Here is a real-life example:
An owner of an older Travel Trailer posted
"Please correct me if I'm wrong... The Michelin Defender LTX M/S 235/75R15 is a true LT tire and does not need to be derated?
Shopping for tires on my Airstream 2017 23FB. I'd love to just go with the 16" SenDel S02/Michelin combo but not sure if the clearance is there for them."
Just before the above post it had been pointed out the correct designation is P235/75R15 XL
The "XL" is the tip-off as that stands for "Extra Load" which is only found in Passenger type tires.
LT tires have Load Range C, D, and E
P-type have Standard Load (no special marking) and XL which is lower in inflation than an LT-C.
Your tire dealer should have made clear the type tire they are talking about. Sometimes RV owners need to know more than the salesman if you want to get the tire you need or want.
I had also previously posted on that thread:
"Be sure you understand if your LTX tires are "LT" type or "P" type. If P you need to calculate the actual tire capacity when used on Trailer, SUV or PU-truck.
The adjustment is
(Load molded on tire)/1.10 = Load capacity on the RV or truck or SUV application.
No load capacity adjustment is needed for LT type tires if placed on an RV, truck or SUV.The LT in "LTX" does not make a tire an actual "LT type tire."
I don't know if the marketing folks at Michelin realized the confusion they were spreading when they came up with the name "LTX" and put that designation on BOTH LT type and P-Type tires. I would not be surprised if there aren't a good number of RV owners who think they have an LT tire when what they were sold was actually a Passenger type tire.