The adjustment is made with the vehicle ready to drive and the fuel tank completely filled.
The driver's seat must be loaded by a person or a 165 lbs. (75 kg) weight and the tire pressures must meet the prescribed values.
After being loaded, the car must be rolled a few meters so that the suspension can settle.
For checking the headlight adjustment, the vertical position of the cutoff of the lowbeam (see fig.) has to be projected on a vertical screen (wall) in distance of 24.6 ft. (7.5 m) from the front lens of the headlamp.
The correct position of the cutoff is 2.0 in. (5 cm) at 24.6 ft. or 7.5 m (0.4°) below a horizontal line, x cm from ground to the center of the headlamp lens.
Lateral adjustment of the headlights should be carried out at a specialist workshop with an optical adjustment unit.
Visual aim shall be performed at not less than 24.6 ft./7.5 m (this value is a rounded down conversion from the 25-foot distance typical of field aim using a screen). The 24.6 ft./7.5 m distance is measured from the headlamp lens to the viewing screen.
The surface upon which the vehicle rests is flat and approximately level.
The screen upon which headlamp beams are projected is perpendicular to the floor and the vehicle's longitudinal axis, flat, uniformly light in color, unobstructed, and wide and high enough to accommodate the vehicle beam patterns to be aimed.
The screen should be wide enough to provide at least 3.3 ft. (1 m) of space outboard of the vehicle's headlamp spacing.