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Tire pressure vs warm weather

Discussion in 'Model 3: Driving Dynamics' started by pastafarian, Apr 25, 2019.

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  1. pastafarian

    pastafarian New Member

    Joined:
    Apr 24, 2019
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    Bay Area
    Hi there

    I have the 18inch tires, which are inflated at 45psi as per Tesla guidelines. However with the warm weather in CA, pressure went up to 51psi yesterday, which is supposed to be the tire recommended max limit. As we're just getting started with the warm months here, I wondered what's best.
    Should we slightly lower cold tire pressure to - say - 42psi, to accomodate for the higher pressure while driving in hot / sunny weather? (85-100F)
     
  2. coleAK

    coleAK Member

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    Oct 23, 2018
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    Location:
    Alaska
    Tire pressure is always measured “cold”. Cold pressure is measured when your car has not moved for at least 4 hours. It is very common to have to add air in the fall and remove air in the spring. Tires warm up due to friction while you drive. The only time “warm” pressure matters as in pressure with warmed up tires is sometimes when you are racing on a track.

    So when you get in your car for the day the pressure should be 45 psi. Buy a good gauge and check it before your car moves. Other than that the only time it matters on the TPMS is if going down because then you most likely have a leak.
     
    • Informative x 1
  3. timk225

    timk225 Active Member

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    Tires change by roughly 1 psi for every 10 degree change in temperature. Set them at 42 psi cold and you're good until Thanksgiving.
     
    • Informative x 1
  4. jadatis

    jadatis Member

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    Location:
    Holland ( Europe)
    If the 45 psi was the lowest safe pressure calculated for speed and load on tires, you could not lower it for safety reasons.
    But on electric cars, the pressure advice is kept verry high for actiradius of battery.
    That high even, so often centrewear of tires so lower milage of tires.
    That lowest safe pressure, I am able to calculate for you, but might even come to 30 psi.

    So you can savely use that 42 psi all the time, calculated back to 65degrF.
    When hot outside , say 90 degr F , you will measure higher, but this is needed to give less heatproduction, because cooling down is also less then because of lesser temp-differences between rubber and in and outside air.
    When colder the other way around, but then you may highen up to 42 psi for reasons of actiradius, but for safety not needed.
    But if you dont mind about actiradius of battery, let me calculate that lowest safe pressure for you, and you have more gripp and comfort and tires wear evenly so last longer.
     

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