Right now Discount tire direct has a promotion for buying a set of 4 tires and on top of that, if you apply for the Discount tire credit card you get another rebate.
For instance on a set of 4 BFG 235/60-15 you get $75 Visa card, and using the Discount tire credit card a $60 rebate. Sale is good till the Feb 15. Just put in tire size you need and see pricing. Free shpg too. For WA state, there is no tax. They probably charge tax depending where its shipping to. This is not the Discount tire store, this is there online store only. They do sell Coopers too.

http://www.discounttiredirect.com/direct/home.do?