its ok to tint all windows behind b-pillar with any %.
its NOT ok to tint front windows (driver's side, front passager's side, front windshield) with any % (you will get ticket).
but if u wanna tint front windows, dont tint same % as your back window, make it ie. f35/r20 or f50/r35 instead of f35/r35 or f50/r50; by these kind of combination, its harder to notice that u tinted front window but u will still get ticket if u got caught
just my 2cp