Wheel spec questions

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chicks

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Hello everyone. I've searched all over and can't seem to find a solid answer. I'm hoping I can get some good info.
I've got a 67 barracuda with rear springs moved in to frame rails, 8 3/4 a body rear end with 10" drums. Im looking at a set of 17" wheels. Can anyone tell me what backspace I should shoot for? Also what would widest tire and wheel combo be?
Front is 74 dart discs/kmember with narrow sway bar. Same question.
Thanks, hopefully I can get this figured out
 
Couple of questions- have you done a BBP axle swap or re-drilled the stock axles? And the springs have been relocated, but did you do a mini-tub or are the wheel tubs still stock?

And, what it the intended use of the car? Street, strip, AutoX, some combination of a couple of those?
 
72bluNblu said:
Couple of questions- have you done a BBP axle swap or re-drilled the stock axles? And the springs have been relocated, but did you do a mini-tub or are the wheel tubs still stock?

And, what it the intended use of the car? Street, strip, AutoX, some combination of a couple of those?
Click to expand...

Forgot to mention that its converted to BBP with stock wheel tubs. It will be street with maybe some weekend strip.
 
Any ideas? Does 275 (or 285)/55/17 sound about right? Not sure on backspacing.
17x8 on front?
 
With the stock wheel tubs you really don’t gain much moving the springs, no more than a 1/2” spring offset really.

So that said, you should be able fit 275’s easily, 285’s if you get the backspace right and possibly 295’s if you’re willing to roll the quarter lip. All of that assumes you want the tires inside the quarter lip, obviously if your car is running super stock springs or sits high in the back you don’t need to necessity have the wheels completely inside the quarter lip and you can go wider. Height wise up to about 28” will work without significant modifications.

Maximum backspace will be around 5.75”, give or take a little depending on your cars body tolerances. If you want a more exact number for your car, measure from the wheel mounting surface (face of the drum at the studs) back to the inner wheel tub. Then knock off a 1/2” for the tire overhanging the rim, and another 1/2” for clearance to the tub. That will be close to your max allowable backspace.

In the front 17x8 will work, you’ll want between 5” and 5.6” of backspace. You can run up to a 255/45/17’s up front but for what you want to do you don’t need to go that wide, 245/45/17’s would be easier to deal with.
 
Thank you. That actually helped significantly! I'll likely run the 17x9.5 wheel with the 285/55/17. That puts me at 29.3" diameter which is about where I want to be with the 3:91 gears.
 
interesting, Tire rack say's " ALL TIRES FOR 285/55R17 WE'RE SORRY. There are no tires in the size you selected."
mmm
 
chicks said:
Thank you. That actually helped significantly! I'll likely run the 17x9.5 wheel with the 285/55/17. That puts me at 29.3" diameter which is about where I want to be with the 3:91 gears.
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I’m pretty sure 29.3” won’t work with the stock wheel tubs. Even at 28” you have to move the axle back to center the axle in the wheel opening.

kursplat said:
interesting, Tire rack say's " ALL TIRES FOR 285/55R17 WE'RE SORRY. There are no tires in the size you selected."
mmm
Click to expand...

Yeah 17’s do not have the selection they did even just a few years ago in the wider tires. Really dries up after 275mm wide.
 
72bluNblu said:
I’m pretty sure 29.3” won’t work with the stock wheel tubs. Even at 28” you have to move the axle back to center the axle in the wheel opening.



Yeah 17’s do not have the selection they did even just a few years ago in the wider tires. Really dries up after 275mm wide.
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Not so blu, I haven`t moved my axle back , I agree w/ most other stuff u said tho. My tires are 28.5 , supposed to be 29 , and the springs have settled to where the tire is up in the fender wells at least an inch , but I did move the front of the fender up to the inner wheel well , which is the same contour. This is before the caltrac single leaves settled -------
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Well damn, I'll have to keep looking into options then. Thanks for all the info
 
famous bob said:
Not so blu, I haven`t moved my axle back , I agree w/ most other stuff u said tho. My tires are 28.5 , supposed to be 29 , and the springs have settled to where the tire is up in the fender wells at least an inch , but I did move the front of the fender up to the inner wheel well , which is the same contour. This is before the caltrac single leaves settled -------View attachment 1715538811
Click to expand...

Right, so you modified the lower part of the quarter opening to make it work, otherwise it wouldn’t have cleared. So how is that different from moving the axle back on a car that hasn’t been cut up? Either way it doesn’t clear without modifications.
 
72bluNblu said:
Right, so you modified the lower part of the quarter opening to make it work, otherwise it wouldn’t have cleared. So how is that different from moving the axle back on a car that hasn’t been cut up? Either way it doesn’t clear without modifications.
Click to expand...

I get what ur saying and pretty much agree, BUT , I would never move an axle back on a traction limited car. Forward yes -------------
 
Hello, this looks like the right place to ask this instead of starting a new thread. I recently purchased a 67 Barracuda Formula S, 273 ci. The car is currently rebuilt in stock configuration with manual steering and brakes. KH front discs. This is going to be a street car which will spend most of its time on the windy roads north of NYC. I'm just now waiting to get my plates from NYS DMV. I've done a lot of reading and am pretty much aware of all the options for suspension and steering mods. For now I want to keep things relatively stock. I have spoken to Peter Bergman at BAC about some moderate upgrades to take advantage of better tires. Which brings me to my question. I'm considering ordering some 17" x 7" Torq Thrust II wheels from American Racing in the 5 x 4 SBP. I know about the benefits of converting to the 5 x 4.5 BBP but for now I'll keep what I have. Since it would be a custom order I want to make sure I get it right. What would be the correct Backspacing and offset for that size wheel, front and rear. I'm looking for a wheel and tire that will fit without any issues at stock ride height. I appreciate any help. Thanks.
 
Do they offer a 17x8?

Based on your “moderate upgrades” I wonder if a 17x7 is what you want. Keep in mind that when you go to 17’s you end up with a shorter sidewall, which means your tread width has to be closer to the rim width. So, in the front that 17x7 would limit you to a 225. Go up to a 17x8 and you could go up to a 245/45/17. Same in the back. Because you can run a taller tire out back you could probably find a 235 that would work, but a 17x8 would let you run a 255/45/17.

Both of those options should fit without modifications with the right backspace. In the front you would want about 4.75” to 5” of backspace with the SBP disks. In the back it would be about 4.5” of backspace for the 17x8”. It’s pretty easy to measure your car in the back, you just need a straight edge across the drum and measure back to the springs. You need about a 1/2” of clearance and with a 17” rim leaving another 1/2” for tire overhang on the rim would be enough. So if you whatever that measurement is and subtract an inch it gives you a rough number for your backspace.
 
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