I work at a very large Ford dealership in Michigan and the only time I have ever seen loose lug nuts on these trucks is when the owner had them off and failed to torque them. A local landscaping business had the wheels fall off two of their trucks last month after they decided to do maintenance themselves. After the tech replaced all of the studs and finished the repairs, he asked the owner of the company what he torqued the lug nuts to. The owner said he didn't know, he just put them on with an air gun until he thought they were good.
From the 2007 Super Duty owner's manual:
WHEEL LUG NUT TORQUE SPECIFICATIONS
On vehicles equipped with single rear wheels, retighten the lug nuts to
the specified torque at 500 miles (800 km) after any wheel disturbance
(tire rotation, changing a flat tire, wheel removal, etc.).
On vehicles equipped with dual rear wheels, retighten the wheel lug nuts
to the specified torque at 100 miles (160 km), and again at 500 miles
(800 km) of new vehicle operation and after any wheel disturbance (tire
rotation, changing a flat tire, wheel removal, etc.).
Bolt size Wheel lug nut torque*
lb.ft. N瀕
M14 x 1.5 150 200
* Torque specifications are for nut and bolt threads free of dirt and
rust. Use only Ford recommended replacement fasteners.
On all two-piece flat wheel nuts,
apply one drop of motor oil between
the flat washer and the nut. Do not
apply motor oil to the wheel nut
threads or the wheel stud threads.