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Help with Tire pyrometer readings

Last post 07-13-2008, 11:11 PM by Rivers. 3 replies.
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  •  07-11-2008, 12:53 AM 309643

    Help with Tire pyrometer readings

    Not too sure if this is the right forum to post, but can someone tell me how I should be interpreting my probe pyrometer readings?

    This is on a Acura RSX-S with Hankook Z214 tires (225/45/17) at a road race course. I started off with 40psi hot at both ends, and finally ended up at 37psi in front and 34 psi at the rear. Optimum grip for for tires from specs seem to be 180-200F, with recommended starting pressure at 40psi hot.

    1st Reading:

    194 187 199    202 176 166
    ===========    ===========
    FL (41psi)    FR (40 psi)

    RL (38psi)    RR (38psi)
    ===========    ===========
    154 160 160    147 138 132


    2nd Reading:
    190 193 197    202 183 174
    ===========    ===========
    FL (40psi)    FR (40 psi)

    RL (37psi)    RR (37psi)
    ===========    ===========
    154 161 160    143 146 156


    3rd Reading:
    205 207 208     212 200 187
    ===========    ===========
    FL (38psi)    FR (38psi)

    RL (38psi)    RR (38psi)
    ===========    ===========
    169 174 168    165 157 153


    4th Reading (Tire temps dropped as I drove into the pits to take my readings)
    178 182 184    192 186 176
    ===========    ===========
    FL (37psi)    FR (37psi)

    RL (34psi)    RR (34psi)
    ===========    ===========
    146 151 150    152 144 148


    1. Should I be adding negative camber in the front?

    2. The front tires are eating quite abit into the sidewalls; would a wider tire in front help?

    3. Does 37/34psi look ok to you guys from these readings?

    4. Any other opinions would be greatly appreciated.
     

    The car handles fine, just trying to go abit faster ;) Thanks Guys!

  •  07-11-2008, 8:58 PM 309810 in reply to 309643

    Re: Help with Tire pyrometer readings

    I dont have tire data to know for sure what pressure is maximum grip for your application.

    But if I am reading the numbers right, you have good or too much negative camber. the temp numbers are outer, mid, inner?

    If you are eating into outer wall, then you should raise the pressure a bit.
     

    Raise the pressure till there be no eating into outer side wall.  Then keep track of your temps, if outer and inner temperatures will have large difference, then reduce the negative camber.  Till outer temp would be no more that 10F lower that inner. The mid temperature should be the avg of outer and inner.

    This is a guess, am I right? 

  •  07-11-2008, 10:06 PM 309817 in reply to 309810

    Re: Help with Tire pyrometer readings

    Hmmm, what can be deduced from your readings?  Several possibilities, I think.

    1) Your first readings, assuming that you are on a clockwise track, are not too bad at all.  The Left Front tire should show the most overall temp rise and is not far from balanced--It could use perhaps 1-2 psi more to cut down on edge wear and bring the center temp up to the edges, but slightly higher edge temps and wear are not uncommon for the car. 

    2) The Right Front shows that the car leans plenty in hard corners and loads the inside of the tire--It could use less negative on that side to level out the tread under load a bit (NASCAR style). That would also make turn in for right handers a bit quicker, but degrade left turns very slightly (How dominant and how important are the right hand turns on this track?).

    3) The rear tires are typical of a front wheel drive car--along for the ride for the most part and aren't going to get much temperature for you.  A slightly overinflated rear tire would help your turn in by reducing rear bite slightly--you can raise the rear psi if the car is plowing too much.  The temps aren't telling you much and aren't so far apart to cause a bunch of concern. Slight psi changes only to fiddle with aiding turn in, I think.

    It would be useful to know what rim widths you are running on.  That effects the edge wear and temperature spread a fair amount (is the tire flat on the track or center bowed out, bowed in?).  It's been a few years since I raced a front wheel driver, but the basics haven't changed much.  The "Kooks" shouldn't be performing much differently from most other brands in that size, so I think you aren't far off in you parameters.  Ask yourself about the turn-in speed and how well the rear seems to be behaving.  You might have a tiny bit too much left front negative camber, but that would be a pretty rare thing, unless you have a very special set-up that allows a ton of negative camber.  Your third set of readings seems to be very close to just about what you should expect--nearly ideal temps and spread across the front (remember that you probably can't get the right front outside to even out perfectly anyway with that car).

    Lee Niff should be the one to advise you on the setup you have, even though he's in a Civic Si, he knows the tire brand well and sure boogies. 

    Hope that helps. 

     


    Jack SSB Z4 #09

  •  07-13-2008, 11:11 PM 309984 in reply to 309817

    Re: Help with Tire pyrometer readings

    Thanks guys. I am actually on a undersized rim for a 225, a 7JJ; not sure how that would affect tire temps across the range. I am thinking of going 1 size up in front and 1 size down at the back (235 and 215), not too sure if this would be recommended based on the tire readings?
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