Most pressure treated wood here in Texas is #1 or #2 Southern Yellow Pine. About 4 years ago the old CCA (Chromated Copper Arsenate) was replaced for a new formula ACQ (Alkaline Copper Quaternary). ACQ requires either galvanized steel or stainless because it is much more corrosive than the old CCA. I sale lumber for a living, and would not recommend using ACQ treated wood for anything that is in contact with painted steel. Even joist hangers that are used with ACQ have to be galvanized. Unless you want bigger problems later go with some form of untreated YP or something harder like Oak. Just my 2 cents.