It’s a trailer, certified just like any other trailer with tires fitted in accordance with the same regulations as any other trailer. Therefore the replacement tires need to have an equal or greater load capacity as the original equipment tires.
New things are happening with ST tires and their speed ratings are going up especially if they were made off shore.
This is not a recommendation, its an option. I’m just using this name brand because I have the reference at my finger tips. There are other manufacturers that also make the 14” commercial LT tires. There are normally three 14” sizes to select from and all are LRD.