A study was conducted to quantify the cornering characteristics of radial truck tire rib and lug tread designs. A Calspan Tire Research Facility (TIRF) machine was used to measure tire force and moment responses to load. inflation, slip angle, and camber. The study condudedthat although tread design parameters are a factor, tire comering characteristics are strongly dependent on load. The cornering performance of lug design tires was not necessarily different from rib tires; the key tread design parameter was non-skid depth. An empirical model was developed for cornering and self-aligning toque stiffness as a function of tread design parameters, load, and inflation.