You picked the exact size that Toyo used as an example. You don't give your OE size, but ASSUMING a 110 rated tire, carrying the same load requires 45 psi. Depending on your hitch (equalizing?), their 40 may be fine; I'd PROBABLY use 45. The 50 in the rear will give more capacity than the OE. The PDF is one page of the Toyo document, a very good reference source. It is at https://www.toyotires.com/media/3729/application_of_load_inflation_tables_20200723.pdf
Thanks. Towed the travel trailer about 2 hours.
The tires felt great and planted. I ran 55psi cold. Steering much more responsive. Handled in turns solid, not like the marshmallow feel of the p-metrics.
I went with Pathfinder LT all terrain tires. Load range E.