Took my pickup truck for a balance/align/rotate recently, and was told that the two rear tires have “slipped belts” and need to be replaced. Having done some reading and thinking, I am skeptical and would appreciate some feedback:
- The tires are modern steel-belted radials that have ~15k miles on them. There are no surface irregularities on the tread or sidewalls. They appear to be in very good shape.
- The truck was, however, parked for almost 2 years, during which time I drove it ~1/2 mile every couple of months. The shop said the two rear tires were the ones with the problem, but that may have been after they rotated them from the front, where one would expect flat-spotting to develop.
- There is a tiny amount of vibration >65-70 mph, but everything feels great at lower speeds. Watching the truck drive, I can also see a barely noticeable amount of wheel wobble up and down at highway speeds.
I’ve read the threads where “slipped belts” are said not to exist any more, except when the term is used to refer to tread separation. So, how does one tell the difference between flat spotting, tread separation, and (if they do exist) slipped belts by looking at the tires?