Don't try the Kelly Grade in a rainstorm. When this steep stretch of the Smoky Mountain Road is wet, its mud surface is impossibly slick. Stay in granny gear, keep a tight grip on the wheel, and hope that nobody else is coming the other way. There's no guardrail and that cliff next to your tires drops hundreds of feet straight down. The shale gives way to sandstone when the road straightens out on top of the Kaiparowits Plateau.