To fit perfectly using STOCK fenders, the only conbination I've come arcoss so far is using 16" Boxster rims. They are 16' x 6" 50mm offset for the fronts and 16" x 7" 40mm offset for the rears and they fill out the fenders perfectly. I can snap a pic of my car if you are interested.
Hehe... And just a shameless plug. If you are interested in a set. I got a spare set you can have. Email me and I can walk you through the whole process.
Sprint.