you can see through the body of the vehicle. Your feet represent the tops of the
tires. Now slowly turn your feet inward to an excessive degree. That’s what your
tires look like when they’re toed-in too far. Now turn your feet outward
excessively. That’s what your tires look like when they’re toed-out too far
When the toe angle is out too far or in too far, tires wear out quickly. This
angle also affects whether or not your car’s steering wheel is straight. When the
toe angle is way out of alignment, the steering wheel is crooked. Excessive toe is
caused by worn tie rods, loose rack mounts, worn idler arms (some vehicles have
two), pitman arm, drag link assembly, or a worn rack or steering box. Before you
can accurately set the toe angle, the steering linkage parts must be tight. You can
adjust the toe alignment angle by either lengthening or shortening a steering
linkage part called a tie rod (found in both conventional and rack and pinion
steering systems).
A tire affected by excessive toe-in or toe-out exhibits a scalloped wear pattern,
also known as “wipe pattern.” The best way to describe this pattern is to
consider how a man’s face feels when he has a five o’clock shadow. If you run
your hand over his face, it’s smooth one way and rough the other way. If you run
your hand across a tire that has scallop wear, it will feel smooth one way and
rough the other. When the toe angle is misaligned, the tires are scrubbed or
pushed down the road and rubber is scraped off as they roll.
Caster
The caster angle is best illustrated by a bicycle experience of your childhood
youth. Remember when you rode your bike with no hands? Remember how the
handlebars returned to the straight-ahead position when you leaned right or left
to turn a corner? This is an expression of the caster angle. The caster angle of
your car expresses itself when the steering wheel returns to the straight-ahead
position after making a turn. It also expresses itself when the car tends to wander
right or left.