The outline of this study examines the elastic limit stresses and failure of rotating variable thickness disk composed of fiber reinforced material via utilizing Tsai-Wu criterion. As known, strength parameters (Fi,Fij), obtained with the tensile and compressive strength of the material, should be calculated to apply this criterion. In the literature, one may come across different approaches that predicts the tensile and compressive strength of the fiber reinforced composites in different material directions. In the study, these approaches are gathered and the ones estimating lower and upper bound strengths are determined. Followingly, elastic limit angular velocity and position of the failure along the disk is calculated with the criterion for lower and upper bound estimations. It has been seen that usage of lower and upper bound strengths can change the magnitude of elastic limit angular velocity up to 35% without altering the position of the failure. On the other hand, the application of different boundary conditions changes the position of the failure in the disk. When the disk has free-free boundaries, it fails at an arbitrary position. However, subjecting the disk to fixed-free boundary condition cause failure at the inner radius.