Just found a dandy chart on rennlist:
http://members.rennlist.com/911pcars/WheelWts.html
Apparently there were two versions of the 993 10x18 hollow spoke rears, one with a 40mm offset and one which is 65mm. Blinkwatt, do you know which version you used?
The fact that the Bentley manual suggests 65mm rear offset would mean you can use either the 65mm 993 turbo or the 996 turbo rears, which in that case would both be 18x10 at ET65.
So, for the 986 do we want 40 or 65 MM of rear offset?
Patrick