Go with stock size if you are unsure of what you want 265 70.

Michelins often get the vote as best tire but they have one big drawback. They last SO long they are often hard and cracked before they are worn. Especially in a car not driven alot, everyday.

If you want some bite in the rain and are willing to sacrifice a bit of long term wear. Get a lower treadwear rating. A 400 will have alot more bit than a 700, especially after a few years.

After reading what you plan on doing with your truck. I recommend either Nokian Rotiva's or Bridgestone A/T Revo2.