An ST235/80R16 Load Range E trailer tire like the excellent Taskmaster Provider # TTWTRTM2358016E features a 3,520 pound maximum load at 80 psi. For a three axle trailer like yours this will provide you with a combined maximum load of 21,120 pounds (3,520 x 6 tires) which is more than enough capacity for the trailer's 19,000 pound GVWR.
A trailer's GVWR refers to the most it can possibly weigh when fully loaded so this particular tire will still give you a healthy safety margin even if... view full answer...