What is a wheel offset?
The offset of a wheel is the distance from the mounting surface of the wheel to the true centerline of the rim. A positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the rim / tire assembly. This in effect brings the tire in to the fender well more. Conversely, a negative offset means the mounting surface of the wheel is behind the true centerline of the rim / tire assembly. This will cause the tire to stick out away from the vehicle.