I have a 2012 JKU with 4" lift and 35's there us no tire vibration or steering wobble.
I have very strange never had vibration before roof rack, after installing roof rack I got this strange vibration around 40 mph to 45 or 50 then goes away. The vibration seems to be coming from like under floorboard on both sides. It isn't a driveline vibration, I have an associate that has a 4wheel chassis dyno and we ran on it and no vibration or anything.
Any ideas would be greatly appreciated, I'm going to drain and fab a deflector for between windshield header and roof rack to see if that will help.