I ran 245/50/16's on ponys on a '91 lx with tailpipes. When I took a left turn, like a freeway ramp, the tire would rub on the tailpipe and smoke. I ended up heating up the tailpipe with a torch and banging it in a bit.
My point is just because they don't touch when the car is sitting still, doesn't mean they won't touch when you are driving.
EDIT: for the record, the catback was a flowmaster system.
Jeff