UK tyre law dictates that in order to be legal a tyre must comply with a number of requirements. These range from what the manufacturer must be responsible for, such as relevant sidewall markings, and what the motorist is responsible for, including selecting the correct fitment and maintaining the tyre condition.

Official guidelines recommend that tyres should be checked on a weekly basis for tread depth, tread condition, inflation pressure, tread or sidewall damage and signs of irregular wear. If in doubt seek the advice of a trained tyre expert who will be able to determine the suitability of the tyre for further use. If you drive on damaged or worn tyres, you are at risk of invalidating your car insurance policy, incurring a hefty fine and/or penalty points and endangering those around you.

Failing to maintain your tyres to a legal standard can result in a Fixed Penalty Notice (a Conditional Offer Notice in Scotland) or a court summons. In the eyes of the law both the driver and the vehicle owner, if different, are liable and both may be summonsed in the event of illegal tyres. The maximum fine a court may impose is £2,500 and three penalty points per tyre.

Tyre Mixing

Drivers must not have radial tyres on the front wheels and cross ply tyres on the rear wheels. It is also illegal to have a cross ply tyre on one side of an axle with a radial on the other.

Unsuitable tyres

All tyres must have a service description, i.e. a load index and a speed rating. If the vehicle operates outside the service description indicated on the sidewall, for instance at a higher speed than permitted by the rating or carrying more weight than the stated limit, then the tyres would be deemed to be unsuitable for the use and a prosecution would follow.

Tyre Cuts

A cut in excess of 25mm or 10% of the section width of the tyre , whichever is greater, measured in any direction on the outside of the tyre and deep enough to reach the ply or cord, would make the tyre illegal.

Tyre ply or cord exposure

If there is any cut in the tyre, no matter how small, which exposes cords then the tyre is illegal.

Tyre lumps, tears and bulges

If the tyre has any lump, bulge or tear caused by separation or partial failure of its structure, it is good practice when assessing the damage to remove the tyre from the rim and systematically inspect it both internally and externally.

Tyre tread Depth

The legal minimum tyre tread depth for cars, vans, eight-seater vehicles and light trailers, including caravans up to 3,500kgs in gross vehicle weight, is 1.6mm. This 1.6mm should be in a continuous band throughout the central three-quarters of the tread width, throughout the whole of the circumference.

Any vehicle with a gross vehicle weight or gross train weight over 3,500kgs or a motorcycle above 50cc, must have tyres in which the grooves of the tread pattern have a depth of a least 1 mm throughout a continuous band measuring at least three-quarters of the breadth of the tread and round the entire outer circumference of the tyre. If the grooves of the original tread pattern of the tyre do not extend beyond three-quarters of the breadth of the tread (this is common with motorcycle tyres) any groove of the original pattern must have a minimum depth of at least one millimetre.

Other points to remember

Damage to road, person or vehicle

If a tyre causes damage to the road, persons or any vehicle using the road it is deemed illegal. Instances include the use of studded tyres in inappropriate conditions and oversized tyres catching against a person or other vehicle resulting in either damage or injury.

Temporary use tyres

All tyres marked “Temporary Use Only” are restricted to 50mph.

Re-grooved tyres

Re-grooved tyres are illegal on any passenger car or utility vehicle below 3,500 kilograms gross vehicle weight.

Driving Abroad

Tread depth requirements vary throughout Europe, so make sure you check the tread depth requirements for all countries you will be passing through. In some European countries it is illegal to use replacements which differ in certain aspects, e.g. size, load and speed rating, from the tyre fitted originally by the vehicle manufacturer.

Tips for safety when driving abroad

Inspect all tyres, including the spare, for signs of damage.

Ensure all tyres are correctly inflated for the load you will be carrying and check your pressure settings regularly throughout extended trips.

Check your tread depth against the legal requirements for all countries you are going to, and allow extra if you plan on covering lots of miles.

Check the age of your tyres: if they are five years old get them changed before your journey.

Avoid sidewall impact wherever possible. If you do knock the sidewall, always check every tyre for signs of damage.

Don’ t overload your caravan as it can lead to a blowout.

If you are driving throughout southern Europe during the summer, stop for rest periods to allow your caravan or motorhome tyres or cool. This will help to prevent damage and disintegration caused by running at high temperatures.

Ensure your vehicle is equipped with all emergency equipment the country requires you to carry by law, e.g. warning triangles and high-visibility jackets.

Make sure your insurance is valid: check with your insurer if you are not certain.