Well no steel or iron core!!!
Now this is confusing!!! What could Ford have done to these wheels to give them these properties, rust when you scrape them and ferro magnetic. It might be in the plating process. A tripple chrome plate is copper nickle chrome, and nickle is ferromagnetic but it does not rust. I will have to dig into this.
Later.

 

I thought that was confusing as well. Someone isn't giving the full story. They seem awful heavy to be aluminum cores.