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Tire pressure - Can I just use a gas station to add air?

Discussion in 'Model S: Interior & Exterior' started by Alex D, Aug 8, 2016.

  1. Alex D

    Alex D Member

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    Excuse me for being a n00b, I am a new owner. I have a 70D with 19" slipstream wheels, took ownership in June.

    My tire pressure sits at 41 PSI cold and gets up to 42 when driving. I feel like it's not enough pressure. Am I able to use one of those gas station air pumps for tires? Or should I go to the SvC to get more air in the tires?

    The reason I'm asking is, I just want to make sure I'm not adding air when there's for example nitrogen in the tire.
     
  2. Gizmotoy

    Gizmotoy Active Member

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    Check your driver's door for the correct inflation pressure. I think 42 is the correct cold pressure for the 19"s, but I'm not positive.

    You can use any air compressor to add air. Just be sure not to over-inflate. Don't go over what it says on the door sticker.
     
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  3. Alex D

    Alex D Member

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    Thank you, sir! :)
     
  4. hiroshiy

    hiroshiy Active Member

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    For 19" wheels the correct tire pressure is 45 psi or 310 kPa.
     
  5. swaltner

    swaltner Member

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    The rule of thumb is that tires that are filled with Nitrogen have green caps on the valve stems and the caps are generally black otherwise. If you don't see the green caps, you can refill them anywhere and not worry about contaminating the 100% Nitrogen with measly 80% Nitrogen. :)
     
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  6. Boatguy

    Boatguy Member

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    Yes, 45psi is the correct pressure for 19" wheels. At the risk of hijacking this thread, why would 100% nitrogen be preferred?
     
  7. Gizmotoy

    Gizmotoy Active Member

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    #7 Gizmotoy, Aug 8, 2016
    Last edited: Aug 8, 2016
    Less pressure variance by temperature. Particularly attractive for those in climates that have large deltas between summer and winter temperatures. For example, theoretically you don't need to keep filling with air as the temps drop in the Winter. It's also less likely to leak through the tire, so should need to be refilled less frequently. Of course, when it does need filled, you need to fill it with nitrogen so that's not as convenient.

    Edit: Wanted to note the pressure variance by temp isn't because nitrogen gas is less affected by temp than air, but rather because air contains moisture which can condense at lower temps and take up dramatically less space in the tire, thus lowering the pressure. Nitrogen fill is completely dry, so is not affected by this behavior.
     
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  8. TexasEV

    TexasEV Active Member

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    My door sticker says 42psi. Is it different depending on battery size? I have a 60 that is an early VIN.
     
  9. SoccerMan94043

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    My refreshed 19" with new goodyear tires state 41 psi on the doorframe.
     
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  10. ishop4more

    ishop4more Member

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    I checked my refreshed with 19" slip stream & goodyear eagles and the doorframe had 45. I just looked this morning. I didn't look on the actual tire.
     
  11. kort677

    kort677 Active Member

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    there is nothing magical about the tires on the tesla, gas station air will work as well as their air works on tires mounted on any other car on the road. other than the method of propulsion and some computer gizmos, the tesla is not that very unique when it comes to moving parts.
     
  12. Alex D

    Alex D Member

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    Just went to a gas station close by. I checked the door sticker, and mine recommends 45 PSI for front and rear. They were on 41, so I was way under, guess I had the right gut feeling. Their air station is actually pretty good, set PSI on the machine and fill each tire till it beeps, love it; very quick.

    After setting it to 45, I noticed on the way home the TPS in the car only showed 44 PSI all around. I know the tires were cold, but the 45 PSI on the door means when cold, correct? I guess I have to set it to 46 PSI next time to get the 45 desired.
     
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  13. Alex D

    Alex D Member

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    I thought so, just wanted to make sure first.
     
  14. SoccerMan94043

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  15. habanero69

    habanero69 I Dont Need Cialis. I Drive an EV.

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    Rated pressure is stated for COLD tires. If you are filling hot, and have been driving long enough for tires to get up to temp (which in summer might be 5-10 min top), then you can safely over inflate by several pounds. THEN when home and the tires are cold RECHECK with an accurate tire gauge and adjust DOWN as required.

    I do NOT depend on those services station auto fill devices to put the proper air pressure in. They can be off 5 or more LBS. Do yourself a favor and invest in a good pressure gauge. You can get then at most auto stores or amazon (https://www.amazon.com/JACO-ElitePro-Tire-Pressure-Gauge/dp/B016R9KKCU/ref=lp_15709131_1_5?s=automotive&ie=UTF8&qid=1470687603&sr=1-5) . Don't need to spend more than $25. Those pencil looking jobs are NO good either. Plus, the good ones have the auto bleed stem that will allow precise lowering. If you own a car like a Tesla, there is no excuse for the auto fill gauge or the cheap ones. ;)
     
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  16. Gizmotoy

    Gizmotoy Active Member

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    I have one similar to the one you linked and love it. Highly accurate, and the built-in bleed has turned out to be WAY more handy than I thought it would. I actually got it for track days and such, but I use it on my daily drivers now too. Highly recommended.
     
  17. kort677

    kort677 Active Member

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    I use a hand pump to top my tires off, the workout is just a bonus
     
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  18. ShockOnT

    ShockOnT Quickish

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    It's mainly marketing.
    There are miles of forum threads arguing the point, and a million "reasons" to pay for nitrogen instead of using air (80% nitrogen), but there's basically no difference.
    Save your money and take a friend to lunch.
     
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  19. TaoJones

    TaoJones Beyond Driven

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    I use this (link below) but have rarely had a need - probably because the car is in for service so frequently and there's always a "Tire pressure check - California Mandate" or similar line item listed as part of the paperwork. I just keep an eye on it in the interim through the TPMS.

    That said, the gauge came in quite handy during the one slow leak episode a couple of months ago. Gas station air machines were wildly inaccurate.

    www.amazon.com/gp/product/B00404WDUC

    I have no idea if this gauge has an auto-bleed feature (never noticed). Will find out shortly, as after getting a new set of tires in the past week or so, I noticed that they inflated one side to a pound or two less than the other, and I'd prefer all to be at 45psi cold as noted on the door panel.

    About that... the car came with OEM Michelins, and were consistently inflated to 45psi. Must have done something right as they lasted 55,000 miles and would have easily gone 58,000. I replaced that set with OEM Goodyears (the 1st OEMs (Eagle RS A-2s) - not the new ones (Eagle Touring, which may have foam) that started shipping this Spring). I do wonder if 42psi is meant for the Goodyears and 45psi for the Michelins, as door panel info has differed over time, yes?

    Guess I'll find out one way or the other as the tires wear down. Hopefully evenly, with the obligatory religious rotations.

    Edit: Aha! The description does list an "air pressure release button". Sounds like auto-bleed to me :).
     
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  20. TexasEV

    TexasEV Active Member

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    That's probably not it, because my early VIN S60 19" came with Goodyear tires and has 42psi on the door label, but when I replaced them with Michelin last week the service receipt said "inflated to 42psi per door label", or something like that. They didn't change the inflation based on the tire.
     
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