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  • smaller tires, Ota legal?

    Ok, I think no matter how I put this i am going to sound stupid. Is it legal to use smaller diameter, as well as width tires? Two of the toyos I was using are worn out. I have a set of RS3s ready to go other then the wheels I ordered, that I was told would be in last Wednesday, now may arrive on the Monday after grandbend. My only option seems to be to use my Dunlop z2s from last year with the prelude but they are 205/50r16 and stock on the s2000 is 205/55r16 with a 225/50r16 on the rear. I didn't see anything in the rule book against it but don't want to show up and be told no. So is there anything against it other than it is probably going to give me some oversteer?
    Jeremy Brutzki
    177 gt3 honda s2000

  • #2
    Re: smaller tires, Ota legal?

    Go for it Jeremy. Wheels are free as long as they don't stick out past fenders (Rule 5.1.A3.7), then 2 sPIPs.

    JohnP

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    • #3
      Re: smaller tires, Ota legal?

      Thanks, John
      Jeremy Brutzki
      177 gt3 honda s2000

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      • #4
        Re: smaller tires, Ota legal?

        Jeremy, I would try and install the RS3's on your stock rims if you can because if your rims come in before the shootout you will be able to use them with the RS3's. If not you will have to use the Star Specs or Toyo's because you wouldn't have recorded a timed run with the RS3's during the season.

        Don't quote me on this, but I believe for the shootout you have to run one of the setups in your car that you used for at least one event during the year. Better to ask Chuck as I am not a hundred percet sure though.

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        • #5
          Re: smaller tires, Ota legal?

          Originally posted by iamthewheelman View Post

          Don't quote me on this, but I believe for the shootout you have to run one of the setups in your car that you used for at least one event during the year. Better to ask Chuck as I am not a hundred percet sure though.
          I actually asked Chuck about this at MIR, as I'm thinking of making some changes. He said you have to run the same class at the shootout, but can make changes provided you remain within that class.

          Jeremy, how worn out are your Toyos? I remember looking at them at Shannonville and they didn't look too bad...
          Barry

          Citizen Cone Dodger

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          • #6
            Re: smaller tires, Ota legal?

            Not saying this is the case here since the difference is minimal, but if swapping a final drive costs pips then running significantly smaller diameter tires should also cost similar pips since you can effectively shorten the final drive the same amount with short enough tires.

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            • #7
              Re: smaller tires, Ota legal?

              Yeah, but that also comes with compromises to contact patch and traction.

              If I altered my gearing, I could cram MORE rubber on and offset the drawbacks that would have had to my gearing, netting benefits on both traction and shorter gearing.

              I'd argue the benefits are dissimilar.
              Barry

              Citizen Cone Dodger

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              • #8
                Re: smaller tires, Ota legal?

                I fliped the toyos on the rims and ran a lapping day on them after shannonville, theirs not much left. The RS3s are 17".

                Does anyone know if we need to the same tires at the shootout, I would be running 225/45r17 and 255/40r17 hankook RS3 if it's allowed they do not come past the oe wheel openings so it would not require any extra pips.

                Yes I did change my mind and want to run 255 all around, but I couldn't change my order on the wheels so just run 225 on the front till I decided I need to go faster :P
                Jeremy Brutzki
                177 gt3 honda s2000

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                • #9
                  Re: smaller tires, Ota legal?

                  Originally posted by Saj5DJ View Post
                  Yeah, but that also comes with compromises to contact patch and traction.

                  If I altered my gearing, I could cram MORE rubber on and offset the drawbacks that would have had to my gearing, netting benefits on both traction and shorter gearing.

                  I'd argue the benefits are dissimilar.
                  Trying to wrap my brain around this, how does a diameter difference alter contact patch (if width remains the same), also the only changes to traction would be in the fact that the wheel accelerates faster, thus requiring either less power input at lower speeds, or a grippier tire?

                  Interesting conversation, I'm actually running a slightly smaller diameter tire simply because I found them used for a decent price, I never really put much thought into whether it changed PIP's.
                  Infiniti G35 Sedan ~ OTA #87
                  AutoSlalom #87

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                  • #10
                    Re: smaller tires, Ota legal?

                    Originally posted by Tunermax View Post
                    Trying to wrap my brain around this, how does a diameter difference alter contact patch (if width remains the same), also the only changes to traction would be in the fact that the wheel accelerates faster, thus requiring either less power input at lower speeds, or a grippier tire?

                    Interesting conversation, I'm actually running a slightly smaller diameter tire simply because I found them used for a decent price, I never really put much thought into whether it changed PIP's.

                    Agreed. Running a 225/45/15 instead of a 225/45/17 is an 8% reduction in final drive and no difference in contact patch, a big upgrade on my car is a 4.55 FD instead of the stock 4.10, which is a 10% difference.

                    Just for clarity, at the sizes the OP mentioned I don't think it matters at all, but it *could* be used to a decent advantage if someone wanted.

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