Chevrolet Corvette 1963 Repair & Tune-Up Manual page 336

306 TROUBLESHOOTING
HOW TO READ TIRE WEAR
The way your tires wear is a good indicator of other parts of the suspension. Abnormal wear
patterns are often caused by the need for simple tire maintenance, or for front end alignment.
Excessive wear at the center of the tread indicates that
the air pressure in the tire is consistently too high. The tire
is riding on the center of the tread and wearing it
prematurely. Occasionally, this wear pattern can result
from outrageously wide tires on narrow rims. The cure
for this is to replace either the tires or the wheels.
This type of wear usually results from consistent under-
inflation. When a tire is under-inflated, there is too
much contact with the road by the outer treads, which
wear prematurely. When this type of wear occurs, and the
tire pressure is known to be consistently correct, a bent or
worn steering component or the need for wheel alignment
could be indicated.
Feathering is a condition when the edge of each tread rib
develops a slightly rounded edge on one side and a sharp
edge on the other. By running your hand over the tire,
you can usually feel the sharper edges before you'll be
able to see them. The most common causes of feathering
are incorrect toe-in setting or deteriorated bushings in
the front suspension.
When an inner or outer rib wears faster than the rest of
the tire, the need for wheel alignment is indicated.
There is excessive camber in the front suspension, causing
the wheel to lean too much putting excessive load on one
side of the tire. Misalignment could also be due to sagging
springs, worn ball joints, or worn control arm bushings. Be
sure the vehicle is loaded the way it's normally driven
when you have the wheels aligned.
Cups or scalloped dips appearing around the edge of the
tread almost always indicate worn (sometimes bent) sus-
pension parts. Adjustment of wheel alignment alone will
seldom cure the problem. Any worn component that
connects the wheel to the suspension can cause this type of
wear. Occasionally, wheels that are out of balance will wear
like this, but wheel imbalance usually shows up as bald
spots between the outside edges and center of the tread.
Second-rib wear is usually found only in radial tires, and
appears where the steel belts end in relation to the tread. It
can be kept to a minimum by paying careful attention to tire
pressure and frequently rotating the tires. This is often
considered normal wear but excessive amounts indicate that
the tires are too wide for the wheels.