Got new Michelin Defenders now getting 9mpg less!

Discussion in 'Gen 2 Prius Fuel Economy' started by parkp81, Aug 19, 2015.

  1. parkp81

    parkp81 Junior Member

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    I have a 05' base and it currently has 114k miles on it. I recently got new tires for it maybe 2 months ago and I used to get around 42-44mpg and now i'm getting 33-34mpg. The weird thing about all of this was I was getting around 36-37mpg for the 1st month I got the tires, and now its worse!?

    I'm sure its hard to answer this question, if you don't have the Michelin Defender tires, but will I ever get back to even 40mpg?

    I wish I could return them, but now it's too late. :(
     
  2. alekska

    alekska Active Member

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    Its not the tires, its something else. Just a coincidence that your mpg vent down after the tire change.
    Check your oil level (overfilled? incorrect oil viscosity?) 12-V battery condition, etc. Maybe check the tire pressure too, just in case.

    - Alex
     
  3. bisco

    bisco cookie crumbler

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    alignment? and it is the tyres somewhat.
     
  4. Beachbummm

    Beachbummm Senior Member

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    if they are NOT Low Rolling Resistance Tires your MPG will drop, any the shop should have told you this or were these tires on sale and you asked for them..they will not suggest the others if they are dumping old over stock tires.

    pump them up from 42 to 44 psi
    it might help
     
  5. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    10 year old Prius.
    I'm thinking there's something else going on besides the tires.

    I have a different generation Prius, but I don't think I could make my car get a 33MPG tank average even if I pulled stumps with it. What else have you done to the car in the last two months?
    Has it been to the dealer?
    New 12v battery?
    Recent brake work?

    Bump your tire pressures up.
    Check your oil level.
    Do a crude alignment check (let go of the wheel on the highway)
    Check for excessive heat on your rotors and drums after about a 10 mile run. They'll be dinner plate warm but not overly hot to the touch.

    If all this fails....keep looking.

    Good Luck!
     
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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  7. parkp81

    parkp81 Junior Member

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    I check the tire pressures regularly and have them at the same PSI as my previous tires. 38F and 36R.

    Oil level is regularly checked, and oil consumption at most is very very little.

    12V battery was changed last year with the bigger Optima Yellow Top, just as preventative maintenance.

    I bought the car with 96k from a Toyota dealer, and the previous owner had all work and recalls done by the same dealer. I have all the records.

    I changed the front brakes last year, with new pads and rotors.

    The only thing I haven't done is alignment. I am pretty comfortable working on cars, and have done a DIY alignment before on my own with my previous cars, so I guess when I get time I can do a rough alignment check.

    I guess I will try to bump up the PSI and also check the alignment, and go from there.

    Thanks for your responses.
     
  8. wjtracy

    wjtracy Senior Member

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    The skinny on the Defenders is they are long lasting, but you do give up a few MPG. So as far as cost-effectiveness they are very good. But you're saving tire change $$$. I opted for Defenders on my van but went with Conti True Contacts on the Prius.

    And of course even going to same tire (see TireRack.com article) you can lose a couple MPG with new because they are less revs per mile etc etc but the drop to 33 is not good or expected.
     
  9. Daves09prius

    Daves09prius Active Member

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    The new tires will need time to "wear-in" and your mileage should go back up eventually after a few hundred miles. Make sure to keep the air-pressure up. Hope the mileage gets better soon!
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    I'm sceptical. If the mpg goes back up, it'll be in the main because you try all the harder, employ more tricks. There's a very slight improvement in mpg over time, but a good LRR tire will deliver good mpg from the get go, with no additional effort.

    Michelin rates the mpg capability of the Defenders two steps down from the Energy Savers A/S, on their website. It rates Premier A/S better, in between the ES and the Defenders.
     
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  11. Bagito

    Bagito Junior Member

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    How do you like the Conti Truecontacts. I'm in the market for new tires.
     
  12. wjtracy

    wjtracy Senior Member

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    I like them because they are quiet compared to the older tires.
    Our driving habits have changed to short trips, so I don't have a good MPG data point.
    Tire Rack though the good reports seem to keep coming in.
     
  13. KV55

    KV55 Member

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    I changed to Goodyear Efficient Grip Performance from the original type Bridgestones last winter and my mpg dropped a little before improving. I am now getting an extra 2mpg compared to last summer (70mpg UK vs 68). The tyres are quiet and they run well at 32psi.
     
  14. Britprius

    Britprius Senior Member

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    I also run the same Goodyear tyres but have fitted 205/55/16 instead of 195/55/16. The 205's are 25% cheaper than the 195's and improve the handling of the car without mpg loss.
    If you are getting 70 mpg at 32 psi I strongly recommend going to 38/36 psi or 40/38 psi as this will raise your figures by another 3 mpg at least. It will also greatly improve the stability of the car.
    The pressures you are using are below even what Toyota recommend that are known to give high ware rates to the shoulders of the front tyres.

    John
     
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  15. Lucifer

    Lucifer Senior Member

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    I'm running the defenders, 58 on trips 53 around home and I live on a mt, it's not the tires, plug it in to an obd2 reader and find what codes are to be found, even if it's a Toyota dealer
     
    #15 Lucifer, Aug 25, 2015
    Last edited: Aug 25, 2015
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