Reset tire pressure warning

Discussion in 'Gen 4 Prius Main Forum' started by Rangerdavid, Dec 23, 2019.

  1. Rangerdavid

    Rangerdavid Senior Member

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    How do I reset the tire pressure warning on my Prius?? I lower the pressure in the winter time from 38 to 35 and I cannot get the light to go off.

    Posted via the PriusChat mobile app.
     
  2. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I'm not sure if it's been found in documentation, but the consensus here seems to be that whatever pressure the tpms was set at, it takes about a 25% drop to trigger a warning. From what you're describing, I'd suspect it was last set with the tire pressures at max sidewall, say at the factory: they tend to inflate the tires to max sidewall pressure, for shipping.

    Dealerships are supposed to drop pressures to spec and reset TPMS, as part of Pre-Delivery Inspection. But they've been known to just "mail it in".

    Have you gone through the steps outlined in the manual? FWIW:

    upload_2019-12-23_10-1-7.png

    I've got a vague recollection, someone else was stuck at step 6, never getting the "Initialization Complete" message?

    My 2 cents: I would reset it at 38 PSI, and you should be good year 'round.
     
    #2 Mendel Leisk, Dec 23, 2019
    Last edited: Dec 23, 2019
  3. Fester

    Fester Active Member

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    Use the ">" button on the steering wheel and go to "settings" then down to "maintenance", the TPMS reset should be there.
     
  4. pjksr02

    pjksr02 Active Member

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    So, if you increase your pressures, the light goes off? And you are seeing a constant light, from the time you turn the ignition on, right, not a flashing light? Just making sure it's a pressure warning, not an error.
     
  5. sam spade 2

    sam spade 2 Senior Member

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    Why in the world would you LOWER the pressure in the winter on purpose ?

    It is a myth that lower pressure equals better traction.......IF the pressure was right in the first place.
    Also, if the weather gets REALLY cold, the pressure will go down even more and might fall below the safe threshold.

    I vote for putting them at the RIGHT pressure and leaving them there.

    And I'm pretty sure that the re-set is not the same for all models.
    See your owners manual or the closest dealer.
     
  6. pianewman

    pianewman Active Member

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    Totally agree with sam spade 2. Counter productive to lower the pressure in the winter, as the ambient temp actually lowers it for you!
    I keep mine, in all my cars, at 85-95% of the sidewall limit. Keep my tires well past 40k miles, at which point they always have tread left, but I change them out BEFORE they're at 2/32". My logic? Texas heat wears the tires out before the treads, in my opinion. Distances are vast, and I don't want to risk a blowout.
     
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  7. sam spade 2

    sam spade 2 Senior Member

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    The consensus of "experts" in the industry doesn't agree with that plan of yours.

    Especially when the max. sidewall pressure differs a LOT from the recommended pressure for that vehicle.

    Having too much air in the tires can cause a harsh ride and can contribute to premature suspension failure.

    But, of course, you are completely welcome to think that you know more than ALL of the scientists and engineers that design and build vehicles.......but just don't try and convince me of that. :whistle:
     
  8. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    The first bit I could put up with, if there was a big improvement in mpg. So far I'm not seeing that though, so stay pretty close to spec, just a wee bit over.

    The second bit: yeah, that worries me, a good reason to stay close to spec. That, and slow to a dead-crawl over those #@$!*! speed bumps that proliferate everywhere.
     
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  9. pianewman

    pianewman Active Member

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    I am not recommending that anyone follow my advice, which is based on close to 2 million miles of driving.

    Scientists and engineers aren't marketing the cars. Manufacturers, for decades, have ALWAYS...yes...ALWAYS recommended tire pressures that are more about a "smooth" ride, therefore softer. Those recommended tire pressures are always a compromise.

    I've always chosen to follow the doorjamb recommended tire pressures with any new car purchase. I start with the assumption that maybe, just maybe, the auto manufacturer has changed its philosophy and have modified their compromise, and moved away from "comfort" as the most important factor. In fact, they have, with some cars: my recently traded 2017Ford Fusion Energi, 2013Ford CMax tire pressures were much higher than any car I've ever owned, and I only drove at slightly higher pressures, to maximize MPG.

    When I was younger, and followed recommended tire pressures, I had issues with premature tire wear, especially on the edges of FW drive cars, bent wheels, tires overheating. Running pressures higher than doorjamb recommended, I've not had premature suspension failure (actually, none, unless you count replacing struts/bushings at 100k miles), NEVER a bent wheel, and tires have always lasted 45-60k miles.

