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22" wheels can only tow 3,500 lbs?

Discussion in 'Model X' started by CTemp222, Feb 10, 2016.

  1. CTemp222

    CTemp222 Member

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  2. pvogel

    pvogel Member

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    Yes. On this forum at least, and the info is in the configuration tool on the tow package option.
     
  3. CTemp222

    CTemp222 Member

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    Ok, but I don't understand why having larger wheels will limit your towing.
     
  4. goneskiian

    goneskiian Active Member

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    It's not so much the larger wheels as it is the lower profile tires that come on them.
     
  5. necho

    necho Member

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    I guess it has to do with the tires available ... as far I know the 22" tires are only available with load index of 106 and the 20" with 112

    106 is up to 950kg (2090lb) and 112 is up to 1120kg (2470lb), so you have to check with the maximum tongue weight according to the trailer and add that to the axle weight of the Model X ..
     
  6. CTemp222

    CTemp222 Member

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    What do you mean by lower profile?

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    That would make sense.
     
  7. pvogel

    pvogel Member

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    There's less rubber and air between the outside of the tire and the wheel rim.

    Fundamentally the outside diameter of the tires doesn't change, so when you go to 22" wheels you have less rubber and air.
     
  8. necho

    necho Member

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    So the gross rear axle weight is 1720 kg (3792 lb) -> Model X Founder Series - Facts - Page 2

    so the 22" would allow 1900kg (2 x 950kg) - 1720kg a maximum tongue weight of 180kg and the 20" 2240kg - 1720kg a tongue weight of 520kg ...
     
  9. retinaguy

    retinaguy Member

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    So it's actually the rim diameter that changes?
     
  10. pvogel

    pvogel Member

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    Exactly. 20" wheels have a rim diameter of 20", 22" wheels have a rim diameter of 22". The Outside diameter of the tires doesn't change (much).
     
  11. retinaguy

    retinaguy Member

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    I've learned so much today. A patient told me he learned patience since he raised daughters; which I thought was a pretty good observation on life!
     
  12. FarmerDave

    FarmerDave Member

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    And yet they cost more!:biggrin:
     
  13. Roamer

    Roamer Member

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    All in how you look at it. You are buying more metal rim and less rubber tire. And with less rubber the rubber has to be better to make up for the fact there is less of it.

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    I ordered 20's for the tow rating, ride and lower noise.

    My car delivered with two other cars on Dec 31st. All three cars were parked in the delivery area a few feet apart. Mine was in the middle. As I walked around looking at the cars I commented to the other owners, "looks like we all went with 20's". They both informed me they had 22's.

    So standing right next to cars with both sizes within several feet of each other it was difficult to see the one inch difference without reading the size printed on the tire.

    I hated to give up the higher cost option on a fixed price Sig but so far I am happy with everything about the 20's.
     
  14. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    When you're in any area where it drops to below freezing, you learn your lesson quickly. Model S came to our family with the 21" wheels. Within 2 months, two tires had split as a result of hitting two very minor potholes on cold days (two separate events). Cold weather turns the tires to brittle rocks. Less sidewall support + heavy car + pothole + cold weather == $$$. Those tires aren't cheap, either.

    We now have 19" tires that stay on the car year round (on Rial Lugano wheels). I'm just fine with 20" on the Model X. I'm a bit disappointed that they used staggered configurations on both 20" and 22", the ability to rotate the tires back-to-front on the Model S is what makes them last nearly twice as long.
     
  15. Monkey

    Monkey Member

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    It an AWD vehicle, rotating tires doesn't buy you much life and if the tires are properly balanced and inflated, they should wear almost evenly to begin with, making tire rotation more an exercise in futility. On RWD vehicles, it's an entirely different story most of the time.
     
  16. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Thanks for that reminder. I'm living in my RWD Tesla world.

    That said, we do know that Tesla modulates the motors during acceleration - not sure about regen - such that it's still a chance you can end up with different wear.

    Would love to hear from anyone who's gone through extensive miles on their Model S with "D"... do the fronts wear evenly compared to rears?
     
  17. ABCCBA

    ABCCBA Member

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    There are a number of things that add to the towing capacity of your wheel/tire set. The biggest is the tire. Let me explain this first, then I'll get to the load capacity. Every car has the speedometer calibrated for a certain circumference wheel/tire setup. Circumference is defined a Pi * diameter. Since Pi is constant, then in the diameter of the wheel/tire setup must be kept constant to keep the speedometer reading correctly. So, let's say that the diameter of a Model X wheel/tire set is 27". With 19" wheels, the tire side wall is then 4" (19" + 4" top + 4" bottom). For a 22" wheel, the tire sidewall is just 2.5". How does this affect load rating (towing capacity)? Well, the sidewall of the tire is what provides the stability. It is like a spring. So, as the sidewall gets smaller, the load index of the tire generally gets less. Now, you can shop and buy tires with all sorts of load and speed ratings, but assume that the tires in my example have the same 'spring rating' of the side wall at say 5000 lbs/inch of compression. If you load the 4" sidewall tire with 5,000 lbs (car and add'l load), the sidewall will deflect approximately 1" or 1/4. However, if you loaded the 2.5" sidewall with the same load, it would deflect the same 1" but it would be 40% of the sidewall and most definitely blowout. I know this is a layman's example and that there are a lot more technical terms and formulas that I could have used, but for the basic answer of why does a larger wheel have a lower load rating, I hope this helps. Mike
     
  18. jackbowers

    jackbowers Jack Bowers

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    The manual says that if you tow with the 22" tires, you must raise them to the maximum psi of 50 lbs, so it sounds like even doing class II is a bit of a push with these tires. On the plus side, they are Pirellis with a treadwear rating of 420, so they might last twice as long as the Model S 21" Michelin tires, which have a treadwear rating of 220. They also seem to do better in snow than the Michelins.
     
  19. CTemp222

    CTemp222 Member

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    Yes thanks for explaining.

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    That rating tho, I wonder if Elon thought it would be funny to go with those :wink:
     

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