This recommended practice applies to the laboratory measurement of rolling resistance of pneumatic passenger car tires designed primarily for normal highway service. The procedure applies only to the steady-state operation of free-rolling tires at zero slip and inclination angles; it includes the following three basic methods: Force Method-Measures the reaction force at the tire spindle and converts it to rolling resistance. Torque Method-Measures the torque input to the test machine and converts it to rolling resistance. Power Method-Measures the power input to the test machine and converts it to rolling resistance.