C 3500 Truck 2WD V8-6.0L VIN U (2001)
Toe is a measurement of how much the front and/or rear wheels are turned in or out from a straight-ahead position. When the wheels are turned in, toe is
positive (+). When the wheels are turned out, toe is negative (-).The actual amount of toe is normally only a fraction of a degree. The purpose of toe is to
ensure that the wheels roll parallel.
Toe also offsets the small deflections of the wheel support system that occur when the vehicle is rolling forward. In other words, with the vehicle
standing still and the wheels set with toe-in, the wheels tend to roll parallel on the road when the vehicle is moving.
Improper toe adjustment will cause premature tire wear and cause steering instability.
Thrust Angle Description
The front wheels aim or steer the vehicle. The rear wheels control tracking. This tracking action relates to the thrust angle (3). The thrust angle is the path
that the rear wheels take. Ideally, the thrust angle is geometrically aligned with the body centerline (2).
In the illustration, toe-in is shown on the left rear wheel, moving the thrust line (1) off center. The resulting deviation from the centerline is the thrust
angle.
Lead/Pull Description
Lead/pull is the deviation of the vehicle from a straight path, on a level road, without hand pressure on the steering wheel. Lead/pull is usually caused by
the following factors:
-
Tire construction
-
Uneven brake adjustment
-
Wheel alignment
The way in which a tire is built may produce lead/pull. The rear tires will not cause lead.
Memory Steer Description
Memory steer is when the vehicle wants to lead or pull in the direction the driver previously turned the vehicle. Additionally, after turning in the
opposite direction, the vehicle will want to lead or pull in that direction.
Scrub Radius Description
Ideally, the scrub radius is as small as possible. Normally, the SAI angle and the centerline of the tire and the wheel intersect below the road surface,
