Camber
A - The cylinder will roll in a straight line; B - The cone will roll in a circle centered on the side of the narrow end; C - Scheme of contact of wheels with the road surface; D - Positive camber; E - Vertical plane
General information
The angles of the wheels determine the geometry of the position of the latter relative to the suspension of the car and the road surface. Violation of the adjustment of this geometry leads to a decrease in the controllability of the car and an increase in the rate of tire wear. The number of angles of installation of the front wheels of the car to be controlled includes camber, run-out (the angle of the longitudinal inclination of the axis of rotation of the wheel) and convergence (see below).
Adjusting the suspension geometry requires the use of special expensive and bulky equipment and should be entrusted to car service specialists.
Convergence
Convergence is the amount of convergence to each other of the front edges of the wheels of the car. Such a violation of the parallelism of the wheels allows minimizing tread wear due to skidding when making turns. At zero convergence, the distance between the front edges of the wheels is equal to the distance between their rear edges. Normal convergence is usually less than a fraction of an inch (1 inch = 2.54 cm). Violation of the adjustment of convergence leads to accelerated wear of the tire tread due to their slippage on the road surface.
Collapse
Camber is the angle of inclination of the plane of the wheels relative to the vertical. If the wheels are tilted with their upper edges outward, the camber is called positive, and vice versa. Camber is measured in degrees. The correct camber adjustment determines the size and position of the tread contact patch with the road and allows you to compensate for changes in suspension geometry during cornering and when driving on uneven road surfaces. A small amount of negative camber allows you to increase the contact patch of the tread during cornering, however, if excessive, it leads to a violation of the vehicle's directional stability and increased jerks transmitted to the steering wheel.
Overrun
The run-out is the angle of the longitudinal inclination of the axis of rotation of the wheel, i.e., the angle of deviation from the vertical of the axis of rotation of the wheel in the plane of the latter. If the axis of rotation is tilted back, the coast is called positive, vice versa. Positive coastdown allows the front wheels to self-return to a straight-line position when exiting a turn, thereby increasing the vehicle's directional stability, however, being excessive, reduces the vehicle's maneuverability.
Note. Lowering the rear of the vehicle leads to an increase in the positive run-out of the wheels.