2000 GMC Sierra 1500 Pickup Owner's Manual - Page 247

yellowblue Front Axle Reserve Capacity This is the difference between your front GAWR and the front axle weight of your truck with full fuel and passengers. It is the amount of weight you can add to your front axle before reaching your front GAWR. The front axle reserve capacity for your vehicle can be found in the lower right corner of the tire/certification label, as shown in this example. In order to calculate the amount of weight any front accessory is adding to the front axle, use the following formula. (W x (A+W.B.)) / W.B.= Weight the accessory is adding to the front axle Where: W= Weight of added accessory A= Distance that the accessory is in front of the front axle W.B.= Vehicle Wheelbase 4-51