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Let's talk tire pressure...

Discussion in 'Gen 3 Prius Main Forum' started by socal13, Aug 2, 2013.

  1. Munpot42

    Munpot42 Senior Member

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    Tried several different combinations of tire pressures with my EP 20's, for me the best compromise is 39 front 37 rear.
     
  2. retired4999

    retired4999 Prius driver since 2005

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    Do not do any side to side!

    A lot of people do front to rear 2 pound difference, 2 pound more in front. I do believe Toyota recomends this. It helps the car to track down the road better.
     
  3. Rupert B Puppenstein

    Rupert B Puppenstein Active Member

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    That infuriates me more because they never get my psi to the pressure listed on the door. It shocks me how little the dealer knows...at least one compared with others. There is no consistency with the service at dealers with this brand.
     
  4. Drdiesel

    Drdiesel Active Member

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    It's this way with most dealers. They have a high turnover rate because they don't pay well.
    Techs go from dealer to dealer trying to find better pay and better working conditions.
    Working for a dealer is difficult because they're cheap and don't care about the people they employ.
    Only thing they care about is selling cars for as much profit as possible. The sales staff is even worse.
    They have ZERO training and come up with all kinds of B/S. I had the last guy tell me he knows nothing about
    cars. He was just someone they hired to try and sell a car because he had some people skills.
     
  5. rdgrimes

    rdgrimes Senior Member

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    I have the same issue at the tire shop. I finally realized that they are filling tires/wheels that are warm, so it'll always be low when checked again cold. You'd think they would deliberately over-fill a couple pounds to compensate.
     
    Rupert B Puppenstein likes this.
  6. RRxing

    RRxing Senior Member

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    195/65/15
    Michelin Defenders
    40F/38R
     
  7. Robert Holt

    Robert Holt Senior Member

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    Anyone keep mpg data records when using higher pressures than stated in owner's manual compared to the basic recommended pressures? That difference may of course depend on the tire, but I would like to see the approximate trade off for mpg gained vs increased pressure. I have the stock Yokohama 195/65 r15s on a 2012 and there should be enough of us to get a decent sample size for stable averages. Anybody else willing to keep track? Given the known inaccuracies of the displayed estimated mpg, we should probably state both displayed and calculated mpgs for each tire pressure.
     
  8. theotherone

    theotherone Junior Member

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    Both of my 2010 Pruis vehicles have Michelin Defenders XT (195/65/R 15), which I keep at 42psi (front) and 40psi (rear)
     
  9. Hoosier1

    Hoosier1 Member

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    I use the Toyota recommended tire pressures. A co-worker previously worked as an engineer for Toyota, and he recommended no modifications to the car. One must assume that Toyota has reasons for establishing specifications. However, I did try running 38 psi in the 13 inch tires and experience a significant change in ride quality.
     
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  10. theshark

    theshark Member

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    Run the recommended Door jam pressure. I find no increase in MPG at 40/38-40/42... none, what so ever.
     
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  11. Robert Holt

    Robert Holt Senior Member

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    Thank you!
     
  12. socal13

    socal13 livin in the foothills...

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    You are the first person on this thread and in Priuschat that I have seen to recommend the door jamb pressure... Higher pressure may not increase mpg as you say (I think it does to some extent), but does it increase tire life mileage?
     
  13. Drdiesel

    Drdiesel Active Member

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    Engineer in what capacity ?

    Toyota isn't the one that sets the tire pressure spec. It's set by the tire manufacturer. The tire plate in the door is a recommended pressure for best ride and handling. It's certainly not set for MPG's.
    I found up to a 3 MPG difference over a 90 mile commute with higher pressures in both my 08 Prius
    and my 2013 C. YMMV!


    What vehicle has 13" tires ????
     
  14. Hoosier1

    Hoosier1 Member

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    Quality Engineer and Purdue Engineering graduate. I meant the wheel size, in other words, the baby tires Toyota installs on the Prius. More than likely, you understood that point, but it's always fun to point out the little things when posting on these types of forums.
     
  15. socal13

    socal13 livin in the foothills...

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    Am I missing something? 13" wheels... baby tires??
     
  16. Hoosier1

    Hoosier1 Member

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    I guess they are 15 inch wheels, but they look like baby wheels and tires...that's my point. First car I've owned with such small wheels and tires.
     
  17. retired4999

    retired4999 Prius driver since 2005

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    For all us old people, You know who we are. 15" tires ar standard anything bigger are on trucks! :D
     
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  18. socal13

    socal13 livin in the foothills...

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    photo (7).JPG I also have a 2001 Avalon which is a pretty sizable car with 15" wheels... looks pretty normal to me. Actually, the 15" OEM tires have a slightly larger outside diameter that the 17" tires on my Persona.
     
  19. Drdiesel

    Drdiesel Active Member

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    So, I guess that makes him an expert on tire inflation "VS" MPG ??? :eek:
     
  20. sarir97

    sarir97 Member

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    What's wrong with green caps? I don't have them, but I'll be installing new tires at Costco and they inflate with nitrogen.