Camber angle is a measurement used in the wheel alignment of automobiles. It refers to the angle of a tire in relationship to the vertical axis of the tire when viewed from the front or back of the vehicle. If the bottom of the tire is farther away from the vehicle than the top, it can be said to have negative camber. If the top of the tire is farther away from the vehicle than the bottom, it can be said to have positive camber. A wheel that is perfectly vertical would have zero camber.
The camber angle directly affects the way a vehicle handles and is taken into consideration when a suspension system is designed. An incorrect camber angle can result in a variety of undesirable consequences, such as improper tread wear or poor handling. Camber angle is only one of the many variables that affect the way any particular vehicle handles.
A tire with zero camber, or a tire that is perfectly vertical when viewed straight on, can impart advantages for a vehicle on straight-line acceleration. This is because a tire with zero camber will have the most contact with the ground when moving straight ahead. A negative camber angle will give similar advantages when turning. This is why vehicle makers will usually be strike a balance between the two, depending on the intended use of the vehicle.
Camber is a measurement that will usually be taken when checking the alignment of a vehicle, though not all vehicles allow for adjustment to be made. Cars with McPherson strut suspensions typically have a fixed camber, though some allow an adjustment to be made where the struts bolt to the knuckles or hubs. Vehicles with a double wishbone type suspension allow for adjustment in many more applications. Adjustment may be required if the vehicle suspension is raised or lowered, parts are replaced, or the vehicle is in an accident.
Though negative camber can be instrumental in the handling of many vehicles, positive camber does see use in many non-automotive applications. Slow-moving off-road vehicles such as tractors will often have a positive camber angle to lessen the effort of turning. Positive camber is also sometimes used in the "taildragger" type landing gear of planes designed to take off and land on rough, unimproved surfaces. Positive camber might be undesirable, or even dangerous, in automotive applications, but it can have a desirable effect in the right applications.