1. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    No problem!

    So a stock A-body 8.25" is about 56.75" wheel mount to wheel mount, so I would wager that what you've got is in fact a stock A-body 8.25. That also matches up with your drum to spring measurement, you've got about a 1/2" less from drum to spring as I do on my '71 Dart with an A-body 8 3/4 and BBP axles. Which is spot on for the difference between those two rear ends.

    And you have ~11.75" spring to fender. That's more than enough to run a 245/45/17 or 255/45/17. It's a little short of what I would like to see for a 275. Not saying it can't be done, but you might have to trim/roll the quarter lip back a 1/4" to keep from rubbing if you did that.

    Anyway, you want about a 1/2" of clearance between the tire and the spring. With a 17x8" and lets say a 255/45/17 the section width is ~10.2" so the sidewall hangs over about .6", call it a 1/2" again close enough (some 255's are 10" sections anyway). So that works out to be a 17x8" with a 4.5" backspace. Which matches up pretty with other 8.25" rear tire combo's I know of.

    So I would say run 17x8's all the way around. In the front you'd want 17x8's with 5.25" to 5.6" backspace, and in the back you'd want 17x8's with 4" to 4.5" backspace. That would allow you to run 245/45/17's all the way around, or 245/45/17's in the front and 255/45/17's out back if you wanted. Only reason I don't say 255/45/17's all the way around is that's a 26.1" tall tire, and on a Barracuda that may cause issues in the front with the lower front corner of the fender.
     
  2. MoparLeo

    MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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    interesting about deciding I want to run a 275mm tire...The suspension dictates the tire. You are going to build the car to that tires capability ? You don't even know what the capability of it is because you haven't run it yet. Just an FYI tread wear ratings are different between all manufacturers and even within the same manufacturer different tire lines. There is NO industry standard on Tread Wear ratings. It was supposed to be that way but to do so would mean that some one like the DOT would have to establish a standard. All manufacturers would have to agree to the same standard and then someone would have to pay to monitor and enforce the standard. Never happen.
    The tread wear rating is established by the tire company as a standard of measure between THEIR own tires. So a 200 twr by Michelin would not be the same as a 200 by Goodyear or Hankook, Pirelli, Dunlop.....And it also is no indictor of the actual traction of the tire. Low tread wear numbers just mean the tire wears faster than a higher tread wear rating of that manufacturer. Not a measure of traction. That is partially addressed by the traction letter codes A, AA, AAA but again not an industry standard. And under what conditions? Tire size, load being carried by the tire, remaining tread depth, speed of the tire, air pressure in the tire, wet or dry, surface, asphalt, concrete, dirt .... The package determines the tire not the other way around, except if you just like a tire and make the car fit it I guess. Not really efficient.
    File:WheelOffset2.gif
    Tire Width for a Wheel/Rim Size Chart
    Moparts on the Web - Main Index
     
    Last edited: Jan 23, 2021
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    • 67notchb

      67notchb Well-Known Member

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      Thanks for the reply, Im going to take your advise and go with 17x8 American racing 515 wheels with 5.5 BS in the front and 4"BS in the back. they fit within the dimensions you suggested and its what Summit has. also taking your suggestion on tires but with 255/45/17 in the back.

      Ill get some pictures up as soon as I get them mounted.

      Thanks again for the help, where abouts in nor cal are you?
       
    • 72bluNblu

      72bluNblu FABO Gold Member FABO Gold Member

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      Still ass backward. Tell "the suspension dictates the tire" to all guys you see running $5k coil over conversions with 215/60/15 BFG T/A's on the front. Colossal waste of money. Or all the guys running BFG T/A radials on the factory suspension components that were set up for bias ply's with half as much grip wondering why they have so much body roll and suspension bottoming out. Seems like the suspension isn't dictating the tires in either of those scenarios. And there are lots of examples of both on here.

      Have you looked at my build thread? It's literally all there, the entire progression. My Duster started out to be a basic daily driver with a 318 that I was going to run while I worked on my Challenger, nothing fancy. I ran it with 225/60/15's, 1" torsion bars, no sway bars, stock UCA's with offset bushings, pretty much no chassis stiffening, etc. In other words, built to the level of grip those 225's would provide. It had a few extra things based on my experience from putting 70k on my Challenger as a daily. But it didn't have subframe connectors, or torque boxes, any of the other chassis work I've done since, or any of the adjustable suspension I run now. So what happened? When I realized the rust in my Challenger would take it off the road for years I decided to put my 340 in it. And as soon as I decided that I decided to do the full build as a corner carver. And with the 275's and hp from the 340 in mind, it got subframe connectors, torque boxes and all the additional chassis stiffening because it would NEED it with that kind of grip. The 1" bars were sold for 1.12's, the UCA's were replaced with tubulars to clear the 275's and provide the alignment setting they'd need, the rest of the suspension that was stock was replaced. I ran it with 225's for a bit with most of suspension and chassis work done just because of the logistics and finances of buying the larger brakes and new wheels and tires while I broke in the engine, but all that stuff was done for the 275's. The sway bars stayed off until the 275's went on. Heck I even screwed it up, I've made the suspension even more aggressive than I originally intended because it became apparent that the 275's were better than I thought they'd be- that's right, tuning the suspension to better match the tires! Weird huh?

