I think there are a lot of other variables going on when it comes to tread life. Driving conditions, driving style, exact type of truck, etc.... I have a cousin that ran almost exclusively rough back roads with lots of curves, turns, and stop and go, a lot of off-road, pulled trailers or hauled heavy loads regularly, and had a heavy right foot. He was lucky to get 20k miles out of any tires he ran. Somebody running the same truck but mostly empty and driving a straight line down the free way with the cruise on would probably get double the mileage.