Is bigger tyres worth it?

Tires and Wheels (Mopar Hubcaps Too)

  1. Hansen

    Hansen Well-Known Member

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    Was testing my 69 dart this today and have no traction. I have about 350-400 hp 360 with 727 and 8-3/4 rear end with 3:23 diff. I have 15x7 steelies rear and 235/55 street tyres.. these are old so anyway I need some slicks or MT drag radials. But my question is how big of a tyre do i need to get good traction? Do i need to put out and upgrade my whole rear suspension from stock to fit 275s or do i get away with 235s wich is the most i will fit without rubbing. Sorry for bad inglesh i am from norway.. lol
     
  2. j par

    j par Well-hung Member

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    Just changing to a drag compound would help a lot....
     
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    • Fisher

      Fisher Old Guy with a Cool car.

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      I have always wanted to try a skinny soft compound winter tire set to about 18 psi? Blizzak winter tires or something along that lines. Can air them back up to 32 psi they are DOT legal and are a radial tire. Last about 5000 miles. You have the right amount of HP and not a lot of rear gear, so something like this may work for you. You dont have a lot of room in the Dart rear wheel well, so you are going to be limited to what the racing tires size has to offer. There is a drag race class running a 26" tire class, not sure if that is something else you may want to look, see what tire they are running.
       
    • rumblefish360

      rumblefish360 So close, yet so far away FABO Gold Member

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      Tires are the first thing everyone goes with for traction.
      The suspension is the other half.
      Sticking with the tire question, there is a sticky on wheels and tires in that section with (what should be) the wheel size and off sets as well as any spring relocation work done to the car in order to make the tires fit.

      On the tire itself, pay attention to the compound of the rubber used on the tire. Also what is legal for you and what is acceptable for use for you personally. Be this for the track and/or the street.

      Wider is almost always certainly better.

      A 235/60/15 is about a 26” by 8” wide tire.
      Even in a drag compound, A sudden mashing or the gas pedal can have this spinning even on a prepped surface.
      It’s a balance game between the right foot application on the gas pedal and what the road surface will handle.

      It is even more difficult for manual trans guys.
       
    • mderoy340

      mderoy340 Well-Known Member

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      235/60/15 MT ET Street S/S on 15x8 rim works great at 20psi cold street/strip for me. The only negative is cost and quick wear on the street. I quit swapping tires to run at the track and drive like Grandma on the street going to the track. They work fine in the rain as long as the grooves are still there. Want to play you got to pay.
       
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      • Fisher

        Fisher Old Guy with a Cool car.

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        In my Duster, I have Afco leafs with Rancho RS9000 10 position adjustable shocks. Up front stock torsion bars with Strange 9 position shocks. car works good with a 275/6-/15 drag radial.
         
      • Syleng1

        Syleng1 Karma is real and Life is short... FABO Gold Member

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        Part of traction is driver related.
        I personally (when itchy) have spun the tires at the track all the way down. Less coffee and more suspension adjustments have gotten 225/60-15 coopers (old Cooper street tires) to grab better than cheap slicks. But nothing grabs better than hot and sweaty fresh slicks. lol! Basically a lot has to do with driver. Get confident with a bunch of runs and dial the whole car in. JMHO.
         
      • stroked340

        stroked340 FABO Gold Member FABO Gold Member

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        My friend runs 235 60/15 drag radials on his '70 dart hooks good,now he needs more power!!
         
      • AJ/FormS

        AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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        My answer, if you can call it that, is for a streeter on street tires, with street suspension..
        I was in the same 350/400hp pickle.

        What are you using the car for?

        In a straight-line;
        I went from 245s to 255s to 275s to 295s, and finally to 325s..... and , the tires never stopped spinning; to 80mph and beyond.

        In the turns;
        with 275s or less, the back-end would step out and spin me around at the slightest provocation.

        In first gear;
        With a stout-360, there is not much you can do, short of detuning the engine to soften the hit to the tires, or
        Up-tuning so you can control it better. A stout 360 will make about 430 to 450 ftlbs, which is like a 440Magnum of the 60s; that's a lotta torque, and it comes in fairly early.

        So for me, First gear at WOT, is just a way to get into second.

        Your tuning tools, with an existing combo,are; TC (Torque Convertor)Stall, carb type and size, and ignition timing. You just have to either; A) learn to feather the throttle, or B) make the engine lazy, or C) some combination of A and B.
        In first gear, traction with a 360 is a joke.
        But first gear will never be good for anything else.
        So I geared my car to put second where I needed it to be.

        But if I had money, I would have put it into two things; A) a traction-aid, and B) suspension
        Unfortunately, the suspension changes required for weight transfer, to better your traction, very quickly take the car out of the realm of streeter.
        That just leaves a traction aid.

        But here's the thing; your 60ft is likely gonna change only a lil,say about .4 second at the best; and up here I would have to spend in the neighborhood of $3000 smackers, including the biggest tires you can fit in your stock tubs, on custom wheels. Your zero to 60mph might improve .5 or .6 second.

        To me, it wasn't worth the coin.
        Instead, I fabricated a throttle stager with a coathanger and a couple of springs, for my 750DP carb. It has a soft spring on the first part, and a stiffer one on the second part. I made it adjustable, so that the first step just gets me 65/68mph. So when I nail it in first gear, I can always feel when I hit the end of the first stage. If I stop there, this prevents tirespin. But I can ignore the signal, and go straight to mega tirespin.
        The bonus is this makes a great cruise control.
        Then I just learned to drive the beotch.
         
        Last edited: Jul 13, 2020
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        • Hansen

          Hansen Well-Known Member

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          great answer, thank u so much. Ill just do the cheapest mods i think to have it still be a streeter, but right now its a little too much street than strip.
           
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          To get 350/400hp with iron heads means you probably have a 240@.050 or bigger cam.
          To have a stout bottom end and be able to complain about traction, means your engine must have a healthy compression ratio, OR your TC is a fairly aggressive hi-stall.
          This guy said;
          With your above combo this is sooooo true.
          And the 3.23s ain't helping cuz once you break traction, they just go and go and go. With a 240 cam, and decent valve springs, your shift rpm in first gear can be well into the 6000s......... which 6000 will get you 55mph; 6500 will get you 60. So pretty much, you have a one-gear requirement for the 0-60 speed-contest. The thing is; at the bottom you will be out of the powerband until about 3500 rpm, and at the top, you will be on the downside of the power curve by say 5500. Converting that to mph means you will be in the powerband from about 25 to 47mph. Of course this assumes yur hooked.
          My math says you could run way less cam, and way more gear, and a matching stall,
          and be just as quick in the 0-60 contest.
          ___________________
          I swapped from the Mopar 292/108 cam and 3.55s, to a 270/110 cam and 4.30s (with an overdrive), and my car was waaaaaaaaaay more fun;and the bonus was that my hiway fuel economy sky-rocketed.
          But; getting off the line without tiresmoke became a bigger challenge. That's when I fit the 325s. In order to relax the bottom end; I tried a Holley 600VS for a short time, but I couldn't stand it for long.It mightabin quicker out of the gate, but the car lost it's personality. So then I tried a Holley750VS with still no personality. In the end I re-installed the 750DP and there it was; personality supreme. So then;
           
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