For cars in Great Britain, the legal minimum tread depth is 1.6mm across the central three-quarters of the tread and around the full circumference of the tyre. Other vehicle types have their own rules, and the figures differ, so check current official guidance for vans, motorcycles and heavier vehicles.
How to measure tread depth
- Tread depth gauge. A cheap and accurate tool. Place the probe in the main grooves across the tyre and read the number.
- Tread wear indicators. Small raised bars in the grooves, marked TWI on the sidewall. When the tread is level with them, the tyre is at the limit.
- The 20p test. Place a 20p coin into a main groove. If the outer band of the coin is hidden, the tread is likely above the legal limit. It is a rough check only.
Measure in several places across the width and around the tyre, since wear is rarely even.
Why 1.6mm is not a safe target
The law sets a minimum, not a recommendation. Tests by tyre bodies and manufacturers have repeatedly shown that stopping distances in the wet increase as tread falls, with noticeable drops below about 3mm. Many drivers change tyres at around 3mm for that reason. If you do a lot of motorway or wet-weather driving, consider replacing sooner.
What uneven wear tells you
- Both shoulders worn: under-inflation.
- Centre worn: over-inflation.
- One edge worn: alignment or suspension problems; see balancing and alignment.
- Patchy or scalloped wear: worn suspension components or balance issues.
- Feathering across the tread: toe-in or toe-out problems.
Legal and practical consequences
Driving with tyres below the legal limit is an offence, and the penalties can be serious. It can also affect your insurance. A tyre may also fail an MOT for other reasons such as cuts, bulges or exposed cords; see tyre bulge in the sidewall. Check current penalties with an official source such as GOV.UK.
Age and tread are separate issues
A tyre with plenty of tread can still be dangerously old. See DOT code guide. Check both.
Vans, taxis and heavy use
Vehicles that cover many miles, such as vans and taxis, wear tyres quickly; see van tyres and taxi and private hire tyres. Check more often, and keep a log.
When tread is low
Plan replacement before the limit, not after. If one tyre is much more worn than the other on an axle, think about replacing both; see replace tyres in pairs. Our technicians can measure your tread and advise honestly. See mobile tyre fitting and emergency tyre fitting. We cover areas such as London, Reading, Bristol and Watford; see the areas list. Call now for a quote on 0800 772 0355 or book now.
Simple checklist
- Measure across the central three-quarters of each tyre.
- Check in several places.
- Compare with the 1.6mm legal minimum.
- Consider replacing at 3mm.
- Look for uneven wear and ask why.
Measuring properly, step by step
Put the gauge probe into the groove closest to the centre, press the base flat on the tread blocks and read the number. Repeat across the width at three points, and then at three places around the tyre. The lowest reading is the one that matters. Do not forget the inner side of the tyre, which often wears first; roll the car forwards a little if you cannot see it. Record the readings so you can see how fast the tread is disappearing.
Estimating remaining life
If your tyres lose about 1mm every 5,000 to 8,000 miles, which varies widely, then a tyre at 4mm may have limited life before hitting 3mm. Divide the remaining millimetres above your replacement point by your wear rate to estimate the miles left. It is only a rough guide, but it helps you plan a replacement before the tyre becomes an emergency.
Frequently Asked Questions
What is the legal tread depth in the UK?
1.6mm across the central three-quarters of the tread, around the whole tyre, for cars.
Is the 20p test reliable?
It is a rough guide only. A gauge is better.
When should I replace tyres?
Many drivers replace at around 3mm for better wet grip.
Can you measure my tread?
Yes. Call now for a quote on 0800 772 0355.
Related Help
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