In general, we suggest 17 inch diameter. We have used 18 inch for racing for particular tire we wanted to fit but ride quality generally not great for 18 inch in street use and we suggest 17. Most 16 inch don't fit, tire selection is weak, etc.
For 17 inch diameter there are a range of widths we use for street cars, depending on how aggressive you want the setup but generally 7, 7.5, and 8 inch. Wider you go for same 205mm wide tire, the more support sidewall has, the better performance BUT lower ride quality is the tradeoff. Thus, on my wife's NC PRHT we used 7.5 wide as a compromise and 215mm tire (205mm would have fit same wheel and again more performance from better sidewall support but less ride quality). If you add a lot of power (turbo, 2.5 liter, supercharger) then 17x8 and wider rubber such as 225/45 or 235/40.