I just got a set of Nitto Terra Grappler G2 XL for my F150. NTB didn't have the E load range. I decided to take the risk. Here's what I found out. The 275/65/18 G2XL has a rating of 2750# per tire. The 265/75/17 Terra Grappler Eload has a rating of 3100# per tire. Not a huge difference. Here's the kicker. I have 16 inch E load range Sumitomo's on my work van and they have a less weight rating than the XL G2's. So, XL rated tires aren't always inferior to E load rated tires.

 

There are pros and cons to both. The XL rated tires is built slightly heftier to handle a little more weight at a higher pressure. But not too hefty to add a lot of weight or rolling resistance. These are perfect for 1/2 ton and lower rated trucks/SUV. Not nearly hefty enough for 3/4 ton+ though.

The LT tire is going to have significantly thicker chords making up the plies of the carcass and a much stronger bead bundle, drastically increasing the durability of the tire to handle high load capacities and high inflation pressure. However this increases weight and rolling resistance of the tire significantly effecting mpgs and acceleration.

I tend to recommend P-metric/Euro-Metric tires to all my 1/2 ton customers unless they haul on a very regular basis.