Again, welcome to the forum. Whenever you build a Jeep, you need to try to have a visual on what the final form will be. For example, as mentioned above, you could fit 31's without flares but 33's if you use cut-out (i.e. cut metal off the vehicle) type flares. It would be frustrating and expensive to fit 31's only to sell them several months later once you get flares and get 33's. My basic motto has been approach it by "system" e.g. suspension, wheels/tires, etc. and buy once. Maybe the vehicle will look kind of goofy for a while as you save for your next upgrade. I've known guys to put 3 or more suspension systems on their rigs due to money. Well, they certainly DID spend a lot of money as they put a series of "economy" kits on. It's kind of like women, when you're young you want every budget piece of equipment that comes your way (and quickly) but once you get older, you would like some quality and not have to replace them every few years (divorce gets expensive too). You should join the crew for an "open" run and get a feel for the style of off-roading you're building toward and ask around about what mods work. "Johnny C" is CJA executive and has a passion for the Grand Cherokee, lots of experience and is just starting the build-up of one.