Now that we are being "civilized" I'll add my 2 cents.
We just traded in our 2007 Jayco Eagle 322FKS that had (OEM) Marathon ST tires on it. Traveled all over the U.S. and eastern half of Canada. Put on many 10's of thousands of miles on them (and some really rough roads). Had one blow out.Replaced all the tires after 5 years of wear with Marathon ST tires.
Having said that I personally would purchase ST or LT tires as long at they are rated at least as high as the OEM tires that come with the units.
RV manufacturers are not in the business of producing "junk". Considering the "pounding" that a RV takes going down our "rotten" roads I think they last quite a while.
There, that's my 2 cents worth.
happy trails,