There was a question in another thread about the actual alloy of Fuchs that didn't really relate to that other thread, so here is what I have.
Fuchs are predominantly Magnesium
The alloy is indicated just under the part number on the back of the spoke. Refer to this pic:
http://forums.pelicanparts.com/uploads2/realfuchsagc1070783562.jpg
in this thread:
replica fuch wheels?
On this 7x15, the alloy is AS1.62, which is a designation for a Mg alloy. The A stands for Aluminum, the S for Silicon. The numbers following are the alloying %. In this case, its 1% Al, 6.2%Si. It could also be 10% Al, I'm not quite sure since on late 6x15s they list the alloy as AS10.62. I tend to believe the latter since wheels with 95+% Mg tarnish so much faster than Fuchs. There may also be near insignificant amounts of Mn, Zn, and Ni. What AS numbers are cast into 77 and older engine cases?
Ever wonder why a Fuchs polishes up so much nicer than any aluminum wheel ever made? It isn't because its forged, there are plenty of forged aluminum wheels out there that look bland when polished compared to a polished Fuchs. The reason a Fuchs polishes up so much nicer is because of the Mg.
One huge problem with a Mg wheel is corrosion. This is why Porsche specified the wheels to be anodized. How many other wheels do you know of that are anodized? Fuchs had to be anodized to protect the Mg.
Notice how light Fuchs are compared to other aluminum wheels of the same size? Again, its due to the Mg, which has a density of 63% of that of Al. Fake Fuchs always weigh around 50% more than the real thing, partly because they are all cast, and partly because they are all made from higher density aluminum.
When Al Reed gets an Alum Porsche wheel that needs welding, he farms it out to a shop just down the street. Any Fuchs that need welding goes to a different welder, since that shop down the street doesn't weld Mg.
Does anyone have the Bentley manual handy that can look up the info on Fuchs in a section called "Road Wheels"? The one for SCs should do. What does it describe them as?