2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 419

In order to calculate the amount of weight any front accessory, such as a snow plow, is adding to the front axle, use the following formula: Where: W = Weight of added accessory A = Distance that the accessory is in front of the front axle W.B. = Vehicle Wheelbase For example, adding a 318 kg (700 lb) snow plow actually adds more than 318 kg (700 lbs) to the front axle. Using the formula, if the snow plow is 122 cm (4 ft) in front of the front axle and the wheel base is 305 cm (10 ft), then: W = 318 kg (700 lb) A = 122 cm (4 ft) W.B. = 305 cm (10 ft) (W x (A + W.B.))/W.B. = (700 x (4 + 10))/10 = 445 kg (980 lbs) So, if the front axle reserve capacity is more than 445 kg (980 lbs), you could add the snow plow without exceeding the front GAWR. (W x (A + W.B.)) /W.B.= Weight the accessory is adding to the front axle. 5-43