I have always been a fan of Continental Tires and first put Terra Trail (40mm) tires on my gravel bike and loved them. Given that most of my gravel riding includes significant amounts of rural paved roads, I decided to switch to Terra Speeds (40mm) for the lower rolling resistance of about 10 watts. I also decided to try Schwalbe Aerothan tubes. I have not gone tubeless, as I want to be able to swap tires, especially to road tires next year as my Gravel Bike is also a capable 17 pound road bike.
So far, I have found no real difference in grip, and the Terra Speed/Aerothan combo *seems* to roll faster. Tomorrow, I am going on a ride with the exact same ending as a previous ride with Terra Trails/Butyl combo and see if I can determine from power meter data any practical rolling resistance improvement.
I could not get data as the friend I was riding with was spent by the end of this long ride and could not match my power during the "test" section. I will say that Terra Speed tires with Aerothan tubes "feel" faster than Terra Trail tires with butyl tubes.
I used some Foss plastic ones on my tube type studded tires and they felt slower than butyl, but it was well below freezing at the time and they may harden up at different temps.
