Tireteam and tire kingdom are two great companies to find cheap prices on continental tires for your sedan.
You can find 4x4 tires at tire kingdom or sears at cheap prices.
Montreal Tires offers some competitive, but affordable prices on tires. Call around and compare prices, you may be surprised where you can find the cheapest.
To find a set of cheap atv tires, you can go 4wheelparts.com. This website specializes in tires for special 4 wheelers such as atvs and have some discounted prices for them.
Sears and Tirepackage are two online stores that you can find cheap prices on mud tires.
From my own experience, tirerack.com is the best place/website for buying tires. Not only are the prices cheap and hard to compete with but they have tire prices listed on the site.
cheap rims and tires is a good site
Onlinetires.com has a good selection of performance tires at fairly cheap prices, including the size tire specified. If you are in the northeast, I've had good luck at Town Faire Tire.
Big O Tires sells tires through their website www.bigotires.com. That is the best place to find their prices. However, if you are looking for reviews please go to http://www.consumeraffairs.com/tires/big_o.html. Here you will find out how others fared at Big O Tires.
You can find cheap tires and rims at Les Shwab tire. Be warned though, cheap rims will often break if you come in contact with a curb and cheap tires often do not last long or have the grip that more expensive tires do.
Costco Wholesale is an excellent place to find cheap car tires although you have to have a Costco membership. Other places to find tires are Sear's and Goodyear Tires.
You can purchase used tires online at Amazon.com, Buy.com or Ebay.com. It would be beneficial online, therefore you can compare prices, read reviews and return your product with no hassle.
Wholesale dealer pricing on radial tires is available through http://www.radialtirewholesale.com/. Another website with cheap wholesale prices is http://www.discountedwheelwarehouse.com/BFGoodrich_Tires.cfm.