I bought my FX4 in late January of 2004.

Around 3,600 mi, a random vibration started to occur. It turns out it was the right rear parking brake sticking. It was fixed under warranty and I've been a happy camper.

Recently I purchased a second set of Ford alloys and mounted some Hakka snow tires on them (Vermont). Within a couple hundred miles, a vibration developed. It vibrates at a very specific speed range (50 - 60 when unloaded;40 - 50 when loaded with about 1500 lbs of firewood).

It turns out Ford determined that three of the four tires are junk (beyond 30 Lbs of roadforce according to their hunter balancer). Actually, I was told the Ford F-150 factory tolerance for roadforce is only 15 lbs.

Based on the fact that I did not have problems before the swap, I have to assume for the moment, that they are correct. Nokia is replacing my tires and I'll report back success/failure.

To date, I've been too busy/lazy to put my orginal wheels/tires back on to sure up the theory that the problem is the new tires.

My truck came with GENERAL tires on 17" wheels.

More Cool info: http://128.242.141.111/pub/technical/index.cfm

I still love my truck!