Component Tests

DESCRIPTION
Excessive radial and lateral runout of a wheel and tire assembly can cause roughness, vibration, wheel tramp and steering wheel nibble (tremor).

TEST CONDITIONS
To avoid false readings caused by temporary flat spots in the tires, check runout only after the vehicle has been driven. Visually inspect the tire carcass for abnormal bulges or distortions. Runout should be measured with a Rotunda Radial Runout Gauge 007-0056A or equivalent. All measurements should be made on the vehicle with the tires inflated to recommended tire pressures.

PROCEDURES
1. Using Rotunda Radial Runout Gauge 007-0056A or equivalent, measure the radial runout of the tire at the center and outside ribs of the tread face.
2. Measure lateral runout of the tire just above the buffing rib on the tire sidewall, see illustration.
3. Mark the high-points of lateral and radial runout for future reference.
4. Tire radial runout should not exceed 1.5 mm (0.06 inch), and lateral runout should not be more than 2.0 mm (0.10 inch).

MATCH MOUNTING
Match mounting is a technique used to reduce radial runout and tire spring rate on tire and wheel assemblies. Excessive runout is a source of ride complaints and match mounting can be used to minimize the runout. There are two ways to use match mounting: positioning the tire on the wheel and positioning the wheel on the hub.
1. Measure total indicated runout on the center of the tire tread rib, and record it. Mark the tire and rim at the center of the tread rib, and record the reading. Mark the tire at the location of the valve stem for reference.
2. Break down the tire and remount it 180° on the rim so the valve stem reference mark is opposite the valve stem on the wheel.
3. Reinflate the tire and measure the total indicated runout, and again mark the high spot.
4. If runout is reduced to acceptable guidelines, the tire is ready to be put back into service. If runout is still excessive, one of the following steps must be performed:
^ If the high spot is within 100mm (4 inches) of the first high spot on the wheel, the wheel may be out of tolerance; check the wheel for runout.
^ If the high spot is within 1 00mm (4 inches) of the first high spot on the tire, and is still outside the guidelines, replace the tire.
5. Measure the radial and lateral wheel runout at the positions shown in the illustration. The radial runout must not exceed 1.5 mm (0.06 inch) and the lateral runout must not exceed 2.0 mm (0.10 inch).