      Yes, tread wear ratings are slightly different from manufacturer to manufacturer. Same with traction and temp ratings. But, what do you use otherwise? You order a sample of tires, do all the testing yourself on your car, and then pick your tires? Of course you don't. Treadwear, traction and temp ratings are GUIDELINES. They put you in the ballpark. Is a 400 treadwear tire from one manufacturer the same as a 200 from another? No, it's not. Could a 300 treadwear tire from one company have less performance than a 340 from another? Sure. But that's why you look at tire tests done by places like TireRack, or reviews by people that have run the tires, see what people using their cars like you are running, etc. Otherwise what do you do? You either test every brand/model that will fit on your car yourself, or just randomly pick one you like? You aren't doing the first, and the latter isn't a better method. So poo-poo all you like, you don't have to listen to me. Why don't you explain how YOU pick a tire by not using any of the manufacturer's published tire specs?

      Nice! Those should work for you.

      I usually prefer to use the max backspace possible since spacers can fix that if you're close since every car is a little different. But I see the AR's are either a 4.75" or a 4" backspace for the back so 4" is the best you can do. You should still have a 1/2" to the quarter with those, so it should be fine as long as your measurements are accurate.
       
      Last edited: Jan 23, 2021
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      • MoparLeo

        MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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        It all boils down to What you want your car to be, A race car or a street car. Do you want everything to fit in the factory wheel openings or are you willing to make body mods. Just saying that it is easy to think you are the smartest guy in the room and recommend things when you are not that guy and can't really know what is in his head as to what he expects. People tend to take something simple and turn it into something complex.
        Right off the bat you say that YOU would run a 275 MM tire. What aspect ratio? 30,40,50 ? That will determine the tire and rim diameter. And then the offsets and backspacing would be determined on that info.
        The farther you get away from the factory set-up the more your info becomes theoretical.
        I would try to make it a simple progression from the stock sizing to maybe explain plus sizing is and how that affects the fitment on a stock suspension. How one change makes other changes mandatory for it to work. Domino effect...
        Get back on your box. I just posted charts for people to reference for themselves. It is up to them what they do. It is after all their money that will be spent.
         
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        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          It's even easier to reply to the OP of an old thread that has now gone a different direction. You started talking about Cragars, which is not what 67notchb wants to run. Did you see his post about "bringing back an old thread"? I was answering his questions about the 17" rims he wanted to run already.

          He asked about running tires that would clear his stock bodywork, which is where the first mention of 275's came from. 275's will fit on the back of most Barracuda's without modifications to the body or the suspension. Now, when 67notchb gave his car's actual measurements, I recommended what would actually fit his unaltered car. That's not theoretical. That's using measurements to determine what will fit his car.

          And based on some of the information I posted, he decided to run 245/45/17's and 255/45/17's on 17x8's. As in, he used the information I gave to make his own decision. So what? All you did was post nonsense about "doing the mods first" before picking wheels and tires.

          67notchb posted his intended use of the car and his desire to run 17's with stock bodywork. He had already posted he was using 73+ factory BBP disks and an 8.25" with factory brakes. And then we used his measurements to come up with wheels and tires that will fit his car without body mods. Seems like you're the one that got twisted here.
           
        • 67notchb

          67notchb Well-Known Member

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          Being new to mopars and cars in general the importance of backspacing is not lost on me but hearing others experience and opinions is a much bigger help than doing it myself. Sound advise and experience given off my measurements is why I come here and many people seek out 72bluNblu just for that reason. On that note I have another question, A-R 515 wheels and even others come in a 4.81" BS size, would that be a good option for the rear with a .25 spacer with plenty of stud engagement or would the 4" BS be a better option? I saw a picture of your challenger with the vision 17 and they did look really good, Id prefer polished wheels but still considering those. Thanks again
           
        • MoparLeo

          MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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          Remember that one of the best resources for spacing is the wheel manufacturer themselves. That is why they all have tech departments.
          Just an FYI about spacers. The vehicle weight is supposed to be supported by the axle register not the wheel studs. Best not to use spacers.
          axle registers - Video Search Results
          File:WheelOffset2.gif
          Save this for the future.
           
