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Aero wheels on P3D+

Discussion in 'Model 3: Driving Dynamics' started by mcbarnet007, Jul 2, 2019.

  1. mcbarnet007

    mcbarnet007 Member

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    I want to share a way for P3D+ owners to increase the car's efficiency. We all know that the stock 18" wheel cannot clear the rear caliper without grinding the caliper. So my solution is to use the aero wheel up front and try to find a light 18" wheel in the rear that won't clash with the front. I've found most of the Konig flow form wheel will clear the rear caliper so I decided on the Ultraform 18x8.5 +35. This result in a 50 wh/mi improvement!

    Before:
    20x9 +35 offset with Pilot Sports 4S (stock 20" tire inflated to 42 psi)
    Averages 285 ~ 290 wh/mi on my mostly highway commute at 60 ~ 65 mph
    20190328_190254.jpg

    After:
    Front: Stock aero wheels with 5mm spacer to match +35 offset in the rear. Stock tire at 45 psi
    Rear: Konig Ultraform 18x8.5 +35 with stock tire at 45 psi. Wheel weights around 19lb.
    Same commute route averages 235 ~ 240 wh/mi
    20190701_191741.jpg 20190701_191734.jpg 65538836_790622848098689_8003198448268476416_n.jpg

    I'll update once I get more miles on this setup.
     
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  2. wenkan

    wenkan Member

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    If you are using different wheels, why it must be a 18" on the rear? I assume the previous 20" still works.
     
  3. quikshifter

    quikshifter Member

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    you should have bought an SR. Aero standard and you would get 200wh/mi
     
  4. Daniel in SD

    Daniel in SD Well-Known Member

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    Can you post a picture/measurement of the clearance to the front calipers? @AlanSubie4Life and I tried my aero wheels on his P3D and it was less than 1mm of clearance (I've heard 3mm of clearance is the minimum recommended).
     
  5. mcbarnet007

    mcbarnet007 Member

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    It will look so weird. Also the stock 18 tire is more efficient
     
  6. wenkan

    wenkan Member

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    Not so weird as you expected.
    A lot of supercars use different sized wheels, like 19" front 20" rear. It actually looks more balanced than using same wheels because the car is always "thicker" in the rear. Roadster 2020 will be using using 20" front 21" rear.
     
  7. mcbarnet007

    mcbarnet007 Member

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    Sure, I'll take some picture when I get home. The 5mm spacer helps because it pushes the wheel out a little more and the barrel clearance gets better.
     
  8. mcbarnet007

    mcbarnet007 Member

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    True, but the PS4s is just not as efficient compare to the mxm4. I want to see what is the best efficiency I can get on a P3D+
     
  9. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Yeah I wanted to do this, but it is just too tight for me.

    I posted the front clearance picture elsewhere, but here it is....

    F7F5A9D6-AC56-4E0B-A010-56FADD9102AE.jpeg BDC468D4-4F94-4250-9D4E-B90CBE470760.jpeg

    I don’t really see how a 5mm spacer would have helped that much - in this picture the wheel is centered, but not completely touching the hub, due to the lip.

    In any case, the Konig wheels have a LOT more clearance. I would estimate 4-5mm - enough that wheel weights would (barely) clear if they were placed in the wrong area.
     
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  10. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    #10 AlanSubie4Life, Jul 2, 2019
    Last edited: Jul 2, 2019
    Thanks for the data, BTW. I was thinking it is possible that calipers could have a tiny amount of play on the mounting which could change the clearance, on some cars.

    I guess we’ll see how your pictures compare to mine.

    This is about the improvement I would expect, though (most of it is due to tires).

    Just have to figure out a way to hack the aeros and attach to the Konigs...that’s the next step for me after I get my range wheels. The biggest issue is the valve stem location...
     
  11. mswlogo

    mswlogo Well-Known Member

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    #11 mswlogo, Jul 2, 2019
    Last edited: Jul 2, 2019
    Will OEM 19" fit, P3D+, I thought I heard it will if newer build and newer wheels? I'm sure After market 19" will fit.

    I swear I'm getting exactly the same efficiency switching from 18" Aero with Covers to OEM 19" Wheels (but NOT 19" OEM Tires).

    I'm running Pirelli P7+ tires.

    Now, keep in mind Aero covers may kick in if you drive much higher highway cruising speeds than I do.
    I typically cruise at 65mph and don't cruise much above 70 mph very often.

    I'm sure Aero covers help. But a larger factor is tire compound between the different Tesla offerings.
    The 20" OEM is a very soft grippy tire. The 19" is also on the softer side. The 18" is the hardest tire Tesla offers, and the primary reason for it's efficiency numbers. But there are harder tires out there.

    For some odd reason these harder tires (nothing above Treadwear 500) don't exist in the 18" aspect ratio with the same load range. But they do in 19". So the Primacy is the hardest 18" Tire with the correct load rating. At least on TireRack web site.

    Bridgestone also introduced a similar tire in 19" called the QuietTrac. No much data on it. Oddly enough the harder tires are also quieter, which is a bonus.

    There is no free lunch though. Harder tires have worse grip in wet roads.

    Neither P7+ or QuietTrac exist in 20" or 18" (with correct load range).

    You can also get Primacy (or Primacy like performing tire) in 19" as well. Which will run exactly like Aero's (with covers OFF).
    The tread wear seems to correlate well with efficiency and quietness.

