The Effect of Tread Loss On Tire Rolling Resistance Under Simulated Driving Conditions

Six tires with known inflation pressure loss rates (IPLR) by ASTM F1112 (static) and ISO 28580 rolling resistance (RRC) values were selected in order to develop a dynamic IPLR value obtained during operation on a 1.707-meter roadwheel.  After each incremental operation on the smooth drum, the inflation pressure and resulting rolling resistance values of the six tires were measured, allowing calculation of a Dynamic IPLR value.  As a follow-up, an indoor treadwear test was developed on the laboratory roadwheel in order to study the IPLR and RRC values of the tires when operating while the tread was being lost.  After each increment of the test on the textured drum, the inflation pressure and rolling resistance of tires were measured, along with detailed treadwear measurements which included laser profiling.  A final experiment was undertaken to study the rolling resistance of uniformly-worn tires at specific inflation pressures.  Using the information from the change in rolling resistance with the decrease in inflation pressure, the competing effects of pressure decrease and tread loss were calculated for each of the six tires modeled during tire operation.  Modeling showed that the magnitude of rolling resistance increase due to inflation pressure loss was significantly greater than that of decreased rolling resistance due to tread loss.  The predictions of the model were verified by testing tires with varying degrees of remaining tread at different inflation pressures.