Ok, I've had this truck for about 30k miles. I believe it has had this problem since I bought it with 30k miles on it. 04 F150 acts like it's binding when in 4x4 on any road conditions driving in a straight line. I'm used to them binding a bit on hard surfaces in a turn but this thing does it going straight down the road in the snow. It feels like the front slips just a little every once in a while. I had to think of gear ratio, that's what it feels like, but I did a test. I jacked up one side and ran it in 4x4 for a while with a paint stripe on the spinning front and rear tire. I can see no difference in the ratio, and everything works smoothly on the jacks. Any ideas?

 

Are the tires all basically the same size?

 

Yep, all identical Michelins

 

Ok, I'm an idiot. They are NOT identical tires. They were sold to me as a set of matched tires by the local Les Schwab, but on closer inspection, two of them are 265/70 17's and two are 245/70 17's. Problem solved.