Backspace difference?

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DartGTDan

DartGTDan

'71 Dart GT Fan
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Is there a backspace difference between the 14" X 5 1/2" steel wheel vs. the 14" X 4 1/2" steel wheel? It is my understanding the 14" X 5 1/2" steel wheel will have a 3 3/4" backspace. I borrowed an original 6.95-14 wheel/tire from a FABO member and made some measurements.

IMG_4177.JPG


My CRUDE measurement tells me the backspace is 3 1/4".

IMG_4178.JPG


I'm thinking this is a 4 1/2" wide rim.

IMG_4180.JPG


Can anyone confirm if this is a 4 1/2" rim?
 
I hope you took a picture of the valve stem area. Like in this sample photo.

Screenshot_2018-01-30-21-53-46.png
 
Backspace is measured from where the rim mounts to axle, or hub inward (under car)to edge of rim
 
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Stand up the wheel, clamp another board against the other side and measure the width directly through the hub hole.

That said, I measured the backspace on my 67 Barracuda rims at 3-1/4, and I thought they were 5.5" rims (that's what my dad told me once). Thinking about it, 3+ inches would be a lot of backspace on a 4.5" rim. I always thought Mopar rims were close to zero offset.
 
This is the correct way to measure back space . From the very edge of the wheel to the back of the center register hole. I stole the picture from above

20190728_185906-jpg.jpg
 
The wood should be always sitting on top of the wheel lip. Not down inside the lip like you are showing it in some of your pics. That's about 1/4" difference.
 
I showed both ways as some do it one way and others do it the other.
 
A lot of confusion regarding width and backspace is caused by the fact that wheel width is measured inside the bead/tire mounting surface and backspace is measured at the outer most part of the wheel. Strange really..
A 5.5" wheel is almost 6.5" measured at the outer perimeters.
One would think that a zero offset 5.5 wheel would have a 2.75 bs (half the width) while it in reality is has about a 3.25bs (half of 6.5)
 
With all the measurements, I'm confident the wheel I borrowed (from 72Dart6pack aka Ken) is in fact a 14" X 4 1/2" rim with a backspacing of ~3 1/4". I used the same measurement technique on my 14" X 5 1/2" Rallye and came up with 3 3/4" backspacing.

With Dana67Dart's photo help I now know the backspacing on the 14" X 5 1/2" STEEL & RALLYE wheel are the same.

I need to find 2 (maybe 4) 14" X 5 1/2" STEEL wheels. Anyone have 2 or 4 they'd like to sell?
 
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