55% is a waste of time and money! I have 5% all the way around and I have gotten 2 tickets in 3 years. ( I live in Alberta) If you wanna try and play safe go 35% on the front doors, It will make a difference, but less likely to have the cops bother you. And do all the other windows the same, if you decide 20% or 5% or whatever it doesent matter in alberta, you could paint over the back windows the only ones they care about is the windshield and both front doors. 55% would be like having 2 pieces of clear glass... a wee bit darker but ont enough to make ANY difference for light and heat!