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Will the real LRR tires please stand up? Tire shopping blows.

Discussion in 'Gen 3 Prius Fuel Economy' started by Absentminded, Jan 29, 2016.

  1. Absentminded

    Absentminded Junior Member

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    I'm a numbers guy. I don't like subjective ratings. One person's 9/10 traction could be my 5/10. What sucks even more, is most review outlets have crappy methodology for evaluating tires that allow them to get bogus results. N=1 isn't good enough unless tires are manufactured to an insanely low tolerance and tested in a controlled environment. Consumer reports doesn't reveal their numbers and instead dumbs down the ratings to bubbles, so it is near impossible to call them out on it. My Nexen CP641 tires that came on the car are downright awful. I can do a burnout starting at 25mph...in a prius! (It is kind of fun, but terrifyingly dangerous if you need to make an emergency maneuver).

    Intro aside, I was hoping you all can help me out. I need more data for the real LRR tires! I've started collecting tire data for the US Market. I have attached an image of selected data from tirerack's testing with consumer reports' results for key areas compared. The top table was tested on the same 2014 BMW by tirerack. It looks like they either had some manufacturing variances or Consumer Reports fudged some ratings on purpose (like rating the Pirelli P4 Four Seasons Plus as Good in wet stops when it had a 42% reduction in grip in a 50-0 mph stop. Tirerack data shows it going from a 88.6 ft dry stop to 153 ft wet, and yet it has the SAME rating given to the Continental Truecontact that went from 88.9 ft dry to 112.5 ft wet with only a 20.9% reduction! That is such a significant variance I just can't attribute it to manufacturing tolerances.

    The legend for the data is as follows: Bold and Highlighted are tires that seem good for a Prius at the moment with decent mpg reported by tirerack's testing. Brown text tires are those to avoid if you live somewhere that gets any rain! Those are the ones most likely to give you a brown moment as you skid to a stop.

    Thus far, the data states the obvious. Michelin and Continental make great tires (with General falling under the Continental brand).


    I'd really like to get some real LRR tires on this list. So far, the test data I can find is far too outdated and many of the tires are discontinued.

    EDITS: I've tried many times to upload the excel file or a picture. It seems like I'm either not allowed to or chrome isn't playing nice. I uploaded a picture to imgur and made it a reply.



    Merged.


    [​IMG]





    Merged.

    One more comment on this. I bought the truecontacts as a replacement for the LRR contiprocontacts that came on our honda odyssey. There was immediate damage to the mpg as would be expected going from a well worn tire to new. After 5k miles, it settled in at about 1mpg less, which would be about 3-4 mpg on a prius. I'd take 45mpg if it had good road manners. I really want that 50mpg though, something these awful nexen tires could never achieve.

    Additional anecdotal evidence: A lot of complaints about mpg on those general altimax tires in the tirerack consumer reviews. I'm surprised the numbers were so much higher on the BMW test mule than the others. Maybe they got the previous version and not the same as tested Aug 2015?
     
    #1 Absentminded, Jan 29, 2016
    Last edited by a moderator: Jan 30, 2016
  2. mrstop

    mrstop PWR Mode

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    That's an interesting dataset. I just purchased the Pirelli P7 205/50R17 under the assumption that MPG was towards the top. However, your list says the contrary. I only have about 100 miles on the tires, so it's too new to sense how they'll perform in the real world.
     
  3. Absentminded

    Absentminded Junior Member

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    I have suspicions that performance may vary by size. Common BMW sizes might be more grabby on purpose since they know the target market vs a 185 ish/15 marketed toward econoboxes. I find it interesting that the P7 was rated so highly by the more recent test at CR. It may very well be better this year, as a significant difference can be seen between two general altimax rt43 tests a year apart.
     
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Let me suggest making a table. Only three tags are needed:
    • "table=head] - replace the " with [
    • | or , - these separate columns and each line is a row in the table. First row is column headers.
    • "\table] - replace the * with [ to end the table
    I throughly agree with your complaints about low rolling resistance . . . I don't trust them. So I've taken a different approach.

