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Last Post 15 Apr 2013 06:17 PM by  Z1NONLY
Street Tires to Slicks how much time gained?
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Canyonfive
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18 Mar 2013 03:49 PM
    How much time gained from 225 RS's to 275 A6's?
    1 second, (2)
     14%
    2 seconds, (6)
     43%
    3 seconds, (5)
     36%
    4 seconds, (1)
     7%
    5 seconds, (0)
     0%
    6+ (0)
     0%

    Im currently in BSP and have prepped the car to mostly an STR Level. Im curious to hear from other guys who have moved from 225 rs3's which are the widest street tire for an nb on 15's to the 275 A6's? The usual guess is 2 seconds for moving to a tire of the size size. So whats your guess for this move?

    SMSupercoupe
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    18 Mar 2013 04:30 PM
    Sort of depends on how long the course is.
    Canyonfive
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    18 Mar 2013 04:40 PM

    Im just ball parking. Figure 60 seconds. 

    wrandleman
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    18 Mar 2013 05:13 PM
    2013 PAX difference between CSP and STR is 1.533 seconds on 60 seconds. R comps wider tire and unlimited rim width are probably the majority of that. Clutch/Flywheel and aero ...
    Canyonfive
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    18 Mar 2013 05:43 PM
    I would imagine thats 255 in 17's vs 275's hooiser. so 2 seconds is minimum but another 35mm in hooiser?

     

    and in my size change I would actually drop 1.28" in overall height. So 6% "shorter gearing" too.

    ratt_finkel
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    18 Mar 2013 06:01 PM
    I would guess more like 3 seconds. How much faster are the 275's vs the old 13x9" combo everyone used to run?
    85rx-7gsl-se
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    18 Mar 2013 06:11 PM
    Are Mazdaspeed Miatas allowed in STR?
    Canyonfive
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    18 Mar 2013 08:14 PM
    Posted By 85rx-7gsl-se on 18 Mar 2013 06:11 PM
    Are Mazdaspeed Miatas allowed in STR?
    no; it would be nice though, sent an seb letter. Still headed for BSP.


    wrandleman
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    19 Mar 2013 10:32 AM

    As the season progresses I can let you know how a BSP Mazdaspeed compares with an STR MX-5. I compete locally with one. Both cars should be pretty well sorted by mid season. STR 1.3 seconds slower on 43 seconds.  My 1st outing with STR suspension.  Exhaust and tune for next time.

    85rx-7gsl-se
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    19 Mar 2013 10:32 AM
    Oh ok. I agree that str would be a nice spot. Still doubt it will be the top performer due to the gearing issues.
    cbramey
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    19 Mar 2013 11:33 AM
    just ran my first practice on old bridgestone true street tires (not the new 'race' 'street' tires, then went to old kumho 710's. 2.1 seconds on a 27 second course. The hoosiers were noticeably better than the kumhos, the next day, but I have no data on it.
    wrandleman
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    19 Mar 2013 03:37 PM
    I compared a still fast set of A6 to RS3 on my stock class '06 MX-5 last year. Same course, same temps. The A6 were only 0.7 sec faster on 50 seconds.

    The MX-5 is camber challenged at stock ride height. I suspect the current setup (2" lower giving a degree more neg camber) would have a bigger split between street and R comps.

    sirele
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    19 Mar 2013 06:53 PM

    Posted By Bill Randleman on 19 Mar 2013 03:37 PM


    <p> The MX-5 is camber challenged at stock ride height.</p>


    No it isn't! It has double A arms in the front and a multilink suspension in the rear. The non MSR is just a little too soft sprung for the grip of r comps.
    Canyonfive
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    19 Mar 2013 06:54 PM
    Talked to another MSM guy. He switched from 225 a6's to 275 a6's ad gained 1 second on a 40 second course. Leaving me with a rough very rough 3.5 ish second gain. based on his experience.
    wrandleman
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    20 Mar 2013 12:45 AM

    I would call -1.2 maximum negative camber with <5 degrees caster camber challenged. The camber curve is good but new unflipped A6 are corded on the outer 2" in 30 runs on asphalt despite proper pressure determined with a pyrometer. The MSR which is over an inch lower gets an extra 0.5 degrees neg camber.

    The stock prepped car hasn't enough camber to keep the RS3 happy either requiring 37psi (5psi overinflation based on temps) to keep the tire off the sidewall.  However, I was still able to trophy in RTR at Packwood on the RS3s.

    sirele
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    20 Mar 2013 08:22 AM
    Calling a Miata camber challenged is a slap in the face of everybody that has to make a strut supension work. If you have a great camber curve, you don't need a lot of static camber. In stock class autocross it is normal that a tire will wear more on the outside, but the only Miata's I have seen to eat tires anywhere near as bad as a strut equipped car, had an issue with the loose nut beehind the wheel.
    wrandleman
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    20 Mar 2013 10:51 AM
    Sirele,

    Just relaying the facts.  Front tire temps always less than 8 degrees hotter than rears. 

    Do what you want with your opinion.

    sirele
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    20 Mar 2013 11:22 AM

    Posted By Bill Randleman on 20 Mar 2013 10:51 AM
    Sirele,

    <p> Just relaying my perception.  Front tire temps always less than 8 degrees hotter than rears. </p>
    <p>Do what you want with your opinion.</p>


    Ftfy
    wrandleman
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    20 Mar 2013 12:44 PM

    Trying to give some feedback on the OP's question.  What's your intent?

    Canyonfive
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    20 Mar 2013 03:23 PM
    Talked to another MSM guy. He switched from 225 a6's to 275 a6's ad gained 1 second on a 40 second course. Leaving me with a rough very rough 3.5 ish second gain. based on his experience.
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