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Are my tires killing my fuel economy?

Discussion in 'Gen 3 Prius Main Forum' started by Sal43, Jun 20, 2019.

  1. Sal43

    Sal43 Member

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    When I bought my used 2011 Prius 4 with 58K miles on it last Summer, it had a set of almost brand new General Altimax RT43 all season tires on it. They are good all season tires for being so inexpensive.
    The thing that I do hate about them is that I think they're costing me at least a couple of mpgs.
    I have to work way to hard to get 50 mpg. I do try to hypermile whenever theres no traffic or there are multiple lanes in each direction. I think I should be averaging about 55 mpg because of the way I drive instead of 50.
    My tire pressures are 46 front and 38 rear BTW.
    I have attached a photo of the tires. Would it make better financial sense to just keep the tires for the next 50k miles or buy a new set of extremely low rolling resistance tires?
    How many mpgs do you think these tires are costing me?
    AltiMAXTM RT43 | General Tire
     

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    #1 Sal43, Jun 20, 2019
  2. jb in NE

    jb in NE Senior Member

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    The problem is - other than anecdotal reports of mileage with a certain tire model, where do you find actual test data on rolling resistance? Manufacturers all claim eco or green focus, but no data is presented. Tire Rack might compare measured mpg for different tires in a tire comparison test, but that is over a very short course and uncontrolled conditions.
     
    #2 jb in NE, Jun 20, 2019
  3. prev93

    prev93 Member

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    Those tires get a "very good" rating with CR for rolling resistance. Your mileage, of course, greatly depends on the speed that you drive and the type of driving you do. Setting the tire pressure way above the Toyota recommended range may be doing more harm than good, especially with regard to ride comfort and possible uneven tire wear. Also,the computer calculated mileage is a complicated number because the diameter of the tires affects the calculation. When the tires are new, they have a different diameter than when they are worn, so the computer mileage also changes.
     
    #3 prev93, Jun 20, 2019
  4. Grit

    Grit Senior Member

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    o_O
     
    #4 Grit, Jun 20, 2019
    bisco likes this.
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    I would just hang in there. They may be impacting mpg a bit, still any tire's rolling resistance will improve with miles. The sand-pounder would be to get some "extremely low rolling resistance" tires, and not see much difference, and/or have other issues, increased noise or lousy ride quality for example.

    You say you expect to get 55 mpg. What are you basing that on? Were you driving another Prius on that route? What kind of speeds are you doing? Higher speed freeway driving, no matter how careful you're driving, is gonna drop mpg.

    I just switch to Michelin Primacy MXM4, and saw an immediate, kick-in-the-gut drop in mpg. About 3 tanks later, it's starting to pick up. I do think they're breaking in, gradually.
     
    #5 Mendel Leisk, Jun 20, 2019
    Last edited: Jun 20, 2019
    Johnny Cakes likes this.
  6. WolfpackBill

    WolfpackBill Senior Member

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    Brand new tires tend to eat up MPG's. The less tread the tires are, the better MPG. Drive it a while, I'm sure you'll get your 50 MPG back.
     
    #6 WolfpackBill, Jun 20, 2019
  7. bisco

    bisco cookie crumbler

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    how many miles on her now? maybe it is time to look at the egr circuit
     
    #7 bisco, Jun 20, 2019
  8. Sal43

    Sal43 Member

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    About 60,600 miles. I only drive it once a week for now. I was pretty sure I was going to get a job in L.A. so I bought it in advance because of the high gas prices there. I did not get that job, but I will be moving to L.A. eventually probably later this year or at the latest early 2020. I will sell my other cars and only drive the Prius after moving to L.A.
     
    #8 Sal43, Jun 21, 2019
    Last edited: Jun 21, 2019
  9. Sal43

    Sal43 Member

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    I wonder if this damage already there when I bought the car is harming my fuel economy by increasing the aerodynamic drag of my Prius.
     

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    #9 Sal43, Jun 21, 2019
  10. bisco

    bisco cookie crumbler

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    the most important thing is the under panels if any were catching the air. no idea how that would translate to lost mpg's
     
    #10 bisco, Jun 21, 2019
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