Dually tire question.

I full time and have a 2013 F350 dually. The original Generals have about 44k on them. The last time I had them measured, the rear inners had a little less wear then the outers. I keep all tires inflated to Ford specs. I just replaced the fronts and will replace the rears before I start traveling this spring. They might make it to 50k if I kept them but why push it when they will be marginal in the rain ? Costco here I come.

I do rotate the fronts but not the rears. I don't believe it's cost effective - the inners are on steel rims so they would need to be dismounted, then remounted - at additional cost.