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P85D Wheel and Suspension Options - Seeking Advice

Discussion in 'Model S: Driving Dynamics' started by yak-55, Oct 25, 2014.

  1. yak-55

    yak-55 Member

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    I know the topic of 21" vs 19" and air vs coil has been discussed at length (I have read the threads). I have converted a P85 order (19", coil) to a P85D. The P85D order was initially configured as (21", air) because other choices were not offered. I'm wondering of I should switch to my original thought of (19", coil) now that that configuration is available, and so am seeking advice.

    To help me make a decision, you should understand my preferences (preferences of others may vary). Here's some background:
    1. I will be a new MS owner. I have test driven P85 models with (air, 21") and (coil, 19") configurations. Unfortunately the tires are significantly different in these two configurations, so its hard to distinguish suspension vs tire vs wheel effects. The (coil, 19") car seemed to meet my expectations.
    2. I am not an "order every option" guy. I don't feel the need to "follow the crowd" nor am I particularly concerned about how these choices might impact resale value. Essentially I expect to keep the car forever.
    3. Even though I'm buying a ~$120k car, expense matters to me. I'd rather spend on performance than looks all else being equal.
    4. While I am mechanically oriented and have modified other cars previously, I don't plan to "re-engineer/upgrade" this one.
    5. The P85D will be a daily driver in Florida. I don't think I'll have much need to raise the suspension to clear obstacles.
    6. I like performance/spirited driving, but won't be tracking this car (I feel there are much better choices available in this price range for that use)
    7. My past experience suggests the best handling upgrade for the money and effort is to buy (really) good tires.
    8. I think about life-cycle costs, so often am more willing than others to spend money in the short term to save (more) money in the long term.
    9. Handling, ride and noise level should find a balance, but I weigh them in that order. Aesthetics (in wheels and tires) don't mean a lot to me. (I think the 19" wheel choice is fine on a car as nice looking as the MS).
    10. Reliability matters. All else being equal, simpler is better. (Although I fully appreciate the MS is not a simple car by any means).

    So with that I am inclined based on my reading of the various forum threads to think:


    1. 19" wheels over 21" wheels - I am indifferent to the styling, there doesn't seem to be a substantial handling improvement on 21" vs 19" on equivalent tires (I will not drive the OEM tires forever, and expect that better replacement tires will be available in either size). I am put off by the cost of rapid tire wear on the 21" tires caused by the negative camber setup chosen by Tesla. The 19" rims (non-staggered) allow more effective and simpler tire rotations to maximize tread life. If the staggered 21"s are really better, I can probably use the $4500 saved to buy aftermarket (or used OEM) 21"s later. And probably install lolachampcar's revised rear link to reduce static rear camber.
    2. Coil Spring over Air Suspension - I am lead to believe both handle and ride well, although there are lots of opinions both ways. I think its true that with good rubber on (light) 19" rims both will perform (accelerate, handle) well. The air seems potentially complex/expensive to repair (although I haven't read of any negative experiences). With the air suspension on low (I'd be inclined to drive with it set there in the belief that it handles "sportier") the high rear tire wear issue seems to be exacerbated. If I go with the coil springs I have $2250 (more) in my pocket to buy good rubber when the OEMs wear out if more (handling or ride) performance is desired.

    I don't expect this to be the most "popular" choice, but believe its right for me. Can anyone see anything I've missed ? The Coil vs Air seems to me the bigger decision as it is for practical purposes irreversible.

    Sorry for the length of this post, but for those still reading, the wisdom of those with more experience (especially anyone with the ability to share experiences driving Air vs Coil with the 19" wheels and the same brand/make of tires) is appreciated ...
    yak-55
     
  2. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    I have only limited experience driving the coil suspension (on a couple of loaners, one P85, one S85), but I was pleased at the way the coils both rode and handled. My Sig S has the air suspension and 19" wheels; I like it that way (and have reserved an S85D in that config), but your reasoning seems sound. I'll be interested to see if anyone else can sway you to change your mind.
     
  3. linkster

    linkster Member

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    Fully agree with your detailed approach in those two areas.

    1. However, coils were not available jan '13
    2. Was out-voted on the 21's
    3. Made every attempt not to scrutinize our early delivery, but within a few days, I realized some adjustments and parts change were mandatory, and that the tremendous camber would detract from our overall (1000%) satisfaction (tire wear, rotation schedule, replacement cost)

    btw, fav combo is coils riding on 20's

    Good-Luck !
     
  4. Brass Guy

    Brass Guy Member

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    I say stick with your instincts. I think the upgraded handling package (P85D) with coil will be the best handling version. It might be a rough ride, but the 19's will help with that. You may not be able to take advantage of the full acceleration without the sticky 21's, but you will get a lot more miles with the 19's. You can try stickier tires later if you want.

    It sounds like you've thought it through very well, and it's probably the right car for you.
     
  5. Ride Long

    Ride Long Member

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    You sound like you've analyzed this at least 95% of the way there. Agonizing over the last 5% is rarely a productive exercise. At this point you will be talking yourself into any change in plan, and in my (n=1) experience talking myself into something rarely leads to long-term happiness. I say you're there: move forward and don't look back.
     
