"One caution: If you plan on going north to I-70, the road from Silverton to Ouray is called the "Million Dollar Highway". Beautiful drive, but no guard rails. (They should have spent a few extra dollars to add them.) Northbound is on the inside, but watch for southbound traffic, as they are riding on the edge and will try to use your lane too."
There are no guard rails so that the plow drivers can push snow over the edge. An alternative route from Cortez is north on 145 to 62 through Delores, Rico, Lizard Head Pass, Telluride and Placerville and over Dallas Divide to Ridgway. Adds about an hour and a half and 60 miles. Also takes you past the Ralph Lauren ranch. Personally, I think the scenery is far better than driving over 550 from Durango to Ridgway.