On the 2007+ Rubicon, you can get a 33" tire under there provided that you are using aftermarket wheels or wheel spacers. However, keep in mind that when offroad you will have rubbing issues when flexed. Would be best to run a small lift kit, even if it's a coil spacer kit.
'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