Tyres and the Law
UK law requires that your vehicle is fitted with the correct type and size of tyre for the vehicle type you are driving and for the purpose it is being used.
This means fitting the right tyres and for safety ensuring that they are inflated to the manufacturer's recommended pressure.
The legal limit for minimum depth of the tread on your tyres is 1.6 millimetres, across the central ¾ of the tread around the complete circumference of the tyre.
For safety reasons it is recommended that you replace your tyres before the legal limit is reached. Many vehicle manufacturers recommend replacing at 3 millimetres, as below this depth stopping distances start to dramatically increase. At 1.6 millimetres in wet weather it takes an extra two car lengths (8 metres) to stop at 50 mph than if your tread was 3 millimetres.
As well as the mimimum tread depth, it is also important to make sure that your tyres are free of any other defects. Lumps, bumps and bulges could mean the tyre is structurally damaged, while any cut of tear bigger than 25mm, or 10% of the tyres width, can mean your tyres are not road legal. The same applies if any part of the tyre's ply or cord are exposed.
A regular check of your tyres can help you to avoid 3 penalty points and £2,500 in fines for having tyres worn beyond the legal minimum limit on your vehicle.
It is also a legal requirement to ensure that tyres of different construction types are not fitted to opposite sides of the same axle. The two main tyre types are radial and cross-ply, and these must not be mixed on the same axle.
Mixing brands and patterns of the same construction type is permissible depending on the vehicle type and manufacturers recommendation. Check your vehicle's handbook for tyre fitment details and options or ask your local Kwik Fit team for assistance.
How to test your tread depth
Perhaps the easiest way to check if you are close to the legal limit is looking for your tyres treadwear indicators. These small bars, usually around 5mm wide, span across the base of the tyre's main grooves. These are set to a low height, so once the surface of the tread begins to wear to a similar level as the indicators you can tell that it is time to have your tyres checked, and probably replaced.
You can also check you're tread depth with the 20p test. Putting a 20p coin into the grooves of a tyre is a simple way to test whether the tread depth is above the legal limit. The outer rim of a 20p coin is just under 3mm wide, so as long as the rim is hidden when inserted then the tyre is above the legal tread limit.
If in doubt, visit your nearest Kwik Fit
If you are at all unsure about your tyre tread or think your tyres are nearing the legal limit, we provide a free tyre check service at all Kwik Fit centres for your convenience. Our trained technicians will carry out a full inspection of your tyres to check the general condition of the tyres, ensuring the tread depths meet minimum legal requirements while also checking that the correct tyre pressure is maintained as per your manufacturer’s recommendation. The findings of your tyre inspection are detailed in a written report for your convenience.