For cars it is a maximum of 35% all the way around. For SUV's, Trucks and Mini Van's as dark as you want in the back and sides up to the driver and passenger window where it is 35% maximum. Illegal to tint the front windshield. A legally tinted vehicle in NC is dark enough and works well. Any darker and it's hard to see at night. A Plymouth Voyager Van comes with approx 20% on the back and rear side glass. That is a great combination for an SUV type vehicle, 20% in the back and rear sides, 35% driver and passenger window.