MOT Tyre Law: Tyre Safety & UK Requirements

Your tyres are the only thing connecting your car to the road, so the law holds them to clear standards, and the penalties for getting it wrong are steep. These guides explain what UK law actually requires, what the MOT checks, and exactly where the line sits between a tyre that is legal and one that is not.

The legal minimum

The headline rule is tread depth. The UK legal minimum is 1.6mm, measured across the central three-quarters of the tyre and around its whole circumference, and it applies to cars, vans and light vehicles. The full tread-depth law explains exactly how it is measured and why safety experts urge replacement well before it.

The cost of getting it wrong is high: up to a £2,500 fine and three penalty points for every illegal tyre, which multiplies quickly across a set of four.

MOT Tyre Law: What the Test Checks

Tyres are one of the most common reasons a car fails its MOT. The test checks tread depth, condition, size, fitment and the pressure-monitoring system, and a tyre can be marked anywhere from an advisory to a dangerous defect. Knowing the faults that fail most often makes them easy to catch beforehand, and a quick tyre legality checklist settles most doubts in a couple of minutes.

Tyre MOT Rules: Tread, Damage & Fitment

Tyre MOT rules require every tyre to meet the same core standards set out in Regulation 27 of the Construction and Use Regulations 1986: legal tread depth, no damage that reaches the tyre's structure, the correct size and rating for the vehicle, and a working pressure-monitoring system. A tyre that fails any one of these is marked as an MOT defect, ranging from an advisory to a dangerous fault. The rules apply the same way whether a tyre is new, part-worn or ageing. The tread-depth rule, how faults are graded and the most common failures cover each of these in detail.

Damage, repairs and part-worns

Beyond tread, a tyre can be illegal through damage regardless of how much tread remains. A bulge means the structure has failed, a cut that reaches the cords leaves a tyre unroadworthy, and cracking and perishing can make even a well-treaded tyre brittle. Damage is hardest to deal with on the sidewall, which cannot be repaired, so it helps to recognise a tyre too damaged to drive. There are also firm rules on when a punctured tyre may be repaired rather than replaced, and on the sale of part-worn tyres, a trade where much of the stock on the market falls short of the legal standard. Guides on each of these follow in this section.

Tyre Sidewall Damage Law UK: When It's Illegal

Tyre sidewall damage law in the UK comes from Regulation 27(1)(c) of the Construction and Use Regulations 1986: a cut deeper than 25mm or 10% of the tyre's section width (whichever is greater), reaching the ply or cord, makes the tyre illegal. No minimum tread reading overrides it. Bulges and deep cracking that expose the same structure are treated the same way in practice, even though the regulation's wording focuses specifically on cuts. Unlike a tread cut, sidewall damage cannot be repaired, because the reinforcing cords sit close to the surface and any weakness there risks sudden failure.

Sidewall damage explained covers how to recognise it, and when a tyre is too damaged to drive sets out what to do if you spot it.

Age, winter and driving abroad

Rubber ages whether or not a tyre is used, and while there is no general age limit for cars, there is a legal one for larger vehicles. Winter brings its own rules: the UK has no winter tyre law, but several countries do, which matters most when driving in Europe. Snow chains and socks carry their own conditions, and winter tyres can be rated below the car's top speed by design.

Why the standards matter

Behind every one of these rules is stopping distance and grip. A tyre at the legal tread limit clears far less water than a newer one, so wet braking suffers badly and the risk of aquaplaning rises, which is why the law is a floor to stay above rather than a target to wear down to. The guides in this section explain each rule plainly, and what it means for staying both legal and safe.

Use the rule for the actual vehicle

Separate ordinary car tread requirements from motorcycle, heavy-vehicle and specialist rules. Also distinguish a legal limit, an MOT inspection criterion and a manufacturer's recommendation: they answer different questions. If a tyre is damaged or the car becomes unstable, deal with its condition rather than waiting to establish the likely fine. For travel abroad, check the destination and route requirements before departure, including seasonal markings and equipment.