I have noticed quite a few late Vanagons with spots on the Carat alloy wheels. A
set I had, showed this malady.

Here's the symptoms:
numerous round approx  1.5" to 2" diameter round blackish colored spots on the
face of the alloy wheel, appear to be some sort of burst of undercoating or waxy
sealant shot on with a spray gun of some sorts. Quite a few on each, but not
all, wheels. 

Can anyone explain this epidemic????

It should be reported to the center for disease control before it spreads.

No, seriously, what are those spots from and why are they there??
some sort of lug sealer of sorts?

chris