Chevrolet 2008 Silverado 1500 Pickup Owner's Manual page 358

You can add heavier equipment on the front of the vehicle
if you compensate for it by carrying fewer passengers,
less cargo, or by positioning cargo towards the rear.
This has the effect of reducing the load on the front.
However, the front GAWR, rear GAWR, and the Gross
Vehicle Weight Rating (GVWR) must never be exceeded.
CAUTION:
{
On some vehicles that have certain front
mounted equipment, such as a snow plow, it
may be possible to load the front axle to the
front gross axle weight rating (GAWR) but not
have enough weight on the rear axle to have
proper braking performance. If your brakes can
not work properly, you could have a crash.
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CAUTION: (Continued)
CAUTION: (Continued)
To help your brakes work properly when a
snow plow is installed, always follow the
snow plow manufacturer or installer's
recommendation for rear ballast to ensure a
proper front and rear weight distribution ratio,
even though the actual front weight may be
less than the front GAWR, and the total vehicle
weight is less than the gross vehicle weight
rating (GVWR). Maintaining a proper front and
rear weight distribution ratio is necessary to
provide proper braking performance.
Total vehicle reserve capacity is the difference between
your GVWR and the weight of your truck with full fuel
and passengers. It is the amount of weight you can
add to your vehicle before reaching your GVWR.