Great Thread..and opportunity to talk Alpina wheels..
First off..if you are hesitant but have already purchased the 10" wide Alpina B6 wheels, I'll be happy to switch with you as I have an extra set of rear 9.5" B6 Alpina C13s.
I've been running 295 PS4S (thanks to xPaniPurix) on 9.5" B6 Alpina wheels on my F10 and they don't look too out of place and perform just fine. I have been wanting to get the 10" wide ones as they have an even more concave look but haven't found a deal on those...yet.
The 2015 B6 came with 9.5" wide wheels but with 2016 MY and the power bump to 600hp, they switched to 10" wide but both fit the B6. I am pretty sure they will fit the B5 as well and am more than happy to be a test mule
The F01 wheels are 21" and they have been successfully installed on F10s with thinner profile tires of course..but that has been done.