The following is an out of context quote from a major tire manufacturer; “Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer.” I have highlighted size designation. Most don’t know that it is the proper nomenclature for tire size. If they do they just overlook it as another obstacle they rather not have to deal with when it’s time for replacement tires.
ST235/85R16 is a size designation. LT235/85R16 is a size designation. In the world of tire industry standards those designations are not interchangeable. None of them are unless approved by the vehicle manufacturer. In the automotive tire world the vehicle manufacturers provide retailers with listings of approved tire sizes and options. That process does not exist in the RV trailer industry. Owner’s seeking recommendations from RV trailer manufacturers seldom get satisfaction with their replies and seek recommendations from elsewhere.
Tire quality grading, load indexes, load ranges and speed restrictions are not a part of a tire’s designated size.