I have literally had to have my tires balanced tires 3X in one day at Discount Tire before they finally got them balanced well enough. They spent a long time on the third attempt and they finally nailed it. Not many tire shops give their tire jocks long enough to get them good enough to not cause problems when the tires are big which requires extra time and care.Balanced the tires this afternoon and it made zero difference.
OK. That tells you that your problem lies with the tires. When I bought my TJ last year it came with BFG KO2A/Ts size 33/12.59R15. I still had a nagging vibration after completing front end work & balancing & rotating the tires. The manager at my local 4 Wheel Parts store said that KO2s don’t do well on Wranglers & he refuses to sell them in his store. I thought that was odd considering how many Jeeps I see driving around with them. Since the tires were 5 years old & I was going to replace them next year anyway I changed them out in desperation. I put on a set of Falken Wildpeak A/T3 tires (same size) and it worked! No more vibration.I have the same thing, with fairly new tires that don't show any abnormal wear. I've had them balanced by a shop that I trust, and they did take quite a while to do it. Said they got each one as perfect as possible. I tend to believe them, at least I believe they believe it.
Things I've done that made no difference.
2.5" spring lift, new shocks.
New adjustable track bars, front and back.
New rear control arms (MC double adjustable)
ZJ steering upgrade, including drag link and stabilizer.
Now all that put together did reduce the symptoms, but I believe the new joints are just masking it a bit. At it's worst the whole vehicle would shake violently at 60mph or so. Accelerating upwards of 70mph may have helped a bit but it was still there. After all the mods it is almost tolerable, but whatever is causing it is still happening.
The one thing I did that had a noticeable effect was rotate the tires. I did that just before having them balanced. It went from really bad, to just annoying. Balancing may have improved things slightly but not by much. I have to conclude that they aren't perfectly balanced, but my problem is I don't know of any shops around here that specialize in big tires and/or Wranglers. Only thing I have left to replace on the suspension is the front control arms, and I suspect if I did that it would reduce the vibration to a tolerable level. But I'd rather find and fix the root cause.
Other things to check which I have on my list are U-joints and transmission mount. I'm probably going to pull the front driveshaft, and see if that makes a difference. Replace the U-joints while I have it out and then do the same with the rear. That's easy and cheap enough, and needs done anyway. Beyond that I guess it's hunt for a shop that really knows tire balancing.