Originally Posted by
noisebeam
At 15mph good 32mm tyres will be faster than good 25s
Ummm, no, they will be the same speed.
DOH!
I mean: "At 15mph good 32s will require less effort to maintain speed than good 25s - because the rolling resistance advantage of the wider tyre will outweigh the aero advantage of the thinner tyre until speed rises; RR being proportional to speed, and air resistance to the *square* of speed, so that aero dominates at higher speeds but may be disregarded at lower ones."