Nice to hear of a Coupe gen Avenger posting in!
A lot depends on what kind of road conditions you'll mainly be driving on. MY experience was to drop from the factory 17" rims to 16" rims due to the harsh country roads I encounter here in the Western NY area. Kept the Factory rated tire sizes due to very limited clearance to the suspension components to the tires.
Some here have posted of using 225/50-17 tires and even lower profile, but rim offset is very critical for enough suspension/tire clearance.
I'd suggest you read thru/ search this forum section for what our small group of Coupe owners have done. This is a topic that has had a good amount of discussion here.
Yea I was looking on that site earlier but I guess what I'm trying to figure out is if I am stuck with keeping the wheel and tire below the upper control arm or if I can install a rim that will go above it.