Due to the high incidence of rollover in the accident experience with Michigan double-bottom tankers, a special study of rollover dynamics was included in the ad hoc study of those vehicles at The University of Michigan. A dynamic model of the vehicle in the roll plane was formulated for study of roll motions under arbitrary lateral force input time histories. The roll response and limit manuever capabilities predicted by the model were compared against that of actual vehicles and good agreement was obtained. The model was used to predict the relative rollover thresholds of the double-bottom tanker and other alternative tanker configurations for comparison to that of other commercial vehicles in a selected double lane-change maneuver. The model confirmed that double-bottom tankers of the current design exhibit a low rollover threshold in comparison to other commercial vehicles; and that certain design changes proposed as a retrofit would effectively eliminate that disparity.