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Car tyres and the law – what are the facts?

We explain what the law says about your car tyres and what you need to do to keep within it.

You should check your tyre tread at least once a month.

You should check your tyre tread at least once a month.

Taking care of your tyres is an essential part of motoring maintenance, let alone a legal part. UK law states that your car must be fitted with the correct type and size of tyres that are free from defects. There are several elements that the legislation covers.

Tyres free from defects

You should check your tyres on a regular basis to make sure they are free from defects. You should check there are no cuts, tears or bulges and that nothing is embedded in the tyre such as nails or screws. If there is a cut in your tyre ideally you should have it replaced as soon as you are able to, however the law states that if the cut is smaller than 25mm or covers less than 10% of the section width of the tyre then the tyre is still legally viable.

Tyre mixing

Although most new cars now come with radial tyres, rather than cross-ply, the two tread types should never be mixed on the same axle. This means that the two front tyres should have the same tread type and the two rear tyres should have the same tread type. The same goes for tyres of different type or size, so if you fit winter tyres you must do so on both sides of the axle, tyre size must also be the same on both sides.

Tyre pressure

You should check your tyre pressures on a weekly basis, if you’re not sure how to take a look at our video ‘how to check your tyre pressure.’ Your vehicle handbook will tell you what each tyre pressure should be; this could be different depending on how heavy the load is in your car. If your tyres are not at the correct pressure your braking and steering ability could be adversely affected, so it’s really important to check them regularly, the recommended timing is at least once a month.

Tyre tread

Tyre tread depth should be checked regularly, legally the depth of the tread on your tyres should be a minimum of 1.6mm across the central three-quarters of the tyre for the whole circumference. Having a low tyre tread will increase your vehicle’s stopping distance significantly. In 2004 the British Rubber Manufacturers’ Association (BRMA) commissioned MIRA to study the effects of tread depth on stopping distances. It was found that tyres with a tread depth of 1.6mm (legal minimum) had an increased stopping distance of 44.6% on smooth concrete and 36.8% on hot rolled asphalt. Following the study RoSPA (The Royal Society for the Prevention of Accidents) recommended that tyres with a tread depth of 3mm should be replaced before they worsen, as this was the point that braking distances were impacted.

Spare tyres

In the UK it is not a legal requirement to carry a spare tyre, but it is advisable. If you do have one remember to carry out these safety checks on that one too, although legally if it is stowed away then it doesn’t need to be up to legal standards – it just makes sense to keep it that way.

If you’re planning to drive abroad you should check the country in question’s legal requirements for spare wheels before setting off.

Some new cars are sold with a space-saving or skinny spare wheel; these are only designed for temporary use in an emergency. They are limited to speeds of 50mph (80kph) and should be replaced with one that matches the rest of your tyres as soon as possible. Some manufacturers really want to save on space and will only provide a tyre repair kit instead; if this is important to you, you should check with your salesperson when you’re buying the car.


Legal standards are there for a reason; if they are ignored there are consequences, not just to the safety of the vehicle and passengers but also in the form of penalties.

If the driver and owner of the vehicle are different then both will be liable and may be summonsed in the event of illegal tyres. Courts can impose fines of up to £2,500 and drivers can receive three penalty points on their licence per illegal tyre.

About the Author

Nicole Ferguson

Staff writer at Arnold Clark