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Can tire pressure be reduced to improve ride quality?

Discussion in 'Model S: Driving Dynamics' started by AmpedRealtor, Jun 16, 2018.

  1. AmpedRealtor

    AmpedRealtor Well-Known Member

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    Musk recently tweeted that Model 3 tire pressures can be safely reduced from 45 PSI to 39 PSI for a more comfortable ride. Does the same apply to Model S? I'm wondering if lowering my tire pressure from 45 PSI to 39 PSI will soften the ride without inducing any strange tread wear.

    Thanks in advance! :)
     
  2. Tdriver

    Tdriver Member

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    Try 39, if you get a warning, bump it to 40-41. Tire wear is not an issue. For 40 years I ran ICE cars at 32 without issues.
     
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  3. FlatSix911

    FlatSix911 918 Hybrid

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    You should keep the tire pressure above 40 psi due to the increased weight of the vehicle. Range and tire wear will suffer with under inflation.
     
  4. melburstein

    melburstein Member

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    The door label on my 2017 Model S calls for 38 front and 40 rear; but the TPMS issues a warning when I set the tires to that pressure.
     
  5. FlatSix911

    FlatSix911 918 Hybrid

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    See the Tesla Manual for the correct tire pressures ... only the RWD Performance Plus Suspension recommends 38/40. :cool:

    tire pressures .png
     
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  6. AmpedRealtor

    AmpedRealtor Well-Known Member

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    #6 AmpedRealtor, Jun 18, 2018
    Last edited: Jun 18, 2018
    My 2013 Model S weighs on the high end of the 7 series. My understanding is that BMW used to recommend 35/38 for its 245/45 R19 tire size on the 7 series. The 7 is rear wheel drive with a 51/48 weight distribution (front/back). My 2013 Model S weight distribution is the reverse of the 7 at 49/51. Depending on flavor, I believe the 7 series weighs between 4,200 and 4,700 lbs.

    I'm going to go ahead and try reducing the pressure, I just wanted to make sure there were going to be no dire side effects. Seeing what pressures BMW recommends is helpful, and Musk saying 45 PSI is for efficiency (not ride comfort) tells me there is some room to play.
     
  7. FlatSix911

    FlatSix911 918 Hybrid

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    The current Model S 75D - P100D curb weight ranges from 4,600 to 5,000 lbs. Tesla Model S - Wikipedia

    I would recommend keeping your tire pressure above 40 PSI for optimum performance and efficiency ... :cool:

    upload_2018-6-18_20-22-37.png
     
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  8. melburstein

    melburstein Member

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    Flatsix911. Great information. Thank You. I now believe the stickers on the door pillar that show 38 PSI (front) and 40 PSI (rear) are wrong. Sadly, a Senior Tech at the Costa Mesa SC told me that he verified that the labels were correct. However, they filled the tires to 42 PSI. Once again, a model S owner appears to have better information than the SC.
     
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  9. thecloud

    thecloud As rhythm raced inside, the ship came alive

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    Keep an eye on your tread wear pattern. If tires are underinflated then the outside edges will start wearing down faster than the middle. I've kept mine at 44-45 psi and the tread wear is pretty even.
     
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  10. ShockOnT

    ShockOnT ⚡️⚡️⚡️⚡️⚡️

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    I don't think weight has anything to do with it, just tire design.
    Bicycle tires go to 100psi sometimes.
     
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  11. Barry

    Barry Active Member

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    For about 6-8 weeks in 2015, Tesla recommended 50 psi, then changerd their recommendation back down to 45. I asked the SC to replace the sticker and they insist it's correct. :eek:

    My road bike has 700x25 tires and the recommendation is 110 psi, with a max of 120 psi. Generally, the thinner the tire, the higher the recommended pressure.
     
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  12. noicepls

    noicepls Member

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    Don't know why Musk would have been talking about 45 PSI regarding the Model 3. Mine specifies 42 PSI on the door sticker. I've set pressures at 40 all round, and it's good.
     
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  13. dark cloud

    dark cloud Member

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    Weight has a lot to do with tire pressures. Anybody who has had a camper or towed with their truck knows about this. But it is curious why the performance plus non-all wheel drive has 4 psi less pressure recommended in the fronts than the D model, as the weight difference is just 200 pounds and it is the same Michelin Pilot sports on both, correct? That is just one passenger, and nobody adjusts their pressures depending on whether they drive alone or have 4 passengers: a difference of 1000 pounds.

    The sticker on my door is redundant, because it is for the 21's on my P85D (performance suspension), and I have the Goodyear 19's on my car. I have played with pressures from 40-50 psi: The ride is a little more complaint with lower pressures, but steering is sharper with the highest pressure, and you supposedly get more range. I plan to test this one day...

    Like someone else has mentioned tire wear is the most critical factor: Typically (with ICE cars) under inflated tires will wear the edges too soon while over inflating will wear the centres out. Premature wear will supersede the positives of economy as far as saving money, whether that is fuel economy or electricity usage.
     
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  14. dark cloud

    dark cloud Member

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    I'll add my car just came back from the dealer; oh whoops; the Tesla service centre, and they set them at 50 psi.
     
  15. AmpedRealtor

    AmpedRealtor Well-Known Member

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    UPDATE... I've been riding at 40 PSI on my 19" Primacies and the car handles better than at 45 PSI. I now believe that Tesla's recommended tire pressures have more to do with efficiency than handling. At 45 PSI the car feels squirrely on the freeway and transmits every imperfection to the cabin. At 40 PSI, the car feels planted and the suspension no longer feels like it has a mind of its own. The ride is more comfortable, less noisy, and at least in my non-expert opinion, more controllable.
     
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  16. FlatSix911

    FlatSix911 918 Hybrid

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  17. TaoJones

    TaoJones Beyond Driven

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    Y'all see that AWD Coil 19" recommendation above of 50psi? Go figure. My 2017 door sticker does not say that. When I got this car last year the OEMs were set at 42psi, which I bumped to 45psi, and that's what the SvCs kept them at all last year and into this year. Go figure a second time.

    I've kept the latest set of tires at 49psi (with happily even wear so far thanks in part to addressing the rear camber thing) but go figure, looks like I'll add 1psi all around in the morning.

    As owners, we are not responsible for much in the way of maintenance with these cars. Wiper fluid and tire pressure being 2 items from a pretty short list, relatively speaking. However, it's all still worth getting right, and consistently even. Tires aren't getting any less costly, for example. Would be nice if the tires came from the factory at a PSI that's reflected in the manual. Or vice versa. Or something.

    Note to self - re-read manual every 6 months when it's time to shop around for car insurance.
     
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  18. KArnold

    KArnold Member

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    I know there are lots of opinions about using 100% nitrogen to fill your tires. I put it in my 19" tires for a 100D @ 51 PSI. They haven't dropped a pound in over a year.

    And BTW, when I asked the local Discount Tire if they could put nitrogen in my tires, they said "Sure, 78%".
     
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  19. SSedan

    SSedan Member

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    Pounds per Square Inch.

    Yes the weight is different bike to car but so is the tire profile. Bike tires ride on the center, cars use full with.

    Weight has a lot to do with PSI and so does the shape of the tire.
     
  20. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Tire life will suffer greatly, as will range. Also, the tires will be more prone to pothole damage. And don't forget to increase the air pressure if you are driving highway speeds.
     
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