On my old tj I had RE 3.5 coils and 33s. The front sagged a lot for some reason and I ended up putting 2" inch coil spacers in the front to level it out. I could have easily fit 35s with this setup and I was planning on it until I sold it and started a new project. 35s and 3.5" - 4.5" should be good. I'd try to stay low with the 3.5"