Non-low-rolling-resistance tires and/or low-profile tires detrimental to the fuel economy

Discussion in 'Prime Fuel Economy & EV Range' started by Gokhan, Dec 25, 2020.

  1. Gokhan

    Gokhan Senior Member

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    This article discusses that non-low-rolling-resistance and/or low-profile tires are detrimental to the fuel economy and EV range.

    Moral of the story: Always replace your Prius Prime's tires with the latest low-rolling-resistance OEM tires of the size and ratings specified on your tire placard.

    Math proves big tire sidewalls are better for the planet
     
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  2. jaqueh

    jaqueh Active Member

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    No thank you! Safety is always more important than fuel economy, and the Toyo Nanoenergy is probably the worst tire I've ever experienced in the wet once they go past 7/32. Never again. Defender or bust!
     
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  3. M One

    M One Member

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    Hard to win this argument.
    You'll be surprised how many would sacrifice safety and comfort for that 0.35 MPG extra.

    Exaggeration a bit you know what I mean..
    Posted via the PriusChat mobile app.
     
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  4. Rmay635703

    Rmay635703 Senior Member

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    Meh,

    And then there are tires that aren’t LRR and have terrible traction (worse than energy savers) but last 90,000 miles

    and a LOT of people will buy a 90,000 mile tread wear warrantied tread regardless of how terrible they are by other metrics just to avoid the hassle of replacing tires more often.

    I guess there is that thing called freedom of choice and oddly enough, regardless of what black rubber donut you ride on you probably won’t hit anything or loose control.

    Funny part is the Michelin’s I’ve owned have been total garbage, I’m probably only gonna see 30,000 miles out of this set (one cracked in the middle at 15k)
    OEM Goodyear’s got me 60k+

    Going back to Goodyear’s and after that maybe some ecopias
     
    #4 Rmay635703, Dec 26, 2020
    Last edited: Dec 26, 2020
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  5. Gokhan

    Gokhan Senior Member

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    Read the article. It claims that performance tires decrease the EV range by 26.5% over low-rolling-resistance tires—53 miles out of 200 miles. This translates as 55 mpg vs. 75 mpg—a 20 mpg difference.

    This is the first time I've heard that Toyota installs unsafe tires on its cars. The Prius Prime with its OEM tires is praised for its safe handling by Consumer Reports—more so than than most other cars.
     
    #5 Gokhan, Dec 26, 2020
    Last edited: Dec 26, 2020
  6. John321

    John321 Senior Member

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    I had two set of Michelin Defenders on my 2008 Prius 1st set lasted 72,000 miles, 2nd set was still on vehicle when we sold it a 150,000 miles. One of the best tires I ever owned.

    My 1st set had to be replaced due to cracking around the rim bead at 75,000 miles and 5 years. I attribute this to me running the tires at 42 psi for high mpg. I think this high pressure in the tires also caused my wheel bearing to fail as well as having to replace my struts and shocks early. Looking back ,the uncomfortable stiff ride and failed front suspension components were certainly not worth the slightly higher mpg.

    I realize others experience with this tire could certainly be different.
     
    #6 John321, Dec 26, 2020
    Last edited: Dec 26, 2020
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  7. Mendel Leisk

    Mendel Leisk Sand Pounder

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    That’s my take too. Maybe stick to 2~3 psi over, max.
     
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  8. Salamander_King

    Salamander_King Senior Member

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    Personally, I would not put low-profile larger tires on my PP, but the entire industry is going in that direction presumably due to consumer demands. For PP, there is no larger wheel on the higher trim, but for regular Prius, Toyota put 17in OEM wheels on higher trims instead of 15in found on lower trims. Yeah, maybe larger wheels with low profile tires may offer better handling. But on Prius does it really make that much difference?
     
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  9. jdenenberg

    jdenenberg EE Professor

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    The Nokian WRg4 "All Weather" tire is safe, strong (get the "H" rated), and LRR (not the "run flat").

    JeffD
     
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  10. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I haven’t been paying that much attention of late, but it used to be higher levels were available with both 17” and 15” wheels. To complicate things, the 17” levels often had a steering/suspension upgrade.

