2008 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 357

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: For example, adding a 700 lb (318 kg) snow plow actually adds more than 700 lbs (318 kg) to the front axle. Using the formula, if the snow plow is 4 ft (122 cm) in front of the front axle and the wheel base is 10 ft (305 cm), then: W = 700 lb (318 kg) A = 4 ft (122 cm) W.B. = 10 ft (305 cm) (W x (A + W.B.))/W.B. = (700 x (4 + 10))/10 = 980 lbs (445 kg) So, if your truck's front axle reserve capacity is more than 980 lbs (445 kg), 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. Where: W = Weight of added accessory A = Distance that the accessory is in front of the front axle W.B. = Vehicle Wheelbase 4-45