Radial Tire Lead; Vibration Diagnosis - Suzuki Jimny Service Manual

Radial Tire Lead

"Lead" is the deviation of the vehicle from a straight path on a level rod even 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 example 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 has a little larger diameter than the other, the tire will tend to roll to one side. This will develop a
side force which can produce vehicle lead.
The procedure in above figure (Lead Diagnosis) should be used to make sure that front alignment is not mis-
taken for tire lead.
1) Part of the lead diagnosis procedure is different from the proper tire rotation pattern currently in the owner
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.
Wheel unbalance causes most of the highway speed vibration problems. If a vibration remains after dynamic
balancing, its possible causes are as follows.
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 TPD is not available, alternative
method of substituting known good tire and wheel assemblies on the problem vehicle can be used, although it
takes a longer time.
[A] : Tire out of round
[B] : Tire stiffness variation
[C] : Rim bent or out of round

Vibration Diagnosis

1. Smooth road
2. Suspension movement (loaded runout)
STEERING, SUSPENSION, WHEELS AND TIRES 3-7