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18" Aero wheels and Model Y load limits

Discussion in 'Model Y' started by Zoomit, Mar 29, 2020.

  1. Zoomit

    Zoomit Active Member

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    There have been a number of people (thread, thread) wondering about fitting the 18" Aero wheels from Model 3 on Model Y. The motivation for me is installing winter tires on a more efficient wheel that allows a taller sidewall. There are a couple things to consider:

    Brake caliper clearance
    I expect the regular Model Y brakes will fit within the barrel section of the Aero wheels but I haven't seen this demonstrated. The question is whether the regular rear calipers are different between the 3 and Y. If they're the same, the 18" Aeros should fit. It looks like the Aero's will NOT fit the Model Y Performance Upgrade brakes per this post (H/T @RoBoRaT).

    Wheel size
    The 18" Aeros are 18x8.5 ET40, narrower than the 9.5" wide and ET45 19" and 20" wheels on Model Y. Using something like a 245/50R18 or 245/55R18 tire results in a similar outside tire fit as the regular Model Y. The inside of the tires would have about 10mm more clearance to the suspension. This is all good, especially for winter tires that can benefit from the slightly narrower tread.

    Wheel load rating
    The 18" Aero's are marked with a 700 kb (1543 lb) rating (picture, H/T @RoBoRaT). This is where the challenge lies and what led me down the rabbit hole looking at Model Y Load limits.

    I plotted the Gross Axle Weight Ratings from pg 189 of the Model Y Owners Manual and added an equivalent line for 18" Aero wheels based on the 1543 lb individual wheel limit. I also plotted the 5302 lb Gross Vehicle Weight Rating for Model Y Long Range. As would be expected, the OE 19"-21" wheels allow the full range of possible axle weights given the GVWR limit. That is, the dashed gray, orange and blue lines are outside the brown diagonal GVWR line. The 18" Aero wheel, assuming a 3046 lb GAWR, would not allow very heavy, rear loading of Model Y without overloading the rear wheels.

    20200329, MY W&B.png

    Let's zoom in and look at these different load configurations to see how big of an issue this could be.

    20200329, MY W&B Table.png
    Config A: Curb weight, no payload
    Config B: Driver only
    Config C: Two front passengers
    Config D: Driver, two kids in back, and some stuff in the frunk and trunk
    Config E: Two big guys in front and a full frunk
    Config F: Four adult passengers
    Config G: Fully laden with four adult passengers and 205 lb cargo
    Config H: Fully laden with two adult and two smaller passengers and 295 lb cargo
    Config I: Fully laden with driver and 715 lb cargo
    Config J: Same as I but with cargo moved forward to stay ahead of 18" Aero rear axle limit
    Config K: Fully laden with speculated 320 lb tongue weight trailer
    Config L: Same as K but with only 265 lb tongue weight to stay ahead of 18" Aero rear axle limit
    Config M: Driver and minor cargo with 320 lb tongue weight trailer

    Caveats:
    - The axle loading calculations assumed approximate locations for the respective weights in the table, but they're pretty close.
    - Nothing has been officially published yet on Model Y tow rating.
    - This only applied to Model Y LR AWD. The RWD and/or Standard Range cars will have different results.

    From this, I conclude the 18" Aero can be used on Model Y LR AWD as long as special consideration is paid to keeping the payload forward when close to the GVWR. YMMV and all that.
     
    • Informative x 18
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  2. RoBoRaT

    RoBoRaT Zero Farts Given!

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    @Zoomit: Wow, thanks for the detailed information.

    Is it safe to use the 20" Model 3 Sportwheels on Performance Model Y?

    Again thanks for the above details!
     
    • Like x 1
  3. PJFW8

    PJFW8 Red Menace may hurt me

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    #3 PJFW8, Mar 29, 2020
    Last edited: Mar 29, 2020
    245/55 18 or 245/50 18? What is the height of these sizes compared to the stock 19. (Edit: other thread says the 50 is smaller and the 55 is larger, .5 inch.) Also, will the software allow selection of an 18". 19, 20 and 21 are the stock sizes. Can I select 19 even though the tire is 18? I have an extra set of aero wheels, so this would be a nice winter option.
     
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  4. Zoomit

    Zoomit Active Member

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    I have no idea what the load rating is for either the 19" or 20" Sport wheels.

    I failed to mention previously that one of the reasons I'd be comfortable using the 18" wheels on Model Y is because the tall sidewall reduces the impact loads to the wheel (yes, it flattens the curve!). The larger wheels have shorter sidewalls which transmit higher road forces, from potholes for example, to the wheels.

    Then you need to question why the Tesla engineers used 9.5" wide wheels for the Model Y. The Model 3 wheels are only 8.5". 255 tires can fit on 8.5" wheels but yet they went wider. Was it for aero efficiency, steering feel, load rating? I'm not sure.

    The software wheel selection adjusts the trip efficiency predictions and the graphics. That's it. It'll only have the original equipment options, so don't expect to be able to select the 18" wheels. Just select 19".
     
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  5. Feathermerchan

    Feathermerchan Active Member

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    I'd want wheels that meet or exceed axle ratings. I wonder what regulations exist for using wheels below axle ratings.
    On my F150 HDPP they used 7 lug wheels (2,400lb capacity wheels) to preclude the use of other F150 wheels which have lower ratings.
     
  6. PJFW8

    PJFW8 Red Menace may hurt me

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    Thanks. Very helpful!
     
  7. RoBoRaT

    RoBoRaT Zero Farts Given!

