Going from Agitator rims to BST's. Front was an 18 inch off a 2010 street glide and went to a 19. Both had Commander II's:
Old 39.8
New 30.0
Saved 9.8
Rear was same size and same tire. Commander II's
Old 52.4
New 40.6
Saved 12.2
All measurements were with brake rotors front and rear. The rear pulley was not installed for either measurement. I also went to a different swing arm and saved an additional 11.8lbs.
Expensive? Depends on how you look at it. If 5 lbs equals a horsepower and 1 lbs of reciprocating weight equals 5 lbs of stationary. It's an easier pill to swallow. I did the whole drive train on my bike. Rode it for a year. Then this winter I shaved weight with rims, swing arm , and inverted front end. Changed it over from street glide to rode glide. My butt dyno tells me it is faster and when I slow down. I'll put it back up on the drum and I bet I that dyno shows more power as well.