If you drive with damaged or worn tyres you risk being fined, invalidating your car insurance policy and endangering lives.

General requirements

Tyre fitted to a motor vehicle or trailer must be fit for purpose and be free from any defects which might damage the road or endanger any person. This means the tyre:

• must be compatible with the types of tyres fitted to the other wheels
• must not have any lump, bulge or tear caused by separation or partial failure of the structure
• must not have a cut or tear in excess of 25mm or 10% of the sectional width of the tyre, whichever is the greater, and which is deep enough to reach the ply or cord
• must not have any part of the ply or cord exposed

A vehicle with any of these faults or with tyres of different nominal size or aspect ratio on the same axle is liable to fail an MOT test.






Duty to maintain

Tyres must be correctly inflated to the vehicle manufacturer's and the tyre manufacturer's recommended pressure. ('Run-flat' tyres partially inflated or in flat condition are permitted in certain circumstances.)

Tread depth

This must not fall below the legal minimum. The tread is that part of the tyre in contact with the road in normal conditions. The minimum depth of tread depends on the class of vehicle.

Spare tyre

You are not obliged to carry a spare and it does not have to comply with the legal requirements while it is stowed away. However, when fitted to the vehicle (for example, following a puncture) it must then comply with the law. The spare is not tested in the MOT but the examiner may draw your attention to an unserviceable item as a matter of courtesy.

Penalties

If you drive a vehicle fitted with an illegal or defective tyre on a road, a police officer may give you a Fixed Penalty Notice or, in Scotland, a Conditional Offer Notice.

A police officer has discretion not to issue a fixed penalty but to report the case for prosecution. In law, the driver and the owner (if different) are liable and one or both may be summonsed.

The maximum fine which a court can impose for using a vehicle with a defective tyre is £2,500 and three penalty points (£5,000 in the case of a goods vehicle or a vehicle constructed or adapted to carry more than eight passengers).

If a vehicle is fitted with more than one defective tyre, you can be summonsed for each tyre which is illegal. Disqualification is also possible in certain circumstances.