even if you go to a 16 inch rim, but you get a taller side wall tire you wont lower your car at all...you have an over all diameter of 24.6 inchs with the size you have now. If you went with a 215/45/16 it would be 23.6. Your car would be physicaly lower by half an inch. But you would have another half inch of fender gap. Use that tire size calc that thing is so much easier then doing the math.

Oh and also helps to know what kind of car its on. Look at what others have done and see what you like.