Hi Doug, I'm a big fan of Forgeline, had them on my '08 M3. (Pic below).
On a 9.5" wide wheel, I did test fit both the 38mm and the 45mm... I would recommend a 'minimum' of 45mm to tuck the Outer Rim inside the fender for Rear, probably more like 50mm would be best, but then it wouldn't work on the front. The front should probably only be 40MM and a 9" wheel, as the 45mm w/ 9.5" wheel is within 1/4" of the Upper Arm/Perch. The Rear had plenty of room to go to a 10" wheel, but Enkei's offsets then don't work, and I wanted to have the ability to rotate wheels front and rear.
For the ultimate setup... for the track... probably an 18 X 9" front with a 265... and 18 X 10" with 295 Rear would be perfect if I were spending the money to have a custom set of wheels built.
This setup cost barely $1,400 for the set of 4 wheels, weighing barely 18lbs.
And I had these 285/30/18's Race tires, sitting around from when we did some test fitting on my Dad's Z-06 that I auto-x. Once I burn through them... I'll do a nice 265 / 295... and she'll look mean. The 285's are honestly a bit too 'low profile' with the 30 series... but their definitely going to stick!
And with that 285 up front... I'm hoping she won't push!
I'll let you know how she fares next weekend.