Steven E. Broomhead, Sr. wrote:

	broom-sr @ southwind.net ("Steven E. Broomhead, Sr.") 
12/20/96 07:49 AM
To: vanagon @ lenti.med.umn.edu (Multiple recipients of list) @ Internet
cc:  (bcc: Karl G Vochatzer/AMR)
Subject: Re: Waht was that about lowering tire pressure on ice?

>Having lived with snow and ice in Illinois for 25 years of driving
>pleasure, I can state truthfully that lowering the pressure in your
>tires will cause them to wear out the sidewalls faster, get you stuck in
>the snow as much or more than properly inflated tires, AND give you more
>surface to skid/slide on the ice.

>In other words, it is not a good idea :(

>Snow tires, studded tires (if allowed in your state), or chains are your
>best choice.

I agree with his recommendation whole-heartedly, however, the part
about the "more surface to skid/slide on the ice" is probably not true.

Under-inflated tires actually buckle inward when in contact with the 
snowy ground due to low tire pressure, thereby leaving only the
edges of the tire to contact the ground as evidenced by the tire
track patern in the snow left by the spinning tire.  This means that only
the edges of the tire are really contacting and gripping the snow. 

With properly inflated tires the tire track patern is even, thus more contact
with the snow and hopefully the pavement.  Try this out on a snowy hill with 
under and properly inflated tires.  I'll bet you get the same results as I did.

In your experiment, you'll likely find that all things considered equal, 
the under-inflated tires will sit and spin more than the properly
inflated tires.

If anyone replicates or finds contradictory results to this informal experiment,
please post your findings.

Karl
88 GL