I have %20 all around and it's plenty dark. I also think that %20 is the legal limit in all states that allow window tint (some state's don't allow it at all). %20 allows shadows to be seen but no colors, %35 you can see shades of color, and anything higher then %35 you can make out details in shapes, colors, and whatever (just a lil sumpin I noticed the past few months while deciding what % I wanted)