My used 11200 lb trailer came with new Marathon ST225/75-15 D at 2540 lb capacity and were 28.3" diameter installed by the rv dealer.
At that time I would have a ST tire even on my wheel barrow so sold them on CL to a guy with a lawn mower trailer.
Bought 4 16" wheels and had LT215/85-16 E at 2680 lbs mounted. I like a tall narrow tread tire for my RV and equipment trailers....less side scrub (ply shear) issues when making those tight turns.
The OEM 15" spare wheel/Carlisle tire on it still hangs under the trailer. It hasn't touched the ground after two sets of LT tires and 130k miles.
You sure don't need a 16" load G tire at 4080-4400 lbs capacity on that size trailer with 4700-5200 lb axles.