Match Mounting Tires

Match Mounting Tires
Match mounting is a technique used to reduce radial or lateral tire runouts 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 of the tire on the wheel and positioning the wheel on the hub.
1. Measure the 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 degrees on the rim so that 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 the runout is reduced to acceptable guidelines, the tire is ready to be put back into service. If the runout is still excessive, one of the following steps must be performed:
a. If the high spot is within 102 mm (4 inches) of the first high spot on the tire, and is still outside of guidelines, replace the tire.
b. If the high spot is within 102 mm (4 inches) of the first high spot on the wheel, the wheel may be out of tolerance. Check the wheel for runout.
c. If the high spot is not within 102 mm (4 inches) of either original high spot of the tire and rim, then draw an arrow from the second high spot to the first high spot (in the shortest direction) and rotate the tire on the rim 90 degrees in that direction. This will normally reduce the runout to an acceptable level.

In the majority of cases, the first 180-degree turn of the tire will either fix the problem or indicate which item to replace.