What backspacing/offset with Icon 4.5" lift 05-08 F-350

[mint-6oh]

Looking to run 20 x 9 wheels with 35 x 12.50 x 20 tires with an Icon 4.5" lift on my 2006 F-350. What backspacing/offset are you guys running? I dont want to have rubbing issues. post pics if you got em with wheel specs. I'd like to have them stick uot past the fender an inch or two. thanks

[SJP1809]

If you want them sticking out that far then go with a negative offset and a low backspacing. Something like -12 offset and 4.5" backspacing, that should get the tire out an inch or two past the fender.