<div class="htmlview paragraph">A study was undertaken to compare values of Truck Tire Rolling Resistance obtained under laboratory conditions to those obtained over the road. Four sets of tires of three tread depths were individually tested at the Goodyear Tire and Rubber Company on Rolling Resistance Machine #72, and at the Calspan Advanced Technology Centre on both the flat belt tester and the 1.7m wheel.</div> <div class="htmlview paragraph">Over-the-road tests were performed on three paved road surfaces, including one wet surface.</div> <div class="htmlview paragraph">A multiple linear regression technique based on the SAE five-point test matrix and the equation FR = a_o + a₁L + a ₂L²/_P + a₃L/_P was used to derive regression coefficients for selected on-road and lab data. Based on the regression analysis, this paper demonstrates that the on-road rolling resistance can be as much as 17% higher than corresponding lab values. There was no noticeable variation in on-road rolling resistance over the two dry surfaces tested.</div> <div class="htmlview paragraph">Half-tread and 100% buffed tires demonstrated as much as 19% lower rolling resistance than new tires. This difference decreased with decreasing inflation pressure.</div>