The roads in Yellowstone and the surrounding area are good quality. An SUV might make a better choice for this trip than a standard car. The roads can be very windy, particularly around the mountainous areas and the upper speed limit is 45 mph. Animals such as bison, bears, and birds of prey can often be seen on the roads so drivers need to be alert for this. Your hire car company at the airport can advise you on what to expect on your journey in the park and the region. Search car hire on KAYAK