If you're unfamiliar with mountain driving, take I-90 to Bozeman, then US 191 S to the West Yellowstone entrance, or I-90 to Livingston, then US 89 south to the north entrance. If you want to see the Bighorns, drive it in a car. My guess is that you've never come across pullouts that tell you to check your brakes before continuing. Remember that you're being pushed downhill by a TT. Uphill is just slow. Downhill can be an adventure. If you want more detail, get a copy of Mountain Directory West. Do not listen to the "Hey, Vern - watch this" crowd.