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New tires & fuel efficiency

Discussion in 'Prius c Fuel Economy' started by Steve Lees, Oct 2, 2017.

  1. Steve Lees

    Steve Lees Junior Member

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    I recently bought new tires, going from the well-worn stock Bridgestones to Yokohama Avids. I’ve noticed an immediate decrease in fuel efficiency - I was averaging low 60 mpg on my mostly highway drive commute with the Bridgestones, and I’ve dropped back to the mid-50s here the last week.

    I jokingly told my wife all of that tread was increasing the rolling resistance. I wonder if there is some truth to that. I’m running 34lbs pressure in the new tires, same as the old. Any comments or thoughts? I ended my run of 33 straight tanks of 60 plus mpg and was bummed out.
     
    #1 Steve Lees, Oct 2, 2017
  2. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Yeah new tread is deeper, squirms more, accordingly has higher rolling resistance. And the rubber is newer, more pliable, same story. And: a well worn tire has a slightly smaller outside diameter, which means more revolutions per mile, which means when travelling the same distance the car thinks you've gone slightly further, which affects both in the in-dash mpg display and the odometer and trip meters, if you're calculating. And it's two different tires of course.
     
    #2 Mendel Leisk, Oct 3, 2017
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  3. wjtracy

    wjtracy Senior Member

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    #3 wjtracy, Oct 3, 2017
    Last edited: Oct 3, 2017
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  4. Steve Lees

    Steve Lees Junior Member

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    Thanks guys. I sort of thought it might be the case but did not realize the effect would be so noticeable. The stock tires were done; I got about 75k miles out of them and they were on the wear bars. They were getting questionable in the rain and would have been unmanageable in the snow if I had kept them.
     
    #4 Steve Lees, Oct 3, 2017
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  5. ztanos

    ztanos All-around Geek!

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    On most cars you'd have never noticed. But when you're getting 60 mpgs, a 10% change is still 6 mpgs. On a 25 mpg car, that's only 2.5, so you'd barely notice it, or chalk it up to cooler air.
     
    #5 ztanos, Oct 3, 2017
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