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New Tires For 2011 - Load Index

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Spoodles, Nov 14, 2014.

  1. Spoodles

    Spoodles New Member

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    My 2011 calls for P195/65R15 89S. I'm not that familiar with the service description at the end, "89S". I was thrilled to find a great deal on Pirelli P195/65R15 91T, a very highly rated 85k tire, so I ordered these. Now the guy at the shop is telling me that people have reported drastically reduced gas mileage, like up to 20MPG less, with this tire!

    Can a load index of 91 vs 89 really make a big difference in MPG?

    I can get the 89S in a Goodyear Assurance or Eagle, but the reviews I find don't regard these nearly as high. And they're more expensive, and warranted to 65k instead of 85k on the Pirelli.

    Got to replace those baldies, the snow's coming...
     
    #1 Spoodles, Nov 14, 2014
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    No.
    The Prius uses Low Rolling Resistance tires. So long as the 91T tires are LRR, there should only be the usual 5 MPG drop until they break in.

    If the tires you are looking at are not LRR, they will have a large drop in any load range.

    A load index of 89 =1279 pounds
    A load index of 91 =1356 pounds
    (A Prius has a curb weight of 3042 pounds, try to stay on all 4 wheels)
    A speed rating of S =112 mph
    A speed rating of T =118 mph

    If what you ordered are Pirelli P4 four seasons, they are not LRR. The P6 four seasons are LRR.
     
    #2 JimboPalmer, Nov 14, 2014
    Last edited: Nov 14, 2014
  3. Spoodles

    Spoodles New Member

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    Ah, so it's all about LRR, not the service index. Now if I could just figure out if Pirelli P4 FOUR SEASONS - P195/65R15 91T are LRR, I doubt it.

    Thanks.
     
    #3 Spoodles, Nov 14, 2014
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    If the guy at the shop is telling you that tire has high rolling resistance, you can believe it, because they rarely say boo on the subject. If he's that worked up about them, it's likely true, lol.

    Rolling resistance ratings are not mandated, and info is spotty.

    If you want just want a decent tire with low rolling resistance, pretty easy to find, Bridgestone Ecopia EP20 is good. Michelin Energy Saver A/S is the LRR leader, but more expensive and limited supply.
     
    #4 Mendel Leisk, Nov 14, 2014
  5. lar.smith42

    lar.smith42 Active Member

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    I have 195/65-15 Yokohama AVID Ascend tires on my 2010. Good tire, better than the Michelin Defenders I had.
     
    #5 lar.smith42, Nov 14, 2014
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    They're one of the OEM tires Toyota chooses, I think? That's one good way to choose LRR, Toyota's going to use tires that roll well. EP20 are also on that list. They tend to be mundane but serviceable tires, not too expensive either.
     
    #6 Mendel Leisk, Nov 14, 2014
    lar.smith42 likes this.
  7. Spoodles

    Spoodles New Member

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    Thanks for the help all. I'm much more informed now.
     
    #7 Spoodles, Nov 14, 2014
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