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How to measure a tyre tread and why you should

Published 12 December 2016 by

There's a lot of work that goes into maintaining a car. You have to make sure you have enough petrol, your oil levels are just right and there's enough coolant in your engine. It's important to remember these car checks, especially in winter.

If you forget to do this, it could not only cause disruption to your daily routine but harm your budget as well. To make sure you avoid one extra cost, we're taking you through how to measure the tyre tread on your wheels and why you should.

How to measure it

The legal minimum tread depth for cars in the UK is 1.6mm. This depth has to be in a continuous band around the central three quarters of the tyre.

An easy way to measure the tyre tread is to take a 20p and simply place it into the main tread grooves of your tyre. If the coin slots into the groove and is partly-covered, then your tyre should have a tread depth above the legal limit. Remember to check this on at least three different locations on the tyre.

On the other hand, if the outer band of the coin is visible, your tyres may be illegal and unsafe to drive. Take it to a qualified tyre professional to check it out if you’re unsure.

Why should I measure my tyre tread?  

You should measure your tyre tread to make sure you stay safe on the road. The legal requirement of tyre tread helps to remove water from in between your tyres and the road surface – meaning that you can steer, accelerate and (most importantly) brake properly.

A tyre with a shallower tread might not be able to perform as efficiently in wet conditions. Your car might aquaplane – travel on top of water instead of the road – if your tyres do not have sufficient tread depth. The AA says that at 50mph, a tyre with 8mm of tread will stop 11.9m sooner than one with 1.6mm.

There's another danger though – the risk of a penalty. If you drop below the legal limit of 1.6mm, you could face a fine of £2,500 and 3 points on your licence for each illegal tyre. You can easily avoid this by checking your tyres regularly.

Is there a risk with part-worn tyres?

When looking to replace your tyres it can be tempting to go for a part-worn one. These are often a lot cheaper than new tyres and can come to as little as £10.

It can seem like a bargain deal – but it's often not. This is because part worn tyres can wear away sooner and therefore become illegal to drive a lot quicker. New tyres on the other hand come with a 7.5mm tread on average.

A better gauge of the price of a tyre is to look at the cost per mm. AA Tyres figured out that you pay £6.33 per mm of tread with a part-worn tyre. And while new tyres might be more expensive, they can work out cheaper per mm of tread.

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