Below are some reasons why the GSP9700 may not match or quantify the value of the tire or the assembly.
Incorrect Mechanical Wheel Mounting On The Shaft.
This can be caused from worn or damaged adaptors, rust or debris on the
wheel, shaft, hub, adaptors, or a cone contacting a wheel on an irregular surface.
Verify proper mounting by performing a centering check.
External Rim Measurement vs. Actual Bead Seat Measurement.
There is a high correlation between external and internal measurement, however
the operator must consider each wheel design individually. Some cast or closed-faced
wheels cannot be accurately measured externally. The tire must be removed for
accurate bead seat runout measurements.
Air Pressure Readings Before and After Matching Differ.
The air pressure should remain constant between each measurement. Always
inflate tires to the recommended pressure specified by the vehicle manufacturer.
Incorrect Tire Bead Seating Procedures.
Tire technology is always changing. Today's vehicles require the tire to
be designed to tightly adhere to the wheel, preventing slippage between the
two components. As a result incorrect tire bead seating procedures are becoming
more of an issue in solving vibration complaints. In many cases, a wheel will
display high non-uniformity values because of increased tire bead interference,
wheel design or improper bead seating procedures. If the tire is re-loosened
from the wheel and properly lubricated and remounted, the level of non-uniformity
may decrease dramatically. On sensitive vehicles, sometimes there is benefit
to slightly over-inflating the tire, deflating the air, and then re-inflating
to optimize bead seating.
Insufficient Use of Tire Mounting Lube During Mounting.
“Lube is Good!” Proper lubrication on the tire bead AND rim areas
including bead seat, hump, balcony, and drop center are vital in achieving proper
seating of the tire bead to the wheel assembly. Aggressive acceleration or braking
should be avoided for the first 500 miles to prevent tire to wheel slippage.
Rim Safety Hump Design 'Hangs Up' Tire Bead During Bead Seating.
Some types of wheels use a square safety hump that may further inhibit uniform
tire bead seating. This further underscores the importance of proper lubrication
and bead seating procedures.
Temporary Flat Spotting.
Flat spotting can occur when the tire is in one position for an extended
period of time, such as a parked vehicle, improper storage of the tire and temperature
extremes. Measurements for force and balance will change as soon as the tire
is driven for a few miles. This important issue can also affect traditional
wheel balancing procedures.
Excessive Lateral Runout of Tire and/or Rim.
A tire or wheel with high lateral readings may affect the predicted results
of radial force after ForceMatching®.