I just bought 5 wheels and tires (5th is on backorder :M ) for my Ram 1500. They just came in last night, so I have not had a chance to put them on. But, I actually went to a smaller tire by about 3/4 of an inch. I went from P275/60R20 to LT275/65R18 LR-E. I figure with my 3.55 gears, the smaller tire will give me a little more RPM. Also, hoping that the smaller tire will offset going with a much heavier than OEM tire.
I am surprised you don't want to stay in the 65 aspect ratio tire. I was so surprised with the amount of choices in that size. Seems like most major brands had both a P rated and LT rated in that size, with one having P, LR-C, and LR-E in the same tire. That is one of the main reasons why I went from the 20" with 2 LT choices in my size to the 18" with over 2 dozen choices.