Tidal truncation radius predictions for a zero-eccentricity binary as a functionof the mass ratio q. The solid lines represent the fitting function R_i,Egg 0.88 ⋅ μ^0.01. In particular the blue line refers to the circumprimary disk, and the red line to the circumsecondary. Similarly, the blue dots are the theoretical predictions for the circumprimary and the red dots for the circumsecondary (data from Papaloizou & Pringle 1977). The yellow square refers to the equal mass case.