Originally Posted by
RChung
Almost always, the rank ordering of tires on rollers is the same as on the road. Sometimes two tires will swap ranking, but usually that's when the tires are pretty close to begin with. An exception can occur when the impedance break point on one tire comes a little earlier than the other. If you're in the neighborhood of that threshold, you can also observe a ranking swap.
Thanks for that - yeah, that does makes logical sense. Is there a very *approximate* ballpark range in terms of closeness where the rankings can change, in your experience? I wouldnt expect a tire to make up a 7-8W gap, but are we talking fractions of a watt,1-2 watts or some other number? To be clear - i realize this is not going to be a scientific calculation, just a guesstimate borne of experience.