You can roll an average riding mower on a 25* slope, under the right conditions.
:frown: Where your CG is located, track width,heading, speed, etc., are obviously some of the variables that come to mind. I have absolutely no affiliation with Ventrac, nor do I even own one :frown:, but do take a look at the video link you can find here on the forum. Other than that, I just recommend caution, and a good "seat of the pants" feel.:thumbsup: