News

Rear Tire Size

Discussion in '348/355' started by cbrody, May 9, 2007.

  1. cbrody

    cbrody Rookie

    Nov 1, 2003
    35
    Southampton, NY
    Full Name:
    Chris
    Hi Guys,

    I'm looking on replacing the tires on my '97 355 Spider. What sizes do you recommend? With 285/35/18's on the rear would spacers be required?

    Thanks,

    Chris
     
  2. To remove this ad click here.

  3. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    That is the rear size I use, with stock in front!! I am very happy with them!! As for spacers you need 15mm in the rear (also what I use) :)
     
  4. TopElement

    TopElement Formula 3

    May 14, 2005
    1,509
    OC & Vegas
    Full Name:
    A Montoya
    For stock wheels, I only believe in the original tire size. Keeps the tire tighter and more consistent handling.
     
  5. F355Bob

    F355Bob Formula 3

    295/35/18 is very close to the stock size.
     
  6. TopElement

    TopElement Formula 3

    May 14, 2005
    1,509
    OC & Vegas
    Full Name:
    A Montoya
    Over an inch wider, which allows the sidewall to flex a bit more. Close to stock diameter though.
     
  7. To remove this ad click here.

  8. J. Salmon

    J. Salmon F1 Rookie
    Silver Subscribed Owner

    Aug 27, 2005
    4,316
    VA
    Loved the switch to 295/35/18's. And they look mean.
     
  9. DannyR

    DannyR Karting

    Apr 6, 2005
    129
    Alabama
    Full Name:
    Danny Roberts
    My understanding was that on the rear if you went to a 285/35 you would not need spacers. In some postings I have seen guys say they went up to 295's without spacers.
    Any thoughts.
     
  10. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    I think you can run 11mm spacers with 295's. I have 15mm spacers with my 285's. I went 285 because the sidewalls were huge on the stock 265/40's. The 285's are just a tiny bit smaller radius which will give you a 'tiny' bit more bottom end acceleration :). I think the 285's are the correct width for a 10" wheel.
     
  11. billyfitness

    billyfitness Formula Junior

    Feb 14, 2006
    581
    Overland Park, KS
    Full Name:
    Bill Leavitt
    I went 295 with no spacers, handles just fine after a heat cycle or two.
     
  12. To remove this ad click here.

  13. F355Bob

    F355Bob Formula 3

    You can go with 15mm spacers in the rear with no problem and 255/35 fronts but the fender lip would have to be rolled. I 've run this setup for 3 year with no problem.
     
  14. Robin

    Robin F1 Rookie

    Nov 1, 2003
    2,893
    Arlington, VA
    Agreed. If the engineers at Maranello thought a 295/35 would improve handling/balance, they would have put them on their to begin with.

    -R
     
  15. TopElement

    TopElement Formula 3

    May 14, 2005
    1,509
    OC & Vegas
    Full Name:
    A Montoya
    I don't disagree with going to a larger tire though, I'm all for more rubber. But personally I'd only do it with a matching increase in wheel width.
     
  16. LetsJet

    LetsJet F1 Veteran
    Owner

    May 24, 2004
    9,243
    DC/LA/Paris/Haleiwa
    Full Name:
    Mr.
    I'm not so sure.............
     
  17. ExcelsiorZ

    ExcelsiorZ Formula 3

    Nov 7, 2003
    1,183
    Beverly Hills
    Beg to differ. Tire is too small for the rim. When Mario Andretti did a track test which included a 355 for Road & Track he had to radically LOWER tire pressure at the rear. Why? In his words, to get more tire to the ground! Porsche Turbos of the same generation used a 10" rear wheel with a 285. Fits perfect. Also, 512TR and M use a wheel just half an inch wider (less than 13mm) yet use a 295, 30 mm larger than a 355 tire. Never assume and never just follow. Your car will handle better and SAFER with a 295 in the rear than with a 265.
     
  18. 355

    355 F1 Rookie
    BANNED

    Jan 4, 2005
    3,643
    Toronto
    Full Name:
    Frank
    Ive had the 295 35 18 on for years and it is incredible. Bridgestones of course and no spacers.
     
  19. LetsJet

    LetsJet F1 Veteran
    Owner

    May 24, 2004
    9,243
    DC/LA/Paris/Haleiwa
    Full Name:
    Mr.
    My car:

    Rear - 295/35/18 w/ 15mm spacers
    Front - stock w/ 15mm spacers

    I'm not saying spacers are needed, just letting you know my fittment.
     
  20. bcwawright

    bcwawright F1 Veteran

    Jul 8, 2006
    5,234
    Georgia
    Full Name:
    Bruce
    Wheel sizes have 3 critical measurements(not 2)...these are width(flange to flange),diameter, and flange height(i.e. J[.68"] or K[.77"]..etc.).......the maximum flange to flange wheel width should be equal to the tire tread width...any wider and it creates a bad rim seal(dangerous) and forces the tread to assume a convex shape causing abnormal tire wear and a reduction of control......
     
  21. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    Isn't yours a really good replicar though?? ;) ;)
     
  22. bcwawright

    bcwawright F1 Veteran

    Jul 8, 2006
    5,234
    Georgia
    Full Name:
    Bruce
    Use of spacers load the suspension differently than what oem design was setup for.....you may be able to get away with this on a street car but for race applications shock valving and spring rates would need to be changed, along with sway bar and camber adjustments.
     
  23. LetsJet

    LetsJet F1 Veteran
    Owner

    May 24, 2004
    9,243
    DC/LA/Paris/Haleiwa
    Full Name:
    Mr.
    Well, it's really, really, good though.......

    I also dialed in about 2 degrees neg. camber in the rear.
     
  24. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    That is true, the wheel gets more leverage with a spacer. It is a small percentage increase of the entire a arm length. So as bca said, street should be ok and as for racing .....well the addition of 'unsprung' weight does not help either so most racers should/would 'retune' their suspension. :)
     

Share This Page