Quite a few years ago I visited the old "Yule" marble quarry, located in the mountains south of Glenwood Springs, near the town of Marble. There was an outfit offering jeep tours in the surrounding highlands, which we did for 2 days. Spectacular country up there. We were in an old Willy, with very skinny tires. It did great walking over the rock strewn trails we traversed. Bigger tires might be good for mud or snow, but I believe big tires are more susectable to punctures when driven over the sharp rocks typical in the mountains of Colorado.
The Crystal River Valley & the Redstone area was a fantastic area to spend some time in, even on just the regular roads. The hills are riddled with trails.
David
Anh-L>