“For vehicles equipped with dual tires, if one of the dual tires becomes significantly underinflated or flat, the other tire will carry the load for both tires, resulting in an overloaded condition for both tires,” said Gary Schroeder, director of Cooper’s truck and bus tire business, which includes the Roadmaster brand. “Mismatched tire inflation on dual assemblies is typically a contributor to faster tire wear.”
Schroeder pointed to this example: In an 11R22.5 tire size mounted in a dual assembly with the same tread design, you would assume both tires are the same size with the same circumference. At 5 PSI difference in inflation, the tire with the lower inflation has a circumference that is 5/16-in. smaller. During every rotation cycle, the smaller circumference tire will scuff ahead to keep up with the tire with more inflation. To make this point clearly: tires rotate approximately 500 times per mile, so simple math tells us that 500 multiplied by 5/16-in. equals 156.3-in. per mile, or 13 ft. per mile.
“Imagine dragging a tire 13 feet every mile! How many feet is that per day or per year?” he asked rhetorically. “That illustrates clearly why you will see more rapid tire wear with improper pressure.”
Fleets that opt for super-wide singles can mitigate the improper tire pressure consequences, due to the fact that there are fewer tires on the tractor-trailer. But checking the super-wide singles’ pressures is still paramount.
“The majority of rapid air loss situations stem from poor pressure maintenance on the inside dual tire—a problem that is eliminated when switching to wide single tires,” said Bill Walmsley, product category manager for Michelin Americas Truck Tires. “You can remove the need to get to and check that hard-to-reach inside dual tire.”