In Reply to: Working off of memory.... posted by Waiky on October 19, 1999 at 19:06:39:
: The sport suspension is stiffer of course. Also I think that the sway bars are thicker for less lean.
: Most likely the reason that you wouldn't want to put on 18" rims on a standard suspension is due to the soft ride, the travel in the suspension might bottom out. Also I read a while back that Road and track did a study on 16", 17", and 18"s and the best performance came from a 17 inch rim, but if you are considering non-sport, I guess that you are not as concern about handling. Hope that helped.
Basically for the most part that is correct. There is no reason you cannot go with 18's on the car, but I would typically suggest to replace the springs with lowering springs (Eibach, H&R) to add a bit more stiffness for that reason, plus it is simply going to make the car look better (not 'lifted').
17" by far is the most common & really the ideal blend. Once you go above that 18/19" you are still getting enhanced performance, but it becomes more cosmetic at that point. If you would be using the car competitively (autocross, for example), or driving very agressively, I typically am going to suggest 17s for the reasons above.
Hope this helps. As always feel free to call or email me!