Went for my second tire rotation at 18,000 mi. and the local service center refused to rotate my tires, because they were cupping on the inside. Explaining it was probably a shock problem they suggested I go to the dealership while it was under warrantee. I did, but the dealership service center (alignment computer) was closed during the holidays. A week later on a road trip my tires began making noise. I pulled into a new shop and had the tires rotated anyway. The shop noted the problem, and again suggested I go to the dealership. Returning home, I went to my local shop, not wanting to go to the dealership, and said fix it. The called the local NAPA dealer, who immediately said changing the shocks won't fix the problem. They reported, Ford used some inferior "nut" on the braking system, which holds the wheel on. The only fix is to replace it with the HD nut and properly torque the wheel. The NAPA tech said he owns two F-150's and both have had this. Further, he contacted Michelin Tire, and got replacements at no charge! I went to the dealership and explained all of this, to which they said I was crazy. My alignment was good. Okay, but what about the tire cupping? Any suggestions?

 

Weird. I know both bad shocks and alignment can cause cupping.