I am contemplating up-sizing the tires on my 06- 3500 to something larger. I'd like to go to 37" but was told I need to install a leveling kit to avoid interference. Does anyone out there have the real answer? It looks to me like there is enough clearance without lifting the truck. The engine seems to run too fast and the mileage is not as good as I would like. Maybe I'm too used to running semi's on the interstate.

 

I would speak to Dan @ Carli Suspension or anyone @ Diesel Power Products in Spokane.
Another option is Don Thuren in Bend. Nice guy and a one man show but he'll return your call or e-mail within 24 hrs during the week.