Snow Design - kinda long

[PDQSHIP@aol.com]

In a message dated 95-12-05 03:02:11 EST, you write:

<< No, No, No, you want the snow to stay between the treads, that's what 
give you the snow traction.  Correct Scott?


 >>

Well you are both right, Eliot on the post patch, you on the patch......
 Snow should be "flung" from the tread at all speeds, at high speeds snow
should take the same route as water.......  At low speeds, the outer edge of
the tire is critical for traction.....  You want a snow that will release M&S
at low speeds right at the outside "blocks" giving a clean tread to bite
(compress, bite, throw) on the next rotation....

Lets look at two popular tread patterns.....  An Eagle P600 and a P210, since
you have the two most popular tread patterns here, a block design with radial
groove, and a V design with radial grooves.....  The 600 will not perform in
snow,  becuz it is a "hard" tire the tread flex resists the ability of the
tire to clean the tread on each rotation.....  So basically you turn that
tire into a "snow slick" that is to say the snow will stay in the grooves and
channels and never get released.....  The consensus is that they suck in
snow......  However, some creative cutting of the tread design can make that
tire perform as well as many of the M&S rated snows on the market, but the
blocks will be weaker than a tire designed properly....  If you send diamond
cut around the circum of the tire, you have in essence designed a pattern
that makes the blocks soft and flexible, and easily toss snow....  A
staggered cut in both edges of the tire will also help this tire.....

Most of us see this custom design as hardly practical (Tire Rack used to
custom cut, don't think so any more) and with more Hi perf M&S tires on the
market, hardly necessary......  So to the 210.....  It has a softer tread
design, a v design that sends a point thru M&S first, moves the crud to the
outside of the tire, and if you look closely at the outside edges you will
see that Pirelli learned something from the rallyes in europe, that is, every
other block is about 1" or so resessed from the former, so the snow release
there is closer to optimal.....  I measured the tires the other day, and the
outside tread blocks measure 205, but the inside measures more like a
180.....   Interesting, and good thinking......   Plus there is a very subtle
ridge that runs about 1/2 inch up the tire that helps prevent buildup up the
sidewall, and helps the throw....

When I went to a "offroad" tire clinic by Goodyear in the 80's, they showed
the most successful tread pattern for a snow, and it was impressive and
excessive, a 33 inch "mud digger" truck tire....   But very much a design
philosophy.......  Large open blocks and a slight angle at the outside edge
to fling the M&S FROM the tire.......

To the width issue......  A narrow tire in theory performs better in the snow
for traction, this is to prevent "floating"......  However, proper tread
design with a heavy car can make that difference pretty slim, and it is
today.....  Common sense applies here, but the difference in the audis from a
175 and a 205 is easily overcome by proper tread pattern.....

The Blizzaks.....  A good concept, but the performance after a couple
thousand miles only rivals an all-season.....  If you look at the Vredestein
for example, the blizzax are using a much softer "hydrophilic" compound, but
the vreds have been around for almost 15 years now, and will give the
Blizzaks a run for the money right down to the wear bars.....  The Hokas:
 one of the best Snow tires available, but it has a single and express
purpose, that is to be a SNOW tire.....  If you are in ME, MI or CO or a
state where snow covers the highway as a general rule in the winter, go for
it, it is rewarding.....  But it also drives like a truck.....  I got a set
for my folks in Northern MI and they love them, but the driving is local and
is snow 90% of the time.....  The rest of us, Chicago included, have "winter
conditions" that might dictate a more mild snow pattern, and a more
aggressive "wet" pattern, cuz the salt boys go crazy when it snows, and the
temp fluctuates between subfreezing and balmy 65 (like now) in the winter
months.....  And there are several of those tires available that perform more
than adequately, esp with four on a q......  In fact, you can prolly leave a
good high performance tire (D40M2, and VR's come to mind) on year round and
not have to hassle with the changes in the winter.......

Sorry for the nerding, been on so many snows in my past lives, that it
becomes a passion.....  Best advice, avoid the two considered M&S but were
garbage IMO, the conticontact and the Pirelli winter 190's.....  My brothers
VR60's on his 89 probe turbo, could outrun me with either one of those
shoes......


Scott