Nw LRR tires but they set to 35 psi?

Discussion in 'Gen 3 Prius Main Forum' started by Jim Caldwell, Sep 14, 2019.

  1. The Electric Me

    The Electric Me Go Speed Go!

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    Shouldn't be deciding your tires PSI based on motive or agenda. Should be choosing it based on safety, and what is recommended by design and the designers.

    Won't change any ones mind, but with any or all experimentation above the recommended PSI, I found little to almost no benefit. You're changing the suspensions interaction with the tire and road, you're changing the braking dynamics of the tire. All IMO....not worth it.

    I know for those CONVINCED they know better and are reaping some huge benefit....none of this will matter.
     
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  2. ASRDogman

    ASRDogman Senior Member

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    For those so concerned about 1-3 mpg, why not just keep the tank at 1/4?
    7 gallons(give or take) weights a lot! You'll get more MPG doing that than risking others well being
    by over inflating tires....
     
  3. sam spade 2

    sam spade 2 Senior Member

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    What exactly makes you think that ?
    Have you surveyed all of the MILLIONS of vehicle owners using LRR tires to see what they have done ??

    I'm pretty sure that more than one person has posted results right on here.
     
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  4. Grit

    Grit Senior Member

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    Over inflating such as exceeding max sidewalk psi?
     
  5. bisco

    bisco cookie crumbler

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    if anyone has done testing, please post it instead of saying you're 'pretty sure'

    i'm'pretty sure' they haven't, but i can't find any of those tests that haven't been done :cool:
     
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  6. Grit

    Grit Senior Member

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    I lose up to 5lbs if pressure every 3 weeks because I drive far and wide often so I notice incremental loss of mpgs. And yes I turn on cruise control at designated spots and there’s no cars in front or back of the agriculture roads in case naysayers say skewed results are possible.
     
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  7. royrose

    royrose Active Member

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    Five pounds over three weeks seems excessive to me. Are you sure you don't have Grit in your valves?
     
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  8. sam spade 2

    sam spade 2 Senior Member

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    I just did a search here for "tire pressure".
    It got about 135 hits.
    I have better things to do with my time than reading all 135 just to satisfy YOU.
    But you are absolutely welcome to do that and find your own answer.
    (y)
     
  9. bisco

    bisco cookie crumbler

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    thanks, but they are all anecdotal, meaningless really
     
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  10. Grit

    Grit Senior Member

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    I’m not in my valves :D

    My tires are at 3/32” they’re leaking air through thin treads. When they were 6/32”, they only needed reair every month. Nitrogen would slow down the process but I have a jncair jump with AC compressor.
     
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  11. Grit

    Grit Senior Member

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    No bed time stories for us (n)
     
  12. Robert Holt

    Robert Holt Senior Member

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    Hey Grit, could you maybe jot down your data a couple times for the first (high pressure) week of your 3 weeks versus the last (low pressure) week? As you know what pressure you pumped them up to initially, you could list those estimated mpgs (say from the MFD) with the associated tire pressures.
    (I’m twitching to drive down to Florida and get decent tire pressure vs mpg data on that stretch of 4-lane rural road at night, but I would also like to stay married.)
     
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  13. Grit

    Grit Senior Member

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    Great idea!(y) I take photos of every drive summaries displayed on the dash so it's already done, it's just not written down. It's an on-going photo log of every trip and fill up that I continue to keep up on. But do you know how many people will say it its skewed, not in a controlled environment and conclude the results not plausible? I don't blame them because I did remove wipers and many things in the back of the car to lighten overall weight/load :cool:

    This is one of my picture log taken from my Sunday trip with 44psi on all 4s; 69.1 MPG on 96.9 mi driven. Not too shabby at 127,XXX miles.

    IMG_E2503.JPG
     
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  14. Munpot42

    Munpot42 Senior Member

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    I tried several different pressures on my11 Prius finally settled on 39 37, any higher pressures and the body squeaks and rattles drove me nuts.
     
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  15. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    I've found our 15" (snow tires) are more tolerant of over-pressure than our 17" (OEM's).
     
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  16. sam spade 2

    sam spade 2 Senior Member

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    Which also applies to about 90% of your posts.
    :eek:
     
  17. bisco

    bisco cookie crumbler

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    agreed, but i'm not trying to prove anything, except my mechanical and electrical ignorance
     
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  18. Robert Holt

    Robert Holt Senior Member

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    Grit data point 1: 44psi 69.1MFDmpg 96.9miles

    Although a lab test (e.g. EPA) or field test under as identical conditions as possible (e.g. Florida rural 4-lane at night) would be best, I think carefully aggregating the pressure versus MfD mpg data from multiple drivers would be informative. You are correct that each single data point is potentially biased, but if we each do high versus lower pressure data collection over a decent period of time, the biases of some factors such as driving style will not be a big factor. Temps and the consequent use of AC could still be biases on each data point, so we should be careful to try to balance those across data collection points.
    I can do this also, but I have to say it will pain me to watch my mpg drop if it does when I drop the psi!
     
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  19. bisco

    bisco cookie crumbler

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    no one here does any serious testing except bob wilson, and he ran his pri at max sidewall
     
  20. spudnut

    spudnut Junior Member

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    My next rotation (every 5 K, since new) of my Michelin IceX tires (kept on all year) will get me right at or a bit beyond 40 K miles. I have someone here to thank for that, an old thread, where they stated they didn't mess with taking them off for summer, and still got a solid 40 K out of them. I'll buy another set when needed. 45 PSI since new, on all 4, maybe down to a low of 41 now and then, as I am lax about checking pressure. Any increased or accelerated wear of my suspension components, is offset by reduced wear on the drive system, so says I! Both theory's equally untested and "who the hell knows." I just did the classic "take a quarter, if the tread depth does not come to Washington's head, you need to replace them". Whatever that is in mm, the wear is even and good, no excess wear in the center at all. I don't consider going up the tires manufacturer's max pressure excessive at all, as they too are conservative, and only low pressure creates excess heat.

    I ride a fat ebike, and I have bush tires on my small kitplane, both are very noticeably easier to push when the tires are at a higher pressure versus a lower pressure. this leads me to believe....the 2013 PIP is also easier to push when at a bit higher pressure, I do know my last tankful was 64.65 MPG. Actually a bit higher then the usual high 50's, due to no cabin heat needed quite yet, but also no AC.
     
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