Mine is an ’06, but this might apply to other years... check the air lines going to each of your steer brake assemblies. While I was under my truck this weekend, I noticed some bad chaffing on the driver’s side air line. Apparently, Peterbilt made the air lines a little too long, and when the wheels are turned all the way one direction or another, the lines would rub on the tires. I only have 251k miles on my truck and the line on the driver’s side was worn completely through the cord in the line. The line on the passenger side was worn almost down to the cord.
I could only imagine the fun I’d have had if one of these had completely blown on the road. I took one of the lines off and took it to my local hose and fitting shop and had them make up two lines that were one inch shorter than stock. It cost me a whopping $45 for both lines (and they are a pretty blue, too). After installation of the new lines I checked and they now clear the tires by nearly an inch when the wheels are turned all the way right or left.
