fairlane292

The stock bullit rim isaccording to fordracing.com)
http://www.fordracingparts.com/parts...tKeyField=7868

M-1007-T178S*

Fits 2005 Mustang

5-Lug 4.5" bolt circle

6.295" backspacing

17" x 8" wide

Now I can tell you first hand that this 6.295 measuremt is from a straightedge on the outer most edge of the rim down to the bolt face. If you measure down from the outer bead mounting edge (as AFS shows in their diagram on their web site) the measurement is 6 inches (you typically get about a 1/4 inch more on any rim going to the outer rim edge) So don't let anyone tell you there is only one way to measure (AFS and Ford do it differently but the difference is only about the 1/4 inch)

Forget about offset; there is no point in talking about both. The backspacing will tell you how far the wheel will go into the wheel well. Anything less than what I mentioned above on a 8 inch rim will stick out that much more. I see for example a 17x9 that says 'Correct for 05, 06 Mustang' with it's 6.55 inch backspacing. I don't know which of the 2 ways above it was measured but since the rim is 1 inch wider than stock, if you don't want anymore sticking outward in the wheelwell then you need a 7.295 (or 7.00 if they measure from the outer bead mounting edge.)

If anyone has any specific examples that they have measured the BS on and can with a plumb line give the distance from the body front wheelwell to the outermost rim edge. I can get the stock one off mine tonight.

Any other measurement info you have would be helpful to all. ty, Jim