I'm running RPF1's and have this fitment which I personally think is spot on...
Fronts: 9.5J ET15 on 225/45/18 tyres
Rears: 10.5J ET15 on 245/45/18 tyres
Tyres have a bit of stretch, not sure if thats what you want though? Should be 245 front and 265 rear recommended sizes I think.