Originally Posted by Tonyg41
Let me give you a little comparison I had a hummer H3 and traded that in for the Jeep, the hummer was very off road capable and I loved doing stupid things with it. The hummer has .1 of a inch less in ground clearance then your jeep. The H3 can ford more water due to its higher hood design but the jeep can do just about everything else the H3 can. If you wanted to get serious about offroading with your jeep I would suggest getting smaller rims around 16" and bigger tires and make sure you have the skid plate package. I am unsure what the max size wheel the well can handle but really those are the only things I think that would make it more capable then it is.
Only one problem with your recommendation: any rim smaller than 18" will not clear the brakes of the Hemi equipped version, and I'm not so sure a 16" wheelset will clear the brakes on a Pentastar WK2.
I fully agree that the one real limitation to the rock hopping prowess of the Grand Cherokee is probably the wheels/tires. With a good set of AT tires, an 18" package should get you the vast majority of the places you might desire to go. If a set of insane off road wheels and tires are required, it might have been a better idea to get a Wrangler that's been suitably modified (or do it yourself), because at that point the owner will be well into the single minded offroading community anyway.
IMO, the WK2 suitably equipped (with the tow hooks, skid plates, and some competent A/T tires) is as capable as a comfortable SUV can be reasonably expected to be.