If you do most of your own automotive suspension work at home, a camber gauge is one tool you should have in your toolbox. Camber is one of the three suspension angles measured when performing an alignment. This term describes the angle between a line drawn through the vertical centerline of your tire and a vertical line. A tire with positive camber leans outward and a tire with negative camber leans inward. A camber gauge measures this angle, usually with a bubble in a graduated cylinder magnetically attached to the wheel hub. A camber gauge works on the same principle as a level.
For more info, see The Hidden Costs of Lowering Springs