Like what others have said: LTs for trucks and big SUVs, and Ps for cars.
I have LT 285/75/16 tires on my 96 Ram 1500 4x4 truck ("E" rated), same size tires but in a "D" rating on my 98 Jeep TJ, and LT 31x10.5x15 tires on my 46 Willys CJ2A in a "C" rating. Oh; and my little trailer (that I pull behind the TJ) has LT 235/75/15 tires in a "C" rating. My wife's Subaru, my Toyota Yaris, and my daughter's bug all have "P" rated tires.
I guess what I'm trying to say, is that just because it is an "LT" tire, it doesn't mean they're all "E" or "F" rated tires with a ton of belts and overly-stiff.