Ford Windstar Owner's Manual page 237

If you suspect that your payload is excessive, have your vehicle
weighed at a highway weight station or another appropriate
commercial facility. Fill the fuel tank. Weigh the total vehicle
and trailer (if applicable), then separately weigh the vehicle at
the front and rear wheels. Finally, weigh the trailer separately if
applicable.
Trailers
Towing a trailer safely means having the proper weight on the
tongue (usually 10-15% of the trailer weight).
If your vehicle exceeds the GVWR, remove cargo from your
vehicle accordingly. If your vehicle exceeds either GAWR, shift
the load or remove cargo accordingly.
Do not exceed the GVWR or the GAWR specified on the
Safety Compliance Certification Label.
Towing trailers beyond the maximum recommended
gross trailer weight exceeds the limit of the vehicle and
could result in engine damage, transaxle damage,
structural damage, loss of control, and personal injury.
Preparing to Tow
For your safety and for the good of your vehicle, use the right
equipment for the type of trailer you tow. Also, make sure that
all towing equipment is properly attached to your vehicle. If
you are not certain that you are using the right equipment in
the proper manner, see your dealer or a reliable trailer dealer.
WARNING
WARNING
Driving
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