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Tyre pressure on 2021 Prius Prime

Discussion in 'Prime Main Forum (2017-2022)' started by syllablelight, Jan 28, 2021.

  1. syllablelight

    syllablelight Junior Member

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    Bought a 2021 Prius Prime earlier this week. I saw that Toyota recommends 36/35 psi for the tyres. I used the Toyota owners app to check and it's reporting that all 4 of my tyres are 50 psi. Is that app wrong, or did the dealer over-inflate my tyres?
     
  2. Salamander_King

    Salamander_King Senior Member

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    Most likely the dealer did not perform the pre-delivery inspection. The tires are over-inflated during the overseas shipment. Just check the tire pressure with a pressure gauge. If you don't have one, you can buy one at any auto shop. The manual type is only a few bucks. Or you could stop at any gas station that has an air compressor. But the in-line pressure gauge is often very inaccurate.

    Did you find rubber plugs in a glove box or somewhere? They are shown in this thread. Rubber plugs installed at pre-delivery inspection? | PriusChat If the dealer skipped checking the tire pressure, there is a good chance they also skipped installing the plugs.
     
    #2 Salamander_King, Jan 28, 2021
    Last edited: Jan 28, 2021
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  3. jerrymildred

    jerrymildred Senior Member

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    If you find that they also didn't install the shipping plugs that @Salamander_King mentioned, along with not prepping the tires, I think I'd go back to the dealer and tell them to either do the job I paid for or give me back the fee they charged for doing it.
     
    #3 jerrymildred, Jan 28, 2021
    Last edited: Jan 28, 2021
  4. syllablelight

    syllablelight Junior Member

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    Didn't find the rubber plugs anywhere. I will head to the dealer to get the tire pressure fixed tomorrow. By the way, I found a copy of the 2020 PDS (https://static.nhtsa.gov/odi/tsbs/2019/MC-10162245-9999.pdf) and nowhere does it say to adjust tire pressure to the recommended pressure. So maybe they did complete the PDS 100%, but forgot about the tires.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    They might be installed. Look just inboard of the rear scissor jack locations: there’s a reinforced plate hump that has an oblong hole, which should have a rubber plug. It’s maybe 1”x1.5” IIRC.

    Thanks for that PDF btw. I think this list on page 5 covers both the tire pressure check (initializing TPMS (Tire Pressure Monitoring System)) and the aforementioned plugs. Items 3 and 8:

    D6431D74-A3AF-42C3-B358-DF5556E220DD.jpeg
     
    #5 Mendel Leisk, Jan 28, 2021
    Last edited: Jan 28, 2021
  6. Salamander_King

    Salamander_King Senior Member

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    If I was you, I would just adjust the pressure DIY and save the trip to the dealer. But, it may be good to complain to make a point. You might want to ask for the PDS check sheet to check if they really did it (although I am almost certain, they will say they did it and produce a sheet of paper with all items checked.)

    BTW, the PDS doc you have linked has the tire inspection item.

    2. Inspect tires for defects/damage
    3. Initialize Tire Pressure Warning System (TPWS) –

    If the dealer followed the procedure, then during the initialization of TPMS, the tire had to be checked for the proper pressure. Only after checking and adjusting the pressure to the recommended pressure on the door label, the TPMS initialization can be performed.
    upload_2021-1-28_23-26-19.png
    upload_2021-1-28_23-36-52.png
     
    #6 Salamander_King, Jan 28, 2021
    Last edited: Jan 28, 2021
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  7. syllablelight

    syllablelight Junior Member

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    I had a look at that other thread, don't you need to jack the vehicle up high to be able to see the rubber plugs?
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    You should be able to just lie beside the car and see under. It’s quite close to the pinch weld seam, just inboard. A mirror might help, and you can just feel. In a pinch the scissor jack will help, good to try it out. Block the diagonally opposite wheel and set the Parking Brake solidly too. And don’t get under there at all, just look with a light. It’s a heavy plate zone and has the oblong slot, and the rubber plug if done correctly.
     
  9. syllablelight

    syllablelight Junior Member

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    TPWS seems to be working, so I suspect they initialized it without resetting the tire pressure to 36/35 psi.
     
  10. Salamander_King

    Salamander_King Senior Member

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    Well, how do you know it's working? If the tire pressure is really at 50psi and TPMS is working, it should be warning at you like crazy because of over inflation. If they did skip the TPMS initialization step during PDS, then the sensor is set at 50psi as initialized value. You will get the warning light if you just decrease the tire pressure down to 36/35 psi.
     
