• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Correct way to measure wheel offset & backspacing

  • Thread starter Thread starter txstang347
  • Start date Start date Jul 15, 2008
T

txstang347

Member
Aug 9, 2007
57
0
6
Jul 15, 2008
#1
  • Jul 15, 2008
  • #1
First off, am I correct in that + (positive) offset measures the distance from center to the outside (street side) of the wheel?

And - (negative) offset pushes the hub in towards the brakes, deep dish style?

Not real clear on backspacing. I'm assuming the amount of space from the hub mounting point to the lip of the rim. I'm assuming I need that # so I know if it will rub with suspension parts.

I'm in the process of gathering parts for an all disc 5 lug swap (99 - 04 PBR/disc/spindles up front) and I am really considering going with 03/04 Cobra IRS rear setup. I can't really decide what is more important to me, ride quality or stance and "the look". In the real world ride quality wins over "the look", but the '91 Mustang GT vert is not my daily driver so it's up in the air. I may have to go with an SN95 rear disc brake setup because of wheel spacing issues. I've read that SN95 setup adds .75" to the fox length and the IRS adds another .75" to the SN95 length. So about an 1 1/2" total with an IRS setup.

Anyways, on to the main question which is:

How do you measure for correct wheel offset and/or backspacing?

Would I measure from the axle hub to the outter lip of the fender well? Then what? How do I come up with a + offset nubmer?

In a perfect world I'd like them to be flush and not stick out, but I could live with 1/4" - 1/2" of rubber outside the wheel well.

Here's an example of what I don't want the stance to look like. This just doesn't look right to me (granted I don't think he's quite done with the setup):
My Fox INDEPENDENT REAR SUSPENSION project - Corral Forums

This does't look too bad:


Oh, and the wheels I want to run in the rear are 18x10, +38mm Offset, 7.0" backspace. I know it's pushing it, but it would be kick ass!
 
You must log in or register to reply here.

Similar threads

Considering widening my rear wheels, would like to verify my thoughts on fitment
  • 2000xp8
  • Jul 9, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
26
Views
646
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Saturday at 10:08 AM
2000xp8
Rear Disc and Rims Offsets
  • TripleYellow
  • Nov 11, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
19
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jan 9, 2026
TripleYellow
C
Help identifying 8.8
  • Caden_H
  • Jun 25, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
10
Views
699
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Nov 12, 2025
limp
J
For Sale MASTER LISTING: Abandoned '66 Mustang Restomod Part-Out (Wilwood, Ididit, Quick Performance, Mishimoto)
  • JasonB66
  • Jul 23, 2026
  • Suspension
Replies
0
Views
166
Suspension Jul 23, 2026
JasonB66
J
B
Where to go from here on my build…
  • B0udreaux
  • Jul 14, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
8
Views
267
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jul 18, 2026
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?