Maintaining and inspecting a tyre extends its life and enables the vehicle to handle, ride and brake at its best. Clearly, this is important for road safety. There are legal implications too. The maximum penalty for having a defective car tyre is a £2,500 fine and 3 penalty points (per-corner). It can invalidate insurance too.
Optimum pressure can be confirmed via the vehicle's manual or a sticker on its a-pillar. Open the driver's door to reveal the latter. A front tyre might – only might – have a different requirement than a rear. It is also common to have a recommendation for lighter loads – such as carrying a couple of people and a little luggage – and a higher recommendation for 5 people and lots of cargo. Check the pressure once per-week using a high quality gauge. The tyre has to be cool for the reading to be accurate. It is also wise to cross referencing the reading using a second gauge.
The purpose of tread is to remove rain water so the tyre makes contact with the road. Without it, the vehicle floats on top of the water and cannot be steered. The legal minimum is 1.6mm across the central 75% of a tyre's width, and around its circumference. This can be checked via a manual or digital gauge. The alternative is the wear indicators. When a tyre is new, these small rectangular pieces of rubber sit deep within its tread. Once it is worn to the legal limit the indicators sit flush with the surface of the tyre.
A front tyre typically wears faster than a rear. Why? Because in a front-wheel-drive car – which most people have – it experiences more stress. It has to transfer the engine power into momentum, take the majority of the braking force, and steer. The solution is to periodically rotate the front and rear tyres to share the load.
Alignment problems cause a tyre to wear prematurely and unevenly. Spotting it early – by checking for consistent wear across its entire width – minimises the impact as it can be corrected before there is significant damage. Alignment relates to angles. The most recognised terms are tow and camber. Imagine an aerial view of a tyre. Toe is the angle its leading edge points to the centre of the car, or out to the road. Then there is camber. Look at a tyre from the front. Camber is the angle its top leans into the wing or outwards. Such adjustments might best be completed by a specialist.
Driving style influences how long a tyre lasts. Hard cornering forces a vehicle to lean heavily onto the shoulder of a tyre, for example, which increases wear in a focussed spot. Hard acceleration that causes wheel spin further reduces life, as does braking hard and leaving skid marks on the road surface. Furthermore, thrashing through potholes at high speed – rather than steering around them or slowing down – often weakens a tyre to the point of destruction.
Damage can kill a tyre. However, spotting certain kinds early ensures there is some chance of a repair. A tyre with a puncture in the centre of its tread might be salvageable – but not if it runs flat at speed and wrecks the side wall. Check regularly for punctures that can be repaired plus cracks and bulges which cannot.