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Reduced Wh/Mi after new tires

Discussion in 'Model S: Battery & Charging' started by cheers3893, Dec 17, 2014.

  1. cheers3893

    cheers3893 Member

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    I am seeing a consistent noticeable decrease in the Wh/Mi for my routine daily drives after I got new tires put on at the service center. I got the same brand/model tires as before. Nothing else changed. I have monitored it for about a month now and it is definitely worse. New tires wouldn't make a difference would it? Has anyone else seen this after getting new tires -- or maybe after a service appointment? I had them check the logs remotely and they didn't see anything. I might take it back to see if they can find something. It's about a 5-10% difference.
     
  2. wycolo

    wycolo Active Member

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    Pressure?? Also has been stated here that 'same' tires get internal changes to their construction that might not show up as different model#. Latest all-season OEMs are supposedly extra efficient.
    --
     
  3. Jeff N

    Jeff N Active Member

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    This is normal. Worn tires have lower rolling resistance. What matters is the average rolling resistance over the life of the tire. It will get better as it wears.
     
  4. Sparrow

    Sparrow S105/ Roadster 189

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    I am assuming you are really saying your Wh/mi have gone up not down. Going down means you are more efficient.
     
  5. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Wycolo and Jeff have it right. Low tire pressure and new tires can easily account for the difference (assuming you actually mean increase in Wh/mi). Of course, the tire manufacturer can easily made an undocumented spec modification to the tires--and they often do (which is why you should rotate your tires so that all are worn out at the same time).
     
  6. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

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    Better grip with new tires give better road handling and less energy efficiency. I've seen the difference with each new set I get... If you slightly overinflate, you may offset some of the changes... I'm sure someone will have issue with that, though.
     
  7. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Just with the terminology. Overinflation means inflating to more than the pressure marked on the sidewall when the tire is cold. Adjusting pressures to suit driving conditions is not overinflation. Bear in mind the vehicle placard pressure is a recommendation based on a set of assumptions--change the assumptions and you need to adjust the pressure.
     
  8. Ddowns2050

    Ddowns2050 Member

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    I just got new tires and I too am seeing a lot more watts per mile. The weather has got colder also. I went from depending on temp. from about 280-330 watts per mile to about 350-430 per mile. Same tire. 19" goodyears. Hopefully if temp. rises this will come down some.
     
  9. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Cold weather always increases energy usage because of heater use, more rolling resistance factors (rain, snow, denser air, and cold tires). Be sure to add air to the tires to compensate for the "shrinkage" in cold weather. A 25% reduction in MPG is not uncommon for ICE vehicles (although few actually track this). EVs are similar, but due to the advanced instrumentation, it's hard not to know that a reduction is happening
    .
     
  10. Bugeater

    Bugeater Member

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    I've been concerned about higher energy use for a while. It too started when I got new tires. I was thinking it was alignment. I had issues with alignment for a while after getting the new tires. Even after the alignment issues were resolved, I still have issues with higher energy usage. I used to get 320 - 350. Now I'm regularly getting 380 - 450. It's been 6 months or more.
     
  11. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I guess we need to know what kind of tires. There are many that will give poor Wh/mi results. I'm sure you've already checked the pressures.
     
  12. Bugeater

    Bugeater Member

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    The tires are stock 21". The same before and after. Haven't had time to check pressure. Maybe today.
     
  13. PaulusdB

    PaulusdB Mayor Gnomus Vintage Limb

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    Actually, the 1/4" threadwear made the old tyres/wheel turn more revs per mile travelled. So your odometer was a bit off, and is now correct again with the new tyres.
     
  14. Bugeater

    Bugeater Member

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    But the old tires had close to the same usage over their entire life. Why would the new tires suddenly be worse than the original tires were when they were new?
     
  15. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Just because the make and model of tire is the same, doesn't mean that the tires are the same. Manufacturers change the tires all the time to improve them in one way or another (improvements are in the eye of the beholder). Buying tires is somewhat similar to buying wallpaper. You want to get the same batch so that the wallpaper will match. That's the big reason to rotate tires so that they wear out at the same time (assumes the same size tire on all wheels.)

    That said, it's normal for new tires to be less efficient than the tires they replace. The best efficiency is always at the lowest tread depth.
     

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