Well, with stock wheels and no wheel spacers you are limited by width. So you could do a 275/70-17 if you wanted and it would look better and wider but it would be the same diameter. Or, you can go 255/80-17 and it'll not be any wider but it'll be taller. Those are really your only options.
If you buy new wheels or if you use wheel spacers then you can get a larger tire under there. I've seen 305 series tires on stock wheels and it worked OK but was definitely the maximum width I'd go on a stock wheel. At that point the sidewalls are starting to bulge pretty good.
'92 YJ - heavily modded
'96 ZJ - heavily modded
'05 KJ CRD Limited - 370 lb./ft. from a 4-cylinder and trail ready. Pure awesomeness.
'11 Mango Tango JKU Sport - Mods
'12 Dozer JKU Sport S - 6-speed - ACE rock rails - Max Tow package - Daystar spacers - 33x12.50 Duratracs