Haymaker, you got me thinking even more. Seems to me many factors go into stability of a tractor on a slope. The tractor weight and height itself, size of tires, inflation of tires, wheelbase, height and weight of implements carried, surface conditions,and even the height and weight of the operator would all impact the center of gravity and stability on the hill. I'm sure some can travel on steeper slopes, but it would have to depend on some of these factors. Each individual's setup or conditions will be different. I will play with the protractor on another pic to see if I can get it to show an angle that I feel is more closely matching the angle I believe this hill to have. I also remembered I have an old surveyors transit that I can try to play with if I can figure out how to use it to get an angle.