Proper wheel alignment will save you money

We know that the front wheels of any vehicle have to be "aligned" very precisely for optimal handling and maximum tyre service life.

We know that the front wheels of any vehicle have to be "aligned" very precisely for optimal handling and maximum tyre service life.

On many modern cars the rear wheels also have to be aligned.

Three terms you often hear when technicians discuss wheel alignment are castor, camber and toe-in and toe-out.

Castor refers to an effect which is familiar to us from the "castor wheels" of a supermarket trolley.

When the axis around which a front wheel pivots when it is steered is slanted at such an angle from the vertical as to meet the ground ahead of the contact path of the tyre, the wheel will have a tendency to return to the straight-ahead position when you release the steering wheel after completing a turn. This is called positive castor.

Camber refers to the fact that when the car is standing on a level surface, the front wheels will probably not be exactly vertical when you look at them straight from the front.

They will usually be slightly wider apart at the top than at the ground, though it will be hardly noticeable without measuring instruments.

This is called positive camber and it works in conjunction with the fact that the steering axis, if you could see it through the obscuring bodywork, will also not be exactly vertical. It will be tilted in the opposite direction.

Toe-in and toe-out is a way of saying that if you could look down on a car parked with its wheels facing straight ahead, the front wheels will probably not be perfectly parallel to each other.

They will either be a few millimetres pigeon-toed or slightly "toed out". This is done to compensate for the fact that on some designs the front wheels have a tendency to splay outward when the car is moving (then you want toe-in at rest), while on others the wheels tend to become pigeon-toed when the car is moving (then you want toe-out at rest).

The symptoms of faulty wheel alignment include:

lAbnormal tyre wear such as feathering on the tread;

lA steady pull to one side on the steering;

l Steering wander; and

l Vibration on the steering, even after all wheels have been balanced.

It's a good policy to have the alignment checked once every 30000km

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