Trust me, even in PA, all they look at is the tread depth. No inspection station is going to gig you on a smaller tire size than what's on the door tag.
I went down from 245/75/16 stock, to 235/75/15. I'll never go back.
You'll like the change in "effective" gear ratio, less down-shifting on hills. I pull out in 2nd a LOT.
You'll like what feels like more power, quicker acceleration.
Your speedometer will read faster than actual, helping you avoid speeding tickets. I keep a cheat sheet in the visor. Odometer mileage will make you THINK you are getting a lot better gas mileage. See here: http://www.dakota-truck.net/TIRECALC/tirecalc.html
Your ABS will act a little differently, not necessarily worse. You will feel the ride improve, less jouncy from less spinning mass/weight. Your braking will IMROVE, but it may not seem so, because the ABS may kick in a little sooner, if you are even used to that happening. http://www.generation-edge.info/topic.asp?TOPIC_ID=5908
I don't THINK you'll have any brake rotor/caliper clearance problems, but you SHOULD make sure. Offset and back-spacing matter too. My wheels came off an Explorer and I just threw them on, with no problem. I don't know to this day if they are different from stock offset/backspacing.