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Lower MPG since new tire

Discussion in 'Generation 1 Prius Discussion' started by PriusLight, May 4, 2011.

  1. PriusLight

    PriusLight New Member

    Joined:
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    New England
    Vehicle:
    2002 Prius
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    N/A
    Greetings,

    I own a 2002 Toyota Prius. I've owned it since 2010 Nov. I averaged 40mpg. Now that it is warmer.... I averaged 45/46mpg.

    But something happened ....

    Upon entering NY, I was excitedly greeted by a pothole that decided my car would look much better with 3 working tires. Since I was in a rush, I purchased a tire that matches size but I'm not sure if it's a LRR tire? The capacity stated on this tire is (36psi) while my other original tires state (50psi). I always fill to 36psi anyway for the smoother ride. However, my gas mileage dropped to 41mpg. And this is the second tank since then.

    Can it all be owed to that one tire that might not be a LRR tire?

    As a side note: A relative of mine drove it on the way back home and this relative drives every single car as if it is a super-charged corvette and there is a huge tidal wave about to come crashing down behind us. Needles to say, I expected a lower overall average miles per gallon from that trip back home b/c of this persons driving habits so it might be the computer needs to re-adjust to my driving style???

    Any help would be GREATLY appreciated!

    Thanks
     
    #1 PriusLight, May 4, 2011
  2. cyclopathic

    cyclopathic Senior Member

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    2014 Prius c
    Vehicle:
    2010 Prius
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    II
    what are the old/new tire brands?

    From what I read the difference in drag btw LRR and non-LRR tires could be up to 30%. Even if you take that for # your MPG will only decrease by 7.5%. Also new tire has ~20% higher rolling resistance then the same tire worn.

    Also, by any chance you don't have mismatched tires up front, do you? If you do, put them back in the rear. Tires are most likely slightly different diameter, and it will cause trans-axle to work (same way as turning) when you go straight. This will increase friction, wear and lower MPG. If diameter is too different, it will destroy trans-axle.

    Also check pressure, new tires usually stretch and drop a few PSI in a few hundred miles.
     
    #2 cyclopathic, May 4, 2011
  3. PriusLight

    PriusLight New Member

    Joined:
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    Location:
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    Vehicle:
    2002 Prius
    Model:
    N/A
    I will try this out. The tire shop that I got the tire from didn't replace it in the same location.... he rotated/swapped them around and put the replacement tire in the right-rear as opposed to the left-rear which had the tire blown-up. So all tires are probably not in their original location. He claimed he had to do this b/c of differences in wear and tear. I will see if I will take it to a toyota dealership and have them take a look see.
     
    #3 PriusLight, May 4, 2011
  4. cwerdna

    cwerdna Senior Member

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    The above is important, please also indicate the model and size.
     
    #4 cwerdna, May 4, 2011
  5. PriusLight

    PriusLight New Member

    Joined:
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    Location:
    New England
    Vehicle:
    2002 Prius
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    N/A
    Most certainly!

    Old Tires (when I got the car): BridgeStone Potenza P1751/65R14/84S

    Replacement Tire: BCT S600 175/65R14/82H

    Extra details: On the way back --- when we got 40 mpg--- The replacement tire was under-inflated...about 25 spi...the 3 other tires were slightly under inflated and we were driving back heading north. When I got back to New England, I inflated all the tires to 36psi and started driving how I normally drive (with a bit more hypermiling) and now my MPG improved up to 44.3mpg during this week. Still.... I was easily getting 46/47mpg once it got warmer and before that tire blew out. I haven't taken it to Toyota yet.... hopefully this helps in diagnosing what happened.
     
    #5 PriusLight, May 6, 2011
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