How to know which tires are most efficient?

Discussion in 'Prime Fuel Economy & EV Range' started by rbwilli, Oct 23, 2022.

  1. rbwilli

    rbwilli New Member

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    As I mentioned in my previous thread, my wife saw a significant drop in EV range in her 2018 Prius Prime a few months ago. (Real-world range, not just predicted; she used to be able to make it all the way home with a little range to spare, now she runs out with some miles to go. I did a test today since the weather was perfect—it was 67 ºF—and even without any heat/AC/fan use at all, the reduced range persists.) The drop coincided with changing from a set of fairly worn-out Toyo Nanoenergy A29 tires to a new set of Primewell all-seasons.

    I have no idea how to predict the impact of a given set of tires on fuel efficiency. Is there such a thing as an efficiency rating for a set of tires? Or the degree to which they have low rolling resistance? How can we know in advance how efficient a particular type of tire will be?
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Consumer Reports does list tires and the relative efficiency within the group (their usual colour-coded up and down arrows). Otherwise, going with one of the OEM models is usually a safe choice (Yokohama Avid, Bridgestone Ecopia EP422 etc)
     
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  3. bisco

    bisco cookie crumbler

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    unfortunately, no efficiency standards, so no ratings. not familiar with primewell, but they could certainly be a large part of the problem.
     
  4. CR94

    CR94 Senior Member

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    Keep in mind that tires have higher rolling resistance when new than when worn. That effect was at least part of the drop you noticed.
     
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  5. rbwilli

    rbwilli New Member

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    Interesting, I figured they would weigh a little more, but I wasn't aware of the explicitly higher rolling resistance with a new tire. Makes sense. Thanks!
     
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  6. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    New tires also have larger OD, meaning the car think's you've travelled not as far, as when those tires are worn down, smaller OD, more rev's per mile, but the car then think you've travelled further. Fairly trivial, but a factor.

    One tire I got (on a privious car) that really hit the ground running as they say, was Bridgestone Ecopia EP20. They were OEM on some Prius, only came in 195/65R15 IIRC. And I believe they've been discontinued. When those were put on, replacing worn Bridgestone Insignia SE200_02 (no mpg slouch either), the mpg never skipped a beat.

    FWIW, mpg aside, they were very noisy when worn, and a menace in any amount of snow.

    Hmm: Canadian Tire claims to have the EP20.
     
  7. rbwilli

    rbwilli New Member

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    That's an interesting thought about the diameter and how far the car thinks it's gone. In this case it's not a factor, though (or only a minimal one), because we know she can't go as far on the same physical route. (That is, she can't make it to work and back on EV mode alone.) Encouraging that the new Ecopia EP20s didn't ding your efficiency! I'll have to keep an eye out for them—or whatever replaced them, if there's a newer model—when it comes time to switch again!
     
  8. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    Probably Bridgestone Ecopia EP422 Plus. I suspect they gave up a slight edge in rolling resistance, but they're an OEM tire used by Toyota on the Prius, so...

    One thing, the EP422 from the factory are a Made-In-Japan version. There's also two other versions, more readily available in the North America: one manufactured in the States, the other in Mexico. All three have physically different tread patterns, and various specs are different. And they all have the same name. One of them, the US itteration IIRC, has very wide longitudinal gaps, one less row of tread, in 195/65R15 at least. There was one member here reported a tire shop tried to sell him 2 US and 2 Mex, when he was replacing all tires.
     
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  9. MikeDee

    MikeDee Senior Member

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    If you buy the Bridgestone EP422 Plus from the dealer, will you get the Japanese version?
     
  10. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    I don’t think so. Ask? Around here I think dealerships mostly sell just snow tires.
     
  11. FuelMiser

    FuelMiser Senior Member

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    Try searching "fuel efficient tires for prius" in your favorite Search Engine
     
  12. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    With the dearth of accurate LRR data, there could be a buisness model for a website, something like "Bob is the Tire Guy"? Develop a database of opinion, for various factors, LRR included? Maybe it already exists?
     
  13. MikeDee

    MikeDee Senior Member

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    Consumer Reports tests tire on a dynamometer for rolling resistance.
     
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  14. pasta4breakfast

    pasta4breakfast Junior Member

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    I experienced the same thing this year with my 2020 prius prime. I was getting arount 6-6.1 miles/KWh until I got a nail in my tire after 42,000 miles. I replaced all 4 of my factory installed Dunlop Ensave tires with Michelin X-Tour tires on June 6th 2022. The efficency dropped about 10% to 5.4-5.5 miles/KWh and hasn't appeared to to recover after driving 10,000 miles. You can see a table of my efficency in 2021 and 2022.

    Effeciency (miles/KWh)
    Month ---------- 2021 --- 2022
    January -------- 5.3 ----- 5.7
    February ------- 5.8 ----- 5.9
    March ----------- 5.6 ----- 6
    April ------------- 5.8 ----- 6
    May-------------- 5.8 ---- 6.1
    June-------------- 5.8 ---- 5.5
    July -------------- 5.9 ---- 5.4
    August ---------- 6 ----- 5.5
    September ---- 6.2 ---- 5.5
    October -------- 6.1 --- 5.5
    November ----- 6.2 ---- 5.4
    December ----- 5.6 ---- 5.2
     
    #14 pasta4breakfast, Jan 6, 2023
    Last edited: Jan 6, 2023
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  15. randerson9248

    randerson9248 Junior Member

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    I have a 2000 Honda Insight hybrid. The original tires were a Bridgestone Potenza. I went thru several sets of those tires, they had terrible tread life, but good low rolling resistance. Those tires are getting hard to come by, so the last set I bought were a LRR Dunlop. MPG dropped dramatically, by about 10mpg. The car can no longer maintain highway speed in 5th gear with the AC on. By highway speed. I mean 60mph. That's how bad the Dunlops are. I wish there were published numbers on actual rolling resistance.
     
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