Tires are built out of round caused by excess over lap in mold. Flat spots are caused by sitting in one spot for extended periods, drive on them they will round out. Real common in old nylon tires. Flat spots caused by turning never heard that one....guess in some conditions it could happen. If you do get a new real out of round tire have them replace it. Do not "true" or shave it. Out of round tires happen but it is not a common thing.
Back in the day truckers use to toss a few golf balls in their tires to balance them.