The rears wear about twice as fast as fronts. However I've always been able to get at least 20,000 miles from each set of RE050A rears. Mostly highway driving.

 

agreed

Do you have the alignment spec sheet from the dealer when you got it aligned last time? Possibly the dealer isnt putting it into spec.

 

Hard to tell for sure. The Field Service Manual shows that the (rear) front lower links are supposed to have a slight curve in them. If you have a significant number of miles on the car and are experiencing such severe wear, then I would look into replacing the rear suspension arms and (rear) front lower links at a minimum. The radius rod, which effectively keeps the rear suspension from toe-ing, could also be bent or the bushings could be worn out, which could cause unnecessary changes in toe while driving.