I am running 235/75/15 on my 56. As it was an occasional driver at the time I bought store brand radials. Before the "Big D" 5 years ago she made the 80 mile round trip to work 3-4 days a month with a average speed of 65-70. NO REGRETS on newer tires (tubeless radials) even as I pulled her out of my Aunts field after sitting 5 years,
https://www.stovebolt.com/ubbthread...;Main=59220&Number=429748#Post429748 , they still held air.
Just my .02 but unless you are building a trailer queen brakes & tires need updating.
OUR hides are worth more than a set of tires.
Brad