News

new tires on my 328 - 50 lbs. pressure??

Discussion in 'Technical Q&A' started by Crawford, Feb 3, 2004.

  1. Crawford

    Crawford Formula 3

    Mar 5, 2003
    1,294
    Nashville, TN
    Full Name:
    Crawford White
    Just got some new Bridgestone Potenza S-03's and the shop filled them to 50 lbs. all around (max pressure for those tires is 51). He said if the ride was overly harsh, I could lower the pressure but should not go below 40 lbs.

    Is it OK to run with tires at max. pressure? The ride may be stiff, but it sure makes it easy to parallel park!
     
  2. 62 250 GTO

    62 250 GTO F1 Veteran

    Jan 9, 2004
    7,732
    Nova Scotia Canada
    Full Name:
    Neil
    Holy crap that seem hight to me. My max pressure is 44 lbs and I only put 35 or 36 in.
     
  3. Schatten

    Schatten F1 World Champ
    Rossa Subscribed Owner

    Apr 3, 2001
    11,237
    Austin, TX
    Full Name:
    Randy
    harsh ride? no wonder, especially with all of that air in there. Read the tire itself, it should be ~32-36#'s C O L D, and that's it. make sure you aren't taking temps once you have been driving around.

    also, tune the front air pressures for ease of turn-in and basic feel for the wheel. tune the rear pressures, down or up a pound for understeer/oversteer characteristics.
     
  4. rob lay

    rob lay Administrator
    Staff Member Admin Social Subscribed Miami 2018 Owner

    Dec 1, 2000
    50,760
    Southlake, TX
    Full Name:
    Rob Lay
    Holy cow they are dumb! Best thing I ever did was take auto tech courses a couple years back and start racing, only now I realize how much I was taken advantage of and given bad information before. I don't know everything, but I can ask the right questions now and know when someone is way off base like this.

    Also, tire pressure increase when you use them, so you'll be over the max under use.
     
  5. BigHead

    BigHead Formula Junior

    Oct 31, 2003
    992
    Outside of Boston
    Full Name:
    Dennis
    Crawford, the shop is filled with morons. 50 lbs?!? That's insanity. Most reasonable shops will recommend what the factory recommends for OEM tire sizes. I don't know offhand what it is for the 328, but check your manual, or maybe you have a sticker on the passenger door post (b-pillar). I suspect that it will be something like 29F/32R, COLD. You may want to play with that to get better performance FOR YOU. Try going up and down in increments. The lower front pressure will tend to increase understeer, a safer bet from the manufacturer's point of view.

    I suspect that you'll be happiest running 33 lbs. all around. If you ever get above 40 lbs. HOT, your cold pressures are too high.

    Just my $.02.

    vty,

    --Dennis
     
  6. Napolis

    Napolis Three Time F1 World Champ
    Honorary Owner

    Oct 23, 2002
    32,118
    Full Name:
    Jim Glickenhaus
    You believe your Auto Tech teacher over Hunter Thompson's tire inflation advice in "Fear and Loathing in Las Vegas"?
     
  7. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,967
    S03s have a max pressure rating of 51 PSI.
    road driving will cause a 4-5 PSI increase in the pressure
    race track driving may cause 6-9 PSI increase in the pressure

    Just because the tires have a high PSI rating, does not in any way shape of form require you to use it. Keep the PSI rating as margin against stupid things happening to you (like the tire shop).

    I assume these new tires have the same footprint as your previous tires. This means you want the same pressures as your previous tires. You may want to add or subtract 1 or 2 PSI either front or rear to rebalance the car due to the difference in grip on the new tires. But there is almost never a reason to make radical moves in tire pressure:: +17PSI is radical! Now lets assume that you increased the width of the tires compared to the old tires: at this point you want to LOWER the pressures--but once again only by a little (like 1 PSI).

    Drop the pressures down to the normal range. Some where in the 30 to 35 PSI range you will find the grip, balance, and ride you enjoy.

    My S03s are kept in the 33-34 PSI range on my F355B for road driving. I tend to like the higher end of the inflation spectrum as the car is quicker to respond to steering, while others may prefer the lower end of the spectrum (30 PSI) for a nicer ride at the expence of quickness. I tried as high as 38 PSI in the first set of S03s and it was "not pretty" with words like, suicidal, nonpredictable, hard-as-a-rock comming to mind.
     
