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Gas mileage and tire size

Discussion in 'Gen 2 Prius Fuel Economy' started by hollybob, Feb 6, 2010.

  1. hollybob

    hollybob New Member

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    Ventura, Californi, USA
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    2001 Prius
    I own a 2007 Prius, the low end model. I purchased it used with 29,000 miles and it appeared to have the factory installed tires. I believe they were 185/65/15. I recently replaced them with a set of Sumitomo HTRH4 195/65x15. Both my wife and I noticed an drop in MPG after installing the new tires.
    I believe I previously averaged about 48 mpg combined city and highway. I now average about 42 mpg combined. Could this be caused by the change in tire width or some other tire related issue. I got a good deal on the new tires. The set of 4 was $313 out the door. So even if my mileage is less is there anyway to calculate overall expense savings or extra cost assuming that the new tires caused the drop in mileage?

    I have noticed the same drop in mileage by using both the mileage indicator in the dash and also recording the mileage each time I fill up and dividing it my the number of miles driven on a tank of gas.
     
    #1 hollybob, Feb 6, 2010
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Many (all?) owners report lower mileage with new tires. It is one of the reasons we assure new owners their mileage will improve, they all start with new tires.

    Heavy tires/wheels will get less gas mileage than light tires/wheels. Your tire weighs 2 pounds more (each) and has a larger diameter than stock, so the speedometer/odometer/trip computers will all be off slightly. (25.1 inches versus the stock 24.4 inches)

    A Low Rolling Resistance tire can get better mileage than a 'normal' tire of the same size, the HTRH4 is not a LRR tire.
     
    #2 JimboPalmer, Feb 6, 2010
  3. malibucarl

    malibucarl Member

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    We put 195/60/15 Falkens on both our cars about 6K miles ago. They are run at Toyota suggested inflation settings. We have both lost +/- 2mpg.
    They ride beautifully and handle great in the recent heavy rains.
    Carl
     
    #3 malibucarl, Feb 6, 2010
  4. priusincc

    priusincc Member

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    Vehicle:
    2012 Prius
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    Three
    I went with a set of GY Assurance FuelMax tires(185/65/15 size) on a warranty replacement. I stuck with the OEM size to keep the speedometer, as accurate as possible. They seem to perform a little better than the Intregrities, and the average MPG has generally increased slightly. I have read posts that others have also experienced an increase. There are better tires available, but the lower warranty cost of FuelMax made it a good deal.
    I agree with JimboPlamer, I think your different tire diameter effected your MPG.
     
    #4 priusincc, Feb 11, 2010
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