Driving with illegal tyres isn’t just unsafe — it can land you with fines, penalty points, and a higher risk of accidents. This guide highlights the most common signs your tyres are no longer roadworthy, including worn tread, cracks, and incorrect pressure. Find out how to stay legal, safe, and confident on every journey.
Most of us use our vehicles on a daily basis to get from A to B – whether that be work, the school run, the shops, or various leisure activities and clubs.
And while we are all well aware of the need to get vehicles booked in for an annual service and MOT, there are other aspects of car ownership that require ongoing management and maintenance to keep our vehicles roadworthy and safe.
Tyres may be just one component of a vehicle, but they are one of the most important – especially when it comes to vehicle control and the safety of both you and others on the road.
The tyres on your vehicle impact its performance, how safe it is, how reliable it is, and of course whether or not your vehicle is considered roadworthy and safe to drive.
With that in mind, what are the signs that indicate your tyres may be illegal – and what should you look out for to keep your tyres in optimal condition?
Why is Tyre Maintenance so Important?
Look at it this way: your tyres are the only part of your vehicle that have contact with the road surface. Therefore, it is the tyres that impact how much grip your vehicle has, how easy it is to control, how long the braking distance is, and more.
On top of all that, the tyres you have fitted to your vehicle can have a huge impact on its performance and efficiency – not to mention whether the vehicle will pass its MOT and be recognised as safe legal to drive.
Common Indicators of Illegal Tyres
Now that we understand a bit more about why tyre maintenance is so important, let’s look at some of the common signs and indicators that tyres may be considered illegal.
- The tyre tread depth is less than 1.6mm.
Tyre tread depth refers to the measurement between the outside surface of the rubber tyre and the deepest groove. The legal limit is 1.6mm, so anything less than this is considered illegal.
As tyre tread depth is constantly being worn away with prolonged use and time on the road, this is an important measurement to keep track of – upgrading your tyres as they start to nudge the 1.6mm mark.
- Tyres are incompatible with the vehicle.
Sure, there are details that you can change about your tyres – for example, changing from summer to winter tyres with the change in season.
However, some aspects of your tyres need to be compatible with the vehicle and need to match the specifications of the tyres originally fitted to the car. You cannot mix and match the tyre size, tread depth, or tread pattern – as changing any of these things can impact the amount of control that you have over the vehicle.
- Tyres show excessive signs of wear and tear.
This one may seem obvious, but if your tyres are excessively worn or have cracks and bulges in the rubber surface and sidewall, then you are legally required to replace them.
A worn, cracked, or damaged tyre is more likely to burst while on the road and potentially cause an accident – either for you or for other drivers around you.
- Your tyre pressure is wrong.
On the inside wall of the driver door on most vehicles, you will find a table that denotes the correct tyre pressure based on the number of passengers regularly transported in the vehicle and the load carried.
Having under or overinflated tyres can lead to your tyres being considered illegal, by putting undue pressure on the tyres and potentially causing a loss of control as well as an increased chance of tyres bursting or becoming damaged on the road.
