Originally Posted by
Calsun
Pro racers realized quite some time ago that going from 23mm to 28mm tires had no discernible impact on rolling resistance but did smooth out the ride and in some cases the much lower tire pressures provided for less rolling resistance with the tire better able to roll over bumps in the road.
Pro racers had very little to do with this and for the most part were very late adaptors, cf., Tom Anhalt.