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Phenomenal JUMP in MPG

Discussion in 'Gen 2 Prius Fuel Economy' started by cyberpriusII, Dec 19, 2013.

  1. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Nearly 10 mpg jump with my new tires!

    I posted in care/maint forum a few days ago about wanting a tire that would withstand gravel roads. Got great help/suggestions, but finally went with the Goodyear Weatherhandler FuelMax from Sears.

    Final, out the door and and down the road price was hard to top ($350~). And that final price was what sealed the deal. Forum-ites suggested tires that would probably been better, but costwise.....

    Well, on the way to the get the tires was getting my usual 43.7 MPG on the 49-mile trip (set the trip meter when I left the driveway).

    On the way back home -- as I pulled into the driveway 53.3 MPG for the 49 miles (set the meter when I left Sears).

    Only real difference was temp was 29 degrees when I left home and 36 on the way back.

    Anyway, hope the difference holds true and it was not just a fluke!

    Otherwise, seemed to handle fine, etc. MAY have been a slight bit more noisy, but would not swear to it, since I was "paying attention" to noise and may have been hypercritical...

    An aside, on the way to get the tires, I drive out of my mountains which logically is mostly downhill. On the way home, I drive up the mountains, which, again is mostly uphill.
     
    #1 cyberpriusII, Dec 19, 2013
  2. bisco

    bisco cookie crumbler

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    wow, congrats! tyres that pay for themselves.(y)
     
    #2 bisco, Dec 19, 2013
  3. nh7o

    nh7o Off grid since 1980

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    That is the first report that I have heard about getting a big jump in MPG with new tires out the door. There is usually a wear in period before any increase becomes apparent. What pressures are you using?
     
    #3 nh7o, Dec 19, 2013
  4. Britprius

    Britprius Senior Member

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    The figures may come down a bit but, still a great result. The Cooper GFE "Greater fuel economy" tyres that they replaced in the US are supposed to be LRR. However the figures for them published in the UK do not bear this out with poor ratings.

    John (Britprius)
     
    #4 Britprius, Dec 19, 2013
  5. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Hey, my post was moved to a different forum....thought I was going crazy when I could not find it....

    I don't know what pressure the Sears guys put in....and I lent my tire gauge to my niece, I hope she still has it....

    I am not happy that they did not use stick-on weights -- noticed when they pulled the car up for me, but did not want to be a shrewish *itch, so did not say anything -- even when I made sure they knew to use them when I brought the car in...oh well...bigger things to do than make a minimum-wage tirebusters day miserable this time of year.

    I will try to check the pressure in the next few days and then post back.
     
    #5 cyberpriusII, Dec 19, 2013
  6. Britprius

    Britprius Senior Member

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    There is no excuse for not using stick on weights I would go back and play hell with them about damage to the alloy wheels, "unless the wheels were kerbed" to start with, but I know where your coming from.
    Yes check those pressures as soon as you can as you may see further improvements in mpg.

    John (Britprius)
     
    #6 Britprius, Dec 19, 2013
  7. Gorilla97

    Gorilla97 Junior Member

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    What size tire did you get?

    I have a 2008 touring model and I'm considering some 205/55/16's in place of stock 195/55/16's in order to have more choices and lower prices. $350 out the door seems like a great price too!
     
    #7 Gorilla97, Dec 19, 2013
  8. Britprius

    Britprius Senior Member

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    The 205's make a great improvement in the car and surprisingly the rolling resistance is lower than the 195's.

    John (Britprius)
     
    #8 Britprius, Dec 19, 2013
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  9. fuzzy1

    fuzzy1 Senior Member

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    Is there an elevation difference between your home and the tire shop? Did the journey home from the shop start with a warmer engine than the journey from home? Both could contribute to an MPG difference.

    To be really picky, we'd also check tire sizes and revs/turn per mile from the tire specs to rule out differences that might cause false optimism.
     
    #9 fuzzy1, Dec 19, 2013
  10. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    All I can say is they are the 185/65/15.

