Here in Cali..the most common combination is 20% for all windows rear of driver and 50% for two fronts. You want classy look...go 35% all the way around. Most domestic pre "shaded" vehicles are 20% so if in Hawaii you can go that dark or even darker at 5% "Limo" tint it becomes a matter of preference. Good luck brah! Hope this newbie's info helped.