Ford F150 rear brakes & tires

I have a ford f-150 2wd pickup . A few weeks ago I had a nail in my tire on the driver’s side rear wheel. The tires and rims are Ford oem plain steel rims which I purchased from a junkyard to run a second set of tires thru the summer. When I noticed the nail in the tire I decided to replace both back tires with the factory oem rims, which came with the vehicle, while I got the tire repaired. I have ran the vehicle with these tires and rims before without incident.Soon after I put the stock rims on I heard a grinding sound from the rear of the vehicle. I assumed that my rear disk brake pads had worn away.I put the car up on jackstands and inspected the rear brakes. I have approx. 1/4 inch of lining material on the pads,what I noticed suprised me. The tab on the outer brake pad that sits above the caliper had some material on it. I turned my attention to the stock factory rim and I saw a ring where the brake pad tab had rubbed the inside of the rim. My short term solution was to get the other tire fixed and put it on . I have had no problems since.What is going on? The pads are not worn badly and if I were to replace them ,the metal backing on the pad would protrude farther out and make more contact with the rim. Is there a problem with the trucks rearend?I can detect no movement in and out with the truck on stands so I think the c-clips should be ok.This truck has traction lock (fords version of posi traction). Could this be getting ready to go bad?Is this a common problem with an otherwise dependable ,trouble free vehicle?