Wheel installation geometry (Audi A4 B6)

Convergence. The front parts of the front wheels are closer to each other than the rear ones. This helps equalize the friction between the wheel and the road, which pushes the left wheel to the left and the right wheel to the right. Toe-in reduces the angular oscillation of the wheels and the wear of the tires. When driving around a curve, the wheel that is located on the inside of the turn turns to support the movements of the steering mechanism and the forces applied to turn the wheel are greater than the wheel that is located on the outside, i.e. toe-in turns into divergence (the wheels at the back are closer together than at the front).



Collapse. Camber is the tilt of the wheels relative to the vertical. Camber reduces the transmission of shocks to the steering components, and it also reduces the effort required to turn the wheel and the friction of the wheels on the road. The front wheels are installed with positive camber, that is, the upper parts of the wheels are slightly further apart than the lower ones,

Transverse inclination of the kingpin. The transverse inclination of the kingpin is the inclination of the kingpin axis relative to the vertical. If you mentally extend the kingpin axis line to the ground and measure the distance to the wheel axis line (to the midpoint of the tire's bearing area), then we get the rolling shoulder. In order to reduce parasitic forces in the steering, the rolling shoulder should be as small as possible. In addition, the transverse inclination of the kingpin in combination with the longitudinal inclination leads to the fact that when the wheels are turned, the car rises slightly. When the steering wheel is released, the wheels return to the middle position (restoring moment).





Longitudinal inclination of the kingpin. The longitudinal inclination of the kingpin is the distance (in the direction of movement) between the imaginary centerline of the kingpin extended to the ground and the midpoint of the tire's bearing area. Due to the longitudinal inclination of the kingpin, the wheels are pulled rather than pushed, so they tend to take and maintain a straight position.

(Read the original source on the website audimanual.ru)