Great All-round Gravel Tire
I've been riding the Maxxis Ramblers for several years now, first in the 40mm version and now 45mm. They are a smooth-rolling and fast tire that works great on all types of gravel (I've never really ridden them in mud, so I can't comment there). The key is to get the pressures down. I weight about 160# fully-kitted out, running 26/28 psi, and with a Red-shift suspension stem and PNB Coast suspension/dropper post have a very manageable ride on all the very rough gravel roads we have here in west-central Idaho. They work well on single-track as well. Only downside is tread life. I ride a lot (10-12 hrs/wk) and typically only get a season out of a set.
David B.