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Cold weather tire pressure

Discussion in 'Model S' started by pedriscoll, Dec 14, 2016.

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  1. pedriscoll

    pedriscoll True Blue Tesla Fan

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    We have had our first single digit temperatures of the season the past few days. Today I had a low tire pressure warning. All 4 tires were at 39 lbs. I used my compressor to inflate all to about 44 lbs. Anyone else have this happen? I don't remember this last winter.
     
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  2. CliffG

    CliffG Member

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    Yup. Happened to me last winter. Hasn't gotten that cold yet around here this year yet. Should be cold enough, if it's going to happen, in the next day or two.

    On the other hand, I just changed my tires before Thanksgiving, so maybe not this year or not this soon.
     
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  3. RogerHScott

    RogerHScott Active Member

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    Just the other day was getting complaints on three out of four tires. Added air, went away, but if it warms up they may be over pressure.
    It is really rather annoying that you can't use these fancy pressure sensors as pressure gauges when filling the tires.
     
  4. CHG-ON

    CHG-ON Still in love after all these miles

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    Looks like you have 19's on your car. The 21's are even more sensitive to temps. For both sizes it's because there is less volume in the tire for air, compared to 60 or 70 series sidewall, so they change much more dramatically to swings in temps. I see a difference with even a 10 degree swing, so I now keep more of an eye on it. I have a compressor in my garage, so it is a quick fix for me.
     
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  5. ev-now

    ev-now Member

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    The fancy gauges need to be spinning to be read unfortunately.
     
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  6. ev-now

    ev-now Member

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    About 1psi per 10F change.

    Also 0.5PSI per 1000ft of elevation - and note that the Tesla system does not compensate for altitude - so the pressures you aim for should be adjusted for the 'kind of ' altitude you are at - otherwise you are likely over-inflating them if you use the TPMS readings as your target.
     
  7. 4SUPER9

    4SUPER9 Supporting Member

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    Interesting thread. I am in Los Angeles, and we had our first "cold" days a couple of weeks ago (42° at night) and my pressure registered at 38 in 1 and 39 in the others. I don't know what they were beforehand, but my guess is not optimized. I inflated them back up and all have been holding steady around 44 PSI.

    I am driving up to Mammoth next week, where the altitude is about 8,000' and the low temp is forecast for 32° high and 1° low. I expect my tire pressure will drop from the temp, but may go up and compensate a bit from the altitude, right?

    How do I handle this? If my pressure goes low, should I just ride it out and hope for an increase in PSI as I head down the mountain in a few days? If so, how low is acceptable? In the past when I took my Tesla, I didn't have the TPMS and did not pay attention (and did just fine), and when I finally upgraded to my new Model S, it was Spring skiing and warm already with no warnings.
     
  8. ev-now

    ev-now Member

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    #8 ev-now, Dec 14, 2016
    Last edited: Dec 14, 2016
    40 degree drop - 4psi drop, 8K increase in altitude - 4psi increase in pressure (which the TPMS will not report correctly). As you say, it'll balance out at the low. At the high, you'll be 3psi up on where you were when you started. As tolerance is tight on the high end (50psi max on a 45psi recommendation) you're better starting low and letting the altitude increase the pressure for you than starting at 45 and hoping the temps keep it below 50! Of course with a 50psi max recommendation I am sure the tire is in no danger, but the handling will not improve with over-inflation on an already 'hard' tire.

    Are you running 'all seasons'?

    EDIT: Reference for tire pressure changes
     
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  9. kort677

    kort677 Active Member

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    as with any tire on any vehicle cold weather will zap your tire pressure. anyone in a cold climate would be well advised to check their tire pressures regularly and top off as needed. conversely when the weather warms up you will need to bleed air from the tires.
     
  10. 4SUPER9

    4SUPER9 Supporting Member

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    Thank you for the info!
    No, I am on 19"s and not running all-seasons (we only have 1 season in So Cal ;))

    The temp should be around 62° at my start at sea level. When I arrive, there would be a net 30° drop in temp at the high. By your formula, this would result in a 3 psi drop for temp, and a 4 psi increase for altitude, so only a 1psi net increase from sea level. Lots of wiggle room there. When the temp drops to 1°, that would result in an additional loss of 3 psi. So, only a net loss of 2 psi from Los Angeles, correct? Seems like I should be fine at 45 psi start. I could always bleed off air if the pressure hits 50 psi.
     
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  11. ev-now

    ev-now Member

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    Your numbers look right. Just remember the TPMS knows nothing about altitude, it is reading the 'sealed' air-pressure not the relative - so if you take a gauge you'll see a difference between gauge and TPMS by the altitude change. Thus 45 on the dash should be much closer to 49 when read with a gauge at that altitude.

    All said, you have the advantage of climbing and dropping temps - so compensating. Those of us starting at a mile high, with potentially very low temps already have more to worry about when driving another mile or more up into the mountains as the temp will not necessarily change in the right way. I've have -4F in town and much warmer going over the Divide.
     
  12. DrivingRockies

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    Has anyone enquired with Tesla about the ability to use nitrogen in the tires?
     
  13. Sharps97

    Sharps97 Member

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    This thread helped me to not lose my mind from earlier today. My previous experience was on an Accord with 17 inch tires - very little change from temperature for the most part. Good to know that what I'm seeing out my way is pretty normal. From what I've read in other threads, heat is more damaging to your tires (which increases with low pressure) than loading up to a higher PSI in cold temperatures.
     
  14. golfnut

    golfnut Member

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    Those in the NE are very familiar with this problem. Just as Tom Brady. ;)
     
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  15. ev-now

    ev-now Member

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    No reason why not air is almost 80% nitrogen anyway. That said my experience is that 100% nitrogen (well what Costco pumps) is MORE susceptible to temperature change - yes this is not supposed to be the case, but over multiple season on big SUV tires I found this to be a consistent probelem. It is supposed to be better in terms of reducing corrosion.

    External ref: Nitrogen vs Air
     
  16. dkemme

    dkemme Member

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    My LEAF honks at me when I get to the correct pressure.
     
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  17. ZERO260

    ZERO260 Member

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    Same thing happen to me yesterday. Driver side front was low. I ordered a precision tire gage from Amazon that arrived the day before. I filled all tires to 45 psi using the precision gage, however the sensors were reading 2-3 psi higher than 45. I contacted Tesla to inquire which to rely on e.g. precision gage or tire pressure reading on dash, they said rely on the dash because the warnings relate to the sensors. I guess based on the scenario above if the 45 gage reading dropped 2 psi to 43 the tire would be under inflated and you wouldn't get a warning. Vise versa if I let the air out of tire to satisfy the seniors I would be riding on under inflated tires, safety and wear issues could occur.

    I'm not sure I agree with Tesla's logic. I think I would rather rely on the gauge, but I guess you would have to check tires every 1000 miles or so.

    What you all think?
     
  18. pf-flyer

    pf-flyer Member

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    That's a good set of rules to know. I'm at about 6000 feet and it's -3F outside!
     
  19. Knightowl

    Knightowl Whovian

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    Been down to single digits and -temps here as well, my tpms though simply does not work once it gets 15F or below so it just gives an error message 'tpms needs service contact tesla' until it warms up. I dont know if this is normal as it is my first winter with the car but that has been my experience of late.
     
  20. ev-now

    ev-now Member

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    Same on my 2015 S60 CPO - though sadly been back up and seemed to still consider one to be faulty - guessing the battery is dead. Off to Discount Tire soon to see if their toys can read the battery level on a Tesla TPMS (as they'll do it for free, not $125 per hour).
     

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