mc-g
Well-Known Member
As the title states. I know the biggest tire and wheel size has been asked a ton.....but does anyone know what backspacing and offset I would need for a b body rear end under a dart. what say you
Ha looks like 72blu was writing up a post about the same time I was tooling around with it. I guess he's right, trying to be precise like I am may not be the best way, because there's always a variation somewhere. So I guess start with grabbing some straight edges and a tape measure and get to it.
awesome guys! THANK YOU for these posts. The science of wheel measurements has always been foggy. You describe it better than pictures. I don't have the rear end yet. I DO know its a '68. I'm wanting to run 15" steelies or torque thrust D's. I'll get to measuring once its all mounted up
Depends on what year B-body housing you have. There are Five different versions, all different widths and spring perch location...
B BODY
'62-'63= 53 1/4" (And '64 Max Wedge)
'64 = 55 5/8" (Exc. Max Wedge)
'65-'67= 54 1/4"
'68-'70= 54 15/16"
'71-'74= 57 7/8"
'71-'73 wagon= 59 7/16"
This should be easy to figure out once you identify which one you have.
I run a FACTORY 8 3/4" rear housing, and I fit a 15x8 rim, with 4.5" backspace, with 255 60r15 tire, Perfectly on the back of my 72 dart.
"Googling" '8 3/4 rear end dimensions' tells us that;
Factory A-body flange to flange is 52 5/8"...
...so just figure out the difference in width flange to flange, divide it by two, and you will have how much longer the housing 'sticks out' from the factory A-body location...
For example.
If we go with the 65-67 B-body housing, the difference in overall flange to flange length is 1 5/8". Divide that by 2, and you get 13/16". That is how much more the tube will stick out past factory A-body housing location.
So you need a wheel that is roughly 13/16" more backspace than the baseline. I used 15x8 with 4.5" BS as my baseline since I know that fits centered in the wheel housing.
May sound confusing but play around with it on paper and it works out well. I'd run a 5"-5.5" backspace wheel and that will get you close to center, depending on how wide you order the wheel.
...........I have a rear out of a 68 road runner in my 74 duster.........my rims are 15x10 in wide centerlines with 5in back space.....have p295/50r15 gy eagle gt2s........i have 1 3/4 in to my springs from the tire buldge.......my tires stick out about an inch, so 6in bs would be better on my car.......kim........
You still may want to have the Rims in hand that you will be using. You may end up an inch or two different than the 7 1/4 for a perfect fit. My Outlaw 2's have about a 5" backspace and are almost perfectly centred. If you end up with say a 3" backspace then you may want to go narrower when do it. I hope that makes sense/Helps you. GerryWell, all I could get was a complete E body setup. BUT....there a local guy who cuts axles and housings, and does the re-splining.....all for $150. He's GOOD too. So now I can rock any width. I'm gonna take him my junk 7.25 with the 8.75.....and just have him match it up to the current width.