RE: Tire width in snow Was: tire size for 94 dakota?

From: Schelling, Paul M (SchellinPM@corning.com)
Date: Fri Oct 24 1997 - 07:34:00 EDT


Jon Steiger wrote:

>>> Speaking of traction: I don't know much about traction on sand,
but
>>> I think you're right, wider is better. (To "float" on the surface.)
But,
>>> with snow, narrow is better. You want to sink through the snow and
down
>>> to the underlying solid layer.
>>>
>>Correct me if I'm wrong, but you are assuming there is a solid layer
>>beneath the snow, if there is 2 or 3 feet of snow on the ground (Which
>>does happen occasionally) and you try to sink the tire to the solid
layer
>>beneath the snow (3 feet down) you're going to be sitting on your
axles
>>aren't you, and it doesn't seem like you'd get any traction...
>>
> Hmmm, I dunno. Maybe it depends on the type of snow? I've always
been
>told narrow is better for snow. I suppose if you had a couple feet of
>hard packed stuff, then you wouldn't want to sink in that, but if you
had
>a couple feet of fluff & slush, you probably want to get down to the
ground.
> I suspect that might be the case, since roads generally don't have
that
>kind of volume on them, unless its right after a serious snowstorm (in
which
>case it would be fluffy or slush). If that's true, then maybe I should
>revise my statement to be "narrow is better for snow on the roads".
>
> Anyone know for sure what the deal is?
>

I don't know about being absolutely sure, but here's what I think I know
(it must
be true because I read it somewhere :-) )

The other thing that is going on with modern snow tires is that they
pack snow
underneath them (not necessarily breaking through the snow to the
pavement
beneath) into the little sipes in the tire, and then use the resulting
little packed
ridges to drive against for traction. This is why narrower is better
regardless of
snow depth - more psi = more densely packed, stronger traction ridges.

I would imagine there is a limit, though - the point at which you start
dragging
your undercarriage in the snow, creating drag and reducing psi on your
tires.

 - Paul Schelling
  SchellinPM@corning.com



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