This was a large motivator for the Epic HT drop bar build that I’ve posted elsewhere on this forum… Its been my hypothesis for a while now, that on a lot of gravel/dirt roads(my local ones included), a larger volume tire isn’t any slower, and in fact is faster while being more enjoyable and forgiving.
The Thunder Burt 2.1" first confirmed this, and the Race King 2.2" further validated it.
link to Epic mentioned
https://www.trainerroad.com/forum/t/drop-bar-mtb-geo/87495/4