FORD 2006 F-550 v.1 - Manual (Page 136)

Stay out of the trajectory (1) as indicated in the illustration.
TIRE REPLACEMENT REQUIREMENTS
Your vehicle is equipped with tires designed to provide a safe ride and
handling capability. Only use replacement tires and wheels that are the
same size and type (such as P-metric versus LT-metric or all-season
versus all-terrain) as those originally provided by Ford. Use of any tire or
wheel not recommended by Ford can affect the safety and performance
of your vehicle, which could result in an increased risk of loss of vehicle
control, vehicle rollover, personal injury and death. Additionally the use
of non-recommended tires and wheels could cause steering, suspension,
axle or transfer case/power transfer unit failure. If you have questions
regarding tire replacement, see an authorized dealer.
It is recommended that the two front tires or two rear tires generally be
replaced as a pair.
2006 F-250/350/450/550 (f23)
Owners Guide (post-2002-fmt)
USA (fus)
Tires, Wheels and Loading
136