I will try to do some kind of coastdown test with two suberb tires:
145/80R14 Bridgestone B381 Ecopias. Original Audi 3L tire size.
175/70R14 Nokian Hakkapeliitta R. One of the best LRR tire available at the moment.
So the test will be a coastdown test from 140 km/h to 0. I will measure the distance diffence but also the times which it will take to 140-65 (aero) and 65-0 (Rolling resistance). I will appreciate more aero but those are also 3% taller so I have to test them also while driving to see which is actually better... Rolling resistance wise Nokians should be best with clear margin
. Pressures in both tire sets always 3.5 bar.