Originally Posted by Hemi4lyfe
I had the similar experience with my truck. It would do it at 60 to 64 mph. The tires where new with about 1200 miles on them. I thought it was my drive shaft or a rear t case bearing because it felt so serious. I took it to a different shop than where I bought my tires for an oil change and I had them balance the tires just to eliminate the chance. It was the balance, have not had the vibe again. They had one of the machines that does the road force balance. I would try that first.
I heard 'ground force balance', probably the same thing...I'd also recommend finding a shop that could perform that balance for you. You may also be experiencing separation in your tires....nor riding on firestones are you?