Have a problem with steering wheel shimmy/vibration on my explorer between the speed 60 and 70 mph. Have replaced tires twice, had them dynamically balanced, checked for loose front end parts, had an all wheel computer alignment. etc, etc, the only thing that changed is the speed in which the shimmy comes and goes. At 70 mph the shimmy goes away.

My 1993 Explorer was shaking around 60mph. I replaced the rear tires and now it shimmies between 64 and 69. Once I get it up to 70 and above, it's just fine, with no shimmy whatsoever.