Validation was performed on an existing heavy truck vehicle dynamics computer model with roll stability control (RSC). The first stage in this validation was to compare the response of the simulated tractor to that of the experimental tractor. By looking at the steady-state gains of the tractor, adjustments were made to the model to more closely match the experimental results. These adjustments included suspension and steering compliances, as well as auxiliary roll moment modifications. Once the validation of the truck tractor was completed for the current configuration, the existing 53-foot box trailer model was added to the vehicle model. The next stage in experimental validation for the current tractor-trailer model was to incorporate suspension compliances and modify the auxiliary roll stiffness to more closely model the experimental response of the vehicle. The final validation stage was to implement some minor modifications to the existing RSC model. Following the steady-state validation of the current model, the dynamic response of the vehicle was tested using a ramp steer maneuver. The current simulation model worked in parallel with an RSC model which simulated the workings of the RSC portion of a commercial electronic stability control (ESC) system. The vehicle model was simulated with the RSC system activated and deactivated to study the effectiveness of the RSC system in preventing tractor-trailer rollover. It was found that when the RSC control was activated, the vehicle experienced much greater dynamic forces but still did not experience rollover until significantly greater speeds compared to simulations with the RSC switched off.