OK. So I just got off phone with rim and tire guy. I have an 06 FX4 with 2in level. Im getting a set of Goodrich M/T KM2. Like the look and good reviews. Problem is the rims. In prior posts I believe Wandell recommeded a 5 inch backspace which is -11 offset. The rim guy says in my truck I need between +27 and +52 offset which is a 7 inch backspace to avoid the tire sticking out from the wheel well. I think the rim guy has it wrong. I played with the numbers on this site: http://www.bigcustomwheels.com/rt_specs.jsp

and it looks like if I go with the rim guys recommendation the tire will stick way out? Wandell, your thoughts??

Also can I go from the stock tire to a 305/60 or a 315/65 without rubbing? This will be on a 9 inch wide rim.

Answer this and I will shut up and observe for a while.

J

 

Offset is harder for me to visualize than backspacing. Also, the BS and offset numbers are meaningless with knowing the width of the wheel. Most people use a 9 inch wide wheel with 5 inches of backspacing. That is a very common spec and means the wheel will stick out 2 inches farther than the OEM wheels. If you don't want the tires to stick out that far, go with a wheel that is slightly narrower or has more BS. As for a wheel with 7 inches of BS, that is a spec used on a street style wheel for people wanting to tuck 22's.

 

If you go with a BFG 305/60 and a 9 inch rim with +27 offset, it is probably going to rub on your A arms (inside of the tire) with the larger side lugs of a mud tire. If you can find something with a 20 - 22 offset you should be okay.

If you go any bigger BFG 315/65 with a 9 inch rim you are going to need to stay between 5" and 5.5" of backspace. Check out PAWPAW's gallery, he had 315's with 5.5 backspace, they looked a little stuffed, not sure if they rubbed.

As for the tires sticking out of your fenders, listen to Wandell. A nine inch rim with factory backspace is going make the tire stick out further no matter what.

 

Got it Wandell. Second part of the question I posed? Biggest tire without rubbing? 305,325? 35x12.5?

 

that depends on what wheel you wanna run.

7" of backspacing is way too much if you want some KM2's, as Dog'em mention , you will most likely rub on the control arms.

general rule of thumb with a leveling kit is

33/12.5 with aftermarket rims

35/12.5 with stock rims or aftermarket rims with specs close to stock

if you want to run the Km2's in atleast a 12" width , you dont want more than 6" of backspacing. as Wandell said i would try and find a 9" wide wheel with 5" of backspacing

 

Right. With a leveling kit, a 325/60-18 (33x13.00) is about the limit, and they will rub if you go with an aggressive backspacing and wheel width (like an 18x10 and 4.5 inches of BS).