Trying to buy tires for my truck, what can I get for as cheap as possible?

I have a 1976 Ford F150 and the tires that are on it right now are 33 inch tall by 12 inch wide with a 15 inch rim. Which translates to a 305/75/15, these are definitely expensive and I can't find any on any tire site. It just says they aren't available. Where can I find some tires, where should I get them from and how much are they going to cost.

Look up 33 x 12.5 x 15 Tire rack has them. 305/75/15 is the car version. You want a truck tire. Stick with the brand names. You'll save a little money with the off brands but usually get less wear and poor handling. B.F. Goodrich KO is great all around tire with a stiff sidewall that's good on the highway as well as off-road.