    The P7+ is harder than Primacy and makes up for the lack of Aero covers (at the speeds I drive at).

    My average is meaningless to anyone else, but I'm getting 230 wh/mi for the last 1000 miles on an AWD.
    But what is important my wh/mi did not change since swapping from Aero's with covers to 19" P7+.

    I'm running the same tire pressure on both.

    For some reason the 19" has the best options because as you go to the lower profile tires the load range requirement drops. So the 19" fall inch a range of lots of tire options in the right load range.

    Keep in mind moving from 20" OEM tire to 18" OEM tire is compromising wet performance as well as many other parameters.
    You just need to pick your compromises. I chose OEM 19" looks, and maintained efficiency and quietness and lost a little wet performance. I lose lots of things switching to Snow tires too.

    You can get most of the efficiency of a Aero/Primacy by just choosing a Primacy like tire, regardless of the wheel. You're already thinking of dropping Aero's in the back.

    The Aero wheel cover is not worth all the trouble. Because that is all your getting.

    Another way of saying all this, is put the exact same tire on any wheel (no Aero covers) and they will all run exactly the same (no such tire exists). And there are tires more efficient than Primacy. But they only meet spec in 19" format.

    And the weight doesn't effect efficiency on the highway that much. Around town the Model 3 is insanely efficient with any wheel combo. Weight does affect acceleration though.
     
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  12. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    #12 AlanSubie4Life, Jul 2, 2019
    Last edited: Jul 2, 2019
    I've noticed this too (for the OEM tires it applies, the smaller the sidewall the lower the load rating). I don't really understand why, hopefully someone can explain. The sidewalls I guess are shorter so maybe they don't have to be as robust? Or maybe the 20" wheels are lower load rating because they have short sidewalls? Does it mean that it would be ok to run an 18" with a load rating of 92 (the PS4S load rating)? Technically 1389 pounds per tire should be fine...

    The CrossClimate+ is 600 treadwear, 98 load rating, in the 18" size, FWIW. That's what I'm going to get. Hopefully I don't regret it when I hear the roaring from the tread. :) I'm used to running RE-71Rs and Direzza ZIII on an STi so I figure it'll feel super plush to me. I don't expect the CrossClimate+ to be quite as efficient as the P7+ but I figure it will be pretty close.

    https://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=CrossClimate+&partnum=345YR8CCPXL&vehicleSearch=false&fromCompare1=yes

    I feel like the aero wheel cover hack that eventually I might try to do with my Dekagrams is really for extended freeway runs at 80-85mph (through Nevada primarily, where that speed is required to keep up with the flow of traffic - it's about 5mph slower in California). The gains become more important there.
     
  13. mcbarnet007

    mcbarnet007 Member

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    The Pirelli P7+ I think is a slightly more efficient tire than the mxm4. Also at 65mph aero doesn't have a whole lot of impact. However at 80+ it is a whole different story. 230 wh/mi is very good! I don't think I can get there as I have a little bit of brake drag in the front brake. However, I am happy if I can get 250 wh/mi at 70 mph steady speed with AC on.
     
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  14. usofrob

    usofrob Member

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    Yeah, I feel like doing a DIY aero wheel cover for the winter. Summer range isn't generally an issue, and I don't want to cover the brakes just in case. But, in the winter, warming brakes shouldn't be so much of a concern, and I need to make up for the lost efficiency.
     
  15. mswlogo

    mswlogo Well-Known Member

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    Good find on crossclimate+. Please report back on how they do.

    Some people say 92 on 18” are fine. But I prefer play it safe. If anything for insurance, liability and warranty. I don’t want to hand anyone excuse for their responsibility, regardless if it’s technically ok.

    What Tesla did looks like no accident to me.
     
  16. mswlogo

    mswlogo Well-Known Member

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    Totally agree. 250 isn’t bad at all cruising at 70 mph. Watts go up fast with mph.

    People report a lot of various numbers for Aero covers on and off, but they don’t always state their cruising speed. I should have measured on/off myself at my typically cruising speed, I never did. I still run Aero with covers for Winter.
     
  17. mcbarnet007

    mcbarnet007 Member

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    Just measured it, I have roughly 1.25mm clearance. I'll remember to push the caliper toward the rotor more next time I install the brake pads.
     
  18. mswlogo

    mswlogo Well-Known Member

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    I don't know what happened but I lost my post.

    I noticed you said you run 45 psi on 18" (3 psi is pretty significant part of your improvement, at least 10 wh/mi if not more).
    If I ran 45 psi, I'm sure I could cruise 70 mph, AC and hit 230 wh/mi easy on my 19".
    I don't dare run 45 psi on the 19" (or 20"), some folks do, I worry (possibly unjustified) 45 psi will wear out the center first and the suspension taking too much of a beating over the long haul. I think with 18" 45 psi should be fine though (if you don't mind the ride).
    I tried 45 psi on Primacy, too much basket ball feeling for me. Efficiency was through the roof though. I forget exact numbers, didn't run it long because I didn't like the feel personally.
     
  19. mcbarnet007

    mcbarnet007 Member

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    45 psi on the 18 is Tesla recommended
     
  20. mswlogo

    mswlogo Well-Known Member

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    It WAS recommended. It's been 42 for a long time now on all wheels, all trims, since around Sept 2018 Build.
     
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