On 11/27/2010 11:47 PM, Walt wrote:
On 11/27/2010 9:05 PM, VtSkier wrote:
On 11/27/2010 05:56 PM, Walt wrote:


Whatever you do, don't let anyone talk you into "all season" tires that
are "almost as good as snowtires". Get dedicated snows.

While I believe this is true, and it's more true for
a "regular" car (2 wheel drive) than for either an
"all wheel drive (full time 4 wheel drive)" or selectable
4 wheel drive.

I've driven 4WD vehicles with all season tires and FWD vehicles with
real snow tires and I'll take FWD with real snow tires in a heartbeat.
It's not even close for most winter driving situations.

Let's discuss driving conditions.

You're in the upper midwest. I suspect that you
have snowy driving conditions on a regular basis.
I'd like to hear from you how the local road crews
handle keeping roads clear.

Even the lake effect snow areas of northern
New York roads are handled differently than they
are here in Vermont.

Here's what the crews do here. Unless it is
pnuking snow, they will salt the roads a lot more
than they plow. This causes a slush condition in
which you want to dig through to gain traction
from the pavement below. I think they do this
because most of our storms happen at relatively
high temps, 20 degrees to 30 degrees. Salt
works at this temp range and by the end of the
storm event the roads are pretty much clear
to pavement.

Snow falling at those temps on a road tends to
get polished down to near ice before the plows
can get to it and if they are plowing, they are
doing so with a truck that is also dumping salt.

My 4WD vehicles with all weather tires track
better in the slush than any FWD car with snow
tires that I have ever owned. The traction on
slippery going on back roads is also better with
the 4WD AllWeather as it is with the FWD and
snows.

Also, I might point out that road crews around
here don't always wait for the storm to start.
I've seen them out putting down salt before the
first snowflake.

So, in my conditions, my 4WD vehicle with GOOD
all weather tires is more than acceptable and
IMO better than FWD with snows. Then, between
storms, I have a comfortable ride and better
gas mileage.

You might also note that the signs they post
in the Sierra's when a storm is expected is that
you must have chains OR 4 wheel drive. It does
not specify snow tires.



Look at the tread of a snow tire, or more properly an
"mud and snow" tire (read the sidewall). These big
grippers are made to dig into a loose material and
gain traction.

The tread pattern is only a part of the picture. The main improvement
of real snowtires like the Blizzak and the Hakkepallita is the material
science behind the rubber compounds. The material just flat out grips
better than normal tire rubber. The tradeoff of course is that the
compound wears out faster, especially at higher temps.

It's just like with skis - the breakthrough is not so much the sidecut
as the torsional rigidity and vibrational damping made possible by
advances in materials.

The only way these are going to perform
on ice is to have studs.

Um.... recent tests have shown the new formulations grip *better* than
studs. Studs tend to tear right through the ice so their grippiness is
limited by the strength of the ice. At near freezing temps, the ice has
little structural integrity, so the studs just rip right through it.
Grippy rubber formulations spread the load over a larger surface area
and hold better than the point-load of a stud.

In my "real world" I'm happy that the studs break
through. In the past it has been noted that narrow
snow tires are sometimes more effective than wide
ones because the wide ones "float" and the narrow
ones break through.

IMO a test which finds a certain solution works
better on a block of ice better than another may
or may not have real world application. The studs
ripping through ice might just be what you want.
There is better traction in the material under the
ice.

So I've already agreed that Blizzaks and apparently
Haks are as good a solution as studs. But...
already having two good studded snows for my wife's
car, I bought two more rather than spring for four
Blizzaks. It seemed a no-brainer to me. For others
following this thread, you should always have the
same kind of tires at both ends of the car. If you
have AWD, you need also to have tires of the same
brand, size, tread pattern and age at both ends of
the car.


Braking.
There isn't a tire in the world that will improve your
braking on ice except a studded tire.


Not true. See above. Studs are an old technology that worked pretty
well but has now been superseded.

Really, the bottom line for driving on slippery surfaces is that a
higher coeffficient of friction will do much more for you than doubling
the number of driving wheels (while keeping the number of braking wheels
the same). I've never understood how anyone could be so penny-wise as
to spend $35K on a 4WD SUV and not pony up another $500 for real snow
tires.

//Walt