FORD 2011 F-150 v.1 - Manual (Page 319)

WARNING: If you are driving in slippery conditions that require
tire chains or cables, then it is critical that you drive cautiously.
Keep speeds down, allow for longer stopping distances and avoid
aggressive steering to reduce the chances of a loss of vehicle control
which can lead to serious injury or death. If the rear end of the vehicle
slides while cornering, steer in the direction of the slide until you
regain control of the vehicle.
Maintenance and modifications
The suspension and steering systems on your vehicle have been designed
and tested to provide predictable performance whether loaded or empty
and durable load carrying capability. For this reason, Ford Motor
Company strongly recommends that you do not make modifications such
as adding or removing parts (such as lift kits or stabilizer bars) or by
using replacement parts not equivalent to the original factory equipment.
Snow plow restriction
WARNING: Ford does not recommend the use of any F-150
model to be upfitted and equipped with snow plow hardware for
use as a snow plow vehicle.
Any modifications to a vehicle that raise the center of gravity can make
it more likely the vehicle will roll over as a result of a loss of control.
Ford Motor Company recommends that caution be used with any vehicle
equipped with a high load or device (such as ladder racks or pickup box
cover).
Failure to maintain your vehicle properly may void the warranty, increase
your repair cost, reduce vehicle performance and operational capabilities
and adversely affect driver and passenger safety. Frequent inspection of
vehicle chassis components is recommended if the vehicle is subjected to
heavy off-road usage.
Driving
319
2011 F-150 (f12)
Owners Guide, 1st Printing
USA (fus)