The incorporation of reliability theory into a fatigue analysis program is studied. A thorough background in probabilistic methods and metal fatigue is presented, allowing a full understanding of these processes. An automotive wheel assembly is then introduced as an example of the applications of this durability/reliability design package. A detailed step-by-step procedure is utilized to develop the basic information needed to analyze the wheel assembly: material properties, geometry, and loading; the relationship between applied load and stress; and the degree of variation in specific material properties, wheel thickness, and service loading. An in depth documentation of the effect of these “real world” variations on wheel reliability is then presented in graphical form. Several different approaches in altering the design variables are used in order to thoroughly illustrate the resulting component reliability. Such information is particularly relevant where product quality and warranty formulation are concerned. / Master of Science