Tyre Pressures
Important for safety, ride and fuel economy
Tyre pressures are quoted for cold tyres and will be specified in the car handbook. They may be shown on a sticker inside the fuel filler flap or driver's door too.
Generally two figures will be quoted – one for 'normal' use and a higher figure for full loads. Be sure to adjust the pressures to suit the conditions.
If you don't know the correct tyre pressures refer to the vehicle manufacturer's customer services department.
Correct tyre pressure is important for several reasons:
Tyre life – under or over inflation increases wear
Fuel economy – under inflation increases fuel consumption
Safety – under or over inflation will affect grip and braking performance
Ride – over inflation can result in a harsh, uncomfortable ride
Check pressures every two weeks with the tyres cold using a reliable/accurate tyre pressure gauge.
Pressures should only be checked when cold which means the car should not have driven for hours prior to checking
At the same time, examine the tyres for any cuts, or bulges which must be checked out by a professional if found – a bulge in a tyre indicates internal structural damage and the tyre must be replaced.
The tyre must also be replaced if you find cuts deep enough to reveal the internal structure of the tyre.
Tyre Life and Age
Influenced by many factors
Tyres are designed to meet different criteria; some for long life are made from a harder compound, but these may be more noisy, though this can also be affected by tread pattern. Others may be made from a softer compound, which will provide a quieter ride but will wear out more rapidly. It's often the case too that first fit (original equipment) tyres last longer than subsequent replacements
Tyre life is influenced by many factors:
Driving style – aggressive cornering and braking increases wear
Position – front tyres wear faster because of movement through steering and driven tyres wear more quickly
Speed – high speed driving increases temperature and hastens wear
Load – excess loading increases wear
Pressure – both under inflation (through increased flexing and temperature) and over inflation (through reduced contact area) increase wear
Alignment – incorrect wheel alignment results in rapid and uneven wear, as can excessive wear to suspension components, such as shock absorbers
Generally on a front-wheel-drive car you'd hope for a minimum of 20,000 miles for front tyres, and double that for those on the rear.
Though the legal limit is 1.6mm, tyre performance – particularly wet grip – gets worse as the tread wears. The rate at which wet grip deteriorates becomes greater as the tyre wears too. Check tread depth more frequently once it reaches 3mm and replace tyres before the tread wears below 2mm – particularly if coming into the wetter autumn and winter months.
Tyre age:
Age is a separate issue to wear – tyres do degrade naturally through exposure to heat, sunlight (Ultraviolet/UV) light and rain. Degradation depends on the amount of exposure and the severity of the weather.
This is a more common problem on caravans, trailers and vehicles only used occasionally. In most cases tyres will wear out before they degrade to such an extent they're unserviceable.
Look for signs of UV cracking on tyres four or five years old on cars parked outside. Tyres should be replaced irrespective of age if cracking becomes severe – any tyre specialist will be able to advise.
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