If you're planning on towing often, and heavy, then it's worth considering. There are a few things to expect though. The ride will be stiffer and more like a truck than like a passenger car. Traction will be less on wet roads because the stiffer sidewalls don't flex as much. MPG may slightly increase and rolling resistance will get better with LT's. I don't think your TPM system will be affected unless it has a preset high pressure warning.
This change from P tires to LT tires has been discussed and tried many times before on the explorer forum I used to participate in before upgrading to the Expedition. Those guys were always happy with the change to LT tires and all stated that the ride got stiffer but towing felt much more "in control" at highway speeds -because the weight of the trailer wasn't having as much effect on the side to side swaying of the truck tire sidewalls.
Just a mental note I've always had- Ford trucks typically always have LT tires on them, and always have a much more "in control" feel to them when towing (from my own experience and comparison). When driving most GM trucks they have P rated tires and ride a lot softer, but towing SUCKS because the trailer feels all mushy and sloppy when pulling down the highway. Honestly I frieking HATE towing using a truck with P rated tires.
Just remember your smooth comfortable ride may be lost if you switch to those LT tires.
