Herk, I have had two Marathon "D" rating failures. Cord break down. Both tires has approximately 20K miles on them. One failed last year on the way to Goshen Rally, Replaced in Goshen. Then I had another to fail this year on the way to Goshen ( again cord break down said GOOD YEAR dealer) Replaced in Goshen. Seems the marathon tire fails around 20 K to 24 K miles. I had plenty of tread left, just wore same as the picture you posted.
The tires got larger in diameter by 2"-3" and the tread became round instead of flat across the face. Even rubbed the top of the wheel well on the
door side of my Rockwood fifth-wheel cutting holes in the plastic liner in the top of the well.
The Goodyear dealer told me this year to just call him and he will have a tire on had when I get to Goshen next year
Herk, Better watch your other tires closely! I use a infrared temp checker each time I stop to refuel or rest stop. The tires that failed started running 10° to 20°
hotter than the other tires each time they failed.
PhoneDude 8289, there was no alignment required when my axels were replaced
in Goshen this year's rally. All holes just line up for replacement.