This paper extends the analysis of empirical methods for describing vehicle–terrain interactions in lunar terrain. Given analytical formulation to predict mobility performance in extraterrestrial environments requires reliable in situ testing campaigns, this imposes fundamental restrictions to conceive a more consolidated theory, and further any possibility to use improved empirical methods to design better space hardware. Hence, we propose an analytical approach to extrapolate data taken in parabolic flights to model vehicle performance in multiple gravity regimes. The extrapolation technique and respective reported uncertainties can be used, therefore, to tune fitting parameters of a set of general formulas in the domain of Terramechanics, allowing to have empirical estimates of the wheel mobility in cases where testing is inherently very complex. Finally, by the analysis of previous Moon and Mars rover missions with the fitted equations, we report an empirical design criterion that allows to generate first estimates of the optimal wheel dimensions, taking into account the eventual longitudinal slip of the rover and including the desired mass of the payload. The introduced rules for geometry optimization can be important for future space rover missions in remote soils.