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Radial Tire Lead / Pull DescriptionS7RS0B2401006
“Lead / Pull” is the deviation of the vehicle from a straight
path on a level road even with no pressure on the
steering wheel.
Lead is usually caused by the following conditions.
• Improper tire and wheel alignment.
• Uneven brake assemblies.
• 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 the figure (Lead Diagnosis) should be
used to make sure that wheel alignment is not mistaken
for tire lead.
• 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.
• Rear tires will not cause lead.
Balancing Wheels DescriptionS7RS0B2401007
There are two types of wheel an d tire balance: static and
dynamic. Static balance, as shown in figure, is the equal
distribution of weight around the wheel. Wheels that are
statically unbalanced cause a bouncing action called
tramp. This condition will eventually cause uneven tire
wear.
Dynamic balance, as shown in figure, is the equal
distribution of weight on each side of the wheel
centerline so that when the tire spins there is no
tendency for the assembly to move from side to side.
Wheels that are dynamically unbalanced may cause
shimmy.
1. Heavy spot wheel tramp [A]: Before correction
2. Balance weights addition point [B]: Corrective weights
3. C/L of spindle
1. Heavy spot wheel shimmy [C]: Before correction
2. Balance weights addition point [D]: Corrective weights
3. C/L of spindle
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