Also, the Wrangler wheels are 6.0" backspacing and I think the Grand Cherokees were always 5.0 or 5.5" so you might have rubbing issues on the upper A-arms regardless of tires. This is not an automatic "it'll work" in my opinion. You'll need to test fit them first.
'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