It might not be just speed too. The minimum grade % a rig can go up before stalling out is 12%. Not sure how many 12+% grades I'll go up today, but that grade is 3% lower than a class 8 uses for OTR work. 8% less than minimum for LDT work. 30% less than rigs potentially used off road, like dump and cement trucks.
The ratings are horribly low from my perspective.
OR, their needs to be more than one tow rating for a given rig, depending upon usage. OR a way for one to know how to derate the max rating, based on ones personal performance standards. Which is what a tow rating is. A performance standard.
Marty