    I know higher pressure tires inherently have lower rolling resistance because I've measured the effect confirming many open and SAE articles. So I find tires that fit the hubs with highest possible, maximum pressure rating. Currently Yokohamas that handle 51 psi. I then size them so the revs/mile corrects the built-in 6% error on our 2010:
    • ride harder and noisier on crappy streets - it is not a problem considering the crap we used to have
    • MPG higher
    • turn handling improved - they really take a curve
    • wet handling improved - the higher pressure resists hydroplaning, not a lot but noticeable
    • higher weight capacity - maximum is at maximum sidewall psi
    Tire Rack and other tire dealers want to sell their 'recommended' Prius tires which I ignore. I pay for my tires, not their mutterings. I also handle tire rotation and replacement differently.

    My front tires wear first. So once I choose the high-pressure, correct revs/mile tires, I drop-ship a pair of them to the local Firestone dealer for service. Then I check the per tread wear of the rear tires to see if a shim kit is needed.

    The rear tires are rotated to the front. The new tires are mounted on the hubs, balanced, and put on the rear. They let the air out and do an alignment.

    When I pickup the car, I borrow an air hose; fully inflate the tires and ;reset the tire pressure sensor:
    • Buy only one pair of tires at a time half-way through their life
      • Rotate in new model tires when old ones leave the market
      • Miss the 3 for cost of 4 sales because tire wear does not follow sales schedule
    • Tire maintenance
      • Once to install or remove
      • Once to move from rear to front
    Bob Wilson
     
    #4 bwilson4web, Jan 29, 2016
    Last edited: Jan 29, 2016
  5. Absentminded

    Absentminded Junior Member

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    Thanks for the input Bob. I have been itching for data on a few Yokohama tires as well. Are you ordering standard consumer tires based on their catalog or fleet versions?

    I might put in an hour or two tonight and see if I can get some hard published data rather than what can be inferred from tirerack and the like. I suspect that the European folks have a better watchdog for tire ratings that I can lean on a little too.
     
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Considering how well they've handled VW-gate . . .

    Bob Wilson
     
  7. mrstop

    mrstop PWR Mode

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    I couldn't stand the Yokohama Avids that came as OEM. I had twice the number of flats in those tires in three years than I did my previous 30 years of driving.
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    @bwilson4web What are you saying has 6% error? Surely not odometer. So speedometer, or mpg display?
     
  9. Absentminded

    Absentminded Junior Member

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    lol. At least they found it! They just couldn't ever agree on who had the responsibility to yell at VW for it. On the US side, it took some complaining to get the EPA's attention.

    In all seriousness, their equivalent rating system at least has a measurement for economy..even if it isn't very good. It is a real pain to get government agencies to push for a change, but the NHTSA really needs to have a public law change to the UTQG to incorporate rolling resistance/economy measures. I'm feeling pretty irritated that anyone can make the claim that their tire is LRR with "less rolling resistance than a major competitor" and not be called out on it. Maybe I should start a petition on whitehouse.gov... [EDIT: Or not, Continental has already asked them to revise it so they can put it on the sidewalls like bragging rights].
     
    #9 Absentminded, Jan 29, 2016
    Last edited: Jan 29, 2016
  10. bwilson4web

    bwilson4web BMW i3 and Model 3

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    What happened is I had been using Sumitomo T4s but several years ago, they derated them to maximum 44 psi. That is when I switched to Yokohamas. it was strictly a question of maximum sidewall pressure.

    Bob Wilson
     
  11. jdenenberg

    jdenenberg EE Professor

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    Bob,

    Nokian WRg3's are rated at 51 PSI and I have documented great MPG for the previous models (WR and WRg2) when compared to the OE GY Integrity and Michelin MXV4+ (energy saving) tires. But living in the NE I want good wet/snow/ice traction tires as well as good MPG and ride stability.

    Jeff
     
    CanuckPT and bwilson4web like this.
  12. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I'm using an HEM mini OBD that reports the vehicle speed in km/h. When converted to mph, divide by 1.61 km/mile, the speed over known sections is off by 6% even though the GPS and speedometer show the posted speed limit. The same metrics come from miniVCI. So I have to multiply this vehicle metric by 106% to get the true mph. But I had already corrected the error by using tires oversized by 6% (actually 5.5%) using the revs/mile.

    Obscure fact, the brake controller takes inputs from all four wheel sensors for ABS control. It then sends a vehicle speed signal to the other controllers. In our Gen-3, it is the brake controller that is sending the false signal.

