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Increasing Speedometer Descrepancy At Speed

Discussion in 'Gen 2 Prius Main Forum' started by a_gray_prius, Jan 6, 2010.

  1. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    I changed to a set of Nokian winter tires a couple months ago from a completely-done set of OEM Turanzas on my 08 Touring. Both are stock size and inflated properly while cold (air temperature/volume is not to blame).

    I had noticed that there was a 1mph discrepancy (to a GPS) with the old, totally worn out tires which I attributed to decreased diameter from tire wear. Now that I have replaced the tires, this has increased to 2-3mph. The difference has been observed to be as high as 4mph. Given that the car is often travelling at speeds where this effect is seen, I'm a concerned about the cumulative effect on the odometer. Is there any verifiable evidence that the odometer isn't diverging from the real mileage?

    In the end it probably won't matter since I fit 205/55/16s during the summer.

    EDIT: I have Nokian Hakkapeliitta snow tires, not any sort of WR. I have dedicated rims for winter and summer.
     
    #1 a_gray_prius, Jan 6, 2010
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Interesting... I haven't checked my speedo against the GPS with the WRs. I do recall it being spot on with the Integritys.

    It shouldn't be too big of a deal esp. if the Nokians that you have are very very close in revs to the old Turanzas.
     
    #2 Tideland Prius, Jan 6, 2010
  3. kenoarto

    kenoarto Senior Member

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    I have checked the speedo vs GPS and get about 1.5 mph at speed. I also changed tire size.
     
    #3 kenoarto, Jan 6, 2010
  4. gak27

    gak27 Prius, Take Two

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    I get about 2 mph difference w/ my new Nokian WR G2, standard size...
     
    #4 gak27, Jan 6, 2010
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