The tread is below the UK legal minimum of 1.6mm, measured across the central three-quarters of the tread width and around the entire circumference. It's a measured, black-and-white item — there's no interpretation involved.
Wording as it commonly appears on an MOT certificate: “Tyre tread depth below the legal limit of 1.6mm”.
What does it mean?
The tread is below the UK legal minimum of 1.6mm, measured across the central three-quarters of the tread width and around the entire circumference. It's a measured, black-and-white item — there's no interpretation involved.
How serious is it?
Usually recorded as: Major. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- Normal wear
- Under-inflation, which wears the shoulders and leaves the middle looking fine
- Over-inflation, which does the opposite and wears the centre band
- Wheel alignment out, which wears one edge in a distinctive feathered pattern
- A worn damper or suspension component causing scalloped, patchy wear
What a mechanic would check
Depth gauge in several places across and around the tyre, not just the one spot. Then I'd look at the wear pattern, because that's the useful part — even wear is just mileage, but edge wear or feathering tells you the geometry needs setting before the new tyres go the same way.
What might need replacing
- One or more tyres
- A four-wheel alignment if the wear pattern is uneven
- Suspension attention if the wear is scalloped
Can you still drive it?
Below 1.6mm you're not only failing the MOT, you're breaking the law every time you drive — and the penalty applies per tyre. Wet grip falls off sharply below about 3mm long before you reach the limit, so don't let it get here.
Repair cost
Tyre prices vary enormously by size, speed rating and brand. Get the alignment checked at the same time if the wear was uneven, otherwise you'll be buying tyres again far too soon.
Before the retest
Check every tyre, not just the one that failed — the legal minimum is 1.6mm across the central three-quarters of the tread, all the way round. Make sure tyres on the same axle match in size and construction, and that all wheel nuts or bolts are present and tight. Set pressures to the figure on the door shoulder or in the handbook the morning of the retest.
Retest rules
If the vehicle stays at the test centre for repair and is retested within 10 working days, a partial retest is often free; some items qualify for a free retest if you bring the car back by the end of the next working day. The exact conditions are set out on GOV.UK, so confirm with the test centre before you leave. A major or dangerous failure means the car cannot legally be driven away unless the previous MOT is still valid and nothing dangerous was recorded — check your certificate first.
Related help
More tyres and wheels failures · MOT failure decoder · Ask a mechanic about your certificate
This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.