Once and for all time......67 B Body wheel backspacing.

[Ghostrider 67]

Okay folks......i have been looking around here and elsewhere for a definitive wheel backspacing chart/graph/ illustration/explanation. The number of opinions and wheel tire combos out there is enormous. Plus, with TBI it is extremely confusing for me.
Once and for all, what tire sizes in 15,16,17,18" rims fit under a 67 Body rear well with mini tubs and spring relocation?
What back spacing/offset is required for centering up a 8", 10", or 12 inch wheel in the same well?
With a stock 8 3/4" rear axle length.
For example: I have 15 3/4" max space in the wheel well. Frame to lip. The mounting surface of the brake drum is 5 3/4" from the wheel well lip and 10" from the frame.
I want to put a 29" tire, 15"x 10" rim under there that has a 13" section width. And have it centered up.
Please compute. Thank you. Ghost.

Discuss....

 

[Ghostrider 67]

Sooo...when I call to order rims, i need 15"x10" with what backspacing? Something between 4" and 5.50" inch I imagine....I just don't want to do this twice or end up with rims I cannot use, with the tires that I want, on the car that I have.

 

[R413]

Since most of us here don’t have a car with mini tubs we need you to tell us. I could measure all day on my stock wheel well and Guess what would fit, bit it wouldn’t be correct.

An easy way is to put on a wheel and measure off that wheel how much room you have to go out on each side.

Let us know what you come up with!

 

[33 IMP]

Agree with above! Get just about any wheel that fits and has the bolt pattern you want (preferably without a tire on it, measure off it to center up the wheel width you want. That will tell you the width that can work, and the backspace you need. (And dont assume left and right are the same!).
Edit: 10 inches to the frame from the drum?!? Youre gonna need a LOT of backspace! (Ive got a pair of rare centerlines that were factory built for your situation. [not for sale, sorry], double drilled, 7 1/4 bs on a 10 1/2 rim.)

 

[gkent]

!0" from the drum face to frame. 13" cross section of the tire means 1-1/2" overhang from the rim. 15-3/4" to play with I think I'd want the tire closer to the frame since the out wheel tub curves inwards. So let's say 3/4" to 1" clearance at the frame to the tire.

so...
1"clearance + 1-1/2" tire overhang = 2-1/2" to the rim
10" frame to hub - 2-1/2" frame to rim = 7-1/2" backspacing
15-3/4" total - (2-1/2" frame to rim + 10 wheel) = 2-3/4" outer rim to outer tub
2-3/4" - 1-1/2" tire overhang = 1-1/4" to outer tub.

Now here's the strange thing ...

I have a '69 B-body. In the stock tub I can fit a 10" wheel/tire combo with 5-1/2" back spacing. The car is not jacked up or anything that would give any more clearance. AND the '68 and later 8-3/4 is actually wider than yours'

Hmmm !!!!

 

[gkent]

There seems to be some discrepancy with your measurements ...

the width from outer frame rail to outer frame rail is roughly 40". The width of the stock 8-3/4 is 54-1/4". So the measurement from the frame rail to your flange should be roughly 7" or so, NOT 10". Either you've measured wrong OR someone has swapped in a much later model 8-3/4 !!

 

[ruffcut]

From what I'm seein g with your measurements, A 10 inch wheel would have to have a 7 inch back spacing to get close to being centered! If you did that, the wheel would be very hard to get over the brake hub to install! Just my 2 cents. ruffcut

 

[65wgn440]

There are fixtures made by a couple different companies that will determine correct backspace and max tire size. Should be able to find one with a quick search. I think last time I checked they were about $150 for a good one.

 

[gkent]

There are fixtures made by a couple different companies that will determine correct backspace and max tire size. Should be able to find one with a quick search. I think last time I checked they were about $150 for a good one.

Seriously ?!?!? A tape measure, pencil and paper will cost you less than$10 !!!

 

[65wgn440]

Seriously ?!?!? A tape measure, pencil and paper will cost you less than$10 !!!

Yeah, good luck with that......

 

[gkent]

Yeah, good luck with that......

Your avatar says it all !!!

 

[Ghostrider 67]

There seems to be some discrepancy with your measurements ...

the width from outer frame rail to outer frame rail is roughly 40". The width of the stock 8-3/4 is 54-1/4". So the measurement from the frame rail to your flange should be roughly 7" or so, NOT 10". Either you've measured wrong OR someone has swapped in a much later model 8-3/4 !!

I laid a 3 foot steel level against the drum face and ran a tape measure to the frame rail. Exactly 10". I ran the tape to the lip and got 5 15/16" but called it 5 3/4" for a margin. The car had all it's OEM equipment including the rear axle. I'll measure the other side and post it up too.

 

[Ghostrider 67]

It's exactly the same on the left side.

 

[67charger383]

15x12s with 2.5in backspacing fit perfect with no problems on a '66-'67 Charger with stock wheelwells and spring location. Only thing non factory is 455/454 Super Stock Springs.

 

[Ghostrider 67]

I get the following measurements:

15 3/4" - (2 1/2" - 10" -1 1/2")= 1 3/4" left to the wheel well lip. That gives me the 1" clearance at the frame rail, the tire bulge, the actual rim and the outside tire bulge. Yes? 7 1/2" backspacing.

 

[Dan64]

Ghost, check out a write up by Randy Bolig titled "Tech:How to measure for installing larger wheels and tires".

 

[Ghostrider 67]

15x12s with 2.5in backspacing fit perfect with no problems on a '66-'67 Charger with stock wheelwells and spring location. Only thing non factory is 455/454 Super Stock Springs.

That would be apples and oranges because mine has been tubbed and the springs relocated. Thanks though.

 

[Ghostrider 67]

Ghost, check out a write up by Randy Bolig titled "Tech:How to measure for installing larger wheels and tires".

Where can I find that?

 

[gkent]

I get the following measurements:

15 3/4" - (2 1/2" - 10" -1 1/2")= 1 3/4" left to the wheel well lip. That gives me the 1" clearance at the frame rail, the tire bulge, the actual rim and the outside tire bulge. Yes? 7 1/2" backspacing.

Isn't that what I said ?!?!?

 

[gkent]

15x12s with 2.5in backspacing fit perfect with no problems on a '66-'67 Charger with stock wheelwells and spring location. Only thing non factory is 455/454 Super Stock Springs.

2-1/2" backspacing and a 12" wheel. I'm a little skeptical since the Charger uses the same rear end, etc !!