Magazine for the professional tire industry
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Quik-Link: 800-687-1557 ext. 15113 4. Make sure a wheel torque program is in place. Years ago, TIA introduced RIST to help tire dealers under- stand the necessary compo- nents of a quality wheel torque program. The "R" stands for remove debris from mating surfaces, the "I" stands for inspect components, the "S" stands for snug the nuts in the star pattern, and the "T" stands for apply the recommended torque. F o r y e a r s , t h e i n d u s t r y preached the importance of torque without addressing the factors that translate into clamping force. As a result, companies that switched to torque control devices like torque wrenches immedi - ately saw the number of loose wheels and related problems go up. I've always said torque is the setting on the oven because it is a measure of force like temperature is a measure of heat. And just like a recipe, if the ingredients are wrong or the directions are not followed, the correct temperature of the oven means absolutely nothing. O n c u s t o m w h e e l s , t h e "Remove" step is critical, espe- cially when the hub bore in the wheel does not have a bevel or recess where it meets the concentric ring on the hub. If there is debris between the mating surface of the wheel and the hub or drum, the correct torque at installation will not be correct for long once the debris works its way out. Also known as "joint settling," the natural fexing of the wheels in service results in the loss of clamping force when the mating surfaces are not clean. The "Inspect" step of RIST should be obvious because worn or damaged components are not going to contribute to wheels staying on the vehicle, with or without the correct torque. It's equally important to inspect the bolt holes for any damage or wear, and if a hub-centric ring is used, it too should be inspected. "Snug" is fairly basic, but it should always be done in a star pattern to ensure the seating process is equal around the hub. "Torque" is the fnal, and most diffcult, step in the RIST proce- dure. The best practice is to use a torque wrench set to the specifcation for the OE wheel. This is the critical area to clean on a hub or drum. If the custom wheel does not have a beveled edge on the center bore, then any debris around the hub- centric ring will contrib- ute to a loose wheel. 22 Feature