1. cdstl

    cdstl Well-Known Member

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    We're doing a disk brake conversion on my son's car and that means going to large bolt pattern wheels. I have a set of 4 15x6.5" steelies.

    I want to purchase a 15x8", 4.5 back space steely for the back and run 275.60 15.

    For the front I would like to use 2 of the 15x6.5" and run a 235.60 15.

    I'm wanting to know if the 235.60 15 will cause any problems with rubbing. We do have a sway bar on the car.

    Thanks
     
  2. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    It's very unlikely the 235's will fit without rubbing. The problem is that a 235/60/15 is 26.1" tall tire, which is already pushing it for clearance with the height and width. Next is the backspace on the front wheels. It's unlikely those 15x6.5" even have a 4.25" backspace on them, probably more like 4". Even with a 4.25" backspace, those 235's would stick out a full 1/4" further than the 275/35/18's I run. And I rolled my fender lips to clear the wheels and cut the lower front corner of the fender back to clear when turning, so going an extra 1/4" further out wouldn't work at all.

    I did run 225/60/15's on my Duster on 15x7" cop wheels which have a 4.25" backspace, and they were very close to rubbing. My car sat a little lower than stock at the time, and ride height is a factor. I only know of one person that runs 235/60/15's up front, and that's @AJ/FormS. But that's on a Barracuda, and the wheel openings are a different shape and the fenders may be a bit wider on a Barracuda. Ride height is a big part too, I know his car isn't lowered much.

    In the back if you have an 8 3/4 with BBP axles the 15x8's with a 4.5" backspacing and 275's should work. It's a tight fit so some cars may need some adjustments based on body tolerances, but that's the typical wheel specs folks run on 15x8's with 275's for a Duster.
     
  3. cdstl

    cdstl Well-Known Member

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    I kind of figured that the 235s would rub but I wanted to hear some first hand experience. I imagine that we will end up using 225s. I have to check the backspace on the 15x6.5s.

    I have a 275.60 15, 4.5" BS rallys on my Cuda so we will test fit them on his car first.

    Thanks
     
  4. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    Yeah a 235 definitely wouldn't have cleared on my Duster. You can see in this picture with the 225's how close they sit toward the outside of the fender, and how close they are to the corners of the wheel openings even when straight ahead.

    IMG_1550.jpeg

    Test fitting the 275's in the back is great. There are a lot of Dusters/Demons/Dart Sports running 275's on 15x8's with 4.5" of backspace, but as you know not all of these cars measure exactly the same, and a 1/4" one way or another can definitely mess things up.
     
    Last edited: Jan 16, 2020
  5. cdstl

    cdstl Well-Known Member

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    Do you have any rubbing issues with the 225s? Do they stick out past the fender at all?

    I ask because I have a set of police wheels that I can compare the backspace to my steelies.
     
  6. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    No, I didn’t have any rubbing issues with the 225’s on the police wheels. I adjusted the lower front corner of the fender as far out as it would go with the stock brace, but with that set of wheels I didn’t have to modify anything. Just made some minor fit adjustments within what the stock adjustment allows.

    The modifications came later with the 275/35/18’s up front and additional lowering.
     
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    • BLKNBLU340DSTR

      BLKNBLU340DSTR 1971 Duster 340 FABO Gold Member

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      I am running 295/50R-15 BFG radial T/A's w/ 15X8 with 4.5 back space on the back of my 71 Duster. I did have to take a small amount off the lip, 1/4", and a small amount off of the leaf spring. Hard running 340 will still roast those tires down to shreds , but looks good doing it.

      20180328_105925_resized.jpg
       
      Last edited: Jan 17, 2020
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      • 72bluNblu

        72bluNblu FABO Gold Member FABO Gold Member

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        295's take a cut down quarter lip and a 1/2" spring offset. If you ground clearance into your leaf springs, well, good luck to you. :rolleyes:

        I have 295/35/18's on my Duster. 1/2" off the quarter lip, 1/2" spring offset. 275's are the biggest that will safely fit inside the wheel wells without cutting stuff or moving the springs.
        IMG_4755.jpeg
         
      • cdstl

        cdstl Well-Known Member

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        Thanks for the input guys.
         
