I've done the vast majority of my riding with 2.0" (actually measure up as 1.9") Bontrager XR Mud tyres on skinny (22mm external) Mavic 317 rims, no suspension, and I'm not light. There's a bit of stability increase noticeable running 2.0" XR1s, which come up a bit bigger, on wider D521 rims (28.5mm external), but I probably wouldn't fit any larger tyres to the 317s unless I wanted to up the pressure a bit.
I can really recommend the XR Mud tyres for most Thetford riding, they dig in to the sloppy bits nicely, shed quickly and are actually pretty decent for anything except really dry hardpack and stuff. Don't slip too badly on roots either. Would like to try Ardents at some point
I've done the vast majority of my riding with 2.0" (actually measure up as 1.9") Bontrager XR Mud tyres on skinny (22mm external) Mavic 317 rims, no suspension, and I'm not light. There's a bit of stability increase noticeable running 2.0" XR1s, which come up a bit bigger, on wider D521 rims (28.5mm external), but I probably wouldn't fit any larger tyres to the 317s unless I wanted to up the pressure a bit.
I can really recommend the XR Mud tyres for most Thetford riding, they dig in to the sloppy bits nicely, shed quickly and are actually pretty decent for anything except really dry hardpack and stuff. Don't slip too badly on roots either. Would like to try Ardents at some point