I've had a violent shake at around 55-60 for almost 2 months. I knew it was alignment, but didn't have time to fix it or even look at it. 20k miles later (yes, I've driven a lot lately - most of it was pulling a trailer, too), and I've ruined all 4 tires. Lots of trips from Salt Lake to Sacramento, or Salt Lake to Spokane. I'm surprised my son and I don't have hemmoroids! lol
Now that things are starting to settle down with the business, move, etc. I pulled the front end apart. Upper ball joints were a little loose, nothing to majro though. Probably from the shake over a 20k mile period? I replaced all of the ball joints and hub bearings (since I was in there already). I also pulled a tape, and realized after rebuilding the front end, my alignment wasn't so far off anymore.
That didn't fix it, which I was kind of glad it didn't, but it would have been nice to
So on went a new set of MT Baja Claws - Bias ply this time.... That fixed it! And I got a new set of tires out of the wife
lol