Stock Series 2 rims are 16x7 with offset +30 all round.
Personally, I wouldn't goto Tempe Tyres because
a ) I've heard their work is below par
b ) The wheels they sell are not as good as Japanese made wheels.
I'd invest in some Japanese made rims from known wheel manufacturers such as Rays, Work etc.
Finally, note that if you get Tempe Tyre 18" wheels, they are incredibly heavy and you will definitely feel this extra weight when driving your car (eg it'll be slower at slow speeds). 18" wheels will also cause your ride comfort to deteriorate slightly.