Part Worn Tyres: The Law And The Reality
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Buying used tyres is legal, and for someone keeping an older car on the road it is an understandable saving. The problem is not the idea — it is that when Trading Standards and TyreSafe go and look, they keep finding that almost nothing on sale actually meets the rules.
What A Legal Part Worn Tyre Must Have
The rules come from the Motor Vehicle Tyres (Safety) Regulations 1994, as amended. Before a part worn tyre can be sold it must:
- have at least 2mm of tread across the full breadth, around the whole circumference — more than the 1.6mm in-use legal minimum;
- be permanently marked “PART WORN” in letters at least 4mm high, not cut or hot-branded into the rubber;
- have no cut longer than 25mm or 10% of the section width, whichever is greater, reaching the cords;
- have no lump, bulge or tear caused by separation, and no exposed ply or cord;
- have any repair carried out to the proper British Standard.
If it is not stamped, it is not a legally sold part worn tyre. That single check disqualifies most of what is on offer.
What Inspections Keep Finding
Multi-agency operations reported in August 2026 give a fair picture. In Norfolk, 191 tyres were inspected across seven businesses: 36% were in dangerous condition — structural damage, exposed cords, unsafe repairs — and one single tyre out of 191 was fully compliant. In Lancashire, thirty tyres were checked and none carried the required PART WORN marking.
This is not new. A national TyreSafe investigation found 99% of the retailers it visited were non-compliant and three-quarters of the tyres inspected were unsafe. The pattern has been consistent for the better part of a decade.
The Wider Tyre Problem
Part worns are one part of a broader picture. The TyreCheck 2025 survey looked at more than 58,000 vehicles at 141 locations and found around 40% were running on illegal or dangerously worn tyres — 8% already below the legal limit, and a further 32% technically legal but worn to the point the researchers classed them unsafe.
The National Tyre Distributors Association has since called for the legal minimum to be raised from 1.6mm to 2mm. That has not happened, and the law remains as below.
The Legal Minimum, And What It Costs You
For a car, van or light trailer the minimum tread depth is 1.6mm across the central three-quarters of the tread, around the entire circumference. Below that the tyre is illegal.
The penalty is up to a £2,500 fine and 3 penalty points per tyre. On all four, in theory, that is up to £10,000 and twelve points — enough for a ban. Courts rarely go that far in practice, but the exposure is real, and an insurer looking for a reason to argue about a claim will find one in a set of bald tyres.
Grip is the actual point, though. Tread exists to clear water. As it wears the tyre’s ability to disperse standing water falls away long before it reaches 1.6mm, which is why the industry regards anything under 3mm as worth replacing rather than running to the limit.
If You Are Buying Used Anyway
- Look for the PART WORN stamp first. No stamp, walk away.
- Take a tread depth gauge and check it yourself — 2mm minimum, and much more if you want the tyre to last.
- Inspect the sidewalls both sides for bulges, cuts and perished rubber.
- Check the date code — a four-digit number giving the week and year of manufacture. An old tyre with plenty of tread is still an old tyre.
- Check the speed and load rating matches what your car requires.
A remould is usually the better budget option. Bought from a reputable dealer, a remould is fully legal, sold as new, comes with a warranty and has a known history — none of which is true of a used tyre off a rack. The price gap between a remould and a questionable part worn is often smaller than people expect.