Hill City, SD to Fishing Bridge in Yellowstone in mid-June

X2 on 2gypsies post. We have used route 16 once and route 14 (not 14A) twice heading eastbound and route 16 does have shallower grades. As long as you take your time and use lower gears when going down you will be OK. You will have a good climb after going through the east entrance to Yellowstone, so the climb up route 16 will be good practice.