There are a variety of companies that sell inexpensive replacement tires for BMW cars. Some of these companies include Tire Rack, etyres, CARiD, Bimmerzone, and many others.
I would look at ebay or craiglist to find cheap rims and tires for your car.
Good year company
Discount Tires and Walmart both sell quality tires at cheap prices. Walmart tends to have slightly higher quality brands while Discount Tires tend to have cheaper prices.
Discount Tire/Americas Tire
They are excellent tires, Yokohama is not a cheap tire company.
Bridgestone make good tires and at sears or Wal-Mart they can be found at a good price. Cooper Tires are also good tires you can find at a cheap price.
Tire Kingdom is a good place to find cheap tires in the Stanford,Fl area. Also check our Action gator Tire Company as well.
Cooper tires sells various brands and there prices range depending on what company you buy it through.
Anyplace that sells Medalist tires.
Maxxis, Dunlop, Metzeler, Michelin, Bridgestone, Pirelli to name a few
Dynamic Tire Co. sells Sailun tires through subsidiary Husky Tire and Mustang Tire in the US.
There are some reliable stores in Deltona, FL that have great rates. One to recommend is Demetrich Tires. You can find them at (386) 789-8479 - 2838 Howland Blvd, Deltona