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Sanity check: change Performance Model 3 to lighter 18 inch wheels, same tire model

Discussion in 'Model 3: Driving Dynamics' started by JeffC, Sep 18, 2018.

  1. JeffC

    JeffC Member

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    [Hope this is the right forum for this. Apologies if there's an existing thread about it.]

    Feedback wanted:

    I have a Model 3 Performance with Performance Upgrade option probably due within a couple weeks. I plan to replace the stock 20 inch wheels and tires with 18 inch racing wheels, Enkei RPF1 in 18x8.5x40mm, and Michelin Pilot Sport 4S 235/45-18 tires. (These are essentially stock Aero 18 inch sizes, but with a lighter wheel and the same tire as the Performance Upgrade in a higher profile.) Goal is to reduce wheel and tire weight to increase performance. (The wheel may be large enough in inner diameter to fit the Performance Upgrade brakes. I'm checking with Tire Rack about it now. See also my measurements at: That $5k Performance Upgrade option, Part Deux )

    (All factory Model 3 tires are 235mm nominal width, which is a bit narrow for the Performance version, but would aid lower drag and longer range by a few percent.)

    This is for street use and matches the width compromise between grip and range that the factory wheel and tires have, but with a much lighter wheel than the factory 20. It would be the same excellent tire as the factory 20s, but in a higher profile and therefore taller sidewall.

    My question to the group is: How much (if any) of the excellent handling / responsiveness of the car might I lose by going with the taller sidewall? I expect acceleration, braking and bump control to be much better due to the significantly lighter wheel and tire combination compared to the factory 20 inch wheel, which is at least 10 pounds heavier.

    Would be particularly interested in the thoughts of the professionals @Mad Hungarian and @MountainPass .


    For track use I would probably get a separate set of 265 or 275 near racing tires on 9.5 or 10 inch wide wheels respectively, per Sasha, on 18 inch wheels if I can find them, or on 19s if not.. Interestingly both tire and wheel choices get somewhat limited 275 for soft compound tires. Toyo Proxes R888 soft compound DOT legal racing tire is available in 275/45-18 for example. 265/35-19 seems to have the widest competition tire availability.
     
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  2. Vines

    Vines Member

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    You will lose some performance with a taller sidewall but mostly it will be in the handling "Feel." 235/45 series is a good balance, where the tire is low profile enough to have decent handling characteristics, yet enough sidewall to reduce road feel for your daily drive.

    You might lose some ultimate grip but really that's what your race tires are for. Just remember that as the sidewall gets fatter the tires also get heavier. What is the weight of the rims you plan on moving to? The stock 18" Aeros are somewhere near 10 lbs lighter than the stock 20" rims for comparison, not sure of the overall package weight difference between both.

    Unfortunately like recommended above you will not be able to run the Aeros, due to the brake size in the Performance package.
     
  3. longshot49

    longshot49 Member

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    Not insane... bigger is not better... *Lighter* is better :)

    Some of these answers to these questions are above my qualification but there is a group buy going currently for 18" forged wheels.

    Cliff notes version: 18x8.5 - Model 3 custom fitment - 18.x lbs ; other size available

    Group buy link

    Bonus point: 18" can clear performance brakes ; unsure about Mountain Pass tho.
     
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  4. SD_Engnr

    SD_Engnr Active Member

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    A couple of questions and data points from my experience with a P3D+ and trying to fit aftermarket wheels. Reference: P3D+ misc info and pics- wheel weight, calipers, suspension

    What's your plan to deal with the 3mm lip on the hub? This lip will require a custom fix, because most aftermarket wheels will not work, unless the manufacturer makes the wheels specific for the 3 with performance upgrade.

    Have you confirmed if the wheels will fit the 14mm studs on the 3?

    If you attempt 18" wheels, you'll need the inner barrel diameter to be larger than 16.75" in order to clear the rear brake caliper. The group buy as posted above may be your best bet.

    I hope it works out, because I'm interested in seeing how the RPF1s look on the 3. I'm putting my wheel search on hold until someone releases a spring or coilover for the Performance 3. I'm not a fan of aftermarket wheels with a car sitting sky high...
     
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  5. Stellavator

    Stellavator Member

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    How about 245/45r18s on those lighter 18 rims? Wider tread for more traction, minimally heavier than the 235s, and slightly larger diameter to fill in a bit of the big wheel well gap.
     
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  6. JeffC

    JeffC Member

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    Thanks @Stellavator. Yes, I saw other people considering going with 245s too. However, it would be a larger diameter, and I'm trying to stick with the standard diameter. Not really concerned about wheel gaps, and the Performance Upgrade option suspension is a bit lower too.
     
  7. JeffC

    JeffC Member

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    Thanks @Vines ! Well it's actually steering/driving/handling feel I'm most concerned about. I care about the quantity of performance a lot (more on a race track), but perhaps the quality even more (more on the street). I really don't want to lose much of the excellent feel of the Performance Model 3 with Performance Upgrade option. But I do want to lose the weight of the factory wheel, as I'm certain that doing so will improve both feel and performance, due to physics.

    The weight of the Enkei RPF1 in 18x8.5x40 is reported as 18.35 pounds. It's a very popular (and somewhat famous) aftermarket racing/tuner wheel, and quite light. The factory Aero wheel without the cover is reported as 21.6. With the cover 23. If so, the Enkei is quite a bit lighter. The Tesla Model 3 Wheel and Tire Guide So the Enkei + 235/45 combination would probably be among the lightest possible; very light wheel and relatively light tire (compared to a larger wheel).

