Backspacing (offset) can be confusing. This 17x8-inch Center Line wheel has an outside width of 9 inches and 0 offset, meaning the mounting flange is right in the middle. The manufacturer of this wheel measures offset from the outermost portion of the wheel flange, so it has a 4.5-inch backspacing. If the flange were moved out towards the street side, it would have a positive offset. Towards the inside means negative offset.