    Bob Wilson
     
  13. wjtracy

    wjtracy Senior Member

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    Nokians sound good but pretty hard to find below Mason Dixon line
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Ok, speedometer error. I just can't see changing tire size to fix a display error, and all the other things being consequently thrown off, odo for instance. Speedo reading high is pretty much mandated I think.



    Merged.



    I used Nokian WRG2 as a snow tire on a Civic Hybrid, and they imposed a distinct mpg hit, comparing to Ecopia EP20 we used the remainder of the year, at least 10%. The WRG3 is advertised as being better for mpg, tho.
     
    #14 Mendel Leisk, Jan 30, 2016
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  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Sorry, I didn't mention the odometer but it has the same error and gave me the first clue to the problem. Using mile-markers, later Garmin Nuvi GPS, I noticed the error showed up not only in speed but more accurately in distance. A typical speedometer, even GPS, only has integer values. But odometers/trip meters, have as much precision as one wants. To see a 6% error, you really need 4 digits of precision. So Scottsboro is just 45 miles away and has mile markers along the State highway.

    To see a 6% error on an integer speedometer, you really need to be at 100 mph and even then it will have +/-0.5 mph error due to integer rounding. It is much easier to use the odometer since ordinary speed are involved and precision increases with distance. In particular, the 0.1 mile resolution of trip meters means we only have +/-0.05 error in the distance metric.
    • 100 mph speedometer error +/-0.5 mph error (and somewhat exciting *)
    • 100 mile odometer error +/-0.5 mile error, ~1%
    • 100.0 mile tripmeter error +/-0.05 mile error, ~0.1%
    Bob Wilson

    * - at 100 mph the applied torque at the wheel begins to approach the traction limit. Small bumps can result in slippage errors of the drive wheels leading to under reporting of the true speed. The passive, rear wheels would have an accurate reading but we're getting into the limits of what we know about the brake controller. Since at 100 mph the traction control light is not on solidly, we're probably OK but in a curve at +90 mph, the car can trigger a traction control problem, which makes it even more exciting. This is observation, not speculation.
     
    #15 bwilson4web, Jan 30, 2016
    Last edited: Jan 30, 2016
  16. wjtracy

    wjtracy Senior Member

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  17. Xterra72

    Xterra72 Senior Member

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    I've been on the Michelin Premier A/S 17s

    It took thousands of miles before I got my MPG back up.

    Pressure at 41 fronts and 40 rear.

    Driving at 55-65 MPH and mixed traffic, I am averaging over 50 MPG

    Best All Season Tire IMO. Best handling and control in wet weather. Safety first.

    So here's one of my better MPG this winter season with my Michelin Premier A/S
    image.jpeg image.jpeg image.jpeg image.jpeg
    But then again I live in California.:D
     
    #17 Xterra72, Jan 30, 2016
    Last edited: Feb 11, 2016
  18. jdenenberg

    jdenenberg EE Professor

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    Mendel,

    If you only used the Nokians in cold weather, the lower MPG is mostly due to the lower temperature. I see a 10-20% lower MPG in the winter than in mild temperatures.

    JeffD
     
  19. Former Member 68813

    Former Member 68813 Senior Member

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    absolutely. i used to have OEM Goodyear integrity in corolla size that was outright dangerous in rain or dry and it was a good thing it didn't last long. however, honda pilot drivers loved their OEM integrities.

    even your table shows the effect (or alternatively, errors in measurements). i have continental puretraction in my prius that was about 10-15% MPG loss over OEM tires.
    the 2nd table shows the best MPG for that tire while MPG is subpar in the 1st table.
    there are similar discrepancies for the yoko Avid ascend,
     
    #19 Former Member 68813, Feb 2, 2016
    Last edited: Feb 2, 2016
  20. Mendel Leisk

    Mendel Leisk Senior Member

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    Ours were "extra load" too, that mighta been a factor. But watching tank by tank, it was like someone released the sea anchor in spring, that first tank back on the Ecopias.

    The Civic could be slipped into neutral without turning the car on, and I would use that to roll the car out into the driveway without firing up. Our garage slab has a slight grade to it, and I'd find with the EP20, put it in neutral, and either right away, or with a slight foot-out-the-door push, it'd start rolling back. With the Nokians, you had to put some oomph into it, and keep pushing, it wouldn't sustain momentum, until it hit the steeper grade driveway.