A seven-company, cooperative evaluation was conducted to investigate the effect of camber and toe on the original tread life of steering axle tires in an operational fleet of Class 8 tractors. A total of 31 set-back-front-axle tractors were configured with steering axles that had one of the following nominal camber values: -3/4 deg, -1/4 deg, +1/4 deg, +3/4 deg, or +2 deg on the left and 1/4 deg more negative values on the right. Toe was then adjusted to one of three nominal settings (+0.140 in., +0.040 in., or -0.060 in.). Tire wear data were gathered over an almost two-year period. Relative tire wear as a function of camber and toe are presented.