I looked at some used, I found a decent price on tire rack so having new will be good anyway.

Looks like a good site, but I have already ordered from tire rack and I don't see blizzaks on their site, at least I can't find them. I will check them out when time comes for summer tires.

Going off of some peoples comments about tire compounds....
The reason for switching your summer tires for winter tires (outside of tread design) is as follows:
Tires get their traction through 3 ways:
1- Keying; This is your tire deforming to the road surface, each rock and every pebble
2- Tearing; the resistance created by microspic parts of the tire tearing themselves off as it is keyed- you usually want a little tearing, but too much otherwise after admiring the grip, you'll complain about the short life of the tire.
3-Adhesion; your tire sticks to the road, When the road is wet, you loose this adhesion and you then are strictly relying on keying and tearing.

Knowing that, the difference between the tire compounds between Summer tires and winter tires (in general) is the temperature range.
As the name inplies, Summer tires are meant to be used in warmer temperatures and at higher speeds (which creates more heat). Because the tire's relation to temperature is logarithmic meaning that its going from a high temperature to a low temperature the amount of 'grip' that you get goes from a high plateu to very quickly dropping down to a significantly less grip at lower temperatures...In short, you'll find that your summer tire 'freezes'... from there, your summer tire then don't key as well nor do they tear as well nor do you get as much adhesion and then that stopped car infront of you comes a lot closer to you. Winter tires are made to operate at this lower temperature and not freeze so you maintain your intended tire compound properties. Problem is that if you start using it in warmer weather, your tires will sort of melt....just think of butter thats been sitting at room temp vs the fridge. With your tire softening up, it tears easier (or quickly wears) and it becomes gooier.
So where's this border at? without specific tire data, its most likely between 30-50 degrees.

In short about the treads:
The treads are also different between the two types, with snow tires, the treads are longer and have more open areas for the slush to go through while summer tires have larger tread patterns which means that the tread doesn't bend and flex as forces are applied to the tire (think of winter tires treads as each one being one of those long clicky erasers which flex really easy and summer tire treas as each tread being one normal block erasers...Block erasers more stable right?) With the longer treads on winters your steering will feel 'gooier' and that will get even worse as your tire softens up in warmer temps

(by the way i highly reccomend reading "The racing and High performance Tire" by Paul Hanley...REALLY a great book)

-- Edited by Venno at 14:28, 2008-11-08

Thank you very much for tat Venno.

So it is safe to say I am safe to put on my Blizzaks when the temp is around the 40-50 range knowing it will be more in the 30-45 range soon?