Check the tread for abnormal wear patterns, cuts or embedded nails or stones. Check the sidewalls for cuts, cracks, abrasions or bulges.
Tyres are put under tremendous strains when a car is being driven.
There are only four relatively small areas of tyre tread in contact with the road. They carry the car’s total weight, and transmit to the road the power that drives and accelerates it over the many changes of surface and gradient encountered.
They must also transmit the forces generated by braking and cornering.
Because they are in constant contact with surfaces that are frequently abrasive, damaged and even broken, tyres are more liable to wear and physical damage than any other car component.
For safety’s sake, keep a regular check on them – and on the wheels that carry them. Make it at least once a fortnight, and also before any long or high-speed journeys.
Badly worn or damaged tyres are both illegal and potentially lethal: they can cost you your licence – or even your life.
It is better to look over the tyres and wheels while they are on the car than not to inspect them at all. But for a thorough examination of the inside walls, the wheels should be taken off about once a year (See Checking, removing and refitting road wheels).
Inspecting tyre treads and sidewalls
The tread is the obvious place to start looking for tyre damage. Begin by inspecting carefully the whole circumference for abnormal wear and flaws in the pattern.
Abnormal widening of the grooves, or the spaces between tread blocks, usually means that the tyres are ageing.
If a series of cracks is evident, replace the tyre – even though there may still be 1-3 mm of tread left.
Pay special attention to the small slots and cuts – known as ‘sipes’. Look for embedded fragments of sharp flint and stones, or the nails and tacks that are the usual cause of punctures and can cause internal damage.
That sort of debris can be prised out with a screwdriver blade. But removing it may leave the tyre with a slow puncture.
Check for loss of pressure, and if it occurs have a tyre-repair shop take the tyre off the rim, inspect it, and make a permanent repair.
Look also for ‘flats’ in the tread, worn perhaps by severe emergency braking – when the tyre of a locked wheel slides on the road, wearing off the rubber and generating a lot of heat.
Abnormally severe wear at the tread shoulders or uneven tread wear are warning signs that should never be ignored.
They could be the result of more fundamental problems perhaps in the tracking or suspension and could soon lead to failure at speed (See Avoiding tyre wear).
Bulges in the sidewalls are signs of carcass damage. Long before cords are showing through, these tyres are unsafe at speed. Sometimes the damage may not be visible, so if you have suspicions – perhaps after hitting a kerb – but cannot see any exterior evidence, ask a professional tyre fitter to remove the suspect tyre and examine it.
Often, fractures are visible inside before they become obvious outside. Any break in the carcass construction means replacing the tyre. It cannot be repaired safely.