Suzuki sq-416-420-625 Service Manual page 140

3-8 STEERING, SUSPENSION, WHEELS AND TIRES
RADIAL TIRE LEAD
"Lead" is the deviation of the vehicle from a straight path on a level
road with no pressure on the steering wheel.
Lead is usually caused by:
1) Incorrect alignment.
2) Uneven brake adjustment.
3) Tire construction.
The way in which a tire is built can produce lead in a vehicle. An ex-
ample of this is placement of the belt. Off center belts on radial tires
can cause the tire to develop a side force while rolling straight down
the road. If one side of the tire is a little larger diameter than the oth-
er, the tire will tend to roll to one side. This will develop a side force
which can produce vehicle lead.
The procedure on previous page should be used to make sure that
front alignment is not mistaken for tire lead.
1) Part of the lead diagnosis procedure is different from the tire
rotation pattern currently in the owner's and service manuals. If
a medium to high mileage tire is moved to the other side of the
vehicle, be sure to check that ride roughness has not developed.
2) Rear tires will not cause lead.
VIBRATION DIAGNOSIS
Wheel unbalance causes most of the highway speed vibration
problems. If a vibration remains after dynamic balancing, it can be
caused by three things.
1) Tire runout.
2) Wheel runout.
3) Tire stiffness variation.
Measuring tire and/or wheel free runout will uncover only part of the
problem. All three causes, known as loaded radial runout, must be
checked by using a Tire Problem Detector (TPD). If a TPD is not
available, the more time consuming method of substituting known
good tire and wheel assemblies on the problem vehicle can be
used.