35% is legal limit here.

the tint laws vary from body styling and years. Here in tx, if your car is made before 1988, you can have the back windows and rear window completely blacked out, but, legally speaking, you must have 35% up front.

same thing for all trucks/suv's/wagons/vans. 35% up front, the rest dark as you want.

now, cars made AFTER 1988 must be 35% on all windows, but the rear window can be as dark as you want.

But it all depends on local legallities. Here, cops won't pull you over for tint. They have better things to do. Granted, if you were being stupid, and have shit on you, and have a dirty record, and you car has more illegal stuff than the tint, maybe you'll get cited.

but I've had my car tinted for almost a year now, and still no tickets. And I've been pulled over a few times, too (not just for speeding )