ASTM International Standard Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions ASTM F1650-21

This practice covers the required correction procedures for examining sequential control tire data for any systematic or bias (not random) variation due to changing test conditions that may influence absolute and also comparative performance of candidate tires, as they are tested over any short or extended time period. The procedures provided here may be used for any repetitive tire traction testing in any environment (for example, dry, wet, snow, ice) where test conditions are subject to change. This practice does not address the issue of rejecting outlier data points or test values that might occur among a set of otherwise acceptable data values obtained under identical test conditions in a short time period. Method A uses the initial operational conditions defined by the first control traction test as a reference point. The calculations correct all traction test performance parameters (for example, traction coefficients) to the initial level or condition of the pavement or other testing conditions, or both. With this method, corrections may be made after only a few candidate and control sets have been evaluated. Method B uses essentially the midpoint of any evaluation program, with the grand average traction test value as a reference point. This grand average value is obtained with higher precision than the initial control traction test average of Method A because it contains more values. However, Method B corrections cannot be made until the grand average value is established, which is normally at the end of any program.