  8. Crawford

    Crawford Formula 3

    Mar 5, 2003
    1,294
    Nashville, TN
    Full Name:
    Crawford White
    I've put the tires back to 32 psi all around. That should make old yeller a bit less twitchy...
     
  9. Mule

    Mule F1 Rookie
    Rossa Subscribed

    Jun 25, 2003
    3,499
    Alaska
    Full Name:
    Mule
    I am running 35PSI in my new Goodyear F1's (max is 51 PSI).
     
  10. 62 250 GTO

    62 250 GTO F1 Veteran

    Jan 9, 2004
    7,732
    Nova Scotia Canada
    Full Name:
    Neil
    How long was the 50 lbs in there?
    Could this chap have damaged tires?
     
  11. dwhite

    dwhite F1 Rookie

    Put in what the owners manual calls for then adjust, as needed, for your preference of understeer / oversteer(many here have discussed this at length - do a search). BTW max 51 psi is for cold tires, the manufacturers know pressure will rise during use and set max pressure accordingly.

    RE: edit - Ooops. forgot to mention, enjoy them they are great tires. I have them on my 308.
     
  12. Crawford

    Crawford Formula 3

    Mar 5, 2003
    1,294
    Nashville, TN
    Full Name:
    Crawford White
    Only had the tires at 50 PSI for about 3 hours and 12 miles....
     
  13. Texas Forever

    Texas Forever Four Time F1 World Champ
    Rossa Subscribed

    Apr 28, 2003
    44,339
    Texas!
    Napolis, I have crossed many rivers since I read the good doctor's postings in the Rolling Rag. Perhaps you could refresh us? I might need this info for my upcoming road trip to Pebble...

    Dr Trips
     
  14. ferrarifixer

    ferrarifixer F1 Veteran
    BANNED

    Jul 22, 2003
    8,520
    Melbourne
    Full Name:
    Phil Hughes
    The "Max pressure" writing on the side of tyres is for installation purposes, and extreme conditons only. Even track work wouldn't get near a tyres max pressure from a sensible start pressure.

    In order to seat the bead when changing tyres, it may be necessary to go to 50+ lbs sometimes, until it pops on, the they should be deflated back to the required pressure.

    To drive in the wet with your tyres at 50lbs would be potentially disastrous...even fatal.

    I'd sack the tyre fitter on the spot if he worked for me...no excuses, potentially business busting law suit in event of accident.
     
  15. DGS

    DGS Three Time F1 World Champ
    Rossa Subscribed

    May 27, 2003
    39,246
    MidTN
    Full Name:
    DGS
    I started the S03s on my 328 at 33, which is spec for the stock tires. (Spec for the other stock type tire is 33f/36r.) I wound up with 35 per corner, which turned out the handling I prefer.

    You might drop the fronts a pound, if you want to put a little understeer bias on the car (e.g. keep the tail from going walkabout as easily).

    Note: these numbers are for the stock (205/255) size tires (not the +1 size comonly used), and I had a four wheel alignment when I installed the tires, so your mileage may vary.
     
  16. TOM B

    TOM B Formula 3

    Jul 24, 2003
    1,038
    Orange County, NY
    Full Name:
    Thomas Buckley
    Put the pressures at recommended levels as stated in the owner's manual. For my 3.2 Mondial that's 37 front and 38 rear. I imagine the 328 is similar.

    Tom
     
  17. Napolis

    Napolis Three Time F1 World Champ
    Honorary Owner

    Oct 23, 2002
    32,118
    Full Name:
    Jim Glickenhaus
    The good Doctor felt that the proper settings for "The Shark" should be 100 psi all around. Even though both of us can prob. handle another ROAD TRIP we are getting a bit older and I'd reccomend using no more than 65.
    Best
     
  18. Texas Forever

    Texas Forever Four Time F1 World Champ
    Rossa Subscribed

    Apr 28, 2003
    44,339
    Texas!
    Okay, now I remember, I think. I was wearing a lot of tinfoil hats back in those days. Are you sure that he wasn't filing those tires with nitric oxide? :)

    BTW, I may have found my Blueman's Enzo for driving to Pebble

    http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=6405&item=2457882951&sspagename=STRK%3AMEBWA%3AIT

    It already has the wing on the back. Now all I'll need is a beautician at the wheel.

    Take Care
     

Share This Page