I tried to read Thai's posts, but couldn't open the links. Not to get too simplistic, but a friend had a similar problem with a brand new 2001 SR5 way back when. Same kind of deal, at 65 to 70 mph there was a tremendous vibration. In this case, the steering wheel also was a little bit off center when the truck was going straight. After trashing a tire, an alignment and a new tire made the difference. I honestly always figured it was the alignment, but maybe it was both fixes-- the tire and the alignment. In this case the steering wheel was also centered in the end.