There are a lot of tire manufacturers building 16” steel cased tires. Some are designed as LT with a load capacity as high as 3750# others are designed as ST in LRG only with a load capacity of 4080#. All 16” LRG designs require a single rim size of 16x6.5” and must be able to support the tire’s load capacity at 110 PSI.
There are at least three major brands (Michelin - Bridgestone - Goodyear) that manufacturer 16” LRE steel cased tires in the LT design. They may be found in four different 16” sizes.
Almost all steel cased tires are regoovable, retreadable or both. They are also almost always high mileage tires, so their tread depth will be tall and their tread and sidewall materials will be much more dense than polyester or nylon designed sidewalls and treads. (You’re going to get a stiffer tire than normal with these designs).
Some of the 16” LT LRG designs are strictly for LT service - such as the Hercules H-901 - and others like the Goodyear G614 (I call it a hybrid tire) were introduced as a “trailer service only” tire with that phrase written right on their sidewalls.
Below are links to pictures I took at a recent RV show. The tire is a Westlake ST235-80R16G. This manufacturer is so serious about the 6.5” rim width, they put it right on the sidewall. Also note it has a “L” speed letter (75 MPH). The ST235/80R16G and ST235/85R16G are both rated at 4080# at 110 PSI. One is a little taller than the other.
I have not found any tires below 16” in diameter to have a steel carcass design.