Test-fit the stair stringer by placing it against the deck, and check the tread level with a small level. Be sure to test-fit the first stringer before you cut the others.

2x12 PT should be fine. <BR><BR>Check for pre-cut/pre-made stringers, too. I know Home Depot carries pre-cut deck stringers and treads. I find cutting stairs to be tedious, so I don't mind getting ...