When rotating my tyres the other day i noticed the rears were wearing on the inner edges.
My Calibra is on standard shocks and springs. I thought the rear camber was only a problem on lowered Calibras.
load in boot can do it too 'sub and amps' or as jjcymru says get some new bushes
or some dtm off centerd ones if you have weight in the boot or have ppl in the rear alot.
or have the tracking checked first by good laser line equipment.