[CrazyHorst]

If you look carefully at a cupped tire, it has a sort of "leading edge"....a gross exaggeration would be the profile of a circular saw blade. When the "teeth" contact the pavement that's where the noise comes from.

So....if you cause it to reverse-rotate it should quiet down IMHO.

Cupping is a strange phenomenon...some vehicles have it *bad* and others you can drive all the tread off the tires without rotating a single one and never have a hint of the noise. Personally I think it has to do with some sort of natural-frequency type of excitation (mechanical amplification if you will), that's perfectly "geared" to the tire's OD, and so the oscillations repeat in the same areas of the circumference over and over.