I went with 235/50/17 but have yet to get the tires mounted on my wheels.
There were several reason I went with nvh's recommendation.
1. basically stock tire height. I hate the tranny and with a bigger tire it may make the problem worse.
2. speedometer. I do not have a chip or programmer to adjust the speedo and my wife is becomming a speed demon and could forget that she is driving faster than the speedo reading.
3. still under warranty and dealer would probably have less problem with a stock height tire.
4. got a good deal on some 235/50/17 's. They were continentals for $70 each at tire rack.
I'm sure there are other things I forgot but that gives you some ideas why I went with the smaller size. The limited 17's with 9.25" wide tires should look better than the stock xl 16" 8.5" wide tires.