Originally Posted by
Steamer
Ok, but what about when wheel size is the primary difference between two machines that you are comparing? At that point the small difference in Crr you might see due to wheel size becomes all of the difference to consider.
Not really. Additionally you have i.e. rotating mass (lower with smaller wheels and therefor better) and - as jur said - aerodynamics (again better with smaller wheels). The question is wether these factors overrule the no doubt slightly higher rolling resistance or not. Not an easy case and I'd assume there exists no general rule here.