Window tint is most certainly covered by NC State inspection.
Every station is supposed to have a tint meter to test the tint ( as well as a sample peice to test and calibrate said meter)
35% (+/- 2%) is the spec on all windows on a passenger car, or the front side windows on a truck or SUV forward of the front seat backs, where the rears windows behind the front seat backs can be 0%
do all inspection stations check them ? nope, will they get fined if caught not checking window tint, yetp if the DMV officer sees the occurance.
AND they are allowed to charge you $10 for the TINT TESTING , which pissed me off when I found out about, I peeled the tint off the windows in the inspection lane, dude thought I was nuts.
I went thru all the classes for State inspection, but did my damnest to avoid getting the license because I didn't want to deal with all the crap, too much crap to keep track of, too easy to miss something trivial and get a $110 fine, seen it happen too many times. You don't get paid enough to warrant playing the fawkin game.