Oops. Internet went down and the edit got lost. Anyway, the front wheels can’t be balanced, so the thinking is that there is a bad tire. Swapping front and rear wheels should prove this out.
I am of the school to leave the rear tires alone. I let them wear naturally undisturbed, and they wear extremely well and evenly leaving them alone. Tire rotation could distribute the weight across the 4 rear tires unevenly which might encourage rear tire blow-out. If the front tires are the matter at hand, just replace them more frequently.