    Agree a taller tire (sidewall) is heavier, but the principle is that tire weighs less than wheel, particularly for relatively low profile (short sidewall) tires, which I think 45 through 30 profile would qualify as.

    I'm also thinking about 19s now also for street use, for the slightly shorter and stiffer sidewall, if it keeps some of the excellent feel of the 20s. If the 18s felt as good, I would probably go 18. Still trying to decide. NEED HELP! :D
     
  8. Daniel in SD

    Daniel in SD Active Member

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    The 18's in the same tire model will probably be very close in handling feel.
    It would be really nice if you could find an aftermarket wheel that fit the aero covers.
    The Pilot Sport 4S weighs the same for 18s and 20s, 23 pounds.
     
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  9. JeffC

    JeffC Member

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    All great points, and also a reason I'm sort of holding off for now too. Was aware of the lip and thicker rotor resulting in less stud for the wheel to grab. Also keenly aware of the (rear) brake clearance issue, and attempted to measure it informally. (See my link.)

    I should have figured that there was an extensive thread about wheel/rotor/suspension fitment on the Performance Model 3 here. Will need to study that thread before proceeding. I sort of started parallel ones on the Model 3 Owners Club forums, for example That $5k Performance Upgrade option, Part Deux
     
  10. ulrichw

    ulrichw Member

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    It's worth noting that while sidewall height is definitely a factor, tire models can have *vastly* different feels. Back when I drove a Subaru WRX STI I had a set of M+S tires on a second set of wheels in exactly the same size as the stock tires.

    The all-season tires had a drastically different feel - significantly more comfortable ride, combined with a lazier, vaguer turn-in. It almost felt like the suspension on the car had been changed (and in a way it had been, since the tire sidewalls could be considered part of the suspension).

    Also, stiffer is not necessarily better. A more compliant tire can give you a better feel and more control at the limit of adhesion. A very stiff tire/suspension combination may have a very abrupt transition from sticking to sliding, making it harder to control when driving at the limit.
     
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  11. JeffC

    JeffC Member

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    Thanks @ulrichw , agree different tires of the same size can have very different feel. I think many non-performance drivers may assume "tires are tires", but construction, compound and design and engineering in general can make tires feel and perform very differently. Given the same suspension, etc., tires are a major determinant in how a car drives and feels, which very much agrees with your experience.

    The Model 3 suspension, including the Performance Upgrade option, is relatively soft, and the relatively stiff 20 inch 4S felt very good to me near the limits. Excellent feel and communication about exactly what the tire was doing. Agree a softer sidewall may actually be easier to drive and more forgiving as you say, but also don't want to lose the excellent tuning of PUO with the 20 inch 4S.

    (BTW A soft suspension is actually good since it allows better compliance over real world bad roads, etc. A more compliant suspension will actually stick better under those conditions than an overly stiff one. I was a "boy racer" with multiple very stiff modified cars, and they were good on a flat autocross course, but not so great on real roads. Lotus has always advocated relatively soft suspensions, and the key engineer who did the Model S suspension was a top engineer at Lotus.)

    Probably need to try both the 18 and 20 to actually know the difference, but was hoping to benefit from some of the experience and knowledge here before trying it.
     
  12. GaryW

    GaryW Supporting Member

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    Hi Jeff. Would you care to update us on your wheel and tire choices? What did you choose, and how happy are you?
     
  13. Orwell

    Orwell Member

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    WedsSport TC105N 18x8.5" +43 5x114.3 weighs 16.7 lbs each. The bolt holes need to be enlarged and Performance brakes need to be shaved barely front and back.

    They look derpy as hell, but makes my car much lighter on it's feet.

    I found a set of 18x8.5" TE37 Mag. 15 lbs each wheel, but feeling a bit apprehensive about magnesium wheels.
     
  14. stickman

    stickman Member

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    You went 43 offset on a performance? And shaved the brakes? You mean you ground the calipers?:eek:
     
  15. GaryW

    GaryW Supporting Member

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    Are you @JeffC?
     
  16. Orwell

    Orwell Member

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    Yes
     
  17. Orwell

    Orwell Member

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    No I mean I took a file to the calipers. No problem. Cameron Rogers did this with his record breaking Model 3 with no problems either. You only need to shave off less about a millimeter off a small corner.
     
  18. SteveIMP

    SteveIMP New Member

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    Hi The 18x8.5 5x4.5 has a much larger than normal center bore at 73mm. Not sure what is need to clear the performance rotors however.
    I got a great deal on some Mustang GT take off.
     

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  19. juanmedina

    juanmedina Member

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    Love the Enkei PF01s. They look great.

    Do you have pictures of your car? I contacted Wedssporst about having a custom set drill for my car and they said that they don't feel safe about making a set for our cars since they are so heavy and powerful. I am just talking about the TC105N and TC105X models.
     
  20. dfwatt

    dfwatt Member

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    Not too many manufacturers are going to be comfortable boring out lug nut holes. The problem is that without a proper metallurgical and stress testing method - which is obviously very expensive relative to a one-off solution - they can't really be sure that the wheel is not significantly structurally weakened. That spells massive lawsuit if the bolt holes fracture and somebody gets injured or killed. So no, you're not going to get anybody to drill out lug nut holes to fit the 14 millimeter lugs on the model 3. You can do it yourself and lots of people are doing it, but you're on your own and it's frankly pretty dicey.
     

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