I own a set of 3,5x12"-rims (made by Fergat in 1962) of which I think, they were made for Zagato or Allemano cars. I want to put them on my 600. Can anyone tell me, what special rims they are and to what car the formerly belonged?
If they were made in 1962, then they'd likely be for any Fiat 600D-based car. Would fit any derivative of that car, like Fiat, Abarth, Allemano, Siata, Giannini, Zagato, etc..
And: I ask myself what hubcaps there have to be mounted on it. I tried a (german) Fiat 600 Jagst hubcap but I think, that 600 hubcap is to big. Can anyone help me and tell what rims that are and what hupcaps there have to be mounted?
The hubcap you tried looks to be the correct type (see first photo below).
If you want a more refined appearance, you might try fitting a Series 2 type Abarth 750 hubcap (normally used with the 7-vent steel wheels), it's a smaller cap & the edges fit flush with the surface of the wheel, rather than above/over the center like the Fiat/Jagst 600 hubcap as you have tried. Unfortunately, they are not as common as the Series 1 hubcap (pie-plate type base with 3-ear "spinner" center cap), so may be a little harder to find. (see second photo below)