Six Million Illegal Tyres Are on UK Roads and Each One Risks a £2,500 Fine

The four patches of rubber touching the road are the only thing standing between your car and a skid, yet millions of British drivers are rolling around on tyres that are not just unsafe but illegal. Industry body TyreSafe estimates that more than six million tyres reach the illegal tread limit on UK roads every year, and the penalty for each one is severe. A worn or defective tyre can land you a fine of up to £2,500 and three penalty points, and that is per tyre. Drive on four illegal tyres and you are theoretically looking at £10,000 in fines and twelve points, which is enough to lose your licence outright. Worse still, defective tyres were a factor in a sharp rise in serious road casualties.

This guide sets out the law, the figures behind the warning, the part worn tyre trade that catches out bargain hunters, and the simple checks that keep you legal and safe.

The law, the fines and the points

The legal minimum tread depth for a car tyre in the UK is 1.6mm. That depth must be present across the central three quarters of the tyre’s width and around its entire circumference. Drop below it on any part of that band and the tyre is illegal to use on the road. The same applies to a tyre with a deep cut, a bulge, exposed cords or one that is not correctly inflated for the load it is carrying.

The penalty is a fine of up to £2,500 and three penalty points for each non compliant tyre. Because it is charged per tyre, a car that fails on all four corners exposes the driver to fines running to five figures and a points total that triggers an automatic ban. Yet awareness is strikingly low. Research by the AA and TyreSafe found that 61 per cent of drivers did not know the maximum fine was £2,500 per tyre, and many had no idea that points were even on the table.

Tyres are also a standard part of the MOT. An examiner will fail a car for tread below the legal limit, for damage to the structure, and for a tyre that is the wrong size or type for the vehicle. A failed MOT means the car cannot legally be driven, other than to a pre booked test or repair, until the fault is fixed.

The safety figures behind the warning

This is not a paperwork problem. As tread wears down, a tyre loses its ability to clear water from the road, which lengthens stopping distances and makes aquaplaning far more likely in wet weather. The difference between a tyre at 3mm and one scraping the 1.6mm limit can add several car lengths to an emergency stop from motorway speed.

The casualty data reflects that. TyreSafe figures show that 190 people were killed or seriously injured in collisions where illegal, defective or under inflated tyres were a contributory factor in 2023, an increase of 29 per cent on the previous year. Separately, more than 6,000 people were convicted of driving on a defective tyre in the same period. Behind every one of those numbers is a stopping distance that was longer than it should have been.

There is an insurance dimension too that drivers rarely consider. If you are involved in a collision and your tyres are found to be illegal, an insurer may question the claim, and at the very least you have handed the other side an obvious line of argument about fault. A defective tyre that contributes to a crash can also lead to a charge of driving without due care, which carries its own penalties on top of the tyre offence. In other words, the worn tyre that seemed like a way to put off a bill can end up multiplying the cost across fines, points, premiums and liability.

The part worn tyre trap

When budgets are tight, second hand tyres look like an easy saving, and a thriving part worn trade exists to meet that demand. The problem is that a large share of it operates outside the law. When TyreSafe inspected part worn tyres on sale, it found that 94 per cent were being sold illegally. In one investigation of 278 part worn retailers, 93 per cent, or 261 outlets, were non compliant, and more than 63 per cent of the tyres examined were judged unsafe to return to the road.

A new tyre also comes with a load and speed rating matched to your car, a full manufacturer warranty, and known provenance, none of which you get with a used one. Fitting and balancing are charged either way, so the gap between a budget new tyre and a part worn one is often far smaller than it first appears once the whole job is priced up.

The rules on selling used tyres are clear, even if they are widely ignored. A part worn tyre must be permanently and legibly marked with the words PART WORN in letters at least 4mm high, it must have at least 2mm of tread across the required area, and it must be free of dangerous damage. A tyre sold without that marking, or with less than 2mm of tread, is being sold unlawfully, and you have no easy way of knowing what punishment a used tyre has taken or whether it has been repaired correctly. In many cases a budget brand new tyre costs little more than a part worn one once fitting is included, and it comes with its full life ahead of it.

What to do to stay legal and safe

You do not need special equipment to check your tyres. The quickest test uses a 20p coin. Insert it into the main tread grooves at several points across and around each tyre. If you can see the outer band of the coin, the tread may be close to or below the legal limit and the tyre should be checked by a professional. Do this on all four, and on the spare if you carry one, because tyres often wear unevenly.

Check the pressures at least once a month and before any long journey, using the figures in the car’s handbook or on the sticker inside the driver’s door, not the maximum printed on the tyre itself. Look over each tyre for cuts, lumps, bulges and cracking in the sidewall, and have anything suspicious inspected. Many garages and tyre fitters will check tread and condition free of charge, so there is no reason to wait for the MOT to discover a problem.

Age counts as much as tread. Rubber hardens over time even on a car that covers few miles, and an old tyre can crack and lose grip while still showing plenty of tread. You can read the age from the four digit code on the sidewall, which gives the week and year of manufacture, so a code reading 2519 means the twenty fifth week of 2019. Many manufacturers suggest replacing tyres that are around ten years old regardless of how they look, and caravans and trailers that sit unused for long periods are especially prone to age related failure. Whatever the tread depth, do not wait until a tyre reaches 1.6mm before acting. Most safety bodies recommend changing tyres at around 3mm, because grip and water clearance fall away sharply in the final couple of millimetres, and the small extra cost of an earlier change buys a real margin of safety in the wet.

If you do need new tyres, buy from a reputable fitter, make sure the size and speed rating match the manufacturer’s specification, and treat any deal that looks too cheap with suspicion. Replacing a worn tyre before it becomes dangerous is one of the cheapest pieces of safety insurance a driver can buy, and it costs a great deal less than a £2,500 fine or a collision.

For more on the small defects that can land big penalties, see our coverage of why a dashboard warning light can now fail your MOT.

Sources:

• https://www.tyresafe.org/tyre-advice/tyres-and-the-law/
• https://www.tyresafe.org/resources/tyre-safety-infographics/
• https://www.tyresafe.org/tyre-advice/tyre-types/part-worn-tyres/
• https://www.gov.uk/tyre-condition-and-safety