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Standard vs Low regen and rear tire life?

Discussion in 'Model S: Driving Dynamics' started by Linux64, Sep 22, 2014.

  1. Linux64

    Linux64 Member

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    With my P85+ my second set of 265/35-21 rear tires are about used up. My first set I got about 7k miles and the second set about 10k miles. Tesla did a tire alignment and installed the new washers/nuts in between the two sets. I also switch to my 19" winter set for 6 months out of the year -- those seem to be wearing at a normal rate.

    I would like to get more life out of my tires. What are your thoughts on standard vs low regen and how that setting might impact tire life (if any)?

    Thanks in advance for your input.
     
  2. kjl

    kjl Member

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    So, I don't have any experience, but my thoughts are - you're going to slow down when you want to slow down whether you're on standard or low regen - it's just a question of whether that energy goes into the battery or the brake pads. So I wouldn't expect any significant difference.
     
  3. Todd Burch

    Todd Burch Electron Pilot

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    #3 Todd Burch, Sep 22, 2014
    Last edited: Sep 26, 2014
    I believe regen level affects tire life VERY little compared to other, far more important factors. (Like, maybe 5% at most).

    Key factors on tire life, in order of importance (highest first, and all IMHO...I merely have anecdotal experience to substantiate this):

    1. High burnout/mile ratio. :rolleyes:
    2. Poor Alignment (toe/camber)
    3. Rubber (soft 'n sticky performance tires vs. touring)
    4. Driving style (hard cornering, heavy acceleration)
    5. Suspension level setting
    6. Tire pressure
    7. Regen setting
    8. Driving surface
     
  4. lloyds

    lloyds Member

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    I agree. I just keep our +s in standard regen. We've had to change the tires out at 8k, but that's because we have the 21s.
     
  5. N4HHE

    N4HHE Member

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    I run my plain S 85 in high regen all the time. This is my right rear at 5000 miles:

    Right_Rear_1.jpg
     
  6. kennybobby

    kennybobby Member

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    Are you replacing that tire--does it have a problem or worn out?
     
  7. TES-E

    TES-E Member

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    You forgot to include tire pressure. Has to at least in the middle of your list.
     
  8. N4HHE

    N4HHE Member

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    No, I had it off at 5,000 to rotate. Looks practically new. And it rained on me before I finished!

    Rotate_1.jpg

    Rotate_2.jpg
     
  9. TsRocket

    TsRocket Member

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    20,000+ on my 21's, but i'm a girl. I learned on other cars, you can leave rubber on the road if you want. I'd rather get the better life from my tires, so i dont peel out. Simple. They've been rotated a few times. Tire store says got 7,000 more miles left, Tesla has said twice "need new tires soon" -- i'm still rollin'
     
  10. Doug_G

    Doug_G Lead Moderator

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    I'm pretty sure tire wear has more to do with pushing the right pedal than lifting it.
     
  11. slcuervo

    slcuervo Member

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    That's right. I would like to know the torque of the regenerative braking. I bet it is quite low, especially if you compare it with the accelaration torque, and even more if we talk about the P85+, which is crazy high. This is what eats rubber like hell, not the regen braking :)
     
  12. yobigd20

    yobigd20 Well-Known Member

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    regen will reduce your rear tire life. as regen is only on the rear 2 tires, when regen kicks in the slowing motor causes increased torque on the rear tires. this generates heat through friction of the tires on the road surface and as a result will reduce rear tire life. if it was AWD that wouldn't be the case. I drive around on low regen a majority of the time. this is probably one of the reasons why my first set of tires lasted 50k miles while everyone else is burning theirs out a lot sooner.
     
  13. slcuervo

    slcuervo Member

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    Well, I am not quite sure that having some regen will reduce rear tire life VS not having regen at all.

    I don't think regen increases rear tire wear more than the friction you would cause by breaking (using brakes) to obtain the same level of decelaration...

    But I am no engineer or specialist, so I could be wrong. Any thoughts?
     
  14. Todd Burch

    Todd Burch Electron Pilot

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    Indeed I did. Good call. I added it where I think it ought to go. Obviously it's a continuum, depending on how low the pressure is.

    - - - Updated - - -

    When slowing the car, you must apply a certain level of braking force to the tires. With regen, that braking force is concentrated on the rear tires. This means regen causes faster tire wear than if you were braking at the same rate on all four tires, because the force would be distributed.

    However, this also means that the front tires receive NO braking torque when using regen, so they receive essentially no wear on regen. If you rotate the rears to fronts, you can spread out the wear.

    All things considered, although RWD regen causes faster tire wear than AWD braking, when you spread it across the front and rear tires by rotating I don't think the difference is dramatic.
     
  15. David99

    David99 Active Member

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    The tire wear is the same with friction brakes or regenerative. Both slow down the car using the wheels. The harder you slow down the car the higher the wear on the tires. Same with acceleration. 'normal' vs 'low' regen only limits the amount of regen. You can do the exact same by using the drive pedal gently.
     
  16. yobigd20

    yobigd20 Well-Known Member

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    Imagine taking a bicycle and locking the rear wheel but not the front wheel. Now drag it down the street. What happens? The front wheel will continue to rotate while the rear wheel drags. This will cause the rear tire to wear out but not the front. Now if you locked both wheels, that stopping friction force would be distributed and they would both wear out more evenly. Same difference to the MS. On the MS regen is RWD only while brakes are on all 4 wheels. Therefore , regen will wear our the rear tires faster than using the brakes would.
     
  17. N4HHE

    N4HHE Member

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    Yes, but the brakes primarily stop the car using the front wheels while regeneration uses the rear wheels. The issue is exacerbated by putting both acceleration and deceleration on the same pair. Much the same happens with FWD.
     
  18. jerry33

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

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    Yet the rear rotor is larger than the front rotor.
     
  19. Doug_G

    Doug_G Lead Moderator

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    Sure, it will have some impact, but the car can deliver 300+ kW accelerating but only 60 kW decelerating - and that number goes down as your speed drops. There's a lot more tire wear when the tire is slipping slightly on the pavement. Gentle actions have far less impact than vigorous acceleration. Vigorous acceleration from a standstill is the worst - and at near-standstill speeds you can do 300 kW accelerating but almost nothing decelerating.

    IMHO you're far more likely to wear the tires out with jackrabbit starts then gentle regen braking.
     
  20. brianman

    brianman Burrito Founder

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    Well, let's see. The highest power usage I've seen is just over 360 kW. The highest regen the UI shows is around 60 kW. So 1/6th at most?
     

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