  6. lolachampcar

    lolachampcar Active Member

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    YYYYYYIIIIIIIPPPPPPPEEEEEE
    Tesla has now allowed me to order coils (whose ride height is easily adjusted with a little work) and not force me to pay for those expensive heavy wheels. I moved my P+ onto coils for the improved feel and handling (although you do loose useful load.. PM and I will explain). That worked wonderfully and I am thankful for Tesla's help in getting the job done. As for wheels and tires, that $4500 goes a long way towards buying light weight wheels and Pilot Super Sports which is the best of all worlds. Just make sure you buy a spare rim (or two if you use stagger) as wheel manufacturers are notorious for discontinuing rims in an effort to refresh their look.
     
  7. yak-55

    yak-55 Member

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    Thanks for all the input. I went ahead and changed my configuration from 21" Turbine with Smart Air Suspension to 19" Standard with (Dumb) Coil Springs toady. General consensus is that I may want to consider larger/wider wheels at some point and upgraded tires. I like the flexibility of aftermarket options in these areas.

    Now that all the tough decisions are made, I can't wait to have it. I hope the factory is running well !

    yak-55
     
  8. yobigd20

    yobigd20 Well-Known Member

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    ^^^^this.

    Go aftermarket 19" or 20" wheels & tires to get exactly the performance and handling you need without the high maintenance cost and inconveniences of the 21s.
     
  9. pmppk

    pmppk Member

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    I ordered with the 19"s but I'm having some second thoughts. I'm wondering if the 21"s on the AWD Model S will have significantly longer tread life than they currently have on the RWD Model S, since the acceleration and regenerative braking forces will be distributed between all four tires instead of only the rear ones. If I could reasonably expect to get 12 - 15k miles out of them, maybe I'd be okay with the increased cost of replacement.
     
  10. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    Where do you live? What is the condition of your roads? It's not just about tread life. It's also about surviving the potholes. I went through 6 tires in 13? months. Four tires got air bubbles after minor potholes, two with less than 1k miles on them. This was on a P85+, so it cost $550 to replace the rear tires (each) and $440 for the front tires (each). It-is-not-worth-it.
     
  11. pmppk

    pmppk Member

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    #11 pmppk, Oct 27, 2014
    Last edited: Oct 27, 2014
    I live in San Francisco and I feel like the roads around here are pretty well maintained.. At least in the areas outside of the city where I do most of my driving. I don't recall ever hitting a pothole in the 7 years I've lived in this area, but then again I have never had low profile tires so I suppose there is a chance I hit one and forgot about it since no damage was done.

    No winters to worry about here either.... I don't ski so won't be driving up to Tahoe or anything. And I haven't scraped a curb after first few weeks of owning my P85, so I am not so worried about curb rash now that I have a feel for the size of the car.

    Anyway, I know the 21" wheels are generally an impractical idea. Then again, so is selling my 18 month old P85 to get a D.
     
  12. ecarfan

    ecarfan Well-Known Member

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    21" wheels are all about looks, not about practicality or superior handling or durability. They are more vulnerable to damage and blowouts.

    I prefer the 19's for all those reasons. I think tires that look like rubber bands wrapped around huge wheels look weird. But others like the appearance of the larger wheels. Personal preference, but if you get the 21's be prepared for significantly higher operating costs.
     
  13. EarlyAdopter

    EarlyAdopter Active Member

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    I love the looks of the 21"s, so I'm stuck there.

    Out of curiosity, is there any benefit to a staggered setup, other than a more aggressive look? Any real world improvements in handling or cornering?
     
  14. lolachampcar

    lolachampcar Active Member

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    EA,
    Tesla engineers determined that they needed more rear grip when they stiffened the P+ if they were going to keep their safety margins in meeting stability control regulations. Wider rear tires, when combined with negative camber, allow the rear of the car to "roll onto" more lateral contact patch when side loading the rear of the car. There is a momentum or pendulum test in FMVSS 126 where you yank the wheel from side to side with a pause in the middle. It is meant to simulate an emergency avoidance maneuver and sets the back of the car up to come around. Active breaking can not control this motion so manufactures use negative camber in the rear (and tire width) to control the back.

    To answer your question, you will loose over steer safety margin if you put a P configuration on a P+. In my opinion, you will not notice it one little bit. If you are really curious, you could take it out to a parking lot somewhere and reproduce the stability control test and see for yourself :)
     
  15. rogbmw

    rogbmw Member

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    Will you be putting the longer upper arms on your new car?
     
  16. lolachampcar

    lolachampcar Active Member

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    I think I am getting done by Tesla which may put an end to my getting a PD :( If I do get one and camber in the rear is in the -2 degree range, I'll be putting the longer upper links on to get it to a more manageable negative camber.
     
  17. ra-san

    ra-san Member

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    Getting done by Tesla? I don't understand. Something you can share?
     
  18. Chuck P85D

    Chuck P85D Member

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    of course on the other hand, i also live in northern virginia and have ran on 21" wheels for two years and 20k miles without one problem whatsoever. hit plenty of potholes and rough patches (last winter was brutal) and not one flat or bent rim. just replaced the tires at 15k miles.

    - - - Updated - - -

    simply not true. the 21's offer better performance. maybe not enough to matter to you, but it does.

    Tesla engineered the P85D to run optimally on 21" wheels, so that's exactly what I'll be doing. at close to 700hp and torque, a lot rides on the margins. if you want something to survive driving thru potholes, go buy a pickup truck. because the 19's won't save you. ask this guy.
     
  19. lolachampcar

    lolachampcar Active Member

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    ra-san,

    I'm am having some difficulty with how Tesla has decided to handle trades now that they have an interest in MS trade ins (for their CPO program). I am trying to work through it with them now.
     
  20. lolachampcar

    lolachampcar Active Member

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