Tire pressure vs temperature. My chart

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  • LCHIEN
    Internet Fact Checker
    • Dec 2002
    • 21082
    • Katy, TX, USA.
    • BT3000 vintage 1999

    Tire pressure vs temperature. My chart

    With all this cold weather and global warming, how do we interpret cold tire pressure vs whatever temperture the car tires are really at?

    I used the ideal gas laws to compute this chart of how pressures behave at different temperatures.

    Click image for larger version

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    Using this chart you can find what the pressure change will be between two temperatures.
    If you know the pressure at a starting temperature (i.e. the "cold pressure" at say 70 degrees) find that temperature on the horizontal axis. Travel vertically from there to find the pressure on the vertical axis. Find the colored line that crosses that point.
    Follow that line... you can see what the pressure will be at any given temperature on the horiz axis, or knowing the temperature, you can see what the pressure will be at that temperature.

    For example, My cold inflation temperature is 35 psi at 70 F, so when I got in the car at 25F yesterday I noticed it was 32 PSI on the tires. THe chart conforms this is correct.
    Click image for larger version

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    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions
  • leehljp
    Just me
    • Dec 2002
    • 8469
    • Tunica, MS
    • BT3000/3100

    #2
    I am so glad you posted this. I almost posted a new thread a couple of months ago asking you to do this. You had discussed this some time ago. Thank you for posting this!
    Hank Lee

    Experience is what you get when you don't get what you wanted!

    Comment

    • LCHIEN
      Internet Fact Checker
      • Dec 2002
      • 21082
      • Katy, TX, USA.
      • BT3000 vintage 1999

      #3
      A good approximation is 1 PSI change for every 12F change

      This is for 32 PSI 70F cold pressure but the others will be close. A little less for lower pressure and a little more for higher pressure.
      Last edited by LCHIEN; 01-18-2024, 09:59 PM.
      Loring in Katy, TX USA
      If your only tool is a hammer, you tend to treat all problems as if they were nails.
      BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

      Comment

      • Jim Frye
        Veteran Member
        • Dec 2002
        • 1051
        • Maumee, OH, USA.
        • Ryobi BT3000 & BT3100

        #4
        I normally run 32 psi in our car tires. The Hondas nag you at 27 psi. I still do my first of the month systems check (tire pressure, washer fluid, oil level, brake fluid level, and coolant level). After all these years the only thing I ever have to do pump up a couple of tires and fill the washer reservoirs.
        Jim Frye
        The Nut in the Cellar.
        ”Sawdust Is Man Glitter”

        Comment

        • Dedpedal
          Established Member
          • Feb 2020
          • 255
          • Palm Coast Florida
          • One BT3000 in use and one for parts. Plus a BT3100

          #5
          If it’s below 70f I consider my tires frozen to the ground and can’t go anywhere. Good reference chart for people in the northern climes.

          Comment

          • Apither
            Handtools only
            • Jan 2024
            • 1

            #6
            I quite like your example of using the chart to verify that your tires are properly inflated at 25 degrees F.

            Comment

            • LCHIEN
              Internet Fact Checker
              • Dec 2002
              • 21082
              • Katy, TX, USA.
              • BT3000 vintage 1999

              #7
              Originally posted by Apither
              I quite like your example of using the chart to verify that your tires are properly inflated at 25 degrees F.
              Thank you.
              Loring in Katy, TX USA
              If your only tool is a hammer, you tend to treat all problems as if they were nails.
              BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

              Comment

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