See if this helps... You need to be more concerned with backspace than offset. Offset is the measurement from center of the wheel in +/- numbers to the mounting surface. Backspace is the measurement from the mounting surface of the wheel to the rear lip of the wheel. The wider the wheel the more the offset can change to achieve the same backspace. If I remember correctly the factory backspacing is 6.5" You really need to look at a 4.5-5" backspacing which would push the wheels out 1.5-2". The offset to achieve that backspace would depend on the width of the wheel since it is measured from the middle.