Tread wear indicators showing
Moulded rubber bars at 1.6mm between the main grooves. Once tread is level with these bars, the tyre is at or below legal limit.
Replace immediately
UK tread law
When to replace your tyres
The UK legal minimum, the safety data, and what failing to replace actually costs. Includes the 20p test, MOT rules and puncture-repair limits.
Tread-depth gauge
8mm
New tyre
5mm
Good
3mm
Replace soon
2mm
Borderline
1.6mm
Legal minimum
The legal minimum is 1.6mm. The penalty is steep.
UK law requires at least 1.6mm of tread across the central three-quarters of the tyre, around the full circumference. Below that, every illegal tyre carries a fine of up to £2,500 and 3 penalty points. All four illegal means an automatic ban.
Fine per tyre
up to £2,500
Points per tyre
3 points
All 4 illegal
£10,000 + ban
The 20p test
Simplest at-home check. The outer band of a 20p coin is roughly 1.6mm wide, the legal minimum.
- Take a 20p coin and push it into the main tread groove.
- If you can see the outer band of the coin, your tread is below 1.6mm.
- Check at several points across the width and around the circumference.
- If the band is visible at any point, the tyre needs replacing immediately.
For an exact reading, a digital tread-depth gauge costs £3-5 from Halfords or Amazon and reads to 0.1mm.
Replace at 3mm
Don't wait for 1.6mm
Tread performance drops sharply below 3mm in the wet. The RAC and most tyre experts recommend replacing at 3mm. You also get to plan the spend rather than panic-buy.
Safety data
3mm vs 1.6mm: the gap that matters
Wet braking distance from 50mph against tread depth. The performance falls off a cliff between 3mm and the legal limit.
| Tread depth | Wet braking (50mph) | vs 8mm baseline | Risk band |
|---|---|---|---|
| 8mm (new) | 25.5m | Baseline | Optimal |
| 5mm | 28.2m | +2.7m | Good |
| 3mm | 32.0m | +6.5m | Replace soon |
| 2mm | 36.4m | +10.9m | Borderline |
| 1.6mm (legal min) | 40.2m | +14.7m | Dangerous |
From new to legal minimum, wet braking distance grows by roughly 15 metres at 50mph. That is four car lengths. In real driving, that is the difference between stopping safely and not stopping at all.
How long do tyres last?
| Tier | Typical mileage | Years (10k mi/yr) | Notes |
|---|---|---|---|
| Budget | 15,000-20,000 mi | 1.5-2 years | Faster wear in wet. Front tyres on FWD wear quickest. |
| Mid-range | 25,000-35,000 mi | 2.5-3.5 years | Best value for most drivers. Predictable wear. |
| Premium | 35,000-50,000 mi | 3.5-5 years | Longest-lasting. Michelin typically leads on tread life. |
What affects lifespan
- Driving style. Aggressive throttle and braking shortens life by 20-40%.
- Pressure. Under-inflated wears the edges; over-inflated wears the centre. Check monthly.
- Alignment. Misalignment can halve tyre life by chewing one edge.
- Road conditions. Potholes, rough surfaces and speed bumps all accelerate wear.
- Front vs rear. Front tyres on FWD cars wear roughly twice as fast as rears. Rotate every 6,000 miles.
- Age. Replace tyres older than 6 years even if tread is fine. Rubber perishes.
Signs you need new tyres
Uneven wear pattern
Worn on one edge means alignment issues. Centre wear means over-inflated. Both edges means under-inflated.
Get alignment, then replace
Cracks in the sidewall
Fine surface cracks mean rubber is degrading with age. Internal structure may be weaker than the tread looks.
Replace soon
Bulges or blisters
Indicates internal structural damage, often from a kerb or pothole strike. The tyre can blow out without warning.
Replace immediately
Vibration at speed
Steering wheel shake at motorway speed can mean tyre defect, balance issue or belt separation.
Get checked immediately
Slow puncture
Topping up pressure more than once a month suggests a slow puncture from a nail or perished valve.
Repair or replace
Puncture repair vs replacement
Repair is possible if…
- +Puncture is in the central tread (not the sidewall)
- +Hole is under 6mm in diameter
- +Tread depth is still above 1.6mm (ideally 3mm+)
- +No sidewall damage
- +Tyre has not been driven flat
£20-45 / 30 minutes
Replace if…
- -Puncture is in the sidewall or shoulder
- -Hole is over 6mm
- -Tyre has been driven flat (even briefly)
- -Sidewall damage or any visible bulge
- -It is a run-flat (most cannot be repaired)
£70-200+ / 30-60 minutes
Tyres and the MOT
Tyres are checked at every MOT. Common reasons for failure:
- Tread under 1.6mm. The most common tyre-related fail.
- Cuts, bulges or cords showing. Any structural damage is an instant fail.
- Wrong size or type. Mismatched sizes on the same axle, or wrong spec for the vehicle.
- Incorrectly seated on the rim. Tyre not properly fitted.
A tyre-related MOT failure means you cannot legally drive until the issue is fixed, so you pay for new tyres plus a re-test. Cheaper to check before the MOT and replace anything borderline.