Denny, this is NOT what I wanted to hear. I've got about $600 invested in brand new tires for this truck. But, after reading your post, I am inclined to think you are on the right track. My local Les Schwab dealer installed new Nanco Super Highway tires. These are 8P.R. Load Range D tubeless 105/101L 700-15LT tires. First off, I didn't think tubeless tires were supposed to be used withy tubes, but they are also also new tubes and flats and the original two-piece wheels. I tried for some time to get something that would clear the front workings behind the rims, but no one could come up with anything. So I guess the next question is, does anyone see significant problems if I try to increase the speed and drive though this? I would really like to be sure the tires and wheels are the issue before dumping $600 and investing a bunch more into this. Also, would it make sense that I would not have had the vibration the first time I took it for a spin and now have it? The tires have been on the ground for about 6 months is all.