The real eye-opener for me were that my kinda knobby MTB tires apparently have nearly the exact rolling resistance as my Schwalbe Marathon Plus on the Gravel Bi

The real eye-opener for me were that my kinda knobby MTB tires apparently have nearly the exact rolling resistance as my Schwalbe Marathon Plus on the Gravel Bike. So although they're a lot thinner, nothing is gained here at all. (If you assume enough pressure in the MTB tires on asphalt).