Match Mounting

Match mounting is a technique used to reduce radial and lateral runouts on wheel and tire assemblies. Excessive runout is a source of ride quality complaints and match mounting can be used to minimize the runout. Match mounting can be accomplished by changing the position of the tire on the wheel or by changing the position of the wheel and tire assembly on the hub.

1. Remove the wheel and tire. Refer to Wheel and Tire .
2. Position the wheel and tire assembly on a suitable tire machine and put a reference mark on the tire sidewall at the valve stem position.
   Fig 1: Locating Mark On Tire Side Wall At Valve Stem Position

   Courtesy of FORD MOTOR CO.

   Item	Part Number	Description
   1	-	Valve stem
   2	-	Reference mark

NOTE: For tires equipped with a tire pressure monitoring system (TPMS), the sensor, cradle and strap may be damaged by incorrect tire mounting or dismounting. Dismount the tire from the wheel as instructed in the Disassembly and Assembly procedure. Failure to follow these instructions may result in TPMS component damage.
3. Using a suitable tire machine, break the tire down from the wheel.
   • Position the tire 180 degrees (half-way around) on the rim so the tire reference mark made in Step 2 is opposite the valve stem.
4. Re-inflate the wheel and tire assembly to the specified air pressure and measure the assembly runout again. Mark the second high spot on the tire.
   • If the runout is reduced to within specifications, the problem has been solved.
5. If the second runout measurement is still not within specification and both measurements are close to each other (within 101.6 mm [4 in]), the root cause is probably the tire.
   NOTE: To be SURE  that the tire is causing the high runout, you must have 2 runout measurements that are not within specification and the high spots must be in approximately the same location on the tire's sidewall. In other words, the high spot followed the tire when it was repositioned 180 degrees on the wheel.
   • If the second high spot is not within 101.6 mm (4 in) of the first high spot, proceed to the next step.
   Fig 2: High Spotting On Tire

   Courtesy of FORD MOTOR CO.

   Item	Part Number	Description
   1	-	First high spot on the tire
   2	-	Second high spot on the tire

6. If the second high spot is still above specification and is within 101.6 mm (4 in) of being opposite the first high spot on the wheel, the root cause is probably the wheel (the high spot followed the wheel). Dismount the tire from the wheel, mount the wheel on a balancer and check the wheel runout. Install a new wheel if the wheel runout exceeds 1.27 mm (0.05 in).
   Fig 3: High Spotting On Each End Of Tire

   Courtesy of FORD MOTOR CO.

   Item	Part Number	Description
   1	-	First high spot on the tire
   2	-	Second high spot on the tire

NOTE: If the second high spot did not follow the wheel or the tire and the runout is still not within specification, you may make improvements by rotating the tire 90 degrees (1/4 of a turn).
Fig 4: Drawing Arrow On Tire Side Wall From Second High Spot Towards First High Spot
Courtesy of FORD MOTOR CO.

Item	Part Number	Description
1	-	First high spot on the tire
2	-	Second high spot on the tire

7. Draw an arrow on the tire sidewall from the second high spot towards the first high spot (in the shortest direction).
   • Rotate the tire 90 degrees (1/4 of a turn) in the direction of the arrow.
8. Install the wheel and tire. Refer to Wheel and Tire .
   • Align the wheel and tire assembly using the index mark made on the wheel and wheel stud during removal.