What backspacing for 35s

What backspacing are you guys with 35s running. I ordered a set of 35x14.5x16.5 Ground Hawgs and am having stockton wheel make me a set of 16.5x9.5 wheels but I am not sure what backspacing I need. SO... any help would be appreciated.

I was running 3.75. 36" tsl's rub the long arms pretty hard.

ya i run 3.75 with 35's and it freakin sucks.