I have extremely limited experience, so probably my input should not be weighted very much. However, I have been happy with the 29 x 2.1 tires that came with my Ogre for a short multiday trip on pavement and a flooded dirt and gravel trail, as well as riding 30-60 miles almost every day on pavement from spring through fall. (I really have gotten rather lazy this winter.) The Surly Extraterrestrial tire in 29 x 2.5 is finally available, and my LBS ordered me a set, which is due in this week. Hopefully my fenders will still fit and there will be no rubbing. At my advanced decrepit age, I am all about comfort.