Haha thanks. I haven't really settled on tire size yet, what would u recommend?
In simplest terms, you can go with 33" tires on a stock JK. For 35s you need at least a 2.5" lift. Since you said you are thinking about a 4" lift, you can easily do 35s and even 37s if you want.
Just keep in mind that going over a 2.5" lift means you are putting an extra strain on your drive line and steering system. With a 4" lift, you will most likely need to relocate your brake and exhaust lines as well.
We have lots of threads here for you to look at and some pretty smart folks (allot smarter than me) when it comes to Jeep mods.