maybe I should have said "are for the most part"
EDIT: I have also heard of some of our chrome wheels developing some sort of rust or flaking that causes them to leak air. I have a slow leak on one of my wheels that I can't pinpoint where it's leaking. Replaced valve core and had the TPMS o'ring(s) replaced last tire change.
Gotcha. Yes, plated aluminum can have problems with the chrome separating from the base and they will then leak, but I have seen that with steel wheels also, just not as much.
I have a slow leaker too. I had three, but a thorough cleaning of the bead area fixed two of them. I am going to have the last one dismounted so that I can clean it again once it annoys me enough.
Sky NA 2007 Midnight Blue
Sky RL 2008 Carbon Flash - Naked