"The drive over the Beartooth Highway from Cooke City to Red Lodge has been labeled "the most scenic drive in America." I highly recommend that you try it WITHOUT YOUR RV (it's a toad or tow vehicle ONLY road!)."
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I don't necessarily agree that taking a toad or a tow vehicle is the only option; the decision of whether to drive one's 'RV' over the Beartooth depends on the type and size of the rig and the skill and 'mountain roads' experience of the driver. I've done the road twice, but I've been driving mountain roads for many years, and I drive a 24' C (wide, but 'short' and no toad).
Many RVers have driven 212 without problems, but if there's any concern about one's rig or one's ability or desire to drive the road safely and enjoy the ride, then by all means, do it in a smaller vehicle. IMO, the Beartooth is a 'don't miss'.