Variation in the effects of tire rolling resistance on passenger car fuel consumption seldom exceeds ten percent. The definition of these effects is therefore a problem in experimental design and control, measurement precision, and careful accounting for uncontrolled variables.
A rolling resistance test conducted on a road surface with a fully instrumented tire test trailer is described and the test results presented. Fuel “economy” test techniques are discussed with emphasis on precautions and recommendations for reliable testing and test results presented. When aerodynamic drag is taken into account with wind tunnel measurements, the results are suggestive of engine characteristic curves.