Tyres are your only point of contact with the road surface, so it makes sense to look after them and monitor their condition. In addition to each tyre being inflated to the correct pressure, the condition and depth of the tread is equally important.
TYRE DOS & DON’TS
√ DO replace the valve every time you change a tyre. By doing so, you guarantee airtightness and extend the life of your tyres; valves deteriorate under the action of centrifugal force.
√ DO check the balancing. As well as suppressing vibrations, this will help avoid premature wear, not only on tyres but also on the suspension and wheel bearings.
The minimum legal tread depth in the UK is 1.6mm, which can be measured using a tread depth gauge. Penalties for using tyres below the legal limit can be severe, including driving licence endorsements and large fines. Badly worn tyres and those in poor condition with cuts and bulges in the sidewalls are also more susceptible to punctures and catastrophic failure. Check the condition of your tyres regularly, particularly for low tread, worn areas or any bulging. All tyres will wear eventually, but you may notice the tyres on your car wearing unevenly. For instance, they may wear on the outside edge only, the inside edge or, less commonly, in the centre, while the rest of the tread is fine. Wearing on either edge could be caused by wheel misalignment, which can be checked at a tyre dealership, a process known as ‘tracking’. More seriously, the same type of wear could also be caused by worn or modified suspension. Wear on both the inside and outside edges of a tyre can occur when a tyre is under-inflated; a tyre that wears in the centre of the tread can be attributed to over-inflation.
Types of tyre
Modern cars are fitted with radial ply tyres, but older vehicles were equipped with crossply tyres. These two types of tyre offer different handling characteristics. The only time mixing the two types is legal is when radials are fitted on the rear and crossplies on the front of a vehicle. If replacing tyres, opt for radials, and preferably keep to the same make and tread pattern.
All tyres have markings on the sidewall to identify the size and speed rating. Below is a radial ply tyre bearing the following mark: 215/65 R 15 102H. The 215 denotes the tyre width in mm; 65 is the tyre height to width as a percentage. The R denotes that the tyre is radial ply construction; 15 is the wheel diameter in inches; 102 is the maximum load rating that the tyre is capable of carrying at its maximum recommended speed; and H is the speed rating for that maximum speed, in this case up to 130mph.
Checking tyre pressures
It is important to maintain the correct tyre pressure for your vehicle, as not only will the tyres wear more rapidly if not inflated correctly, but the handling of the vehicle will suffer. For example, if the pressure in one tyre is particularly low, you may notice the car will seem to pull slightly to one side. In addition, lower than recommended pressure in the tyres will cause more drag when driving, resulting in a loss of fuel economy.
TYRE PRESSURE DOS & DON’TS
√ DO check your tyre pressures every two weeks or at least once a month, as this will ensure your vehicle maintains its best roadhandling capability.
⊗ DON’T ever over-inflate your tyres, as the vehicle’s roadhandling will suffer and the tyre treads will wear in the centre.
√ DO bear in mind that tyre pressures should be checked ‘cold’– that is, before you have driven very far.
Tyre pressures should be checked regularly to maintain your vehicle’s optimum performance and road holding. Remember to check the spare tyre, too, as, should you ever need to fit it, the last thing you want is to discover it is flat! Tyre pressure can be checked at most petrol stations, which will have compressed air available to inflate the tyres. Most are free to use, although some may require tokens from the forecourt attendant. Remove the cap from the valve and push the end of the airline onto the valve stem, locking it into place. A gauge either on the airline or on the pump housing will show the pressure in the tyre. Inflate the tyre until it reaches the recommended pressure, shown in your handbook or sometimes on a chart next to the air pump. Manual and digital pressure gauges are also available to enable you to check tyre pressure at home.
A variety of pumps can be bought to inflate tyres at home. Electric pumps are the most expensive of these and can be plugged either into your car’s cigarette lighter socket or into the mains electricity, depending on the model. While the dearest of the group, electric pumps require the least effort on the part of the user. Manual pumps come in both single and double cylinder form, with the double version inflating the tyre more quickly.
To operate a manual pump, remove the cap from the tyre valve and attach the airline as described above. In some cases, a hubcap or wheel trim may need to be removed to access the valve. Attach the end of the pump’s tube to the valve, release the lock mechanism on the pump (usually a clip) and press down on the lever with your foot. The gauge on a foot pump usually has two needles. Set the red indicator to the maker’s recommended pressure. The black needle will rise up the scale; when it reaches the same point as the red needle, the desired pressure will have been reached.