If you're staying legal, no tint can be applied to the front door windows, 75% of light has to show through, and most car windows are lightly tinted from factory anyway, so any tint would tip it over the limit. My old car had slight tints on the front windows, I had no problems in 2 years (Although I bought the car like that, and wasnt 100% on the rules back then) but the person who bought it from me was stopped in the first two weeks and made to peel them out by the side of the road.

Hope this helps.