      • RPMagoo

        RPMagoo Just An Old Motorhead

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        -- I was thinking about 15' X 8" wheels with 295/50-15" tires, but I was concerned about the extra width of the tire beads vs, the width of the wheel. It looks like quite a bulge. Do You think that it's safe ? -- This is for My 64 Falcon Sprint with mini tubs, and the springs moved in.
         
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        • BLKNBLU340DSTR

          BLKNBLU340DSTR 1971 Duster 340 FABO Gold Member

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          An 8" wide rim is the minimum recommended width according to Summit Racing. I shaved a little off my leaf spring from occasional sidewall contact, NOT a safe thing to do, just temporary until new offset spring kit is installed.
           
        • RPMagoo

          RPMagoo Just An Old Motorhead

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          -- Yep ! -- But, does the, extra, bulge bother You, from a safety standpoint ?
           
        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          You can look up the manufacturer’s recommendations on rim sizes. BF Goodrich says a 15x8” is the minimum. If it wasn’t safe, they wouldn’t list it as the minimum. In today’s world of lawyers and lawsuits I’d say that’s a safe recommendation, they wouldn’t hang themselves out for a lawsuit.

          Tread width on those tires is listed as 10”. An 8” rim is actually 9” wide outside lip to outside lip, so you’re talking a 1/2” of tread on either side. The section width is 12.2”, but that’s measured on a 15x9.5” so they won’t be that wide on a 15x8. The tread will end up rounded across the tread profile at the normal recommended tire pressure. So you’ll have to lower the tire pressure to get a nice tread pattern.

          A 15x10 would give better performance.
           
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          • QuickDart360

            QuickDart360 Well-Known Member

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            Love that rear wing!!:thumbsup: Is that something you fabbed up? Man just thae stance wheel size awesome you nailed the perfect stance/look!!! Terrific!!:)
             
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            • QuickDart360

              QuickDart360 Well-Known Member

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              I ran bulged tires in the past on my dart sport with no ill effects whatsoever. The place that mounted the tires told me that it was risky to mount the tires with bulge. I yeah ok. Took my chances all went well!!:steering:
               
            • 72bluNblu

              72bluNblu FABO Gold Member FABO Gold Member

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              This kind of false logic is rampant. Just because you didn’t die doesn’t mean it’s a good idea. You were just lucky enough to not get into a situation where it made a difference. That’s not the same as it working well.

              Even within the manufacturers recommended width range there are differences in the tread patch that need to be tuned with tire pressure for optimal results. That’s a level of performance that doesn’t make itself obvious on the street, but if you start tuning for racing becomes apparent. Is there a factor of safety built into the manufacturer recommendations? Of course there is. But just because somebody did it doesn’t make it safe, or a good idea.

              The other thing is, you may not even realize it if does bite you. Something jumps out in front of you and you swerve and lose the back end. Are you going to know that you lost the back end because the sidewall rolled over? Probably not. Will you know that if the sidewall hadn’t rolled over that you’d have saved it? Nope. Could that have been the difference? Absolutely.
               
              Last edited: Jan 17, 2020
            • BLKNBLU340DSTR

              BLKNBLU340DSTR 1971 Duster 340 FABO Gold Member

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              Thanks. Most people don't like the rear spoiler,(guess who don't care, it's a tribute 340 Duster), but I did make 3 of them, and have 2 more in boxes. Direct Connection used to sell one very similar back in the 70's out of fiberglass. The Snake &The Mongoose Duster Funny Cars had spoilers on them at the drag-strip when I was a 'little' younger...lol...

              20180328_105905_resized.jpg
               
            • QuickDart360

              QuickDart360 Well-Known Member

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              I think that wing style is better looking than the duckbill wing mopar offered.
               
            • BLKNBLU340DSTR

              BLKNBLU340DSTR 1971 Duster 340 FABO Gold Member

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              Right on, I appreciate that.....I think a few modifications may even improve on it.....see what happens when I get some time for it.....
               
            • duster2

              duster2 Well-Known Member

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              275-60-15 on a 15 x 8 steel wheel. As far as the bigger sizes on a 15 x 8 steel type wheel. Just because you can , don't make it right ( or smart ). It's a waste of rubber that will not be made use of , on the street.

              Frank
               
            • BLKNBLU340DSTR

              BLKNBLU340DSTR 1971 Duster 340 FABO Gold Member

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              I only wind up the Duster really hard on desolate country roads , by myself. Not really bothered by the 'bulge'. I get bothered when I run out of road, or horsepower.
               
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