Thats why everyone is not responding to be honest. Did you try to search at all. There have been a couple threads very close to this in only the past week or so. You can fit 33s on a stock rig with enough trimming and bumpstopping. It depends more on what kind of a look do you want your rig to have, would you like a better break over angle, are you willing to cut, how much money do you want to spend. My personal opinion is 33s look really good on a XJ with 4.5 to 6.5 inches of lift with minor trimming. It will perform well too at that height. Just keep in mind that once you go over 3 inches you really have to start changing alot. Long arms or drop brackets, upgraded steering and steering box brace, adjustable track bar, and so on. Try to search a little bit more and ask more specific questions that havent been answered time and time again. There is alot of reading that you can do on this site.