Tyre Tread Depth & UK Law

UK law requires that your vehicle is fitted with tyres that are in a roadworthy condition and are fit for the purpose they are being used.

This means fitting the right tyres, and, for safety, ensuring that they are not damaged. You should also ensure tyres are inflated to the manufacturer's recommended pressure. Find out more about tyre law essentials below.

What is the legal tread depth limit?

The legal limit for the 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 car 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, compared to if your tread was 3 millimetres.

What additional tyre checks should be done regularly?

As well as the minimum 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 or tear bigger than 25mm, or 10% of the tyre’s width, can mean your tyres are not road-legal. The same applies if any part of the tyre's ply or cord is exposed.

Can you mix different types of tyres?

It is also a legal requirement to ensure that car 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 manufacturer's recommendation. Check your vehicle's handbook for tyre fitment details and options or ask your local Kwik Fit team for assistance.

A weekly check of your car 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. Why not book a free tyre check at your local Kwik Fit centre, and catch any potential issues early.

How to test your tread depth

Treadwear indicators

Perhaps the easiest way to check if you are close to the legal limit is looking for your tyres’ tread wear indicators. These small bars, usually around 5mm wide, span 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.

20p Test

You can also check your 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. They’ll also check 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.

If you’ve got any questions in the meantime, or before you can make it into your local centre, don’t hesitate to get in touch.

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