Stock size on Sweetie is 6.00x16. Your 6.50x16 would face the same situation of supply & demand. Due to accidents, vehicles being modified to use modern running gear, etc. not many vehicles use that tire size any more so each production run is smaller. The cost of each production run has to be spread evenly between the tires produced in that run. Because of that the cost of OEM size tires is a bit higher than one would think it should be. I buy Columbia 6.00x16 bias ply blackwalls locally and pay $100 per tire not counting the tube.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.