This may not matter in many states but you will notice that when you link to
Discount Tire, Custom Wheels, Truck & Car Rims | Discount Tire Co. you will find that there are two divisions of this company, America's Tire and Discount Tire Direct. In California, if a mail order business has a physical presence in the state, the business is required to collect sales tax. For some reason these guys do not. Rather than trying to find a mail order company in another state and wondering how to get them mounted and balanced you can buy from Discount(with no tax) and then go to America's and have them mounted and balanced for $19.99 each. The Anmerica's near me will price match the no sales tax price by dividing the Dicount price by 108.25%, calling the result the "selling price" and then charging tax on that. The price of a mail order seller with the convience of a local dealer.