What makes tyres illegal?


While it may seem like there are no obvious problems with your car tyres, there are a variety of factors that can impact how they perform. If it’s been some time since they were last checked, it could even be possible that you are driving with illegal tyres. As a result, it’s essential to check your tyres regularly to avoid potential fines and to stay safe on the road.

Knowing exactly what to look out for when it comes to tyre maintenance can be a challenge. That’s why we’ve put together this handy guide to highlight how to identify tyre problems and what exactly can make tyres illegal.

What happens if I drive with illegal tyres?

Driving with inadequate tyres can not only be extremely dangerous but could also potentially result in fines of up to £2,500 per tyre, three penalty points on your license and invalidated car insurance. Therefore, it’s crucial that your tyres are roadworthy and that you conduct regular tyre safety checks.

If you’re concerned about the state of your tyres, you can book a free tyre check at one of our Halfords Autocentres.

Did you know?

  • There are an estimated 6.1 million illegal tyres on Britain’s roads – that’s 1 in 4 unsafe vehicles

  • Over 2 million cars fail their MOT due to tyre defects every year

  • On average, defective tyres result in the death or serious injury of 159 people every year

  • Over half of UK tyres are either illegal or borderline when they’re replaced

Low tread depth

Low tread depth is one of the most common tyre problems and can lead to serious issues such as loss of traction and aquaplaning. The legal minimum depth of tread is 1.6mm and anything below this can lead to ‘bald tyres’ where the tyre rubber has been completely worn down. You can expect three points on your license and a fine of up to £2,500 per tyre if you’re stopped by the police with low tread depth, so it’s crucial to get your tyres replaced if you’ve noticed any kind of excessive wear.

Discover more on how to check your tyre tread depth with our tread depth and safety guide.

It’s also worth noting that a tyre depth check and tyre inflation check and top-up is included within our 10-point Car Check.

Damage to tyre sidewall

Your tyre sidewall can become damaged in a variety of ways including scratches, bulges, cracks, and cuts. Each scenario can occur for different reasons:

  • Cracked tyres are often due to aging tyres but can also be impacted by UV rays and extreme temperatures.
  • Cut or slashed tyres in your tyre sidewall are often down to debris in the road such as nails or glass.
  • Scratched and scraped tyres can be a result of mounting the kerb.
  • Bulging tyres can be down to driving over an object too quickly such as potholes or speed bumps or if you have overinflated your tyres.

While it may seem ok to ignore a minor scratch on your tyre sidewall, this can weaken the overall tyre structure, which could lead to tyre blowouts and cause a serious accident. Each of these tyre defects are also likely to cause your car to fail its MOT, so it’s important to get them replaced as soon as possible.

Under or over inflated tyres

Maintaining the correct tyre pressure allows the weight of your vehicle to be evenly distributed. As a result, both under and over inflated tyres can lead to serious issues.

Under inflated tyres are a common issue and are the leading cause of tyre failure. Tyres that are under inflated can not only lead to fines and penalty points but can also:

  • Increase fuel consumption
  • Increase braking distances
  • Create uneven tread wear
  • Lead to poor handling

Over inflated tyres can also pose a threat to your vehicle such as:

  • Poor traction
  • Braking difficulties
  • Uneven tread wear
  • Poor handling

For more information on tyre pressure, check out our guide on how to check and inflate tyres.

Tyres that are unsuitable for your vehicle

Choosing tyres that are unsuitable for the purpose of your vehicle can cause major problems such as not meeting your car’s load requirements and the maximum speed rating of your vehicle. Fitting tyres that are too small or large for your vehicle can have a significant impact on handling and could lead to fines and penalty points.

To find the right tyre size for your vehicle, you can either check the tyre markings on your current set of wheels, look at your vehicle handbook, check your door jam or inside the fuel cap.

For more information on choosing the right tyres, check out our guide on how to choose the best tyres for your vehicle.

If you’re still concerned that you could be driving with illegal tyres, it’s best to get them looked at by a professional. For peace of mind, book in a free tyre check with Halfords to avoid potential fines and penalty points.


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