I painted my stock steelies "Old Ford Gray" then added a little green and they came out nice. I know that is not very precise, but they are a green/gray, often described as concrete gray, as in wet concrete.
Literature says: Toyota T1447 Gray. I have gone to some body shops and no one seems to be able to x-reference this to get a modern mix for this color. But, I recall others have been able to do this. So maybe just the shops near me suck.