Ill be running the MT et radial 2's in 305/40/18
You'll rub a little, the reason being is the -38mm offset (If your wheels are 12" wide). I'm guessing thats your offset given 5" backspace, how wide IS your wheel? That tire isnt that big, only about 28" diam but.. it's 12" wide, and with that offset.. that tires gonna be way out there.. and you're gonna rub.
Why do you want this tire size? Have you bought your wheels yet? i could probably find something better for you if you havent