Wheel Inertia explained.

Discussion in 'Gen 3 Prius Technical Discussion' started by SpaceShip1, Jun 12, 2016.

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  1. CR94

    CR94 Senior Member

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    Regarding air drag, you are substantially correct.

    Regarding rolling resistance, you are still confused. "Contact friction" is not the same as rolling resistance. Even if (hypothetically) a wide tire and a narrow tire were made of identical materials and had the same friction coefficient against pavement, on the wider tire, a larger area of tread rubber must flex from round to flat (at the bottom) and back to round with every revolution. Flexing rubber absorbs energy through mechanical hysteresis. That's not the only reason the wider tire is likely to have higher rolling resistance, but might be the most obvious.
     
    #21 CR94, Jun 17, 2016
  2. ftl

    ftl Explicator

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    Or is that Will Bobson? :D
     
    #22 ftl, Jun 17, 2016
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  3. bisco

    bisco cookie crumbler

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    will do!(y)
     
    #23 bisco, Jun 17, 2016
  4. SpaceShip1

    SpaceShip1 New Member

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    Yeah contact and rolling have nothing to do with each other, not sure why I said that...

    But I still respectfully disagree with you. The rolling resistance of a tire is based on the amount the tire deforms in the radial direction, and if a wide tire and a narrow tire are at the same pressure, the narrow tire will deform more in the radial direction. A tire that deforms more in the radial direction will be less round, and therefore have a higher rolling resistance. See this article: Rolling Resistance | Schwalbe North America
    And also, wider tires are typically run at a higher pressure.
     
    #24 SpaceShip1, Jun 17, 2016
  5. Toppcat

    Toppcat Member

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    Very true! But the more weight will carry more rotational inertia! But requires more energy to turn over! I observed my Prius w 17 inch will over take Prius w 15 inch wheel on a down hill.
     
    #25 Toppcat, Jun 18, 2016
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