correct rim backspacing

The stock bullit rim is (according to fordracing.com)
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=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

Can you check your TT with plumb line?

Hey spdbrake, thanks for the link, that is good info. Since I am interested in a American Racing rim (the 200s grey center) 17x8 it would be super helpful if
you could do a plumb line check of the measurement from the front wheelwell body edge to the outer edge of your AR TT 17x8. I will do the same on the front of my GT with the stock 17x8 bullit. I'm hoping it's less because I'm ready to buy the AR 200s but the 5.5BS being 1/2 to 3/4 inch less than the OEM bullit should position your (my)ARs 1/2 to 3/4 further outward in the wheelwell (probably not very noticeable but I would like to know) Did you notice any visual difference 'outward in the wheelwell, and could you do the measurement for me when you get a chance. I'll post the factory value tonight after I get home. Thanks so much!!

P.S. got any pics of your car that you can share?

AR 17 probably won't fit

First of all let me say that you ride looks terrific; no bling for me either. I'm really looking to stay with the 17's (have two new sets of Pirelli 17" now and larger sidewall means softer ride to me; I won't be road racing anyway... well maybe in a straight line (lol))

CL200S (Series 402) is actually a different rim than you have. note...

http://www.americanracing.com/wheel...-piece painted center, polished rim&section=V

...yes I have been concerned about the front caliper and was just going to order a 17" to test (supplier will do that no problem); sounds like the odds of it fitting are slim, but this rim has a different profile than the Torq-Thrust II Classic Custom Offset (Series CL205). Already I believe the 5.5 BS will move the rims outward 1/2 to 3/4 and to add another 1/4 for a spacer just isn't acceptable. Yours looks great; however in the pic the rims/tires do look more outbound in the wheel well than my stocker. ...not that it's a bad thing. I'll tell you what my front plumb line distance is when I get home; I bet you're out 1/2" or more from that. ...as I say not a bad thing; looks good and handling must be great. Thanks for all the insight!!! ...Jim

Looks like 200s will fit (will order and test soon)

spdbrake: Thanks for the great info link. Yeah it looks like the 200S may very well fit. I would love to go 8 in front and 9.5 in rear as you mentioned but I had done lots of research on tire sizes in 17 to maintain close "revs per mile" front and rear. Pirelli didn't have anything as tall in diameter as the 27.1 stock p235x55 in a wider tire for the 9.5 rim. I did find a nice setup (for 8s and 9.5s) with Goodyear (have info at home), although the diameter was about an inch lower than stock Pirelli which is not a problem except for the added 1/2" tire to wheelwell spacing look. Because I have this "inventory" of two complete sets of new OEM GT Pirelli's I will likely just go 8s all around for now which is a lot less $$$ and more practical given the circumstances, than going out for 4 new Goodyears. There are advantages too, of less weight, probably better ride and easier 'burnouts' with the Pirellis; and I won't mind lighting up the Pirellis as much either since I have plenty, whereas I'm sure I would be less likely to with the wider (pricey) tires for the 9.5s. It's the ole balance between looks, driveability and $$$; but I totally agree the 9.5s would look better as that was the initial plan. Can always go there later of course. Appreciate very much your help with this topic. ...Jim