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    @Zoomit

    I've been looking for the load rating for 20" Sportwheels but can't find legit info.

    I have a set of 20" Sportwheels, and no marking for load rating (like the one 700kg in 18" Aeros) seen on one.

    Don't have a clue and can't decode all the markings that could be the load rating.
    I'm going to look at the other 3 and see if with load rating marks.

    20200325_144458.jpg
     

    Attached Files:

  8. Zoomit

    Zoomit Active Member

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    All your wheels should have the same markings. None of them appear to be a load rating to me.

    I looked at my 19" Sport wheels and found similar types of markings as your 20", though it's a lot harder when the wheel is mounted on the car to be sure.
     
    • Informative x 1
  9. RoBoRaT

    RoBoRaT Zero Farts Given!

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    Does this change anything?
    Screenshot_20200726-223109_Drive.jpg
     
  10. Zoomit

    Zoomit Active Member

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    Not really. The only meaningful difference is the limit on the front axle, but it’s impossible to overload it anyway. I had already updated the charts with the front axle limit and corrected hitch tongue limit for this thread: Model Y Cargo Loading

    [​IMG]
    D397E855-3A6D-4BAE-A3E5-D359F13468AA.jpeg
    Config A: Curb weight, no payload
    Config B: Driver only
    Config C: Two front passengers
    Config D: Driver, two kids in back, and some stuff in the frunk and trunk
    Config E: Two big guys in front and a full frunk
    Config F: Four adult passengers
    Config G: Fully laden with four adult passengers and 205 lb cargo
    Config H: Fully laden with two adult and two smaller passengers and 295 lb cargo
    Config I: Fully laden with driver and 715 lb cargo
    Config J: Fully laden with 350 lb tongue weight trailer
    Config K: Driver and minor cargo with 350 lb tongue weight trailer
    Config L: Two front passengers with 971 lb in trunk
     
    • Like x 3
  11. Snow Drift

    Snow Drift Pirelli P Zero Winter

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    Amazing analysis as always.

    I really wish the MY came with 18" Aeros from the factory as when initially debuted. The 19s are unnecessary and not as good looking as the Aeros, IMHO. Plus, I already have great snow tires for them! haha
     
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  12. Kabillyhop

    Kabillyhop Member

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    I've read through 3 threads on this topic and I'm still a litlle confused.

    Has anyone actually put 18" Aeros on a Model Y and confirmed that they fit?

    Is there an issue with sensors not being compatible? And if so, is the solution as simple as changing to the new sensors?
     
  13. ryanpei

    ryanpei Member

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    That is amazing data.
    I see that Martian Wheels has an 18" for the Y.
    I would love to know if 18" aeros fit, as I'll be looking for a winter tire solution and I would prefer to go 18" and narrower.
     
  14. RoBoRaT

    RoBoRaT Zero Farts Given!

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    This LR AWD owner put 18" Aero wheels on, so they will clear the brake calipers.



    His video/picture, not mine.
    Screenshot_20200827-170108_YouTube.jpg


    The rear brake calipers on Performance with (red) PuP calipers are bigger/sticks outward more than the regular rear brake calipers, so I have not actually mounted an Aero wheel on the rear. I am to damage the calipers.

    You will need to buy new Bluetooth TPMS sensors from Tesla Service/Parts at $75 each.

    Screenshot_20200317-222609_Video Player.jpg
     
    • Informative x 1
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  15. Feathermerchan

    Feathermerchan Active Member

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    So the TPMS system is different on the Y?
    ie TPMS sending units for the Model 3 won't work on the Model Y?
     
  16. Zoomit

    Zoomit Active Member

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    Correct, they’re Bluetooth on the Y and currently only available from Tesla.
     
  17. Stach

    Stach Member

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    That sucks. Hopefully there will be some good 3rd party options for the bluetooth sensors, before winter hits / by the end of the year.
     
  18. xtnvieira

    xtnvieira Member

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    #18 xtnvieira, Aug 30, 2020
    Last edited: Aug 30, 2020
    Won’t 18” wheels change your speedometer and odometer readings? Seems like 235/50/18 would be close enough or would this still throw things off a bit? Here’s a comparison between MW03 19x8.5 and a 18x8.5 wheels with 19/18 tires, respectively. I’m contemplating between Martian MW03 19x8.5 and 18x8.5 right now... FB6E8F88-A745-4756-8D52-C10AEE62ED43.png
     
  19. Zoomit

    Zoomit Active Member

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    Wheel size has nothing to do with the speedometer calibration. That depends completely on tire outer diameter. The stock 19" tires are 255/45R19, not 235.

    This thread is about using the Model 3 18" Aero wheels, which would optimally have a 255/50R18 tire to match the OE tires, but that size isn't available with any real selection of tires. The closest sizes that do have tire choices are 245/50R18 or 245/55R18.

     
  20. xtnvieira

    xtnvieira Member

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    A8EDBC54-8DE5-430E-AFC7-A70A53FA0DC5.png I suppose it’s worth also showing stock 19” Gemini tire size as compared to the MW03 18x8.5 since there seems to be much more difference which looks like it would throw off speed/mileage. So I may have answered my own question? I was hoping to get: (a) a lighter wheel for weight reduction and efficiency gains (b) a slightly narrow wheel for less rolling resistance (c) not throw off my speed and odometer - the speed is the bigger issue because it would drive me nuts. So maybe the safest bet is to go with MW03 19x9.5 after all is said and done... I just don’t know what to do
     

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