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Thread: New ai/cmc tire thread

  1. #11
    Senior Member Grass-Passer MikeP99Z's Avatar
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    I burn a new set of RRs in a weekend. 5 or 6 heat cycles max, after that, they aren't competitive. Usable for practice for heat cycles 7-10.

  2. #12
    There's an R888R out now. 100 treadwear at ~6/32" tread depth (RR is 4/32" RA is 8/32"). I wonder if a higher treadwear tire will be more consistent across heat cycles?

    Toyo/Nitto have a bunch of tires with varying tread depths in the 100 treadwear range, R888R, R888, RA1, and NT01. There's also an RS1 full slick, however it's non-DOT.

    https://www.toyotires.com/tires/competition-tires

    - Josh
    CMC #50

  3. #13
    Senior Member Carroll Shelby ShadowBolt's Avatar
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    Quote Originally Posted by MikeP99Z View Post
    I burn a new set of RRs in a weekend. 5 or 6 heat cycles max, after that, they aren't competitive. Usable for practice for heat cycles 7-10.
    So what is the real deal? Gone after 5 or 6 heat cycles or still competitive at 20 heat cycles? It can't be both.


    JJ

  4. #14
    Quote Originally Posted by ShadowBolt View Post
    So what is the real deal? Gone after 5 or 6 heat cycles or still competitive at 20 heat cycles? It can't be both.


    JJ
    It probably depends on the load the tire sees. Mike's car with full aero likely puts significantly more load on the tires than a CMC car. A few degree temperature increase due to higher load per heat cycle might make them drop off much more dramatically, just a hypothesis. So when comparing across platforms it could be both. Tyler is seeing potential better life on the Miata.

    I'm assuming the tires are 'curing' with heat cycles, (i.e. getting harder, would last longer rubberwise but have less grip). Does the length of the heat cycle matter? If you over cook a set by trying to pass Jerry for 10 laps can you use them up in one race by getting the tire temp to 250*F? If you don't get them up to 220* (max recommended temp) is it a partial cycle? Clearly, I don't understand tire design.

    - Josh
    CMC #50

  5. #15
    Senior Member Carroll Shelby ShadowBolt's Avatar
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    Quote Originally Posted by Sook View Post
    It probably depends on the load the tire sees. Mike's car with full aero likely puts significantly more load on the tires than a CMC car. A few degree temperature increase due to higher load per heat cycle might make them drop off much more dramatically, just a hypothesis. So when comparing across platforms it could be both. Tyler is seeing potential better life on the Miata.

    I'm assuming the tires are 'curing' with heat cycles, (i.e. getting harder, would last longer rubberwise but have less grip). Does the length of the heat cycle matter? If you over cook a set by trying to pass Jerry for 10 laps can you use them up in one race by getting the tire temp to 250*F? If you don't get them up to 220* (max recommended temp) is it a partial cycle? Clearly, I don't understand tire design.

    - Josh
    I certainly don't understand either Josh.

    JJ

  6. #16
    It was the fast miata guys that introduced me to the phrase "no more than five to be in the top five", so my guess is once Tyler is at full song in a Miata he'll have the same experience.

    I am getting comfortable with the notion that the thin to win RA1s weren't actually thin to win, rather that we were just slow.
    Al Fernandez

  7. #17
    Senior Member Carroll Shelby Supercharged111's Avatar
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    Quote Originally Posted by Sook View Post
    It probably depends on the load the tire sees. Mike's car with full aero likely puts significantly more load on the tires than a CMC car. A few degree temperature increase due to higher load per heat cycle might make them drop off much more dramatically, just a hypothesis. So when comparing across platforms it could be both. Tyler is seeing potential better life on the Miata.

    I'm assuming the tires are 'curing' with heat cycles, (i.e. getting harder, would last longer rubberwise but have less grip). Does the length of the heat cycle matter? If you over cook a set by trying to pass Jerry for 10 laps can you use them up in one race by getting the tire temp to 250*F? If you don't get them up to 220* (max recommended temp) is it a partial cycle? Clearly, I don't understand tire design.

    - Josh
    Every time I've probed my RRs they're in the 140s, even post Hallett final. Granted I probe them back in the pits when I get out of the car and not trackside, but still I never get them as hot as Toyo recommends unless my probe sucks?
    RM CMC Director

  8. #18
    Quote Originally Posted by Supercharged111 View Post
    Every time I've probed my RRs they're in the 140s, even post Hallett final. Granted I probe them back in the pits when I get out of the car and not trackside, but still I never get them as hot as Toyo recommends unless my probe sucks?
    Tire temps drop fast, even one turn to a next they can change pretty dramatically. We had live IR temp probes looking at wheels on our FSAE car for test and tune. Not our car, but same idea: http://sine.ni.com/cs/app/doc/p/id/cs-722#
    CMC #50

  9. #19
    Quote Originally Posted by 39PitCrew View Post
    So, if say one of the the Texas region guys were to move to Ohio in the next
    couple months, where might he connect with some of the Great Lakes CMC guys?
    One way is for him to come out to Mid-Ohio for one of the three races (April, May and August) there this year and hang with the group. He could also contact the regional director Bob Denton. His contact info is in the back of the CMC rule book.

    Where in Ohio would this guy be moving to? We have a couple of racers in the north east ohio area.

  10. #20
    Senior Member Carroll Shelby
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    Spec Corvette is running a Falken street tire with a 200 treadwear rating. Those cars have to weigh 3,200 post race with driver at have around 320 rwhp.

    http://www.falkentire.com/tires/pass...is-rt615k-tire
    Bryan Leinart
    CMC #24

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