The wheels on my R65 were definately painted. However that is not to say that they should have been. 30 years is a long time. However they were also discoloured in places as if the paint was very lightly applied.
Even after I painted them again, I eventually replaced them with spoked wheels.
The R100 looked similar, but they were so grubby I just paint them over with some Halfords Satin Black with a brush. The PFM cast iron discs on the bike soon discolours anything in close proximity.

One rain storm and my wheels turn brown...along with the discs! Work well though when it comes to the tug, so its not all bad news bears.
Steve H