Does the rear suspension have adjustment? Despite the pretty heavy camber, I have some outside wear on the right rear conti. Not so much on the left. I wouldn't think I drive that differently right to left! Just over 27k on the ContiTourings...will need replaced soon.

 

Natural tendency to accelerate harder turning left than right, which would wear the outer edge of right rear tire. Just the opposite in right-hand drive vehicle.

 

Since it is an IRS, I'm sure there are adjustments that can be made. You're not by chance hauling to much weight in back are you? The Crossfire has a pretty "limited" cargo weight capacity. Since the Conti's aren't directional, try rotating them.
As Danimal pointed out, maybe your cutting those left hand apex's a little faster than the left ones and just don't realize it.