Track day tyre pressures for 308? | FerrariChat
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Track day tyre pressures for 308?

Discussion in 'Other Racing' started by f308jack, Jan 25, 2008.

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  1. f308jack

    f308jack F1 Rookie

    Jun 7, 2007
    4,300
    Cape Town, South Afr
    Full Name:
    Jack Verschuur
    #1 f308jack, Jan 25, 2008
    Another track day coming up here in Cape Town, and on the last one my front end felt a little 'late' to react to steering input in tight corners.

    Car is an '82 GTSi.
    I am using street Bridgestones on 16" rims.
    Tyre pressure used on last track-day was 2.5 bars all round.

    Any suggestions?

    Happy motoring,

    Jack.
     
  2. ProCoach

    ProCoach F1 Veteran
    Owner

    Sep 15, 2004
    5,465
    VIR Raceway
    Full Name:
    Peter Krause
    #2 ProCoach, Jan 25, 2008
    Jack, 35 psi (2.5 bar) sounds a little low, especially as you're going quicker.

    The best thing to do would be to take some white shoe leather polish and place a 35-40mm "dot" of it on three points equidistant around the outside of the front tires at the juncture between the outside of the tread block and the sidewall. The tread block is the outer most raised tread. Then, go drive and if all of the tread block is not clean of white, lower the pressures and if the sidewall is scuffed beyond the edge of the tread block down onto the sidewall, add some pressure.

    My feeling is you could afford to go to 2.9-3.0 in the front and leave the back alone. The car naturally understeers anyway, so tightening up the front (getting rid of the "late" or lazy front end) is your goal in all cases.

    Good luck.
     
  3. tuttebenne

    tuttebenne F1 Rookie

    Mar 26, 2003
    3,208
    Bay Shore, NY
    Full Name:
    Andy
    #3 tuttebenne, Jan 25, 2008
    When are you measuring the tire pressure? At my last track event I was running 38 and 38 fr/rr cold. This puts it way over 40 when the tires are hot.
     
  4. ProCoach

    ProCoach F1 Veteran
    Owner

    Sep 15, 2004
    5,465
    VIR Raceway
    Full Name:
    Peter Krause
    #4 ProCoach, Jan 26, 2008
    Most DOT tires specify COLD pressures. Some of the newer R-rated DOT tires and ALL of the racing slicks have a specified desired HOT pressure.

    Over 40 hot is desirable for most DOT R-rated tires and mandatory for floppy sidewall "street" (more than 140 treadwear rating) tires. YMMV.

    I tell everyone who is just starting out with OEM tires to go 5 psi higher than stock (factory recommended on the car sticker) cold pressures.

    Heck, 38/39 cold is my STOCK recommended cold pressures for my Mondial t Coupe!
     
  5. Pcar928fan

    Pcar928fan Formula 3

    Jan 21, 2008
    1,702
    Austin, TX
    #5 Pcar928fan, Jan 27, 2008
    Stock cold on my '88 Porsche 928 S4 are 36/44 F/R! That rear pressure is crazy high...it works though!
     
  6. f308jack

    f308jack F1 Rookie

    Jun 7, 2007
    4,300
    Cape Town, South Afr
    Full Name:
    Jack Verschuur
    #6 f308jack, Jan 28, 2008
    Thanks for the advice to all! Unfortunately I got to read it only today.

    That was fun, lots of fast cars, the 308 ran great and we didn't break anything:)

    Tyre pressures, however, at 2.5 bar definitely too low. We drove it a lot harder than the previous track day, balance was absolutely perfect with the increased rear track, making for some spectacular 4-wheel drifts (well, we were chasing a 430 Challenge....) but next time must have decidedly more pressure.

    No oil-starvation (overfilled 1 liter), temperature rock-steady, sunshine. A perfect day.

    Even got better when I got a ride in a 430CS with an experienced driver. Awesome automobile.

    No pics yet, will post some as soon as they are available.

    Thanks again,,
    Jack.
     

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