We consider spectral characteristics of rotational perturbation for CO2-Rg collisions (Rg = Ar, Xe) using molecular torques time correlation function and three-dimensional classical trajectories without several conventionally used simplifications. The results are applied to the band wing calculation. The calculated wing profiles depend on the potential energy surface and agree well with the experimental data. The relative contributions of collision-induced absorption and the role of dimer absorption are discussed.