Michelin tire pressures

Discussion in 'Brakes, Wheels and Tires' started by 2012Boss302, Sep 9, 2018.

  1. 2012Boss302

    2012Boss302 TMO Addict

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    First, I'm not looking for a tire pressure recommendation.

    I just did a track day here in Houston. I think I may have lowered my tire pressures too much.

    Somewhere I read that Michelins like a little higher pressure. Is this correct ????
     
  2. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    Not sure if it's 'correct', but I share that opinion!
     
  3. 2012Boss302

    2012Boss302 TMO Addict

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    I was running 35 psi hot. Checked straight off the track. I think it should have been around 38 ish
     
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  4. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    I'd have to double check my log book, but that's very similar to my view when I first ran the PSS and adjusted pressures into the upper 30s hot front and mid high 30s rear with a staggered setup.
     
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  5. Bill Pemberton

    Bill Pemberton TMO Addict

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    Assume you are talking about PSCup 2s?
     
  6. VoodooBoss

    VoodooBoss Rick Moderator

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    He is not.

    I also ran the PSS in mid to high 3o’s. Check the rollover marks too.
     
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  7. Bill Pemberton

    Bill Pemberton TMO Addict

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    Customers, in a different car (years past) ,often started at 30 rear , 32-33 front, cold.
     
    Last edited: Sep 10, 2018
  8. 2012Boss302

    2012Boss302 TMO Addict

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    Pilot Super Sport
     
  9. eng90

    eng90 TMO Race

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    insteresting info,

    shall i stick to 32-33 fronts and 30 back ?

    or would it better if i stick to 35 all around? (255/40r19 fronts & 285/35r19 rear)
     
  10. Bill Pemberton

    Bill Pemberton TMO Addict

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    I would stick with the 32-33 front and 30 back ( cold ), as the other issue is the smaller size tires up front, imho.

    Funny , but years ago we found the same thing on other cars , and it definitely seems they work better with a higher inflation starting point.
     
  11. fpGT350

    fpGT350 TMO Intermediate

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    Bill, in the old days we simply trusted the pyrometer.
     
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  12. Bill Pemberton

    Bill Pemberton TMO Addict

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    Ha, ha, but Frank you were always out there racing and I was just a Time Trialer. You had them fancy pyrometers, and the rest of us were still using the tire gauge we got free from our local gas station, ha. Thanks for jumping in here, we need you to post more often! Get that GT 350 broken in , you need to wander to Nebraska in September for the Mustang Roundup!!!!
     
  13. fpGT350

    fpGT350 TMO Intermediate

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    Thanks for your kind words Bill. I am loving the GT350 but for me it is simply a boulevard cruiser. Tire pressures are such an interesting topic because there are so many variables that are constantly changing such as track surface conditions, ambient temperature, tire brand and condition, alignment and suspension settings on the car, driving style, track configuration, on and on and on. Whenever I sought advice from either Michelin, Hoosier, or Goodyear tire specialists, they always asked what my temperature readings were across the treads on all four corners in the hot pit lane immediately after leaving the track. The rubber compounds on each series/brand of tires are engineered so that maximum traction is achieved at a designated tire temperature. It pretty much takes all of the other variables out of play if you follow your hot temperatures and know what the optimum temperature is for that particular tire. You adjust your tire pressures until you are achieving optimum temperature when hot. The first thing I would recommend is to talk to the tire engineers specific to the brand and model tire you are running, and find out where the optimum hot temperature is. You will need a pyrometer to take the temperatures and you will need to learn how to take them properly. Have your crew or a friend right there in hot pit lane to take them immediately after exiting the track because the temperatures will cool quickly and give you false readings if you lolligag around:) I highly recommend the probe type pyrometer that actually sticks deep into the tread; not the infrared type. Hope this helps!
     
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  14. Bill Pemberton

    Bill Pemberton TMO Addict

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    I sure your comprehensive analysis will be quite helpful to alot of folks. You are a solid track pilot and you may need to get that Boulevard Cruiser out so you can shock all the Corvette and Porsches drivers on track? Keeping that sweet sound at 8250 rpms ends up surprising alot of folks, including new owners!
     
  15. Coz

    Coz TMO Race

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    Is it actually a specific temperature or is it more important that the temps in the three zones across the face of the tire be about even?
     
  16. fpGT350

    fpGT350 TMO Intermediate

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    Great question Coz. The answer is both, my friend. Not trying to get cute here, when I have a little more time I will retrieve one of my old tire data sheets from a race weekend, attempt to post it here, and then we can commence a most interesting discussion!
     
  17. fpGT350

    fpGT350 TMO Intermediate

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    TIRE DATA SHEET.jpg
    Here are three track sessions at the main track at Firebird International Raceway in Phoenix. Session one was practice, session two was qualifying, session three was the actual race. Notice the ambient air temperature and time of day for each session. This particular Hoosier tire behaves best at 180-200 F. degrees. This track runs counter clockwise, so every lap there is 360 degrees more left hand turns than right hand turns. Therefore you should expect hotter tire temps on the right-side tires, correct? Hoosier advises optimal tire temps will be experienced at hot air pressures anywhere between 43 and 48 PSI. If you look at my remarks for each session you will see that in session one the car felt totally unstuck to the track, I suspect largely because we never got the tires up to optimal temperature. We did not adjust air pressures at all after session one was over because we were close to the PSI sweet spot already and the ambient temperature was 5 degrees warmer. We adjusted shock settings and achieved much better tire temps, the car felt much improved. Session three was the race and the tires got much hotter even though the air pressures remained very close to session two. The temperature variations across the treads are not bad at all but I do see a little too much negative camber and also too much rear wing downforce causing the rear temps to be higher than the fronts. When you are trying to win races you need to pay attention to the details or at least have someone else do it for you. I am analytical in nature so I enjoy the details but not nearly as much as piloting the car. BTW, for all of you that care about this stuff, TIRE PRESSURE GAUGES DO NOT ALL READ THE SAME PRESSURES. Once when participating at a World Challenge race, I became extremely frustrated because my lap times were pathetic compared to my competitors in similar cars. We compared data sheets and I found similar car set ups and PSI. We happened to be on Toyo tires which were the spec for the race series. My first time on these tires and I hated them. I could not get them up to temp. Come to find out, my tire pressure gauge was reading 6 PSI different than another one of my competitors. I threw my old gauge out and spent $300 on a new digital gauge that reads to the tenth of a PSI. 16 years later and I am still using that same gauge. Hope this helps anyone that is interested.
     
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  18. Coz

    Coz TMO Race

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    Wow. Lots of detail. Thank you. Are optimal tire temps only published for slicks or are they available for 200tw tires too?
     
  19. domesticpower

    domesticpower Track Addict

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    The reason people say Michelin's like a little more pressure is because they have soft sidewalls and roll over too much. In my experience, they don't like high pressure (i.e. high temp) any more than other street tires in their class, some people just try to pump them up to make the tire stiffer.

    fpGT350 is absolutely right! If you have a pyrometer, that's your best bet of making sure the tire isn't too hot (or too cold) and your camber and alignment are proper (even temps across the tread).
     
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  20. Norm Peterson

    Norm Peterson Corner Barstool Sitter

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    Even stretched out a bit, MPSS tires seem to be better at 37 or 38 (front) than at 35. I run the rears about 3 psi lower than the fronts (whether on the track at track hot pressures or on the street setting them cold).

    285/35-18's on 18x11's


    Norm
     

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