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18-inch winter wheels?

Discussion in 'Model S: Driving Dynamics' started by Zagor, Nov 7, 2013.

  1. Zagor

    Zagor New Member

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    Hi guys. I'm sort of windows shopping for a Model S and it has been very interesting to read the adventures of owners experiencing the car in harsh winter climate. Since I live far north, this matters to me.

    It is a little unfortunate that the Model S only comes with 19 or 21-inch wheels. The range of winter tires in those dimensions is rather limited and very expensive. But I wonder if perhaps 18-inch wheels could fit. Has anyone physically tried fitting 18-inch wheels to their car?

    The limiting factor to downsizing wheels is typically the brakes. The disc and caliper needs to fit inside the rim. The rear (largest) disc of the Model S measures 365x28 mm. I compared with the BMW M5 (E60) and it turns out it has much larger brake discs: 374x46 mm. Yet the M5 can be fitted with 18-inch wheels. BMW even sells 18-inch OEM wheels for the M5.

    So unless the calipers of the Model S are significantly bulkier than those of the M5, 18-inch wheels might actually fit. That would open up a much broader selection of tires in dimensions 245/50/R18 and 225/55/R18.
     
  2. doc@tirerack

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    Based on our measurements, 19" is the smallest diameter wheel we can guarantee to clear.
     
  3. Panu

    Panu Member

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    Anyone tried 18 inch wheels?
     
  4. jerry33

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

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    So far no one has been able to find 18" wheels that will fit except for some temporary spare tire wheels.
     
  5. Panu

    Panu Member

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    Yes I found the thread:

    Compact Space Saver Tire/Wheel Solution - Page 12

    If 18" works as a spare tire why doesn't it work as a longer term tire?
     
  6. Zextraterrestrial

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    Even one of my 19" sets rubs the suspension a tiny bit on really hard cornering when the wheel flexes, and they were 'guaranteed' to fit the S
    good luck w/ a 18" that is strong
     
  7. Panu

    Panu Member

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    OK the suspension is the problem.
     
  8. wycolo

    wycolo Active Member

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    I thought there have been a few references to MS owners running 18in rims but never giving particulars. Could also be that they meant 'not the 21in rims'.
    --
     
  9. comanchepilot

    comanchepilot Member

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    If you go with 18" wheels - you want 225/55-18 - its the EXACT same tire diameter as the 19" 245/45 thus nothing will change - except you WILL get a lot better 'dig' into the snow - with better go ahead traction - you will lose some handling - but its snow application.

    The exact same diameter only narrower - its called a Minus 1 conversion. Nothing is going to rub - the tire is the same diameter - and being narrower you get more clearance.

    I did it in my wife's Saab for years when we lived in Connecticut and she NEVER once got stuck. Ever.
     
  10. f-stop

    f-stop Member

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    Yes, at least for the front wheels on the Model S, it’s NOT the brakes that are the limiting factor for wheels that will fit, it’s the steering knuckle (I believe that’s what it’s called). This is based on my experience shopping for 3rd party 19” wheels for my summer tires

    example photo below: these are 19x8.5 wheels mounted on my 70D - the manufacturer’s website said they would fit the MS but as you can see while there’s plenty of room for the brakes, there’s only a paper-thin clearance for the steering knuckle at the bottom. (No, I did not buy these wheels!). Moral of the story is you can’t simply go by the brake rotor/caliper dimensions

    9C25A84B-046D-49D8-9DF6-FC18F9112CF1.jpeg
     
    • Informative x 1
  11. emailSGI

    emailSGI New Member

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    f-stop, what are the offset on that 19x8.5" wheel? Perhaps 18x8"et40 or so will fit?
     
  12. f-stop

    f-stop Member

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    The OEM 19” wheels are 19x8.0 et40
    The pictured wheel above is 19x8.5 et35 (though again as mentioned, those particular ones have a clearance issue on the inner diameter)

    The other wheels I ended up buying in the end for my summer tires were also same, 19x8.5 et40. I don’t know if 18x8 et40 would fit or not...
     

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