  11. syllablelight

    syllablelight Junior Member

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    But TPMS doesn't warn you about the absolute pressure, it only warns you when the pressure drops by a certain amount from the benchmark. The benchmark pressure is set to whatever the tire pressure is when the system is initialized. So if TPMS was initialized at 50psi, I suspect it will start warning me of underinflation if the tires are adjusted to 36psi.
     
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  12. Salamander_King

    Salamander_King Senior Member

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    Yes, that is exactly what I just wrote. So, did you drop the pressure to 36psi, and TPMS did not signal the warning light?
     
  13. syllablelight

    syllablelight Junior Member

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    No I haven't, because I don't own a tire pressure gauge so I wouldn't know where to stop deflating. I'm bringing it to the dealer tomorrow morning because it's just 3 miles away, and I will have them adjust the tire pressure and re-initialize the TPMS. I also want to ask for a copy of the pre-delivery inspection check list, because if they forgot this, who knows what else they might have also forgotten?
     
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  14. Salamander_King

    Salamander_King Senior Member

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    If your connected service app is correctly working and showing accurate TPMS data on your phone, then you could deflate the tire slowly and check it on the phone app. If it goes down to 36psi and TPMS light comes on, then you know the dealer did not initialize the TPMS at proper tire pressure as they should have.

    But, all of this may be too much work. Yeah, if it's only 3 min drive, then just go visit the dealer and give them hell. lol

    BTW, you may still want to pick up a tire pressure gauge just in case you have to adjust the tire pressure DIY.
     
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Get several pressure gauges, different styles, check them against each other. You should consider a floor style bicycle pump too, they’re more than capable of bringing car tire pressures back up, when needed, and are less hassle and complexity than 12 volt powered pumps, my 2 cents.

    Another thing: I don’t believe TPMS warns of over inflation, only under. And the TPMS system can easily be reset by owner; procedure is outlined in owners manual.

    In this instance it’s likely (hopefully) best to let dealership handle it; and they WILL be on their toes this time..., if they have ANY sense. But yeah, for the owner, being knowledgeable and capable of DIY’ing all this stuff is good for keeping those buggers honest. Not to mention saving time and hassle, down the road.
     
  16. Salamander_King

    Salamander_King Senior Member

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    I always thought that was the case. I never had experience with overinflation triggering TPMS on my PRIME usually kept at 38 psi all around, but there is a thread someone had his TPMS being triggered by overinflation.
    Maximum PSI ? | Page 2 | PriusChat
     
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  17. Mendel Leisk

    Mendel Leisk Senior Member

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    Too, I strongly suspect that at the factory, they set tire pressures to spec, initialize the TPMS, THEN air them up say to 50 psi, for shipping. The ONLY thing they really expect from the dealership monkeys is to bleed them back down to 35ish. But they mention the TPMS reset in PDI document, to cover themselves. Trust but verify.

    What is it now, 36/35? When is Toyota going to wise up and spec ONE psi for all four; I mean: what’s a pound diff...
     
  18. Trollbait

    Trollbait It's a D&D thing

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    Nope. Installed my own, and the hole is within easy reach. Remember, this is a hole someone has to hook a chain too for tying the car down.

    It is a good idea to have a tire gauge in the car. I wouldn't trust the one on the goo compressor if you ever had a flat.
    Really easy for a rushed dealer employee to skip checking the tires pressures, and just hit the reset button.
    The legal requirement is to warn of underinflation, but a manufacturer can also have it warn of over. Have heard stories of people, without a gauge, just adding air to tires when the TPMS light came on, and they take the pressure past the tire sidewall without that light never going off.

    I suspect the factory sets the tire pressure high after mounting on the wheel. Flat spots can develop in holding lots before getting to the ship after all. More importantly, you don't have to pay for the equipment and labor of pumping up every tire, while on the car, before shipping off.

    Yeah, they are TOYOTAS, not sports cars.:p
     
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  19. srivenkat

    srivenkat Active Member

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    I wanted to check the tire pressures of my 2021 before I started the long journey home from the dealership. The caps couldn't be turned by hand (too tight from the factory?) and I asked the sales rep to have the pressures checked, which he did. Not sure if the caps were tightened at the dealership or at the factory, but all ended up being good.
     
    #19 srivenkat, Jan 29, 2021
    Last edited: Jan 29, 2021
  20. ETP

    ETP 2021 Prime(Limit),Highlander HYB Plat,B52-D,G,F,H

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    I run mine, since 2002, at 42 PSI. 40-42 stone cold is your best MPG balanced with ride and handling.
    51PSI can have control issues and I have not run that high of a pressure since my old Honda Hybrid days.
    Caps are very tight but do come off.
    Also the valve stems are very short and tucked in tight into the rims.

    All the dealers never question my 42 PSI at service as they have been educated.
    Low pressure on a hot day will leave you stranded.