the wheel is 20 x 9 with a 30mm offset that is about 6.25" of backspacing. with a toyo mt 35 x 12.5 x 20 tire. This is going on a leveled 06 Mega 2500.
thanks for the help

 

Yep, but you'll rub on the control arms at steering lock.

 

do you have a similar set up?

 

Nope. Well, the overall diameter is the same but that's it. Here's what I have:

17x9 with 5.71" b.s.
325/70-17 (35"x13") Toyos

The wheels you spec'd are 1/2" wider than stock with 10mm less offset, which puts the outside edges (inside and outside) about 1/4" further away from center. 35's on the factory wheels rub the control arms at steering lock. So those will rub a little sooner.

 

I thought stock wheels were 8 wide? none the less it sounds like it will be too sucked in and I want a wider stance

 

You're right. Stock wheels are 8" wide. I had H2's on the brain. So those wheels will stick out about 0.9" more than stock. I'm tired, so I may be botching the math right now.