Recommended tire pressure doesn’t seem to be ok any more! | FerrariChat

Recommended tire pressure doesn’t seem to be ok any more!

Discussion in '348/355' started by johan6504, Jun 9, 2007.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. johan6504

    johan6504 Formula 3

    Jun 28, 2005
    1,168
    Sweden
    Full Name:
    Johan
    #1 johan6504, Jun 9, 2007
    Have had some problems finding the right chassis settings in my new 355 lately. I have checked and corrected the wheel alignment and made sure the wheel balance is ok. But I still had a vague feeling in the car.

    Yesterday I checked the tire pressure and the readings were spot on. 2.2 in front and 2.0 in the back all good and well according to the manual for my Pirelli P Zero.

    But just to se what happens I increased the pressure to 2.5 in front and 2.3 in the back and it made a HUGE difference. I have now been playing around with different settings and they all make the car behave in different ways. It is now clear to me that the pressure setting is very vital to the over all behavior of the car.

    This makes me wonder if the new Pirelli P Zero as of to day really work with the same setting as the old that was produced in 1999. I think the new P Zero tires work better with a totally different pressure setting. Any one else with Pirelli P Zero Asimmetrico and if so, what setting are you using?
     
  2. Lars_vet

    Lars_vet Formula Junior

    Feb 25, 2007
    603
    On the open road
    Full Name:
    Lars
    #2 Lars_vet, Jun 9, 2007
    2.2 in front and 2.0 in the back seems low...Why lower in the back?
     
  3. johan6504

    johan6504 Formula 3

    Jun 28, 2005
    1,168
    Sweden
    Full Name:
    Johan
    #3 johan6504, Jun 9, 2007
    The setting for the 355 is different depending on the type of tire it was delivered with.

    The manual states:
    Bridgestone Expedia S-01: front 2.5 rear 2.2
    Michelin Pilot SX MXX3: front 1.9 rear 2.1
    Pirelli P Zero: front 2.2 rear 2.0
    Good Year GS Fiorano: front 2.6 rear 2.3

    So different settings were recommended depending on the tire brand. But these tires have been developed over the years and the pressure instructions probably no longer apply, at least that is what I am trying to figure out. What I have found out is that the Pirelli setting doesn’t seem to work well anymore. But what the optimal settings are is the tricky question.
     
  4. 355

    355 F1 Rookie
    BANNED

    Jan 4, 2005
    3,643
    Toronto
    Full Name:
    Frank
    #4 355, Jun 9, 2007
    I have the bridgestones and I run 35lb or 2.4 all around and it works great. Mind you my back tires are 295-35.
     
  5. johan6504

    johan6504 Formula 3

    Jun 28, 2005
    1,168
    Sweden
    Full Name:
    Johan
    #5 johan6504, Jun 9, 2007
    Hi
    I tried 2.4 all around and it works ok for me too.

    The over all feeling is that the front gets little more nervous and more precise as I increase the pressure in front and the back seem to be more stable with increased pressure. There seems to be some correlation between the pressure settings as well, not sure how it all works together yet though.
     
  6. conscom

    conscom Formula Junior

    Jan 6, 2008
    467
    Vancouver BC Canada
    Full Name:
    Gary
    #6 conscom, Apr 1, 2008
    I've Michelin Pilot Sport original size tires. Contacted Michelin and their recommendation is 36 lb. front and back. (2.5). Explanation is larger tires in back carries the extra weight. I'm going to try 35 lb. (2.4) all round.
     
  7. 285ferrari

    285ferrari Two Time F1 World Champ
    Sponsor

    Sep 11, 2004
    20,845
    Southern Md
    Full Name:
    Robbie
    #7 285ferrari, Apr 1, 2008
    Conversion chart?
     
  8. conscom

    conscom Formula Junior

    Jan 6, 2008
    467
    Vancouver BC Canada
    Full Name:
    Gary
    #8 conscom, Apr 1, 2008
    Conversion is 1 psi = .0689 bar
     
  9. vvassallo

    vvassallo F1 Veteran
    Silver Subscribed

    Aug 4, 2006
    8,281
    Palos Verdes
    Full Name:
    Vince V
    #9 vvassallo, Apr 2, 2008
    Isn't it easier to say that 1 bar = 14.7 psi, or just under 15 lbs?
     
  10. Ferrari Fanatic

    Ferrari Fanatic Formula 3

    Apr 2, 2003
    1,317
    SoCal
    #10 Ferrari Fanatic, Apr 2, 2008
    Yes much, I am prety good at math and had a bit of a WTF?
     
  11. 355

    355 F1 Rookie
    BANNED

    Jan 4, 2005
    3,643
    Toronto
    Full Name:
    Frank
    #11 355, Apr 2, 2008
    Get a tire gauge from Canada and it has both.
     
  12. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    #12 gothspeed, Apr 3, 2008
    +1....... :)
     
  13. cf355

    cf355 F1 Rookie

    Feb 28, 2005
    4,208
    Full Name:
    chris
    #13 cf355, Apr 3, 2008
    As we are all on 'modern' tires now is there a consensous now that we should be using the same tire pressures all around (ie 35 lbs) vs Ferrari's original recommendations for staggered tire pressure rates front and rear?
     
  14. vvassallo

    vvassallo F1 Veteran
    Silver Subscribed

    Aug 4, 2006
    8,281
    Palos Verdes
    Full Name:
    Vince V
    #14 vvassallo, Apr 3, 2008
    Staggered tire pressures were recommended by manufacturers predominately to introduce understeer and a margin of safety for US drivers, who are notoriously underskilled. :) Frankly, with a natural tire stagger we have in the Ferraris, it seems ludicous to add additional understeer with varying tire pressures. In fact, it makes more sense to stagger pressures in opposition to the recommended. However, I use 35 or 36 psi in all 4 and play with it. When I am just recreational driving, I leave it alone and tune for ride and light cornering. When doing auto cross or more enthusiastic driving, it makes sense to take a pyrometer measurements to fine tune for your venue.
     
  15. conscom

    conscom Formula Junior

    Jan 6, 2008
    467
    Vancouver BC Canada
    Full Name:
    Gary
    #15 conscom, Apr 10, 2008
    Depends which way you are converting. Anyhow, just answering an inquiry exactly. Thx for your later post on Apr. 03
     
  16. veryfast355

    veryfast355 Karting

    Sep 24, 2007
    120
    gt neck long island
    Full Name:
    michael c
    #16 veryfast355, Apr 10, 2008
    I am really confused - I tried to reach Michelin on this and got nowhere. I am at 31 front and 29 rear but I would welcome any comments or suggestions on this.
     
  17. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    #17 rexrcr, Apr 11, 2008
    Needless to say the the tire is the most complex, most important and least understood component on a car.

    Manufacturer recommended pressures are a great place to start tuning your setup. Your car is supported soley by the volume of air in the tire, changing pressure alters the spring rate of the tire, plus ride and responce characteristics. It's safe to say that a given tire's spring rate is 10,000 lb/in, altering air pressure 1 psi makes a large change in spring rate.

    I suggest all things equal, as long as you're not going lower than 25 psi cold, nor higher than 44 psi cold your okay in regards to safety UNLESS going for a top speed run, just tune pressures for what makes the car feel good.

    This characteristic is one of the many benefits of a Ferrari, the next best thing to a race car, it's very responsive to tire pressure, alignment and geometry changes.

    There is not a specific right setting that's the same for all, tune to the tire, road, and taste.

    Best,
    Rob
     

Share This Page