I've been having a problem w/ a vibration in my truck (Y2k, XLT, 4x4 ORP, extended cab w/ 8ft bed, 34k mi) between 40 and 45 MPH. The whole truck seems to shake while in this speed range. It's been to the dealer probably 6 or 7 times in the last 2 years w/out any luck. Most of the time they told me they couldn't feel it, then finally back in the spring they checked the tires and told me both rear tires had excessive runout.

I had those 2 tires prorated and replaced (265/70/17 GY Wrangler ATS), and then replaced all 4 because I didn't care for the GYs. After having those 2 replaced, on the way to the other place to have all 4 replaced, it still had the vibration in the same speed range. After having all 4 replaced it seemed better but still present. Now it is doing it as bad as ever again, so I took it to another dealer to have them look at it (I got tired of the first one telling me it was the tires and the shift point in the tranny), and they told me both rear tires have excessive runout (vertical and horizontal).

The service guy told me he argued w/ the tech because the tires had been replaced so he went out and looked at it. They have some sort of machine they put under the tires to observe runout. He said both rear tires were flopping all over the place as soon as the truck hit 40 MPH. I asked about the wheels possibly being bad and he said they appeared to be OK. I'm going tommorrow to have the tires replaced.

Here's my question - is there anything that can appear to be excessive runout in the tires and be something else? or is there something that can be causing this tire problem? I've changed the tranny fluid, so it's not the torque converter shudder, and I've also had the tires road force balanced, and I've been rotating the tires about every 4-5K mi. Oh yeah, the new tires tires are Hoosier Radial DTs 265/70/17 - same thing as Big O XTs.