Last year I replaced the OEM springs on my 92 400e with Eibach springs. (I already had Koni adjustables front/rear)I went thru a new set of tires in 7 months. I just put another set of tires on it and with less than 2K mi.,am again experiencing tire wear particularly on the inner Rears(-Camber).
The W124 cars apparently have no rear Camber adjustment. RennTech markets a device that is supposed to allow for rear Camber adjustments. My question is, Can any of the (-) Camber be corrected by replacing the spring pads with thicker ones.I know that there are spring pads of varying thicknesses. As I recall mine were very thin either due to the 100+Kmi on them or they were the thinest ones from the get go. I installed the springs so refitting the pads ain't that big a deal. Is it worth giving it a shot? Right now I'm just rotating like crazy to even out the wear.
I'm sitting on 17in AMG "Original" Aeros and 245 x 40 x 17 Kumho's. Replacing rubber ain't no cheap fix

I had this situation sometime ago, ...the rear is too low and the rear tires is not straight enough and had always wear in the insider. Your right, ..there's no adjustment on the camber itself. I measure the rear height elevation and from there, ..I based me decision on what size (thickness) of spring pads that I have to use. I install the one with a three star (19MM), ...the ride height was corrected, same as the camber. Hope this helps......
Please check if your control arm bushing is okay.....
Also, ..make sure there's not much weight inside the trunk.