This is my opinion - You want to buy tires that are designed for trailers. Don’t be confused or mislead that deeper tread depth is better. Trailers tires have tread rubber that is formulated differently then passenger or truck tires. On certain applications increased tread depth can cause tread squirm, the feeling that you are on ice is one of the ways to describe it. Second make whatever load range you choose matches or exceeds the OE tires. If you decide to go up one load range make sure your wheels are rated to handle that increased carrying capacity. In no uncertain terms would I ever recommend exceeding your wheels capacity by installing tires capable of exceeding the rims capacity. The reason is simple. The sidewall of the tire will state a PSI that if inflated too, can lead to bead area failure.

Also if the rims/wheels can handle the higher rating of the trailer tire I would still use the RMA load and inflation chart to set your air pressures to match the weight requirements of your trailer. This will promote your best tread footprint and lead to your best wear (all things considered such as proper alignment and loading of the trailer).