Some is more easily rideable. I have ridden the whole thing with 700x42c gravel tires, but I suggest at least 27.5x2.4" for the rougher bits. When wet, there are large boggin' holes from the ATVs, some can be 4'+ deep, others can be ridden through with dry feet. The mud/chipstone can completely freeze wheels with fenders when the trail is wet, though this is more relevant in the sections south of Theresa and towards Philly than for the Redwood section.