Rear tires after moving springs

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g49bridges

g49bridges

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Hey guys, I know there's a lot of posts about tire size, but haven't found any talking about tire size after moving the springs. Sorry if I missed it. Anyway, just wondering what the max tire size I can fit on the rear now. It's a 74 duster, A-body 8.75, rear springs moved in 3'' on each side. Car is NOT tubbed. Looking at 255/60/15s, but I'd love to go wider.
 
If I read right, with the proper backspacing, 275s SHOULD fit without moving the springs

But since we're on the topic, how did you move them?
 
Springs are moved into the frame. Frame cut out and boxed back in with a relocation kit from mancini.
 
I have 275's with the 3/4" offset hangers, no tubs, on 15X8.5 wheels with a 4.5" backspace. They would definitely fit with a 3" relocation. You should be able to go to a 295, and maybe a 325 without tubbing, and could go with more backspace.
 
What would be the point of moving the springs into the frame and not tubbing it? I mean that is the whole point of going more than the 3/4 inch required to get to flush with the inner tub wall. Now you are ready for 2 inches of tub. And then narrowing. And then almost any tire.
As it is, you are limited to the stock tub size, but no longer limited by the spring.
Because of the new shock orientation, and the highly arched SS springs, body side shift motion may be an issue for you. So although the 325s might fit in there, if perfectly fitted, I doubt they will endure much cornering,before rubbing.
It is my opinion
that 295 s will be safer. These will work on 10s at 24 psi. 24 is Not ideal for cornering, but for a streeter they are not sticky enough anyway; and drifting is way big fun.
 
275s on 8" rims, with 4-1/2" B S, should fit & look real good. - I did it on a 68 Dart.
 

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275's will fit with the stock spring location and no cutting or trimming whatsoever. Nothing other than proper backspace is needed to run 275's on a Duster, Demon, or Dart Sport. So, the 255's you want to run would have fit easily with no modifications whatsoever.

295 is the widest you can go if you keep the stock wheel tub. That's it, that's all you get. 325's will definitely NOT fit into the stock wheel well, regardless of where you put the springs. Maybe they might work if you put the tail end of your car 4 feet in the air and the tires hang out past the quarters, but that's not the same thing as the tires fitting in the wheel wells.

I have a 1/2" spring offset installed in my '74 Duster. The springs are inside of the inner wall of the wheel tub, meaning, the tires hit the inner wall of the stock wheel tub before they hit the springs even with just a 1/2" offset. I had to trim the lip on the quarter a 1/2" for clearance on the outside too. Now, my car sits low and with SS springs the OP's will not, so the quarter lip probably wouldn't be an issue with 295's and SS springs.

Now, if you do a mini-tub you can pretty much put anything you want back there, 345's would work.
 
Woods74 said:
When you move the springs in 3", does that not give you 3" more tire to work with given the right back space?

Given a site like this:

https://tiresize.com/chart/

You could nail the size down immediately.
Click to expand...

No, because the wheel tub isn't 3" wider than the original spring location.

In the case of our A-bodies, the original spring location is only about a 1/2" wider than the stock wheel tub. Meaning, the springs only stick into the wheel tub by about a 1/2" So, if you use Dr. Diff's 1/2" spring offset, or Mopar's mislabeled 3/4" spring offset, the springs are even with, or inside of the stock wheel tub already. You could relocate the springs 6" at that point, if you don't widen the wheel tub you can't run any more tire.

Now, if you do a 3" relocation AND a mini-tub, then you can run and extra 3" of tire.
 
So, now, that you spent the time and or money, to move the springs in, you just spend a little more of it, and mini-tub it. Then you getyousome 12s and go crazy.

Oh wait, you will also want to narrow the rear,cuz custom-12s will look silly with something like 9 inches of backspace.......

That reminds me; I think I still have a custom narrowed rear 8.75 kicking around here with Moser axles. Hmmmmmmmmmmmmmmmmm
 
Check out my 73 duster in wheel and tire combo post # 77. Fit 325 on 10 inch rims with 3/4 inch offset kit, 5.5 inch backspace rim, SS springs.
 
rowinafour said:
Check out my 73 duster in wheel and tire combo post # 77. Fit 325 on 10 inch rims with 3/4 inch offset kit, 5.5 inch backspace rim, SS springs.
Click to expand...

Riiiight.

This is your car yes? (and it's a beautiful car, btw. I love black cars :thumbup: )

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You can fit any width tire you'd like on that car, because your tires are outside of your quarters and the quarter lip is 3" above the tire. Lower your car 3" and see if they still fit without rubbing. I'll cut to the chase, they won't.

On a Duster without any significant trimming/rolling of the quarter lips there's a little less than 13" of space between the inner wheel tub and the quarter lip, and the wheel tub has a "bump" an inch or so above the quarter lip that reduces the clearance even more. Most 325's have a section width of 13". So, yeah, that's a no go- unless your wheel openings are high enough above the tires so that the tires never get near them. The 325's will not fit in the stock wheel tubs. The only way they "fit" is if your car is significantly raised from the stock ride height, as yours is. If your car is at the stock height, or lowered, they won't clear.
 
g49bridges had mentioned his car had SS springs, just wanted to show him how his car would look with 325 tires with similar suspension without tub change. Thanks for compliment on car, have since sold it and have 67 barracuda project to fill the void.
 
Love how that black duster looks. I'm not too big on cars sitting real low...like the big tire, tall stance. I've bought 275s now, but I will measure to see if I can fit 325s and might go with that next time.
 
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