No, it's not. I'm not sure what measurement GM used. These days, offset is the distance of the wheel mounting surface from the center of the wheel, and the backspace is the distance of the wheel mounting surface from the back face of the wheel. So a 15x8" wheel with a 4" backspace has 0 offset.
SeatGuy, it depends what tires you're running as well. Is your truck stock height? Have the springs been replaced or are they original?
Someone else will chime in about whether they'll fit, but these are all things to think about.
