Wheel / Tyre size on my STI
 

Hey guys
I've got 17" alloys on my prodrive STI, with 225 46 17 tyres fitted.
This car is going to do some hill climbing and track days and I'm considering the options.
Do I go 18"? The car has been perfectly geo'd as every component of the suspension is adjustable, and set for fast tarmac. If I got to 18" will I have to change all that?
If 18"so, which wheel?
If 18" which Tyre size is best?
If I stick with the 17", which Tyre size is best?
Thanks y'all:luxhello: