A stock DI Land Rover says can handle a 45% grade before rolling over, this is with good suspension, good tires and no load on the roof.
38% and you will be changing your pants, I cant imagine 45%.
The off road track at the dealer is 38% and all you see is sky, it is awesome!!

 

is that 45 head on or side to side?

 

I-pod touch or your i-phone has an app for that--the level I used it to take a picture to show my brother got it to 30 degrees for him. Whoo Hoo!