This study was conducted to determine the differences in performance between 102-in. (259-cm) wide and 96-in. (244-cm) wide trucks and the impact that these trucks have on other traffic. Trucks which were studied primarily included random trucks in the traffic stream, although a limited amount of control truck data were also collected to account for driver differences. Truck data were collected on rural two-lane and multilane roads which included curve and tangent sections and a variety of roadway widths and traffic conditions. The data collection effort resulted in approximately 100 hours of videotape and 9,000 slides from which various measures of effectiveness (MOEs) were extracted. A number of MOEs were used to test for the operational effects of differential truck widths, lengths, and configurations. Such measures included: (1) lateral placement of the truck and the opposing or passing vehicle, (2) lane encroachments by the truck or opposing vehicle, and (3) edgeline encroachments by the truck or opposing vehicle.