Originally Posted by
furballi
Mass of tire, size of tire, and construction of tire (tread and casing) all affect speed.
No, mass doesn't. You think it does, but you're wrong. See those links.
The penalty of a heavy rim+tire is approximately 1.8x the penalty of a non-rotating mass on the bike. The 28C has lower mass, smaller
See my explanation of how angular KE affects (very slightly) acceleration but not speed.
(Btw - I have a physics degree from the UK's equivalent of MIT. Trust me: a lot of people think what you do, but it's complete bs and against the laws of physics.)