Complete Four Wheel Thrust Alignment

Complete Four-Wheel Thrust Line Alignment:
Individual rear wheel angles are measured, then adjusted so the thrust line coincides with the geometric centerline. The front wheels are then aligned to the geomenic centerline/thrust line. This sets all wheels straight ahead and parallel, and centers the steering wheel.

Why Is 4-Wheel Alignment Recommended?
Your front wheels “steer” the vehicle, but your rear wheels “direct” the vehicle. Say your rear wheels are tilted to the right. Even if your steering wheel is pointed straight, your vehicle will travel left. Four-wheel alignment solves this problem by referencing all four wheels to a common centerline.