I agree with you.
When I replaced the crappy OEM Goodyear Wranglers on our 2012 Ram 1500 4X4 w/Michelan LTX AT2 tires at 10,000 miles, I assumed
the tire dealer would put LT tires on. But nope, they put P series tires on and I didn't catch it until I checked the tire pressures once a month like I always do. Was I surprised and mad at myself 'cause I sure can't afford to get a new set and it wasn't the tire dealers fault at this point. I should have insisted on LT series; but they will only put what the factory put on unless requested. While our FR Surveyor 220 trailer only weighs 5000 lbs loaded the P series is not as much of an issue as with your scenario; but it just galls me that the counter help at these tire places can't just ask "whatca gonna use these tires for?" and help avoid this problem. My P series tires ride well and I am pleased with them as far as that goes but for safety and load, I really
wished I had been more attentive at the tire dealer and got what I wanted!
2013 Forest River Surveyor SP220 Sport
2012 Ram 1500 4X4, 5.7L Hemi quad cab