Not endorsing this company, and have no affiliation with them whatsoever,
but I notice they're having a tire sale promotion that might be of interest to forum members.
"Between June 29th and June 30th, 2012, receive a $100 Visa® Prepaid Card by mail when you purchase a set of four tires or four wheels installed. Or receive a $50 Visa® Prepaid Card by mail when you purchase two tires or two wheels installed."
Here's a link to the details:
Promotion - Discount Tire