shiny_car

easiest to refer to other sites.

Offset & - Wikipedia, the free encyclopedia
Tire Factory

google is your friend.

i forgot to add earlier, that choice of wheel will also be limited by whether they can clear the Brembo calipers on the front (on GTA, V6 GT, V6 GTV, etc). you need a lot of clearance behind there, so even if the offset is appropriate, the back of the spokes may hit the caliper. i believe the wheel guys refer to this as 'X factor' or you may read about suitable wheels as having 'high disk'.

when searching for wheels, i found there wasn't much around that would fit straight on, particularly because of the Brembo's. though i'm unsure whether the 305mm versions are less of an issue compared with 330mm brakes.