Tires are one of the most important components on any vehicle, and not an consumer item to skimp out and go cheap on in my opinion.
Spend good money and buy good all weather's to begin with and you wont have to "fix" them by doing any aftermarket siping.
Many quality tire manufacturers sipe their tires at the factory now. On my Denali I have Nokian Vatiiva's All weather all terrains, and on the Subaru, the newer Continental ExtremeContact DWS (Dry-Wet-Snow) tires...both factory siped. These tires typically are made using Nanotechnology silica-based tread compounds to reduce operating temperature, improve traction, and extend the life of the tire. A little more $$'s spent up front for a better quality tire will give you better performance and longer wear-life in the end.
These days there is no excuse to not know what you are buying before walking into a store. The interwebz is full of reviews, product comparisons, etc. Do you homework and have a gameplan before you enter any retailer, instead of walking in and asking to get bent over cause you don't know sh!t about what you need.
Larry, fact is there are probably 300K people are looking for tires in Seattle today. Even if you were to find tires, getting them put on will probably take days. Wait until the next warm-up and things get back to normal then try to find the tires she needs. I had a buddy that foolishly went into Discount tire yesterday at 2PM. At 10Pm, he was still there...no freekin thanks!
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