When a motor vehicle has an especially good suspension system, one way of describing the driving experience is that it feels like it is floating on air. However, whether they ride like a ton of bricks or figuratively float over potholes, roll on the thinnest strips of rubber or have tyres with sidewalls which look like waterboots, all motor vehicles ride on air to some extent.

That air is in the tyres, of course, put there under high pressure to a desired psi (pounds per square inch). While many people pay scant attention to the air pressure in their vehicle's tyres, unless one or more of them go noticeably soft, the much better - and less expensive - approach is to monitor the tyre and maintain the correct air pressure. This is noted on the side of the tyre, with the motorist having a little leeway to determine the required ride quality.

The result of driving without enough air is that the outsides of the tyre wear down before the rest of the surface which comes into contact with the road. On the other hand, a tyre with too much air will wear excessively in the centre of its surface.

Although replacing tyres much sooner than would normally be required is an expensive exercise, there is also the potential danger of a blow-out from an over-inflated tyre or a soft tyre going totally flat. At the very least, this will result in inconvenience. At worst, there can be an accident, or the driver having to change a tyre in a dangerous spot.

Driving a car without enough air in the tyres also affects how it handles. If there is unequal air pressure in the front tyres, the vehicle will drift to one side, which causes excessive and unequal tyre wear as if it is not aligned properly. It also affects the vehicle badly if the brakes have to be applied sharply, causing it to swing significantly to one side.

Over-inflated tyres result in a bouncy, very uncomfortable ride.

Tyre pressure issues actually affect the suspension, leading to prematurely worn rubbers and shocks. This in turn affects the vehicle's handling.

With many service stations no longer offering air pump facilities, many motorists have added a small pump, which plugs into the car's 12V power outlet to their car-care kit. However, these pumps have notoriously unreliable gauges, motorists are advised to get a small handheld gauge to ensure that they are riding on the correct air.

- M.C