Does anyone know the procedure or proper way to do this. I have an 05 silverado 4x4 with the 4.8l and a 5 speed. When the tune is pulled from the truck, it shows an "error" in current tire size and the size calculator will not pull up. The truck has stock 3.42 gears and I went from a 265/70/17 to a 305/70/17. Any help would be greatly appreciated.
Jack