I drive a '17 FX4 Lariat SuperCrew. I've narrowed my tire choices down to 2, and they're both P-rated tires. The tire that I'd prefer is a 111T, but the OEM tires are 113T. My driving habits are 99.9% on pavement, towing <1,000 miles every year. How much a difference is there with going from a 113T tire to a 111T tire, in real world terms? What am I going to be missing / giving up? How will that manifest itself?

 

you're giving up 132lbs of capacity per tire, 2,403 for the 111 rated tire and 2,535 for the 113. This usually means the sidewall is slightly less stiff, but your rear axle weight rating isn't 4800lbs so your tires aren't the weak link. You may want to run a couple more psi to have it feel better, especially when towing, but I wouldn't worry about it.