          Last edited: Jan 26, 2021
        • 67notchb

          67notchb Well-Known Member

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          I completely agree with you about large spacers say .5” and up are problematic. I’m considering .25 if it would be the best option to make A-R 515 with 4.81” BS or go with 4”BS. Another big issues with spacers is not enough lug nut engagement which I know will not be a problem.
           
        • 71GSSDemon

          71GSSDemon FABO Gold Member FABO Gold Member

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        • 33IMP

          33IMP Well-Known Member

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          I have a set of centerlines with 4 7/8 bs that i use with 10 1/2" slicks, but i have to use a .350" spacer to make them work. This is on a b-body with an unknown vintage 8 3/4 under it, so it doesnt directly apply, except that 4.81 is a lot of backspace. Like blu, i like wheels with too much bs, so i can use a spacer to get them exactly where i want them.
           
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          • 67notchb

            67notchb Well-Known Member

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            It is a good amount of BS but like you said I can adjust with small billet spacers. Also what are thoughts if I go with a narrower 245/45tire rather than 255/45 to lessen the sidewall bulge and not need spacers?
             
          • MoparLeo

            MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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            Also need to consider that if you are driving on the street that the tire will move side to side whenever you make a turn, so you need to make sure you have enough clearance there, not just sitting still or going straight like a drag car. Also that a tire will grow vertically on acceleration and will squat down on braking.
             
          • 72bluNblu

            72bluNblu FABO Gold Member FABO Gold Member

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            In your particular case I think the 4” backspace would fit better. But spacers aren’t a big deal at all as long as you use properly fitting spacers and long enough studs to get the proper thread engagement on the lug nuts. My cars have been lug centric for over 100k now between them. Most aftermarket wheels are, and those little hub centric rings are a joke for most applications.

            With a 4.81” backspace you’d still probably need spacers with 245’s. They might be a touch thinner, but it would one that much. With 245’s you’d also be safer with the 4” backspace though. You could run 245’s all the way around, see how they fit, and next set of tires go 255’s in the back if you have the room.

            A 1/4” is as big as I like to go for a spacer though. The spacer/adaptors that start at about 3/4 thick and have their own lug studs are fine, less than a 1/4” plain spacer is fine. Between 1/4”-3/4” is no mans land for me, I don’t like plain spacers that thick and it’s too thin for a separate set of studs.

            The only other thing is the rear brakes. If you’re considering converting to rear disks you should go with more backspace. Rear disk kits usually add about a 1/4” of width to each side. With your 4” backspace wheels you’d have no extra clearance to do that, you’d need new wheels again if you added rear disks. With the 4.81’s you’d need a spacer with your current drum brakes, but if you added disks you could toss the spacers and not need new wheels.
             
            Last edited: Jan 26, 2021
          • 33IMP

            33IMP Well-Known Member

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            I think you should make room for these.

            20200302_122341.jpg

            20200302_122304.jpg
             
          • 67notchb

            67notchb Well-Known Member

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            If Im having this many questions about .25" of backspacing, you guys dont want me to get started trying to make those fit.
            72bluNblu you bring up very good points as always I didnt consider. In the future I would like to put a larger rear end under the car and with an 8.75 or the proper 9" it would would push the wheels out a little farther than the 8.25. Spacers would get me through till I do the swap and not have to buy new wheels. As for spacers I would go with with Billet spacers. I would consider ET lug nuts although I have plenty of engagement.
             
          • Needswork

            Needswork Well-Known Member

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            Hi 72bluNblu,
            On the Vision American Muscle 141 wheel, do you happen to know if there is an issue with the spindle nose protruding when using a stock '73+ front rotor? I see their specs say it has a 3.268 center bore, which is large enough, but it's hard to determine if the stock dust cap might stick out.

            Thanks!
             
          • 72bluNblu

            72bluNblu FABO Gold Member FABO Gold Member

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            There is not. There is a little bit of taper on the center bore for the wheel cap, but it's still a good 3" in diameter. It looks like the style of the cap has changed a little from the version of the Vision wheels I have on my Challenger, but on my Challenger everything fit under the cap with the wheel bolted straight to the rotor (no spacers). And the new cap doesn't look smaller, it's just more squared off. I'm running 11.75" disks on that car, they have the same hub as the 10.95's and I had the dust caps and everything on there without any issues.

            Pictures of everything on my Challenger - the 11.75's (old picture when they were new!), the vision's with their round cap, and my Challenger with the 17x9" vision's and 275/40/17's all the way around.
            IMG_3774.jpeg

            IMG_3485.jpeg

            IMG_3017.jpeg
             
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            • Needswork

              Needswork Well-Known Member

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              That's great info. Thanks!
               
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