It sounds complicated but it’s simply a way of using light beams to check your car’s front wheels are set up as they should be. You’d think this means simply pointing forwards but in fact, wheels are set up to point at specific angles to ensure the car rolls along smoothly.

To check the alignment, a technician attaches brackets to your car’s wheels and shines a light from one to the other or, using an overhead projector, to all four. Depending where the beams of light fall on a scale, the technician can see whether the wheels are in or out of alignment.

For greater accuracy, a computer is used to check the position of the light in relation to the scales. Once the degree of misalignment has been established, it’s a relatively simple job to adjust the suspension so the wheels are set up correctly once more.


Three angles of wheel alignment are checked, called camber, caster and toe. Each has a different angle calculated by the car maker to improve the performance of the car’s steering and suspension systems with the goal of making the car handle smoothly, responsively and predictably.

Camber: This is a measure of how vertical a tyre is. If it’s set so that it leans slightly towards the wheelarch it’s described as having negative camber. In the other direction, it’s called positive camber.

Caster: this is slightly harder to visualise, but concerns how directly above the wheel’s centre the suspension sits and, therefore, how central the angle of the tyre’s placement on the road is on the front to back plane. If you think of a ‘chopper’ style motorcycle with its suspension steeply raked back, this would be an example of extremely positive castor.

Toe: wheels that point inwards at the front towards the centre of the car are experiencing toe-in, while if the front of the wheels point outwards towards the road, this is toe-out.