Location: London Road, Portsmouth, Hampshire, PO2 9RR

What Makes Your Tyres Illegal & How to Make Them Last Longer

Many drivers know that their tyres should last between 4 and 6 years and sometimes even longer, so they’re less aware of when their tyres are actually illegal. Unfortunately, driving with illegal tyres fitted to your car can lead to a £2,500 fine and 3 points on your licence!

In this article, you’ll learn what makes your tyres illegal, what to do when you notice these issues and how to make your tyres last as long as possible.

Low Tread Depth

The most common issue that can make your tyres illegal is low tread depth. By law, you must have at least 1.6mm of tread depth across every tyre fitted to your car. If it is any lower than this during your MOT test, your car will fail.

You can easily check your tyre tread depth at home. Just take a 20p piece and insert it into each of the tread grooves. If you can see the inner rim of the coin, your tread is too low. If you notice this, contact Smile Servicing in Portsmouth immediately. We will provide you with an affordable quote and book you in for an appointment to change the illegal tyres.

Underinflated Tyres Can Also Be Illegal

Low tyre pressure is another common issue that drivers may not always be aware of. Underinflated tyres are less responsive when changing direction or at high speed, which can reduce the control you have over your car.

You can find the correct tyre pressure for your vehicle in your handbook or, more commonly, on a sticker on the inside of the driver’s door. You can also check your tyre pressure for free at many petrol stations. If it is a little low, make sure you pump them up to avoid driving with illegal tyres.

Excessive Damage

If your tyres are very damaged, they may also be illegal. Frayed rubber, cracks or bulging sidewalls are all signs of damaged tyres. These are very unsafe as they can ‘blowout’ easily. If you notice that your tyres have seen better days, contact our garage in Portsmouth and we will quote you for a replacement.

Mixed Tyres on the Same Axle

We strongly recommend that you always replace your car’s tyres like-for-like to avoid having illegal tyres fitted. This includes replacing your tyres in pairs.

You must not mix cross-ply and radial tread tyres on the same axle, which can be easily done if you replace your tyres one at a time.

How to Make Your Tyres Last Longer

We have a few simple tips if you’re looking to make your tyres last longer. These are:

  • Avoid hitting kerbs and driving through the worst of a pothole. This will avoid damaging your tyres.
  • Always change your tyres in pairs to avoid uneven or excessive wear.
  • Drive sensibly and at an appropriate speed.
  • Check your tread depth and tyre pressure regularly.


While it is easy to assume your tyres are legal because your car passed its MOT, they may have deteriorated and now be illegal. Now that you know what to look for, make sure you keep checking your tyres and book an appointment with Smile Servicing in Portsmouth for expert tyre fitting if you ever notice an issue.

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