Tried my standard 11/32" adapters in some 165 express today and they seemed to large.  Now I also have some 135 standards on the way and i was trying to figure out what adapters to order.  5/16" maybe?

Yes 5/16 will work

Anyone carry steel 5/16" adapters?

Try Kustom King or Black Widow. Brad I am using 160 gr Ace STds with a 25 grain alum adapter for my fall bear hunt, you will love the Aced broadheads.