Wheel back spacing?

[Pullinpower7.3]

Hey y'all. Just wondering what the correct back spacing is to run 35" tires. I have a 3.5" lift and the tires but no wheels yet. They gave me the option of 4.5" or 5.5". They guy said that normally he sells the 4.5" to guys with lifts but never run across a truck with my lift height. I was gonna just go with the 4.5" but i dont want to if i dont have to as he said the tires will stick our even more with them. Thanks for the input!

[clmtng]

I have absolutely no idea what backspacing is, but wouldn't bigger be better? If you need I have a leatherman that you can use to pull out the ricers from your suspension.