wicked vibration part 2

[denverpete]

I've been following this thread and Larez2's comments finally reminded me of something that happened to me (not in the Box).

I had a Jeep Wrangler that started to vibrate at highway speeds. I took it in and had the tires balanced. Went out on the road and still had the vibrations. I checked the wheels and found MASSIVE balancing weights. Hmmm, first clue.

Turns out, one of the tires had a "belt" separation or was dented inside the tire. Replaced the tires with nice, new, bigger ones and the problem was GONE!

Seriously, I think this is a tire issue. If you have a friend with a similar Box - maybe you can swap out the tires and see if that fixes the problem. If it's a belt separation (or dented belt) inside the tire - no amount of balancing is going to solve the problem....

[Ronzi]

Pete raises a good point. Ply or belt separations, and tread seps as well, can result in vibration.
The separation can be very visible, an obvious bubble in the sidewall for example, but also can be not visible at all. Tread seps are frequently this way, although they do tend to reveal themselves by a heavily worn flat spot in the tread surface.
It doesn't take long for a tread separation to peel the tread off the tire, as witnessed by all the truck tire treads you see strewn all over every interstate.
I don't recall that you have said what brand of tires are on your car, but some brands are notorious for the smoothness going to hell as the tire wears. I think every set of BF Goodrich's I ever had did that.