I was looking at them (Michelin Pilot Power 3) and noticed that their load rating was a little lower than the Pilot Road 3's (73 vs. 75). So after checking, that's a 47lbs. weight differance (73=805lbs, 75=853lbs per a website I found).
Yes I know it's only a 47lbs. differance, but that "may" be a issue for some.