Originally Posted by NoGears

My rides have not shown any difference in average speed between 28c slicks, 35c knobby with slick center, and 40c gravel tires. Only time my speeds suffered was when I tried 40c knobby tires (WTB Nano). The speed didn't drop but the effort was harder. I'm on 40c GravelKings now and I'm just as fast as I've been on any other tire which isn't saying too much because I'm slow no matter what...lol...but the comfort and stability increase going to 40c tires outweighs any small lose in speed IMO. Unless you're racing and seconds count. Then maybe I'd sacrifice some comfort. But I don't race.

I'll also add that after going with a 40c tire...I'd never run even 35c again unless it was 100% pavement riding and even then...not sure I'd drop down below a 40c tire. Just so much more comfortable.