I just purchased four ST205, 15 inch, radial, load range "D", new valve stems, balanced and mounted for $345.00 from the local Goodyear dealer. They were not the cheapest but they had had good luck with them and were not afraid to recommend them.
They replaced the seven year old ST205 load range "C" that were on the TT when I bought it used two years and 15,000 miles ago. There is enough tread left to use them on my farm trailers.
I paid extra for the balancing and the "D" load rating. We will see how they work when we head for AZ.