Largest size are 245/70/17 as seen on the SEMA Trailhawk. Stock Trailhawks are
245/65/17.
That being said, if u do 245/70/17, a 15" tire equivalent is 245/80/15 not sure if they make em that size). If my theory is correct, the stock KL's have a high backspacing of over 5.5 (I say that because most jeeps have high backspacing...wrangler and grand Cherokees) it's just an assumption but if I'm correct, u can get a 4.5 backspaced wheel and add a lil more width to it @255.
As for the the sensors, switch em off with the oem ones. If u don't, you'll probably have to go to the dealer to calibrate (if they are able to).
Good luck.