Why Tyre Checks Matter
Tyres are the only point of contact between your car and the road. A tyre in poor condition reduces your ability to brake, steer, and handle wet roads. In the UK, driving with illegal tyres carries a fine of up to £2,500 and three penalty points per tyre. Four illegal tyres could mean twelve points and a driving ban.
Checking your tyres regularly costs nothing and takes minutes.
The Legal Tread Depth Limit in the UK
UK law requires a minimum tread depth of 1.6mm across the central three-quarters of the tyre width, all the way around the circumference.
Most tyre safety organisations recommend replacing tyres at 3mm, because wet braking performance drops significantly below this threshold. A car braking from 50mph with 1.6mm of tread needs several extra metres to stop compared to a car with 3mm of tread.
How to Check Tread Depth
Using a 20p Coin
The quick and easy method. Insert a 20p coin into the tread groove. If the outer band of the coin is hidden, your tread is above the legal limit. If you can see the outer band, the tyre is at or near the minimum and should be checked properly or replaced.
Using a Tread Depth Gauge
A tread depth gauge costs around £3 to £5 and gives you an accurate reading in millimetres. Insert the probe into the shallowest part of the tread groove and press the gauge down until the shoulder is flush with the tyre surface.
Tread Wear Indicators
Modern tyres have moulded wear indicators in the main tread grooves. These small raised blocks sit at 1.6mm depth. When the tyre tread is level with these indicators, the tyre is at the legal minimum.
Checking Tyre Pressure
Incorrect pressure is one of the most common tyre problems. Both underinflation and overinflation cause problems.
Underinflated tyres:
- Wear faster on the outer edges
- Increase fuel consumption
- Reduce handling precision
- Increase the risk of a blowout at speed
Overinflated tyres:
- Wear faster in the centre
- Reduce grip because less tyre surface contacts the road
- Make the ride harsher
Check your tyre pressures cold, ideally before driving or within two miles. The correct pressure for your vehicle is found inside the driver's door sill, in the owner's manual, or on the fuel filler cap on some vehicles. Note that front and rear pressures may differ, and many manufacturers specify a higher pressure when carrying a full load.
Checking for Tyre Damage
Walk around the car and inspect each tyre carefully:
- Bulges or bubbles: A bulge on the sidewall means the internal structure has failed. The tyre must be replaced immediately and the car should not be driven.
- Cuts and gashes: Deep cuts can compromise the tyre's structure, particularly on the sidewall. Shallow surface cuts in the tread area may be acceptable but should be checked by a tyre specialist.
- Embedded objects: Screws, nails, and glass can puncture a tyre slowly. If you spot one, check the pressure regularly and book a repair or replacement.
- Cracking and crazing: Old tyres can develop fine cracks in the rubber, particularly on the sidewall. This indicates the rubber is degrading and the tyre may need replacing regardless of tread depth.
Tyre Age and Replacement
Tyres degrade over time even if they are rarely used. Most manufacturers and tyre safety bodies recommend replacing tyres over ten years old, and many advise inspecting any tyre over five years old more carefully.
You can check the age of a tyre by looking at the DOT code on the sidewall. The last four digits show the week and year of manufacture. For example, 2318 means the tyre was made in the 23rd week of 2018.
Spare Tyre Check
Do not forget the spare. Many drivers check their road tyres regularly but ignore the spare until they need it. Check the pressure and condition of your spare at least twice a year.
Note that many newer cars come with a space-saver spare or a tyre inflation kit rather than a full-size spare. Know what your car has before you need it.
When to Get Tyres Professionally Inspected
Book a professional inspection if you notice:
- Uneven wear patterns (points to wheel alignment or suspension issues)
- Vibration through the steering wheel
- The car pulling to one side
- A tyre that keeps losing pressure without a visible cause
