Dynamometers are used by truck manufacturers, and frequently by truck distributors or large fleet operators, to test the engines and other parts of the driveline.
Dynamometer rolls vary in size from 8-5/8-inch to 50-inches. The smaller rolls have a greater potential for damaging the tires.
During a dynamometer check, there is little weight on the tires and only a small area of the tread face (usually the center rib or center portion of the tread) is in contact with the roll. Excessive heat builds up in this small area. If the test runs too long, the excessive heat can damage the tire to the point where it could fail later on the highway.
The maximum safe time for running tires on a dynamometer roll varies with the roll diameter, speed, the power or torque transmitted from the tire to the roll, and, to some extent, the load and inflation.

Figure 12.1 shows general rules for limiting the time for maximum power testing.


For 50 percent power, the time can be doubled. For 25 percent power, the time can be quadrupled.

*Goodyear Tire Reprint*