All depends on the Jeep. 4:88 is about where they start to get goofy. I have 4:88’s and 33’s and have the same vibration, I did the hub conversion last year and it solved my problem.
I'm starting to get this thread off topic, but I have one more question. What speed is the vibration noticeable? Above 35, 45, 55, or 65 MPH?