As a woman works out by flipping over an over-sized tire, she suddenly has a "new" idea: online tire buying. Little does she know, Tire.rack.com already offers online tire buying plus services like shipping directly to a mechanic and booking appointments. The woman thinks her idea could change tire buying forever. Too bad it already has. For a limited time, Tire.rack.com offers a $100 prepaid MasterCard when you purchase four select Kumho tires.