An investigation is presented of the spin-orbit mixing within the Sr[5s5p(P-3(0,1,2))] manifold on collision with Ne, Kr and Xe at elevated temperatures following pulsed dye-laser generation of Sr(P-3(1)). The population profiles of all three states were monitored individually by laser-induced fluorescence and fitted to a kinetic model involving six collisional rates connected by detailed balance. The model also includes mixing by Sr(S-1(0)) itself. The resulting rate constants, together with those for Sr(S-1(0)), Ar and He reported previously, are considered using a standard model employing the potential wells of the reactants and also a collision-complex model.