DanBell has the right idea. Are you going on mountain bike single-track, or gravel multi-use type bike paths? Because if you're riding a flat multi-use path, you do Not need mountain bike tires. You don't need anything close to a mountain bike tire. I personally would run the exact Schwalbe Supreme he recommended. That was my first thought too. Or get something with a Little bit of tread on the sides, but a nice smooth center tread. Then if you know you'll be spending a day on the gravel, air the tire down a little. Then when you hit the road again, top it up to your road psi. There's zero need to go pushing knobbies around for thousands of miles on the road because you might ride on a little bit of flat sand and pea gravel once in a while. And besides, those knobbies won't make it those thousands of miles. They won't last very long on the road compared to a tire meant for the road and smooth paths.
If you are talking a mostly road and path tour, but just feel more comfortable with some tread, maybe something like the Vittoria Randonneur Cross Touring? Or a Continental Travel Contact? ...if they make those tires in a high volume size.
Last edited by 3speed; 08-17-19 at 02:29 AM.