A mobile robot traversing an uneven terrain can undergo tip over instability when one or more wheels of the mobile robot losses contact with the uneven terrain. In this paper, we study the tip over stability of a three wheeled mobile robot. The three wheeled mobile robot studied in this paper has torus shaped rear wheels and have the ability of lateral tilting – a condition required for slip free motion on uneven terrain. The torus shaped wheels and slip free motion makes the dynamics and tip over stability analysis more difficult and interesting. In this paper, the force-angle stability measure technique is used to analyze and detect tip over instability. Simulation results of the stability analysis shows that the wheeled mobile robot with lateral tilt of rear wheels is capable of moving on certain kinds of rough terrains without tip over.