The effect of that the tire has on the overall aerodynamic drag in a car-tire assembly has been studied and deemed considerable from past studies. It has been shown that to know how tire parameters affect the drag on the car-tire assembly, it is important to understand how the vehicle body and the tires influence the flow structures. Previous studies have focused on the tire attributes that have some impact on the aerodynamic performance of the vehicle. These tire attributes, however, haven't been studied to the extent where one can get a better understanding of the impact of each of these attributes. This paper studies the impact that specific tire attributes have on the overall aerodynamic drag on the vehicle based on a thorough and systematic sensitivity study. The effect of tire attributes in a vehicle assembly as well as the sensitivity study of a rim protector on a standalone tire is conducted. This helps in better understanding the flow structures around the car body and around the tire for the improvement in the aerodynamic performance of the vehicle. This is a two-part study. One component of this study is a parametric sensitivity analysis of a tire in a tire – vehicle assembly. The other component is a parametric sensitivity analysis of the rim protector design on a standalone tire. / Master of Science / The drag performance is one of the most important factors that contributes to the overall efficiency of a vehicle. There has always been a huge demand in the automotive industry for such studies. Over the years, experimental studies conducted have shown to be invaluable to the industry. But a big downside to experimental studies is that they are extremely expensive. Experimental studies on Vehicle bodies require a wind tunnel and expensive measurement equipment. This has led to a high demand for more computational studies in this field. Various authors over the past few years have studied and challenged various solution procedures used in computational studies. The trade-off for these studies is always cost vs. accuracy. This thesis attempts to simulate both for a vehicle assembly as well as a standalone tire model to come up with a robust solution method for the computational analysis of flow over a vehicle body. The goal of this thesis is to conduct a parametric sensitivity study for the cross-section profile of the tire in vehicle assembly as well as a parametric sensitivity study for the rim protector profile of the tire in a standalone tire. At the end of the study, we will get a better understanding of the impact that each of the parameters have on the drag performance of the vehicle and the standalone tire.