How much air to put in temp spare

Discussion in 'Gen 4 Prius Main Forum' started by Ozark Man, Apr 13, 2021.

  1. Ozark Man

    Ozark Man Member

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    I just bought a temp spare for my 2017 off ebay. It says on the side the max load is 1653 lbs with the max tire pressure of 60 psi. The manual also recommends 60 psi. The seller's description said he ships with it aired up but there was only 45 psi. I know on the regular tires the max psi is usually much more that the recommended. Not knowing the age of the used tire I don't know if I should just leave it at 45 psi and that would be sufficient. Hopefully it will never be driven very far if at all. On another subject I had hoped I could figure out a way to put it in the provided space underneath in the hatch but there is no way with the insert there now. I tried ebay for another one but no luck. I just can't see the price someone on here quoted from a dealer, about $400 I think. So I guess I'll just leave it up top with the groceries. If I need to haul something bigger I can always take it out temporarily.
     
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I would trust the manual.

    There are a number of reasons not to run at max: Braking distance, handling, and ride comfort to name some, but the temp spare is not supposed to offer handling or comfort, it is to get you to a real tire.
     
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  3. Ozark Man

    Ozark Man Member

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    But the max is what the manual recommends which is not usually the case.
     
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I have never had a manual tell me not to run the temp spare at max pressure, can you give an example where one does?
     
  5. Ozark Man

    Ozark Man Member

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  6. jdenenberg

    jdenenberg EE Professor

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    These temp spares tend to lose PSI over time so set it at the recommended 60 PSI and check it every couple of months. The one in my 2016 Prii and my spouse's 2016 Subaru were both below 20 PSI as I had not checked either of them for a couple of years.

    JeffD
     
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  7. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    I think we're trying to over-think this a little.

    This isn't a passenger radial tire, it's a piece of damage-control equipment....just like a fire extinguisher.
    If you use it...you're already not having a good day - and the idea is to use the spare to get you to a place where you can immediately get a replacement passenger radial tire, and maybe re-stow the spare for the next emergency.

    I'd set it to 60, and check it in a few weeks.
    If the pressure drops significantly....say much more than a couple of PSI, then setting it to 60psi didn't cause the problem, but rather you detected a pre-existing problem and you need to get another spare, and make sure that IT is inflated to the manufacturer's recommend pressure and it is able to maintain that pressure more or less.

    I don't drive through very many sketch neighborhoods.....but I HAVE driven through some.
    I do not often drive during extremely bad weather.....but it DOES happen on rare occasions, with me being a utility worker.
    I don't really remember the last time I had to yank out a spare tire and mount it to get me back to the barn......but it HAS happened.

    Murphy and Darwin are NOT limited to one unfortunate circumstance at a time.....so I don't limit MY options.
    Spare tire....
    Extinguisher....
    First aid kit.....
    Jumper cables.....
    Charger pack....
    EDC piece...WITH....a "spare" mag. :D


    AS always.....
    ACTUAL mileage WILL vary.
     
    #7 ETC(SS), Apr 13, 2021
    Last edited: Apr 13, 2021
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Manual says 60 psi, and that’s what I’d set it too. It’s sieve-logic to rely on the arrived pressure of an eBay purchase.

    regarding:

    there IS an age code on the sidewall. If it’s over 10 years I’d be thinking about replacing.

    come to think of it: our 2010’s spare... :rolleyes:
     
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  9. ChapmanF

    ChapmanF Senior Member

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    Anybody had much luck finding replacement tires of that size just as tires, as opposed to premounted on the matching rim?

    I'm pretty sure the pressure requirement in the manual follows the fact that the tire is physically smaller, and needs the higher pressure to carry the designed load.
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Tire rack had several candidates, last time I checked, and at least one looked a dead-ringer for the OEM tire. Can’t recall if it was same brand; that involves dragging it out to check.

    come to think of it I should do that, check pressure and so on. I’ll take a pic of the make and model too.

    AFAIK: the 3rd gen (16”) spare should also be compatible. 4th gen went to a 17” spare. The 16” size is very close to stock (195/65R15), while the 17’s undersized some.
     
  11. PaulDM

    PaulDM Member

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    15 inch spare in the uk
     
  12. Rmay635703

    Rmay635703 Senior Member

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    I fill mine to 80psi then in 3-6 months fill it up from 30-40psi back to 80psi
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    In 195/65R15? (aka full size)
     
  14. Ozark Man

    Ozark Man Member

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    Hope that's not soon, I just bought it.
     
  15. PaulDM

    PaulDM Member

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    Ok please ignore my last post.
    Just checked and it’s a Falken T125/70D17. “Inflate to 60psi”
    BAF57A9E-A56F-43B4-9C19-2C21801D7B7B.jpeg DFD137B1-DE81-4A09-B5AE-AB4824B2AB66.jpeg
     
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  16. Mendel Leisk

    Mendel Leisk Senior Member

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    #16 Mendel Leisk, Apr 13, 2021
    Last edited: Apr 13, 2021
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  17. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    As folks post temp spare pics, notice they do not say max pressure 60 psi, they say inflate to 60 psi. It does not sound optional. Just do it.
     
  18. PaulDM

    PaulDM Member

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    Agreed
     
  19. Ozark Man

    Ozark Man Member

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    That's it, it has that tractor yellow rim.
     
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  20. Mambo Dave

    Mambo Dave Active Member

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    1.) max load - it's a small tire, and if asked to be on the front for both braking and for cornering, the forces on the tire very well may approach max load - unless you have dead-straight roads. I'd have the pressure at 60 in case it does end up on the steer tires under unplanned hard cornering and braking conditions.

    2.) Remember that tires leak air over time. Most of us find that checking a spare tire's pressure is a pain in the rear. Fill it to max, forget about it for a year, then check in a year - each year.
     
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