I just recently put a set of 19's on my rx8 and they are staggered they are 9.5" in the back and every time i hit the slightest bump the tire rubs on the fender. Anyone have any suggestions on stiffer springs or where i might find some. Possibly a different alternative?

What is the tire size and offset of the wheel? You might have to roll your fenders, or you might just need to dial in a little bit more negative camber.

Rear suspension isn't the problem, its the wheels. You didn't rub on stock wheels did you?

More info is needed, but like topgear said, you may need to roll your fenders and add in some negative camber. It would help us to know what the tire size and brand is as well as the offset of the wheels.

roll the fender