Wheel alignment is a term used for adjusting the angle of the front and in some cases the rear wheels on a vehicle. Throughout the life of your vehicle the suspension and steering start to wear, your wheels take impact from kerbs and pot holes which can all disturb the alignment set up. This causes your tyres to wear unevenly and ultimately effecting the safety of your vehicle.
Wheel alignment, also known as tracking can be adjusted by the toe in, toe out of the wheel or adjustment of the positive and negative camber, this is all set to the manufactures specification.
Before having your wheel alignment checked, always make sure you have the correct tyre pressure in your tyres, as this also makes tyres wear uneven.
This image above shows a car with a positive camber. From the front of the vehicle, the camber is pointing the tyres inwards. As a result of a positive camber the tyre would wear on the outer edge.
Above is what a negative camber looks like, the bottom of the wheel is pointing out over resulting in the tyre wearing on the inside edge.
In this image the wheels are toeing outwards. The distance between the front of a tyre is greater than the rear of the tyre causing the tyre to wear on the inner edge.
The distance at the front of theses tyres are less than the back. So these front tyres are toeing inwards which would cause wear on the outer edge.
Having your wheel alignment checked is so important, not just for your safety but to increase the lifespan of your tyres. It should be checked at least once a year, you can keep checking for the signs of wearing using the pictures above as reference.