[urq] Tire pressure for ice racing ?

[qshipq at aol.com]

 Winter conditions make Greg's point valid.  As a rule, on the urq, you will end up somewhere in the 24-28range with an Ice Tire.  Much of the exact pressure has more to do with the track conditions than the tire itself.  By this I mean that a softer suspended car on ice tends to have better grip, and can run higher tire pressures, than that of a stiffer suspended car.  The object in ice tires is to leave the tread on the ice with a lower 'effective spring rate' which would include the sidewall of the tire.  I did some testing on this at Steamboat with my 94 Supercharged Landcruiser with DMZ3.  With stock suspension and airbags, I would find that increasing airbag pressure would result in a slower lap, and that decreasing tire pressure could compensate for increasing airbag pressure.  Ultimately, I set the airbag pressure as low as possible and ran 28psi tire pressures.  

That said, after 17 years at Steamboat, 10 of that in an urq, IME the best ice tire pressures are going to be in the 24-28 range (depending on amount of snow, condition of ice, and effective spring rates) using a stock suspension.  IME2, front rear pressure variations don't appear to be a significant factor in a locked center diff scenario.  I suspect this is because the locked center has significantly more effect on dynamic handling than front/rear tire pressures do.

Scott J
84 Urq
83 Urq Ice Track Car


 

 

-----Original Message-----
From: LL - NY <larrycleung at gmail.com>
To: Greg Smith <lifeisabirdie at yahoo.com>
Cc: urq at audifans.com; vittorio at mybares.com; quattro at audifans.com
Sent: Mon, Feb 15, 2010 11:14 am
Subject: Re: [urq] Tire pressure for ice racing ?


I daresay, the same thing applies to pavement tires in racing, but the range
of variation seems smaller, though not insignificant.

On Mon, Feb 15, 2010 at 11:39 AM, Greg Smith <lifeisabirdie at yahoo.com>wrote:

> I don't think that you can give a blanket statement as to a certain
> pressure for front or rears with plain snows.  In my 31 years of ice trials
> and ice racing; I have found that even within a specific tire brand when you
> have a certain model of tire vs another, they will perform differently with
> different pressures.  As an example the Nokian Hak NR09 used to work much
> better with a lower pressure than the Nokian Hak 2 or Hak Q.  On the same
> car there was a variation of over 9psi where I would get optimal times. I
> used to just go out to a lake and set up a basic course and start doing
> hundreds of laps and adjusting pressures.  I would bring out different tread
> patterns from Nokian and have at it for hours at a time.Just my .02 that
> thee is no magic PSi setting for all brands and models of snow tires.  I
> don't think that anyone has addressed that.
> Greg Galinsky
>
>