What's the best size?

Hey everyone,
I plan to get some new wheels this summer and was curious to know what that best size would be. Is it possible to go 18 without any problems? My car is already lowered about an inch and i wouldnt want any rubbing. Otherwise, i guess i would be stuck with some 17s.
Anyone have pics of 17 or 18 on their cars? i'd love to see them.
Thanks,
Mike
 
I have 18's on my car although it isnt lowered, i plan on doing that once it gets nice out. I dont have any problems with my wheels, 18's with a smaller profile tire equal out to about the same size as a stock 17 inch tire.

rgrgr.jpeg
 
what are tire prices for 18's compared to 17's? I would hate to have to kep forking out mucho dough for 18 tires.
The roads here in montreal arent the greatest. I dont know if 18 and low profies would do the job without damaging the rim.