I went 18" on my car primarily for handling and to have the clearance for big brakes. Something to look out for is if you're running factory sized torsion bars you might run into rubbing issues with larger tires up front. And you will feel more of the road, a lot more vs a 15" tire. If you're only looking at 18s for aesthetics then I would go 17" to give yourself a taller sidewall.