Testarossa with 360 modular wheels and tire size? | FerrariChat

Testarossa with 360 modular wheels and tire size?

Discussion in 'Technical Q&A' started by DetroitDetomaso, Feb 25, 2021.

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  1. DetroitDetomaso

    DetroitDetomaso Formula Junior

    Mar 6, 2006
    455
    Las Vegas
    Full Name:
    Chris
    I need wheel help. Formulas and conformation would be great.

    I’m going to put 360 modular wheels on my 1989 Testarossa.

    I’ve read here on FChat that I need 360 wheel lugs to accomplish this. Is this correct? What length are 360 lugs and are they the same length as any other Ferrari Models?

    I’m probably going to buy Continental ExtremeContact tires based on recommendations from friends but I’m also open to opinions.

    I want my new wheels and tires to be the same diameter as stock.

    89 stock Testarossa is
    225-50 16 front
    255-50 16 rear

    Discount tire recommends
    225-40 18 front
    255-40 18 rear

    Will this be the same diameter?

    I want to get this right. Any and all help is appreciated.
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  2. krazykarguy

    krazykarguy Formula Junior

    Apr 17, 2014
    716
    Fort Mill, SC
    Full Name:
    Matt
    As info, I work for Continental... the Conti ExtremeContact Sport or the DWS06 are both great choices for the Testarossa.

    It looks like the front tire size of 225/40/18 is appropriate, as it is less than 1% (0.92%) larger than the stock overall diameter.

    However - the rear size you're proposing is slightly smaller than stock (661.4mm vs 661.2 mm). I would actually suggest a 265/40/18 tire to match the slight height increase of the front tires (which is 1.18% larger than the stock Testarossa tire) - which happens to be the stock size for 355 rear fitment.

    Furthermore - TireRack has exceptional catalogues of specific tire information - overall diameter, weight, revs/mile, of every single tire they sell. My calculations are in millimeters above and TireRack lists inches for dimensions, but it is very helpful for choosing the right tire.

    My biggest concern would be offsets and suspension clearances - although I am sure that others have more experience in this arena than myself. I'd actually suggest that you check what the offset and backspacing for the 512TR are - if the 360 modulars are nearly the same you should be good to go.
     
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  3. Redneck Slim

    Redneck Slim Formula 3
    Silver Subscribed

    Mar 10, 2011
    1,440
    Palo Alto,CA,USA
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    Walt Kimball
    The critical figure is the revolutions/mile of the tires. 225/40-18 and 265/40-18 would be best,although the difference between 265-40 and 255/40 is minimal. You have lots of good choices in performance tires when you go to 18".
     
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  4. krazykarguy

    krazykarguy Formula Junior

    Apr 17, 2014
    716
    Fort Mill, SC
    Full Name:
    Matt
    Yes, revs/mile is the ideal calculation for determining proper sizing.

    However - O.D. is the 'visual' that is critical to getting the new sizes to 'look' right. But even the wheel dimensions can impact this - I personally prefer a 'square tire' appearance, one where the sidewall is basically vertical with the edge of the rim. Not pinched like the stance idiots putting 195 width tires on 10" rims, or 'fat' meaning too much tire width on too narrow a rim.
     
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  5. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Here are the specs on both sets of wheels. Front 360 wheels are actually 1/2" narrower than TRs and it looks like your rear wheels will stick out ~20 mm more than the TR wheels, which should actually look pretty good. The narrower front wheels will tend to make her understeer a bit more. The Conti Extreme Contact Sports should work well, but I would not put the DWS tires on a Ferrari.

    Testarossa



    Five Spoke 16”, 5 X 108 mm

    Front 8J x 16 ET 34.2 mm, Rear 10J x 16 ET 59.6 mm

    360


    Five Spoke and Modular 18”, 5 X 108 mm

    Front 7.5J X 18 ET 31.5 mm, Rear 10J X 18 ET 38.95 mm
     
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  6. Redneck Slim

    Redneck Slim Formula 3
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    Mar 10, 2011
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    Walt Kimball
    My first choice would be the Michelin Pilot Sport 4S,which is available in all three of the 18" sizes discussed. The 225/40-18 is approved for rims from 7.5" to 9" wide.
     
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  7. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Walt- Affirmative, that would be my first choice, too, and have them mounted on my 575M.
     
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  8. Meister

    Meister F1 Veteran
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    Apr 27, 2001
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    The Meister
  9. DetroitDetomaso

    DetroitDetomaso Formula Junior

    Mar 6, 2006
    455
    Las Vegas
    Full Name:
    Chris
    Thank you very much everyone.
     

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