73 Duster rear fitment

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dart_68

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I'm looking at getting some new wheels and tires for my 73 Duster but I'm not sure about fitment. The rear wheels I want are American Racing VN10558065B American Racing VN105 Torq-Thrust D Black Wheels with Machined Lips | Summit Racing. They are 15x8 w/4 1/2" back spacing BBP.

The tires I want to run are Mickey Thompson 3451 Mickey Thompson ET Street S/S Tires | Summit Racing. They are 275/50-15.

The above tires have a 11.10" section width and by my calculations with the above wheel the tire would extend inboard from the axle mounting point 2.05". I'm thinking that this might be 1" too much and will have to get a smaller wheel/tire combo or a different wheel with less backspacing but I'm not sure without mocking one up, which I don't have. Is my math right and what is the max backspacing for a 73 Duster?
 
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We’re missing some info. What rear axle do you have? It does make a difference, not all A-body axles are the same width. They vary by type and the bolt pattern makes a difference too.
 
We’re missing some info. What rear axle do you have? It does make a difference, not all A-body axles are the same width. They vary by type and the bolt pattern makes a difference too.
The current axle is an 8 1/4 BBP.
 
On my 74 Duster, with the 7.25" rearend, I have AR Torq Thrusts all around.
Rear-
VN105D Series Torq-Thrust D Wheel Size: 15" x 8"
Part Number : 286-VN10558065
245/60/15 Tires

Front-
VN105D Series Torq-Thrust D Wheel Size: 15" x 6"
Part Number : 286-VN1055665
215/60/15 Tires (I think)

The 245's on the rear are TIGHT. The passenger side tire would rub the pinch seam on the inner wheel well, and was only about a 1/4" from the leaf spring on either side. I hammered the pinch seam a little bit on the passenger side, and am using a really thin, 5mm I think, spacer. Fitment is great now. Not sure how different the 8.25" is compared to the 7.25" fitment wise. You can also get spacers in the thickness you need, but 275 might be a little too tight. You'd probably be better off with 245's or 255's unless you're tubbed or have offset leaf springs.
 
The current axle is an 8 1/4 BBP.

Ok. In that case I think you’re right. The BBP 7.25 and 8.25” are the same width, so, Fawkes experience is right on. I had a simile experience with a BBP 7.25”, I barely fit a set of 17x9’s with 275/40/17’s with a 4.75” backspace. Don’t let the number fool you though, on a 17x9 there’s very little tire overhanging the rim, on a 15x8 with a 275 they’re be a lot and in my case the section width was 10.8”. And I still would have probably needed another 1/8” of spacer to drive it without rubbing.

With an 8.25” you’d want a 15x8” with a 4” backspace to clear 275’s without spacers.
 
I have had a few 74 Dusters and currently have both the 8 1/4 and the 7 1/4. With a 8" wheel 4.25 backspacing works the best. My opinion is not to go bigger than a 255/60/15. I run 245/60/15's in the back and they fit just right. 4.5 backspace works too. any wider and you will get rub and most likely will have to do some modification
 
You can check out my youtube video- 1980's tribute plymouth duster- They are 15X8 with 4 inch b/s but they are very close on the outside edge. Car is all stock back there.
 
You can check out my youtube video- 1980's tribute plymouth duster- They are 15X8 with 4 inch b/s but they are very close on the outside edge. Car is all stock back there.
I will def check it out. Thanks!
 
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