Re:
I am currently running Schwalbe Rock-Razor tyres both front and rear and fitted with large inner tubes and puncture sealant. I like the fact that they are quiet running and have a low rolling resistance at all pressures.
At higher pressures they mainly run on the small block pattern inner tread apart from cornering and riding accross cambers where the large outer blocks also come into contact with the trail surface. At lower pressures, both sizes of tread contact the ground. I use the large inner-tubes because they allow for pressures just as low as you can get when running tubeless. They also puncture less than when used with smaller diameter tubes.
The Schwalbe website says that the Rock-Razors are for use in dry conditions and gives them zero marks for use on soft ground. However, I have been using them in all conditions including extreme mud and soft sand without any traction problems. In mud the treads clear well and the large closely spaced outside blocks help to reduce the amount of side-slip.
All in I recommend them as a good all purpose tyre though they are only available in 2.35" and 2.6" widths, so will not fit all frames.
