Being new to this off road malarky this year, I too was a bit non-plussed about tyres. I ended up getting a set of Ritchey comp Z Max for the proper muddy stuff and a set of less knobbly Continental Race king for road / tow path / cycle path use, thinking there would be less rolling resistance on the less heavily treaded Conti's. In truth, the Conti's have been consigned to the spares bin. The Ritchies give very good muck and mire grip, perhaps not as good as a deicated mud tyre, but certainly more than adequate, while they also offer what feels like noticably lower rolling resistance on tarmac, certainly at lower pressures. I think i've been very fortunate to luck upon such a versatile tyre in my first off road winter. IMHO I wouldnt recommend the Conti's, I found them quite draggy on tarmac, even at pressures up to 60psi as well as untrustworthy on mud with pressures as low as 25psi, but the Ritchies rolled really well with pressures down to 30psi but also offered all the grip I needed in the muddy stuff.