Tumbling robots provide the potential to produce increased mobility on smaller scales with respect to their size and/or complexity. In this paper we explore the frictional interactions between a tumbling robot and the terrain while climbing a single vertical step to illustrate the advantages of tumbling. We present a set of parametric configuration equations that express the relationships between the robot’s configuration parameters (morphology, geometry, mass, etc.), the environmental/task parameters (step geometry, available coefficients of friction, etc.), and the performance parameters (step height). The required body coefficient of friction is examined in detail for idealized tumbling and wheel-tail robots. We further illustrate the results of our analysis by experimentally determining optimal tumbling and wheel-tail configurations for a given step size and body (wheel) friction.