Mustang offset for 18's & 20's

[dodger562]

Hello guys,

I found this site a few weeks ago and have been lurking as the time got closer to getting wheels. My question is....I am trying to run American Racing Razors in 18x9's in the front and 20x9's in the rear. I can't find what offset or back spacing to use? (sorry if I missed it) I keep seeing post of 18's in the rear, but I like the look of the 20's - Can someone help me out?

Thanks

[smple]

What year mustang?

[dodger562]

It's a 69...

[EBMC]

Welcome to the site! On my 70, I'm running 18x9 up front with 4.625 backspacing and total control suspension. The rear is narrowed 2" on each side and I'm running 19X10 with 4.25 backspacing. (stock width housing would be 6.25) I also am running G=bar rear suspension and am not sure if I the stock leafs would interfere. If you run 10" in the rear, you will have to do some massaging of the front of the wheelwell. recomend rolling the lips front and rear.

[dodger562]

sweet stang bro, I like that look. Judging by the pic... it doesn't look like I am gonna get a 20'' with stock suspension on there.

[Boesch]

Welcome to the site! On my 70, I'm running 18x9 up front with 4.625 backspacing and total control suspension. The rear is narrowed 2" on each side and I'm running 19X10 with 4.25 backspacing. (stock width housing would be 6.25) I also am running G=bar rear suspension and am not sure if I the stock leafs would interfere. If you run 10" in the rear, you will have to do some massaging of the front of the wheelwell. recomend rolling the lips front and rear.

Your car looks good! I'd like to see a side shot!

[Benoit23]

On my 70, I'm running 18x9 up front with 4.625 backspacing and total control suspension.

Is 4.625 the max backspacing you can run on the front?
& does the "Total Control" suspension give you more room than the stock components?
The reason I ask is because the front rims I’m looking at for my ’73 Mustang are 18x8 with 6.15” backspace.
I know the dimensions will be different due to the body styles but, I’m sure the front suspension is pretty much the same, Right?

[fast Ed]

Max backspacing on 18" for the front with OEM style suspension is around 5" ... more than that, you'll be contact the upper control arms. That is up to 1970, not sure if the 71-73 is much different that it would allow more backspacing, but I don't think so.


cheers
Ed N.

[EBMC]

About 4.75 is the max backspacing i could have used in this application. I've never ran this size wheel with stock suspension so I can not say if the Total Control stuff affects much. I used a Percys Wheelrite tool for figuring specs. It's sort of a flimsy tool but works good if handled carefully. BTY, thanks for the comments, I'll have some complete shots soon, after I install glass and rest of trim.

[Bad94]

On the 69 Convertable im doing right now, is getting 17x7 4"BS and 17x8 5" BS

[hossdoc]

I've tried my best to do better than 5" bs on my '71. No go at least with a 17" wheel. There seems to be no getting around it unless you go 19 or maybe 18(I haven't played with those sizes). I can tell you that a 255/45R17 on a 9" wheel with 0 offset fits. I tried a 275/45R17 and it rubbed the fender lip at full jounce and full turn left and right. I have stock arms but I have spoken with Brian Gluck at Darkhorse racing and he is running that 275 on the front of his AI car. Of course he has glass fenders with no lip. The TCP stuff he runs also gives a little adjustability in and out. I don't know his alignment specs either. And according to TCP a 17" wheel won't clear the upper ball joint. After endless hours under the car I believe them.

Someone please prove me wrong!

[MBD]

I've tried my best to do better than 5" bs on my '71. No go at least with a 17" wheel. There seems to be no getting around it unless you go 19 or maybe 18(I haven't played with those sizes). I can tell you that a 255/45R17 on a 9" wheel with 0 offset fits. I tried a 275/45R17 and it rubbed the fender lip at full jounce and full turn left and right. I have stock arms but I have spoken with Brian Gluck at Darkhorse racing and he is running that 275 on the front of his AI car. Of course he has glass fenders with no lip. The TCP stuff he runs also gives a little adjustability in and out. I don't know his alignment specs either. And according to TCP a 17" wheel won't clear the upper ball joint. After endless hours under the car I believe them.

Someone please prove me wrong!

I've long suspected that the 69-70 cars are like you're saying the 71-73s are. That is, with a stock suspension, we can run a little wider wheel in an 18 versus a 17. It seems that 4.75 is about max for a 17.

[hossdoc]

I just gone fine tuning the BS for the new wheels I got for my '71 Mustang. In the stock configuration, 4.75 is the max. With Opentracker's UCA "negative wedge" modification and the right ball joints, and a little trimming of the ball joint cap, 5.25 BS is possible. Past that the steering arm gets in the way. Of course that is with 17" wheels. However, I suspect even an 18" will hit the steering arm and ball joint cap.