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Tire pressure?

Discussion in 'Gen 4 Prius Fuel Economy' started by Yippeekyaa, Aug 2, 2017.

  1. Yippeekyaa

    Yippeekyaa Active Member

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    just read the recommended pressure sticker on my new Prius. On my gen3 I ran the usual 42/40. Sticker on new one says 35/34. Any real world experience to share running higher tires pressures for better mpg as in the older model?

    Introduced old car to its new garage mate this morning.
    IMG_6082.JPG
     
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  2. Prodigyplace

    Prodigyplace Senior Member

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    Is yours a Touring with 17" wheels?
    According to my notes, my recommended is 36/35. The Eco recommended is 39/36.
    I ran 39/36 for a while but after my first check, the dealer paperwork said they set the pressure to 32 but they actually set it to 39 all around. I have left it at 39/39.
     
  3. Yippeekyaa

    Yippeekyaa Active Member

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    Not a touring. bigger wheels mean more expensive tires. I'm too cheap for that. Thanks for the info. I'll pump them to 40 all around and see how it drives.
     
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  4. bisco

    bisco cookie crumbler

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    the old one was 35/34 as well, so just run them at whatever you're comfortable with. there's no scientific proof that higher pressures improve mpg's, but it seems logical. the ride is so much nicer at recommended though.
     
    #4 bisco, Aug 2, 2017
    Last edited: Aug 2, 2017
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  5. wjtracy

    wjtracy Senior Member

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    hmm...well I'd say there is scientific data to show higher pressure helps MPG.
    But it is not a huge impact. It's a curve downward so as you get too low below 30 psia, then MPG falls off faster.
    As you get above 40, the curve is quite modest. What we do lack is specific data on tires, we just know the generic trends.
     
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  6. bisco

    bisco cookie crumbler

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    that's good to know, is there a testing methodology and graph here somewhere? bob wilson i suppose?
     
  7. Yippeekyaa

    Yippeekyaa Active Member

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    I'm rethinking the idea of bumping the pressure to 40 all around now. Brand new car with 80 miles on it. Think I'll set at the recommended pressure for a while to establish a baseline to start from. Up the number after a few k miles and see what happens. Considering that I'll have 12-15k on this car in 6 weeks will make this easy.
     
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  8. Prodigyplace

    Prodigyplace Senior Member

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    That's quite a few miles! I have had my car since last October and have just under 10K on it.
     
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  9. bisco

    bisco cookie crumbler

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    is that 100,000 miles/year?:eek:
     
  10. Yippeekyaa

    Yippeekyaa Active Member

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    We travel quite a bit. 30 states since thanksgiving. Two big trips planned. Nc to Maine in 2 weeks then a 7500 mile trip to glacier national in September. Those two trips total 10k plus miles. The gen3 averaged 44mpg while towing the small camper. Hoping for a bit more with the new car. Camper weighs 280 and barely notice it behind the car.
     
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  11. CoastRider

    CoastRider Active Member

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    30 states? Man, I wish I was you! And that gold Prius is beautiful. You see that fellas? You boys need to get out and drive your Prius! :) Quit talking about it so much… and drive it! :D I did 3 tire pressure tests, with the OEM Toyo tires, and didn't see any measurable difference in gas mileage... Certainly not worth the harsh jarring ride that the increased pressure brought.

    (My factory recommended psi is 36/35 for my 15 inch tires. I'm just a little over that, so as to allow for the natural bleed.)
     
    #11 CoastRider, Aug 2, 2017
    Last edited: Aug 2, 2017
  12. Yippeekyaa

    Yippeekyaa Active Member

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    Thanks for the kind words. The gold is my favorite color. This is my third Toyota in that color. The gold car was in okefenokee state park in February, Grand Canyon in march, fla keys in April, cape cod in may, outer banks in June, southern Missouri in July. Like you said, get out there and see the world. Just drive it. Fuel, food, campground fees for our trips are less than 100$ a day. It doesn't have to cost a fortune to travel about. Have people driving giant RV's laugh at our setup. Then we tell them what it costs us a day and we end up with the last laugh. They spend more than 100 bucks on fuel a day to drive their rig around. Sure we don't have a bathroom, shower, washer, dryer, fridge,etc. but we get along just fine without all that junk too. North America has the best state and national park system in the world and it's cheap too.
     
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  13. CoastRider

    CoastRider Active Member

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    That sounds great! If I may ask, what is your age? That is a lot of driving to many beautiful places. I envy you. Is all that driving ever hard or stressful? I am in the big cities of Southern California, and it is certainly not pleasant driving around here. :( I am newly retired and wanted to start doing some long trips. But the traffic here is just insane.

    My parents always had gold Toyotas. Great color.
     
  14. Yippeekyaa

    Yippeekyaa Active Member

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    It's not easy, but wife and I switch every 2 hours except when she is working. She works virtually and often works while I drive. When that happens I stop every 2 hours and walk the small dog that travels with us. 10/15 minutes of walking around and I'm ready to go another 2 hours. The interstates are stressful. We take back roads when time allows for it. Oh, I'm 50, semi retired.
     
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  15. CoastRider

    CoastRider Active Member

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    50 is still a kid! :LOL: Enjoy your travels. You are sure getting great use out of your Prius (plural) :)
     
  16. jdonalds

    jdonalds Active Member

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    We've kept our Prius tires at 44 front, 42 back, for years. I've not noticed any effect on how the tires wear. In my experience that pressure plan results in about a 2 mpg improvement overall.
     
  17. RCO

    RCO Senior Member

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    Does your insurance allow you to tow a trailer in USA as I understood that Toyota has not approve the Gen 4 for towering over there?
     
  18. wjtracy

    wjtracy Senior Member

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    bisco I have posted a Pressure vs. MPG plot...but that was one computer ago so I'd probably have to start up my old machine to get it.

    Actually what the science shows is that higher tire pressure reduces tire rolling resistance, and each tire has its own unique rolling resistance curve. From that we can infer MPG goes up.
     
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  19. bisco

    bisco cookie crumbler

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    is it tied to controlled testing?
     
  20. Yippeekyaa

    Yippeekyaa Active Member

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    Insurance doesn't care what Toyota says. I have a rider that covers my camper. It added 25$ every 6 months to my policy. They didn't ask what i tow it with nor do they care. I know some of the more anal retentive people here will cry foul over that but I don't care what the anti towing crowd here thinks anymore. I've towed this camper 30k trouble free miles with the 2011 Prius that is maintained better than most golf course greens. The 2017 will get the same if not better care.

    It's the people that never check their oil or tire pressure that seem to have the biggest churn here on this forum. They post their issue here, ask for advice and never respond as they know they screwed up by not taking an active role in maintaining their Prius and depending on others to do so. It all comes down to the basics. Check your oil, tire pressures and do what it takes to keep the car in top running shape. Or not and your down 4 quarts and the local stealership quoted ya 4500$ for a used engine they can't afford and come here looking for help because they were lazy.
     
    #20 Yippeekyaa, Aug 3, 2017
    Last edited: Aug 3, 2017
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