Imp4, Did you have the fronts checked for nails etc???? Were the tires that wore out on the back? Did you have the alignment checked? My friend owns a tire shop and the Cooper CS5's are his most popular with the least of problems.
I'm looking at putting them on the rear of my Challenger R/T in a 255/50/r20 to fill in the rear fender wells more. The stock tires (245/45/r20) look little back there.
No nails in the fronts and the car is reasonably aligned but not perfect. The fronts were slightly more worn out then the rears but when Walmart does a mileage warranty claim, they take the tread depth reading from the back tires anyway. Needless to say, mine were completely shot at 34,000 miles.
I will say that this car is used the majority of the time by my teenagers so I'm not close enough to monitor daily useage.
I did a ton of research before I bought the CS5's and I choose them because they were so well reviewed.
Others may have different experiences and this model may work well for them.
I just couldn't pass this thread up without adding my 2 cents about how disappointing CS5's were for me.