Great post, redpoint5.
The moon disc idea has me thinking -- one of the reasons just about all wheels have
"spokes" or other cutouts is to ventilate the brakes and prevent fade. Hypermilers can get away with covering up those slots with moon discs because we typically drive slower than average and leave lots of following distance, so maximum braking on already-hot parts is a very rare occurrence. For a semi-truck, there may be liability issues.
P.S. I remembered reading a little about super singles and other efficiency improvements on semis on Wayne's site a while back. I think these were the threads:
http://www.cleanmpg.com/community/in...threads/20739/
http://www.cleanmpg.com/community/in...threads/49495/