dropping the car with 17's....

right now the car is dropped 2.5 inches which is pretty damn low, and i personally think makes the whole thing look much nicer. the thing is ill be getting rims and tires soon. preferably 17's. i realized and i've been told i will be rubbing alot with that kind of setup. i want to try and see how low i can actually drop the car with 17's/low profile tires without having some scraping/rubbing problems? because stock height just won't cut it...