When Should You Change Your Tyres? Signs to Look For
UK law requires a minimum tyre tread depth of 1.6mm across the central three-quarters of the tyre. Drive below this and you risk a £2,500 fine and three penalty points — per tyre. But the legal minimum and the safe minimum are not the same thing. This guide explains when you actually need new tyres, and how to tell.
The Legal Minimum vs. The Safe Minimum
The UK legal minimum tread depth is 1.6mm. However, most independent tyre safety organisations — including TyreSafe — recommend replacing tyres at 3mm. Here’s why the difference matters:
Wet braking distance at different tread depths:
- 8mm tread — baseline (new tyre)
- 3mm tread — stopping distance increases by approximately 8 metres
- 1.6mm tread — stopping distance increases by approximately 18 metres
Source: TyreSafe / MIRA testing data. At 80 km/h on wet roads.
Eighteen extra metres at the legal minimum. On a wet UK motorway, that’s the difference between stopping safely and hitting the car in front. The 3mm recommendation exists for good reason.
How to Check Tread Depth
The 20p Test
Insert a 20p coin into the tread grooves. If the outer band of the coin is visible, your tread is below 3mm and you should consider replacing your tyres soon. If you can see the outer band clearly and it’s close to flush with the tread, you’re close to the legal limit.
Tread Wear Indicators
Modern tyres have built-in tread wear indicators — small rubber bars moulded into the tread grooves at 1.6mm depth. When these become flush with the surrounding tread, your tyre is at the legal minimum and must be replaced immediately.
Tread Depth Gauge
For an accurate reading, use an inexpensive tread depth gauge (available for under £5). Measure at multiple points across the tyre width and around the circumference — wear isn’t always uniform.
Signs You Need New Tyres Beyond Tread Depth
Sidewall Damage
Bulges, bubbles or cuts in the tyre sidewall are serious. A sidewall bulge means the internal structure has been damaged — usually by a pothole or kerb strike — and the tyre can fail suddenly without warning. Replace immediately.
Cracking
Fine cracks in the sidewall or tread area (sometimes called crazing or weather checking) indicate the rubber is hardening and drying out with age. This is particularly common on older tyres that have covered low mileage. Age matters as much as mileage.
Vibration or Pulling
If your car vibrates at speed or pulls to one side, it can indicate tyre issues — uneven wear, out-of-balance tyres, or a damaged tyre. It can also indicate wheel alignment problems. Both should be investigated.
Uneven Wear Patterns
- Wear on both edges, less in centre — underinflation
- Wear in centre, less on edges — overinflation
- Wear on one edge only — wheel alignment problem
- Patchy or diagonal wear — suspension issues, or wheel balance problems
How Old Is Too Old?
Tyres degrade over time regardless of use. Most manufacturers recommend replacing tyres after 5–6 years, even if tread depth looks fine. After 10 years, tyres should be replaced regardless of condition.
To check your tyre’s age, look at the DOT code on the sidewall. The last four digits indicate the week and year of manufacture — for example, 2318 means the 23rd week of 2018.
How Often Do Tyres Need Replacing?
There’s no fixed mileage. Tyre life depends on driving style, load, road surfaces, climate and tyre type. A typical UK driver covering 10,000 miles a year on a standard family car might expect to replace tyres every 20,000–40,000 miles on the front axle, with rears lasting longer. Performance cars with wider, lower-profile tyres can wear through fronts in 15,000 miles or less.
The only reliable way to know is to check regularly — the monthly pressure check is a natural opportunity to inspect tread depth at the same time.
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