    I’m thinking long and hard about going to 15” all-seasons on our 2010 Touring (CDN level), have some sweet rims ready to go. Best of both worlds: suspension/steering upgrade plus more fuel efficient and cushier tires.

    Mostly holding back to see what Toyota does next Fall, if they come out with a 5th gen that’s not a monstrosity I may rethink it.
     
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  11. Salamander_King

    Salamander_King Senior Member

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    I just checked the US Toyota site. Yes, both Prius XLE and Limited trims have 15" tires "available" as part of an option package while the special 2020 Edition has no such option listed. I really wonder how many Prius XLE and Limited trims are sold with 15" tires as an option? I think that would be a very small number.

    upload_2020-12-26_11-35-50.png
     
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  12. Gokhan

    Gokhan Senior Member

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    I doubt the tire, wheel bearing, strut, and shock failures were caused by the high tire pressure. My guess would be that you were driving too fast on very rough roads or speed bumps or hit the curb, a pothole, or some other object at some point. A lower tire pressure wouldn't help much in those conditions and/or incidents.
     
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  13. John321

    John321 Senior Member

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    I was basically the only driver of the2008 Prius and bought it new. Always drove cautiously as I am by nature a slow cautious driver. While the roads aren't perfect and neither am I the roads I drove were in good shape.

    I replaced the wheel bearing myself and then took the time to remove the old bearing from the hub, clean it and then cut it apart with a Dremel tool to diagnosed the failure. I am a mechanic by trade who eventual moved into Engineering. I felt content with my diagnosis of the wheel bearing cause of failure after looking at the cut apart bearing but as I admitted earlier I am not perfect just passing along my experience.

    Also replace the struts and shocks myself on the vehicle. The difference in the ride between the 42 psi I was running and the recommended 35 psi is remarkable. I actually feel a little foolish admitting I ran the tires at 42 psi but you live and learn.- wouldn't ever make that mistake again. No wonder the rest of the family wasn't interested in driving Dad's Prius.
     
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  14. AldoON

    AldoON Member

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    I have to disagree with this.

    Regarding tire size, I agree that smaller rims are better. Unless you're really interested in making your car look nicer, 15" will be more fuel efficient and tires are less expensive to replace. Also, ride will be less harsh. Most likely a Prius isn't driven hard enough to make use of the handling advantages of a larger rim.

    Regarding more rolling resistance tires, I wouldn't make any black or white statements. Depends on how much you drive, where you drive, how you drive and how much you value safety. No right or wrong answers there. Key thing is to consider everything when deciding... Not just MPG.
     
  15. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Funny, in Canada there’s no 17” tires, on any level anymore. Maybe as option, I didn’t deep-dive.
     
  16. Gokhan

    Gokhan Senior Member

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    OK, but didn't the wheel bearing and tire fail only on one side? How do you explain only one side failing if the cause was the higher tire pressure?
     
  17. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Higher pressures can’t help. You are transmitting more shock. Likely many factors contribute to suspension/bearing failure, but why discount it?
     
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  18. Gokhan

    Gokhan Senior Member

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    Yeah, but 42 psi is not that high. Often tire-pressure gauges have ±3 psi accuracy or less and temperature changes between day and night can easily make ±3 psi or more of a difference. So, having 6 psi more than the factory spec shouldn't be detrimental. Of course, one can also have a faulty gauge and the tire pressure could be really off. I Google'd wheel-bearing failures and no one seems to have ever mentioned the tire pressure. Dealers often put 40+ psi, too.

    Was the damaged wheel bearing on the right side? Often people hit the tire to the curb while parallel-parking and damage the tire, wheel, and suspension components.
     
  19. jaqueh

    jaqueh Active Member

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    I think most Prius Primes are now getting installed with Ecopias, but mine was an earlier model with Nanoenergy. They are seriously the worse tires I have ever driven. Thankfully I no longer have a Prius Prime (just got a Model 3 LR AWD), and those tire widths are a revelation. Why would anyone trade 5% efficiency gains for IMO 20% loss in grip? Makes no sense to me.

    However, I totally agree that going with the largest sidewall that a manufacturer has to offer is a good call. I just don't believe LRR tires are worth the tradeoff in grip.
     
  20. Mendel Leisk

    Mendel Leisk Sand Pounder

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    What does that mean? Typo?
     
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