From the looks of it; it's probably only a year old. It has definitely been replaced from stock. And it looks to be in good shape

 

Could be bad tires. Put the stock ones back on to test.

 

You said it was Aligned, but before you said maybe the tierod was bad.Who did your Alignment, with bad or worn parts it wont stay in Alignment long????? Also X2 on bad tires.

 

I would dismount your tires from the rims and check the rims as well just to eliminate another possibility. If the rims are out of round (just put the rim on the balance machine and give it a spin, you'll be able to spot it right away if there is a high spot) they could give you a vibration like this. Thing is, I think you'd feel it all speeds rather than just over 50. Does sound like a balance issue to me though.

 

Makes you wonder if the person that had them before had a bad alignment or camber issues and wore the tire wrong, causing the imbalance @ the right speed to widen the tire just enough for the wobble? Could just be the rubber.

 

If its Death Wobble, the shake will be uncontrollable and at high speeds you would likely not be able to hold the wheel. We aren't talking about a vibration or even a bad vibration. Can you say which it is? If its just a really bad vibration its probably the tires.

 

wait till the end of the month see what happens

 

Maybe the bigger tires make bad ball joints or a track bar bushing more noticeable?

 

I agree I had a buddy that had a tire with a bad belt and it caused this same problem....we found this out after we replaced all the steering parts and wheel bearings(they needed to be replaced anyway)

 

It feels exactly like the deathwobble I get in my 92 Cherokee with a bad trac bar. My trac bar is completely tight.... My guess is it's something in my steering. It's a bad vibration like DW but it comes and goes.

 

nah I looked at my rims real close when I took the stock tires off in the shop. they're all perfect minus little scratches and nicks and some brake dust haha

 

Nothing was bad when I did my allignment. I did it in auto shop on a expressallign machine. Everything was torqued to spec and no parts had problems at all. I checked the entire front end out with a fine tooth comb. My guess is as a result of larger tires, a part became fatigued and now is worn.

 

Thats what I'm Thinking!!!!!

 

put the tires on one of your friends vehicles and see if it does the same thing to theirs. Maybe you know someone with another xj?

My guess is that maybe they weren't balanced properly, because this is exactly what happens with unbalanced tires.

 

I went from 33's on my 86 cj to 35's. It did weird lane moves while slowing down and kinda did a lopping at mid speeds. I found out that I had worn out front ball joints that didn't make itself obvious with the 33's.