Most places will tell you over the phone they won't do anything darker than 35%. If you go into their shop and ask, they'll probably change their minds. I don't suggest going any darker than 20% all around. I've been driving with 20% on both front and rear windows for around 4 years and have never gotten pulled over for tint or even been questioned about it. Though it does make safety inspections a little tricky. I think I got mine done at Tint & Accessories a few years back. The dude was super cool and actually tried talking me into a darker tint but I"m glad I stuck with 20%. I'd go into a few shops and ask in person that way they don't think you're a cop over the phone trying to shut them down.