I suppose it’s possible… visually comparing the two tires:
- due to prolonged trainer wear, the old road tire was quite ‘squared off’, so to speak
- the newer trainer tire is more rounded (due to less wear)
I say that the former would have had much more surface contact with the trainer roller than the latter… which may go to support your theory that the trainer tire (with less surface contact) has a longer spindown time --> less power.
That said, last night I took some time and tested my trainer tire at higher/lower tire pressures and also tighter/looser roller tension. After each tweak (and recalibrating in Tacx Utility each time), I rode a quick 2 km stretch on flat road in Watopia to see if the wattage would change.
Remarkably, the wattage stayed very consistent in all scenarios (at most 3-5% variance). Couldn’t at all get to a setting that I could explain the 20% drop in wattage I had experienced with the tire switch.
I still have the old road tire, I may very well try swapping it back on and seeing what it does.
Wanted to share on the forum for input as reading through the posts, I was not coming across much of anything regarding a power drop due to a switch from road to trainer tire.