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Rotationally resolved infrared photodissociation spectra of $CH3+$-$Rgn$ ionic complexers (Rg = He,Ne,Ar, n=1,2), have been recorded in a tendem mass spectrometer. The spectra of the dimers are compatible with $\pi$--bonded equilibrium structures where the Rg atoms are attached to the vacant $2pz$ orbital of the central C atom ($C3v$ symmetry). In the case of Ar, partial charge transfer into this orbital leads to a large binding energy of the complex (ca. 0.5 eV), so that only overtones of the CH stretch modes can be observed in the photofragmentation spectra. The strong intermolecular bond induces a massive deformation of the $CH3+$ ion which transforms from $sp2$ towards $sp3$ hybridization. In the $Ar-CH3+$-Ar trimer the second Ar atom is weakly attached to the other side of the $2pz$ orbital of C ($C3v$ symmetry). The two C-Ar bonds are not equivalent: one is strong and short, the other one is long and weak. However, tunneling splittings reveal that they can exchange their role via the intracluster inversion motion of $CH3+$ through a transition state with $D3h$ $symmetrya$. The intermolecular bonds in the He and Ne containing complexes are much weaker and result mainly from induction interactions. The $CH3+$ deformation is smaller and the absence of the tunneling splittings in the $Ne-CH3+$-Ne spectrum suggests that the trimers have $D3h$ equilibrium geometries. The experimental results are supported by ab initio calculations.