I've been drooling over wheels, but I was still fuzzy on the whole offset thing and what it meant. Thank god there's Google! Sorry if this has been addressed ad nauseam. Offset-Definition The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types (measured in millimeters).* Zero Offset The hub mounting surface is even with the centerline of the wheel. Positive The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars. Negative The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset. If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. *Backspacing, similar to offset, is the distance from the hub mounting surface to the inside lip of the wheel (measured in inches). Wheel Tech - Offset Regarding the Ford Raptor specifically, please see this expertly written Forum Sticky. http://www.fordraptorforum.com/f25/stock-raptor-wheel-specs-frp-raptor-wheels-55/ To summarize said Sticky: "The stock Raptor wheels are charcoal grey painted + clear coated. 17" x 8.5", 6 lug x 135mm, with 34mm offset( 3.41 front space, 6.08 back space) The frontspace and backspace measurements are based off the rim's full section width edge to edge(9.5" approx.) where the 8.5" width rating refers to inside edge to inside edge(tire mounting surface). The wheels are hub-centric which means the weight of the rim is supported by the hub bore(the hole in the middle) rather than lug-centric which would use 60* conical lug nuts to center the wheel and support the weight." Regarding acceptable offsets for our Raptor, it is commonly agreed upon that a 0 offset is the maximum you can leverage before creating trouble for yourself. Greater offsets, like -12, can cause rubbing of the fenders at full suspension compression, and can cause issues with the CV joins on 2012+ model when placed at Full Perch (to avoid fender rubbing). http://www.fordraptorforum.com/f25/12-offset-doable-19225/ So in short a 17" x 8.5", 6 lug x 135mm with 0 offset and you're in the money!