    Since I received the car new, the mpg has stayed in the 42-44 mpg range, irregardless. Cold, hot, elevation, no elevation.

    Today is probably a fluke, but I sincerely hope not. I took it out this afternoon to get my hair done and it was still hitting 52 mpg and that is all backroad, mountain driving.

    I had planned to adjust the pressure into the 42 psi range, but considering how well they are preforming at the moment, I may just leave well enough alone.
    Kris
     
    #10 cyberpriusII, Dec 19, 2013
  11. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Sad face:(

    Second day with new tires and on mile 106 and mpg is now 47.6.

    Better than my "old" average, but not in the 50's.
     
    #11 cyberpriusII, Dec 20, 2013
  12. Data Daedalus

    Data Daedalus Senior Member

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    Really? Are you using 205's? What's the approximate difference in MPG between them? Are there any pitfalls to using them? I will seriously consider them as a way of optimising my 2008 Prius T Spirit :)


    iPad ? HD
     
    #12 Data Daedalus, Dec 21, 2013
  13. Britprius

    Britprius Senior Member

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    Yes 205/55/16 tyres have many advantages over the OEM 195/55/16's that I list below. The only downside that I have come across is that the oddo under reads your millage slightly by between 2&3% depending on the tyre chosen.

    (1) They are surprisingly at leased 25% cheaper than 195's. Meaning at minimum you get 4 tyres for the price of three.
    (2) There is a much greater choice of manufacturers and types of tyre with205's
    (3) The rolling resistance is lower for 205's against 195's of the same type and make. My own car improved by about 3 mpg from OEM size tyres.
    (4) The road manners of the car are greatly improved, much more stable in a strait line on the motorway, and handling is is sharper.
    (5) The MFD readout of fuel consumption becomes much more accurate "although fuel consumption may appear to fall a little", this is only because normally it is very optimistic against calculated figures to the point where I rarely now bother to calculate my mpg as the readout is so good.
    (6) The speedo becomes more accurate, but still reads around 2 mph fast at 30 mph. (Speedo reads 30 mph, actual speed 28 mph)
    (7) The wider tyre helps to stop kerbing of the wheel trims
    (8) There are no problems with clearance or fit of 205's.

    When you are ready for tyres contact me and I will guide you, but in the mean time have a look at my post below. Scroll down to the section on 205/55/16 tyres.

    Low Rolling Resistance replacement tyres (Europe)

    John (Britprius)
     
    #13 Britprius, Dec 21, 2013
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  14. HaroldW

    HaroldW Active Member

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    Up the pressure to at least 38-36. I find the fuel max are great with 36 and up, depending on road surface. H
     
    #14 HaroldW, Dec 21, 2013
  15. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    My tire gauge came home today. Sears put 35/33 in the tires. Just as they should have.

    I debated about changing it to the 42/40 or 38/36 or something else. And may still do so, but the Cooper GFE I had rode so poorly at the higher psi, I am just going with the factory setting at the moment.

    As an aside, I ran 42/40 on the original brand new car from the dealership Goodyear Integrity and did not notice any difference in ride, but no difference in MPG, either. I don't remember if the Cooper gained any MPG at the higher PSI, but seem to think they did not.
     
    #15 cyberpriusII, Dec 22, 2013
  16. usbseawolf2000

    usbseawolf2000 HSD PhD

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    The return trip was pre-warmed-up from the initial trip. Something to consider.
     
    #16 usbseawolf2000, Dec 22, 2013
  17. Stevevee

    Stevevee Active Member

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    We had a Bridgestone LRR tire on our Camry hybrid, which I changed to Yokahama Envigors. Even when new, the Yokohamas delivered better mileage from day on. The General snow tires delivered about the same mileage. A friend of ours had a 2010 Prius LB. He made the same change, and reported the same conclusion.

    My new V has Yokahama LRR tires, and during the warmer week I put the General snows on, no drop in mileage. The Yokahams on the Camry hybrid still look fantastic, and that's after almost 4 years.
     
    #17 Stevevee, Dec 22, 2013
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