    When I lived in NYC, in the 70s, with...uhh...hellish potholes, I kept my Michelins above doorjamb recommended pressures...never a suspension failure, never a bent wheel, tires lasted 70k miles.

    Based on my experience, for my 2018 Prius Four Touring, with 17" Ecopia Plus, I've decided, for the time being, to run 42/40, f/r. Doorjamb says 33/32, Ecopia max is 51psi, loaded to 1201 lbs (that would be 1800 lbs of people/cargo in my Prius!...that's not going to happen) Maximum burst pressure for the EcopiaPlus is probably around 150psi.

    Oh, and by the way...all four OEM EcopiaPlus tires on my 22k miles new-to-me car, with regular dealer service (5k rotations), 33/32psi recommended pressure, had feathering, and one of the rims was bent.
    Two of them were feathered severely enough that the dealership replaced them, free of charge. Alignment was out a bit, but not sufficient to feather all 4 tires.

    I honestly don't think anything I've written here is challenging, "...ALL of the scientists and engineers that design and build vehicles..."

    YMMV (your mileage may vary):)
     
  10. pianewman

    pianewman Active Member

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    Oops! I need to edit my post (#6) above. Major typo.

    "I keep mine (psi) in my cars, at 70-85% of the sidewall limit."
     
  11. sam spade 2

    sam spade 2 Senior Member

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    Your choice.
    BUT.....you should at least LOOK at the sticker with the recommendation on it before you make that decision on any new vehicles.

    IF you should happen to buy a "heavy duty" vehicle, like an RV or big truck, the recommendation might actually be 100% of the sidewall limit.......and 70% might end up being dangerous.
     
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  12. pianewman

    pianewman Active Member

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    Paragraph 3 of post #9. I already said that. I START with the manufacturer's doorjamb, and then, adjust accordingly.

    I think post #9 was clear. If not, tell me!.:)

    I'm 65, lived through the Ford/Firestone tire PSI debacle, as well as the totally nonsensical "unintended acceleration" accusations at Audi and other manufacturers. Tire maintenance is one of several OCD aspects of my auto ownership, especially now, since I live in Texas and do NOT want to have tire issues while on the road.

    I appreciate your caution, and your concern, but I continue to believe I'm well within engineered tolerance of tires/wheels/suspension.
     
    #12 pianewman, Dec 27, 2019
    Last edited: Dec 27, 2019
  13. blane

    blane Carmudgeon

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    I understand that's what you do. But please clarify WHY you do that.

    Have you read any authoritative documentation that makes such a recommendation? If so, please provide a link or links.
     
  14. pianewman

    pianewman Active Member

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    You ask why? Please re-read post #9. I thought I explained it rather clearly.
    1) Protects wheels from damage from potholes.
    2) Maximizes longevity of the tread, keeping the tread wear even from shoulder to shoulder
    3) Maximizes MPG
    4) Decreases heat buildup in tires when ambient temps are high

    I have been driving for almost 50 years. The decision to raise PSI above that stated on the doorjamb is based on all those miles, having owned RWD, FWD, AWD cars, vans, trucks. My tires last a LOOONG time, and are frequently replaced because of age, NOT worn-out tread. I have NEVER had an emergency steering/braking maneuver that felt compromised in any way. In fact, I've locked up the wheels probably fewer than 5 times in my entire life.

    Please, please, do whatever you want with your tires. The car's OEM recommendation is just fine. I just don't believe you'll get the longest, most even, wear out of your tires, and for sure, not the best MPG.
     
    #14 pianewman, Dec 27, 2019
    Last edited: Dec 27, 2019
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  15. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I would take 5K kms less tire life, vs fighting with a lower control arm. It rarely if ever comes down to tread depth for us anyway, tires tend to age out first, especially running separate snow tires 4~5 months per year.

    Just for the record, if you do the math, that 70~85 percent of max sidewall, works out to around what's on the decal.
     
  16. pianewman

    pianewman Active Member

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    Hmm...never had premature lower control arm bushing issues. (VAG products, regardless of tire PSI, are notorious for noise, as well as 50-70k mile wearout, and no big deal to replace)

    With the 17s, 33 sticker/51 on the sidewall = 64.71%...so yes, bumping up to 42/40 (82%) isn't all that dramatic.

    With the 15s, you're right, it's much closer...36 on the sticker, 44 on the sidewall. Going to 40psi is right in the middle.

    (It was much closer with the Fords I referenced above)
     
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