circumference.
- This requirement is set out in the Road Vehicles (Construction and Use) Regulations 1986.
- A close to the legal limit advisory means the tyre still passes, but tread is approaching the 1.6mm minimum.
- Driving on an illegal tyre can bring a fine of up to £2,500 and 3 penalty points per tyre.
- A tyre that is below 1.6mm at the test is a major defect and an MOT failure, not an advisory.
The figure that matters is 1.6mm. Under the Road Vehicles (Construction and Use) Regulations 1986, a car tyre must have at least 1.6mm of tread depth across the central three-quarters of the breadth of the tread and around the entire circumference. A tyre measuring at or just above that level will pass with this advisory; a tyre measuring below it fails. The advisory therefore signals that replacement is likely needed soon, even though no legal line has yet been crossed.
The legal minimum and how it is defined
The 1.6mm requirement is more specific than many drivers realise. It does not mean any single point of the tyre needs 1.6mm of tread. The law requires that depth across the central three-quarters of the tyre width and right around the circumference. This central band is the area that does most of the work in dry and wet braking, so the regulation focuses on it. A tyre worn unevenly, with plenty of tread on the outer edges but a bald strip down the middle or vice versa, can still be illegal even if parts of it look healthy.
Tread depth matters because the grooves channel water away from the contact patch. As tread reduces, the tyre is less able to disperse water, increasing the risk of aquaplaning and lengthening wet stopping distances. While 1.6mm is the legal floor, tyre and safety bodies often note that wet performance begins to degrade noticeably before that point, which is part of why the advisory exists: it gives the driver time to act before grip is compromised and before the tyre becomes unlawful.
How tread is measured at the test
During the MOT, the tester inspects each tyre across its width and around the circumference, checking the tread in the principal grooves. A calibrated tread depth gauge is used to take readings, and most tyres also carry moulded tread wear indicators: small raised bars set into the base of the grooves at 1.6mm. When the surface of the tread wears down level with these bars, the tyre is at the legal limit. The tester records an advisory when the tread is close to those indicators but has not yet reached them.
Drivers can carry out a rough check between tests. Placing a 20 pence coin into the main grooves gives a quick guide: if the outer band of the coin is hidden when inserted, the tread is likely above the legal minimum, and if the band is visible the tyre may be close to or below the limit and should be measured properly. This is a guide only, and a calibrated gauge or a tyre specialist gives a definitive reading. The table below sets out the key thresholds and what each one means.
| Tread depth | Status | Consequence |
|---|---|---|
| 3mm and above | Healthy | Pass, no advisory expected |
| Just above 1.6mm | Legal but worn | Pass, close to legal limit advisory |
| Below 1.6mm | Illegal | MOT failure, major defect |
| Below 1.6mm on the road | Offence | Up to £2,500 and 3 points per tyre |
Fines and penalties for an illegal tyre
Once a tyre drops below 1.6mm it is no longer legal to use on the road, and the consequences are significant. Driving on an illegal tyre can bring a fine of up to £2,500 and 3 penalty points, and crucially these penalties apply per tyre. A vehicle with all four tyres below the limit could in principle attract penalties on each one, meaning 12 points and a substantial financial penalty from a single check. Penalty points of this scale can lead to disqualification, particularly for newer drivers.
The advisory is the point at which a driver can avoid all of this at modest cost. Acting on a close to the legal limit note before the tread reaches 1.6mm keeps the vehicle both lawful and safe. Leaving it risks the tyre becoming illegal during normal use, since a tyre near the limit may wear past it within a few thousand miles. There is no grace period for an illegal tyre: the offence applies as soon as the tread is below the minimum, whether or not the MOT is still in date.
When to replace and what to check
There is no fixed deadline attached to the advisory, but the prudent course is to monitor the tyre and plan to replace it before the tread reaches the legal minimum. How quickly that happens depends on mileage, driving style, tyre quality, wheel alignment and tyre pressures. A tyre flagged as close to the limit should be measured every few weeks if the car is driven regularly.
Replacing tyres in pairs across an axle helps keep grip balanced from side to side, although it is the depth and condition that the law assesses, not whether tyres are matched. Uneven wear, such as a worn inner or outer edge, can point to misaligned wheels or incorrect pressures, and addressing those causes helps new tyres last longer. Any tyre work should be carried out by a competent fitter, and the spare, if fitted, should also meet the legal requirement before use.
It is also worth remembering that tread depth is only one of several tyre checks carried out during the MOT. The tester also looks for cuts, lumps, bulges and tears in the tyre wall, for cords or ply showing through the rubber, and for damage to the valve. Any of these can be a major or dangerous defect in its own right regardless of tread, so a tyre that is close to the legal limit and also damaged may fail for the damage even though the tread alone would have passed. Keeping tyres correctly inflated to the pressures in the vehicle handbook reduces uneven wear and helps the whole tyre last to its full mileage.
Frequently Asked Questions
What does 'tyre worn close to the legal limit' mean on an MOT?
It means the tyre passed the test but its tread depth is approaching the 1.6mm legal minimum. The tester has flagged it as an advisory so the owner can replace the tyre before it becomes illegal, but the car remains road legal for now.
What is the legal tyre tread depth in the UK?
The legal minimum for a car tyre is 1.6mm, measured across the central three-quarters of the tread width and around the entire circumference. This is set out in the Road Vehicles (Construction and Use) Regulations 1986 and applies to all cars on UK roads.
Will my car fail its MOT for a worn tyre advisory?
No. An advisory means the tyre is still above the legal limit and the vehicle passes. A tyre only fails the MOT if its tread is below 1.6mm or if it has other defects such as cuts, bulges or exposed cords, which are recorded as major or dangerous faults.
How long can I drive on a tyre close to the legal limit?
The MOT stays valid for its full term, so there is no legal cut-off tied to the advisory itself. The safe approach is to check the tread regularly and replace the tyre before it wears below 1.6mm, because at that point continuing to drive becomes an offence.
What is the fine for driving on an illegal tyre?
Driving on a tyre below the legal tread limit can bring a fine of up to £2,500 and 3 penalty points, and these apply per tyre. A car with several illegal tyres could face penalties on each one, which can quickly lead to a large fine and possible disqualification.
