Re: 04+ steel rims on a 03 f350?
04 is the same as 1999-2003. 2005 they changed to greater backspace.
I run a 16" steel rim for winter with 255/85-16 tires. If you want to run a newer style rim, you will need to use 1" spacers. They will need to be hub-centric style.
2016 F-350, FX4, CCLB, 6.7PSD, 7" OUO/ICON/FOX lift, 38x13.50-18 Toyo MT