Ford 2013 F-650 Owner's Manual page 260

Wheels and Tires 259
Oil-lubricated Front Wheel Bearings
During normal vehicle duty cycle, the lubricant and air inside the
hub/wheel cavity expands and, if not vented, causes pressure build-up
that could cause accelerated seal wear. There are two venting methods
that can be used to prevent pressure build-up:
• a slit or small hole in the rubber check vent
• the window.
Over a period of time, if not routinely cleaned, a slight film of oil can
collect dirt around the rubber fill plug and face, which could appear to
be a leak. Routine cleaning makes sure that the lubricant level can be
easily observed through the window as intended. In situations where the
window is clean on the outside but discolored on the inside, the
lubricant level may be checked by inserting a finger through the rubber
check vent hole.
The specified lubricant level for a window-type hubcap is from the
minimum line to 5/16 inch (8 millimeters) above the minimum line. If the
lubricant level should suddenly drop dramatically below the minimum
level, see the Workshop Manual for diagnostic procedure.
Installation, Tightening and Alignment
Make sure the threads on the studs and nuts are clean to permit correct
torque when installing wheels. The mounting surfaces of rims, wheels,
spacer rings and clamps must be free of dirt, rust, lubricants or damage.
Use a wire brush to clean the mounting contact surfaces. Do not use
lubricant on threads.
Check the rim or wheel for proper alignment after it has been properly
tightened. Rotate the wheel with a piece of chalk attached to a steady,
firm surface, and placed to just barely clear the outside surface of the
tire bead seat; this procedure points out the high spot. A high spot does
not necessarily mean that the lug nuts have been unevenly tightened,
but could be the result of a bent wheel.
Use the following installation procedure:
1. Slide inner rear or front tire and wheel in position over studs and push
it back as far as possible. Use care so that the threads on the studs are
not damaged.
2013 F-650/750 (f67)
Owners Guide gf, 2nd Printing, March 2013
USA (fus)