550 from Durango to Silverton is not bad, its the section from Silverton to Ouray that scares some folks (red mtn pass). I drive over it all the time in either my MH or 5'er, but I've been driving up & down Co mountains for 30 yrs. The switch back turns, steep drop off, exposure and lack of guard rail scare some folks. In reality the scariest part is other drivers inexperienced with mountain driving. If you were a trucker you know the type that burns out their brakes and don't slow down for sharp turns,
The alt route is 145/62.