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What size tires are best to fit 19" wheels on a 456

Discussion in '456/550/575' started by crmlcruiser, Dec 6, 2009.

  1. crmlcruiser

    crmlcruiser Karting

    Dec 28, 2005
    150
    Carmel ca
    Full Name:
    Michael
    I just bought a set of 19" wheels for my 456. They are 9.5" fronts and 12.5" rears. Does anyone know the best size tire to put on these? I want to keep it as close to the same ride height as the car just barely clears from scraping in my parking garage with the stock wheels.

    any help would be appreciated,thanks.
     
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  3. tajaro

    tajaro Formula Junior
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    Mar 22, 2009
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    Erik V
    #2 tajaro, Dec 6, 2009
    Last edited: Dec 6, 2009
    For my 456M I run 255/35-19 on the front and 295/30-19 on the back. No issues whatsover. You can also go much wider on the as some run 355 like on the Maranellos (per Taz in another thread).

    I will upgrade to 355/25 when these run through- great look.
     
  4. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
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    Terry H Phillips
    Michael- The size of tire is really dictated by how wide your rear wheels are. If you have a rear wheel 10-11" wide, the OEM 19" tire size of 305/30 19 is used on the 575M and Superamerica and would work fine.

    For the very wide 12.5J X 19 Novitecs or the wheels you bought, the 305/30 19s are too narrow, and you need 355/25 19s or a near size. TireRack has a list of Pirelli P Zero Rossos showing recommended wheel widths for each size. The 255/35/19s Tajaro mentions should work fine on 9.5" front wheels.

    Taz
    Terry Phillips
     
  5. crmlcruiser

    crmlcruiser Karting

    Dec 28, 2005
    150
    Carmel ca
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    Michael
    Thank you, with the 355 25 19 the ride hieght is about the same even with such a low profile? I just want to make sure it doesnt rde lower than it is nopw or i won't clear my parking garage at work. I love that at leastone of my Fcars will make it inside :)
     
  6. tazandjan

    tazandjan Three Time F1 World Champ
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    #5 tazandjan, Dec 6, 2009
    Last edited: Dec 6, 2009
    Michael- Here is how to crunch the numbers on tire diameter. Math is pretty simple.

    550/575 OEM 18" R 295/35 18

    (295 mm X 0.35 X 2 (top and bottom)) = 206.5 mm ÷ 25.4 (mm/in) = 8.13" + 18" = 26.13"

    550/575 OEM 19" R 305/30 19

    (305 X 0.30 X 2) ÷ 25.4 = 7.20" + 19" = 26.20"

    355/25 19

    (355 X 0.25 X 2) ÷ 25.4 = 6.99 " + 19 " = 25.99"

    Close enough. 0.54% difference between the 295/35 18 and 355/25 19.

    365/25 19 would be closer, but nobody makes one.

    Taz
    Terry Phillips
     
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  8. crmlcruiser

    crmlcruiser Karting

    Dec 28, 2005
    150
    Carmel ca
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    Michael
    Taz thank you so much, so that helps, my stocks are :
    285/40/17 rear=25.98"
    255/45/17 front= 26.03"

    So if i go with

    355/25/19 rear=25.99"
    295/35/19 front=26.13"

    This should work my only worry is that 355 is a lot wider than the 285s now. You dont think that the 305/30/19 rear = 26.2" would work on my 12.5" rims. The height and width may fit my situation a bit better I think of course only if the 305s can work ont these wheels at all.... what do you guys think.

    And thanks again for all your valuable help guys!!
     
  9. tazandjan

    tazandjan Three Time F1 World Champ
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  10. tajaro

    tajaro Formula Junior
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    Mar 22, 2009
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    East Hampton NY
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    Erik V
    I really don't think we can put 295 on the front - I'd be shocked if they wouldn't rub. And it's odd the 345 in 20 inch rim says 11-13.5 inch rim while the 355 wants 12.5-13.5. You think that's a typo?
     
  11. tazandjan

    tazandjan Three Time F1 World Champ
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    TJ- Entirely possible. Always have to look at the big picture and apply judgement on this kind of data.

