I would think 8-9lbs per wheel in rotating weight would be noticeable, and especially on the CF angle. I always wondered why city buses don't have Alum wheels (6?), since they start and stop nearly every block, for their entire life cycle and alum wheels them saves 40+? lbs per wheel, but fire trucks have them and they maybe move twice a day?
fire trucks have aluminum wheels because firemen like them shiny [not that there is anything wrong with that]. city buses have steel wheels because they run into, and over, all kinds of stuff that would trash aluminum wheels in quick order. plus, i believe steel wheels are cheaper than aluminum and don't require constant polishing that will save the city big bucks in their yearly budget. garbage trucks are steel wheels for the same reason and i would hazard to guess they start and stop way more frequently than city buses.
