>>1205973>rolling resistance atleast the wider the betterNot exactly, since you can run higher pressures in narrow tires and therefore have less deformation in the sidewall.
Wider tires however reduce suspension loss aka losses due to road-buzz.
The best trade-off for most roads is about 25mm, a bit more if you want more comfort.
>how would a fatbike with completely smooth and very soft tires handle?It would have a lot of grip, but rotational mass and rolling resistance.
AKA only realy good for realy fucking hardcore cobble, but still not any better than a 29er hardtail MTB with dropbars and fast tires.
>how it would fare for touring, especially touring on rough gravel roads where you can't really go all that fast anywayRolling resistance and weight are a bitch at any speed, if you want to ride gravel more comfy get a MTB with 2" tires.
That beeing said:
I ride 25 mm on my roadbike on smooth tarmac, high grass, nasty cobble and gravel with no issue.
I ride 2,25" knobbies on my 650b MTB as well, since I need the grip there.
The main thing I change for different surfaces is pressure:
When I want more comfort, grip and lower suspension losses, I go down in pressure.
When I want less deformation losses, I go up in pressure.
25mm gives me lots of space to alter the characteristics of my tire in that aspect, as the tire handles totaly different at 3 bars and at 9 bars.
At 9 bars it is basicly solid, has little grip, jumps during sprints and is only realy good for realy smooth pavement.
At 2-3 bars its is comfy as fuck and has a shitload of grip, but deformation losses increase a lot.
I also heared about fat people getting pinchflats at that pressure.
