Ok, so I think I understand about the swing arc. I still have trouble understanding how offsets work, but that basically has to do with how far the tires/wheels stick out from the car, right? I guess I don't understand how it affects the arc, though.

So I think the wheels are American Racing Fuel 18x8. Will that wheel coupled with 265/65-18 tires likely result in rubbing between the cladding and the tire (assuming a more aggressive tire, I suppose).

It seems like while there are some maths involved, there is also a fair bit of try-it-on-and-see. So if I order these tires, I'm assuming I will find out pretty quickly if I need to trim the cladding. In the event that that occurs, how trivial a feat is it to shave some of that off?

Thanks everyone for the responses!