I don't know why, but I feel like chiming in here:
My tint on my windshield is somewhere around 40% (just enough to take the edge off of headlights at night, but not hinder the vision there), the front sides about 28%, and the rears about 5%. I have done nighttime wheeling, and the tint makes a huge difference (with the exception fo the very light tint on the windshield). At Centralia, and on my prior excursions, the windows were definitely down when I was doing anything other than moving forward, and about halfway down otherwise.
We were actually wheeling at night the one time and it was low teens out. That kinda sucked, but was fun at the same time. Tint made a difference though.. So just be careful.