If anyone was curious, my OEM tires did pretty good. 59,000 miles on my 2022. If I lived in Texas or something I could maybe go longer but I will replace this fall. From looking at the pics here between the 255/80/17 and the 255/85/17, I think the 80 wins unless you’re lifted.
As for a spacer, a good lug nut only needs its stud width to grab and hold. If ours are 1/2” wide studs, half inch of grab should be fine. Stock looks like it grabs over 1” with some protruding out the lug. 1/4” or a 1/2” spacer should be fine but I wouldnt go 1/2” unless it’s hubcentric. You should be ok with 1/8-1/4” spacers that are not hubcentric. Just air up when towing.