I've always wondered that. Sometimes my runs are packing foam with a full trailer to the door being 2000lbs and sometimes I run paper loads right at max gross of 80K. For people who run their trucks at full gross all the time, does that hurt the truck? I mean logic would say that it is going to wear out some components faster but if the truck is designed for it, it shouldn't do much right? When someone buys a used truck they always talk about miles. But I would think that a truck with 400000 miles hauling packing foam would be a better buy than an otherwise identical truck at 200000 miles running those heavy paper loads. What do y'all think?