Figure 8-50.A. Toe-in; B. Toe-out.
measured at the hub height. Toe-in causes the wheels
to point inward at the front.
TOE-OUT results when the front of the wheels are
farther apart than the rear. Toe-out causes the front of
the wheels to point away from each other.
The type of drive (rear or front wheel) determines
the toe settings. Rear-wheel drive vehicles are usually
set to have TOE-IN at the front wheels. This design is
due to as a result of the front wheels moving outward
while driving, resulting in toe-out. By adjusting the
wheels for a slight toe-in (1/16 to 1/4 in.), the wheels
and tires will roll straight ahead when driving.
Front-wheel drive vehicles require different
adjustment for toe. This is due to the front wheels
driving the vehicle and are pushed forward by engine
torque. This makes the wheel toe-in or point inward
while driving. To compensate for this. front-wheel
drive vehicles have the front wheels adjusted for a
slight toe-out (1/16 inch). This adjustment will give the
front end a zero toe setting. as the vehicle travels down
Steering Axis Inclination
Steering axis inclination (SAI) (fig. 8-51) is the
angle away from the vertical, formed by the inward tilt
of the kingpin, ball joints, or MacPherson strut tube.
Steering axis inclination is always an inward tilt
regardless of whether the wheel tilts inward or
outward. Steering axis inclination is NOT a
tire-wearing angle. As with caster it aids directional
stability by helping the steering wheel to return to the
Figure 8-51.Steering axis inclination angle.