backspace question

Just wondering on what backspace I need for my 06 F-150. Ordered belltech 3/5 today for starters and will be getting 305/40/22s soon. i don't want them to stick out at all so what do I need?? Thanks

anyboby?? any ideas?

Not bagged.......I would say 35mm+

thanks, just looking for clean and tucked nicely, have seen a few rolling around that looked terrible