My buddy has a 3500 diesel that he took off the dually's and put on a standard bed. He has 315's on his and he gets a very small rub at full lock and his is all stock suspension. He got a leveling kit for the front and it dern near fixed it.

 

i have these with 35x1250x20 there 20x9

http://www.discounttire.com/dtcs/whe...98225&pc=49118

i have no rubbing at all and i have a 01 dodge ram 2500 4x4 with a 2in level kit in front

 

widest tire you can legally put on a 7" wide rim is 11.5" I believe...8" is the narrowest rim for a 12" wide tire...and that will make the tire seem thinner than it should ..as for backspacing ironically the factory backspacing on an *" wide rim cleared and had less rubbing issues than my rims Im using now which stick out more and give the truck a slightly wider looking stance..(I have 35" tires with a 3" body lift.)
There must be a steering ratio adjustment because I had no rubbing at full lock against anything but the body when on and angle and the spring (s) were partially compressed.

 

Thanks augie for the info.