I will second the suggestions for using the Kumho tire from the Tire Rack.

My second set of these are on my Cobra carrying a DG1000.
C185R-14 Kumho Radial 857 Trailer Use Only

They eliminated sway problems encountered with the tires that came on the trailer. It is easy to order them on the internet, which saves a lot of running around and debating whether some slightly different size the dealer has in stock will work as well as any debate about truck tires versus trailer tires.

John