    Taz
    Terry Phillips
     
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  13. Jagbuff

    Jagbuff Formula 3

    Jan 13, 2004
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    Franck
    If you have Novitecs the only wheel package that will work properly without rubbing is what Taz suggested - 255/35/19 upfront. and 355/25/19. I am speaking from experience as the 355 were back-ordered for almost a year when I got my set so I had to try different permutations. You can't fit a 315 on the 12.5 rim, I put 345/30/19 (Viper tires - only other "close fit") and the different diameter with the fronts causes ABS to go crazy, so you have to go with a taller tire in the front to correct that - and then the tires will rub. Anything wider then the 255 will be problematic.

    Avoid the headaches, go with recommended sizes and use 25mm spacers in the back (not the 30mm which causes the wheels to stick out too much)
    Franck
     
  14. tazandjan

    tazandjan Three Time F1 World Champ
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    #11 tazandjan, Dec 10, 2009
    Last edited: Dec 10, 2009
    Frenchie- Thanks for the real-life input on 456 sizes. An adjunct to that is the ABS system can apparently only handle about 4-5% difference in sizes front to rear. More than that and you end up with an ABS light and no ABS capability. Usually more of a problem with the mid-engined cars than our front-engined V12s, but worth noting.

    I really wish Michelin would come out with sizes for their PS2 Zero Pressures for our cars. Same tire fitted to the ZR1. Stick like glue, last 20K miles or so, and no worries about getting a flat. Pretty much only Corvette sizes so far, but more are being added.

    I put 25 mm spacers on the back of my 575M in hopes I could eventually afford Novitecs. Plus they look better with stock 550/575M 18 and 19" wheels.

    Taz
    Terry Phillips
     
  15. crmlcruiser

    crmlcruiser Karting

    Dec 28, 2005
    150
    Carmel ca
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    Michael
    I found a set of Michellin pilot Sport PS2s at a great price, $1600.00 shipping and taxes in. I love the Ps2s and they are a lot less that the Pirellis I found.

    The fronts are 255 35 19= 26.02
    The rears are 345 30 19= 27.14"

    The fronts are the same as stock height but the rears have 1" larger diameter. Will these be ok or will they cause the ABS to go nuts?

    If anyone knows of a better price for these or the pirellis let me know. althoough I really like my Michellins they are both great tires.
     
  16. tazandjan

    tazandjan Three Time F1 World Champ
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    Michael- 27.14"-26.02" = 1.12" ÷ 26.02" = 4.3% difference, which is approaching, or may exceed, the ABS limit. I would also worry about those rear tires being 1" larger than stock and rubbing, but no way to tell without doing a fit check. Franck (Jagbuff) says that combination will give you problems with the ABS from personal experience. Read his post again. Apparently the rears fit ok, but......

    Also remember he has Novitec NF2s with rear offset of 51 mm, what offset are your new rear wheels? Will make a difference

    Taz
    Terry phillips
     
  17. SFchallenge

    SFchallenge F1 World Champ

    Jun 28, 2004
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    Jon Wijaya
    Hi boys, has any of you used non factory spec tire sizes for your stock 17" on the 456?

    I can't find the 255 & 285 over here and the only set I managed to find is 4yrs old but unmounted for the rears.

    I was told that 275, 40 & 17R is a lot easier to get for the rears.
     
  18. Mark456M

    Mark456M Formula Junior

    Aug 26, 2008
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    UK
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    Mark Hannaford
    Franck is correct about the 30mm spacers being too big. The wheels will stick out beyond the wheel arch. I used 15mm spacers from Hills and find them just right. Even 20mm were just a bit too close to the edge of the arches but 15mm brings them just inside and look the nuts!
     
  19. tazandjan

    tazandjan Three Time F1 World Champ
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    Dave- I can do tire calculations just about as fast on a calculator. Plus when you are done, you actually understand what you did. Guess I was an instructor in the AF too long.

    Taz
    Terry Phillips
     

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