Ford 2013 F-650 Owner's Manual page 258

If rib tire is used on front axle and lug or off-road type on rear axle
positions:
• Front (Steering) Axle: Replace tires at front wheels when tread is
worn to 4/32 inch (3 millimeters) or less.
• Rear Axles: Tires must be removed when the tread is worn to
2/32 inch (2 millimeters) or less. Tires identified with the word
re-groovable molded on the sidewall can be re-grooved. A minimum
of 3/32 inch (2.5 millimeters) of under-tread must be left at the
bottom of the grooves.
Wheel and Tire Balancing
Out-of-round or out-of-balance wheels or tires can cause vehicle
vibration, bounce and shimmy. Replace damaged or out-of-round wheels.
Out-of-round tires and wheel assemblies can be corrected by re-clocking
the tire relative to the wheel.
The tire and wheel assembly should then be dynamically balanced.
Tire Wear
Radial tires can exhibit three types of normal wear patterns:
• Even
• Erosion
• Chamfer
Even wear: A sign that the tire is being properly used and maintained.
Erosion wear: Also called rolling wear, channel or river wear. Erosion
wear is found more often on free-rolling tires. This is an indication that
the tire is being used in a slow wearing operation. What happens is that
the belt plies are held very rigid and the tread is not allowed to distort
as it passes through the contact area. Wear only occurs at the edge of
the tread. No corrective action required. If erosion gets to be 1/16 inch
(2 millimeters) or more, the tire may be rotated to a drive axle.
Chamfer or shoulder wear: With tires inflated properly, this is a
normal tendency of most radial tire designs. If both inside and outside
shoulders are wearing evenly around the tire, no further action is
required. Over-inflation is not effective in correcting this effect.
Irregular Wear: If irregular wear is present, check the axle alignment,
tire pressure, wheel balancing, shock and suspension component
condition, and wheel bearing end play.
This condition not only shortens tire life, but adversely affects the
handling of your vehicle, which is dangerous.
2013 F-650/750 (f67)
Owners Guide gf, 2nd Printing, March 2013
USA (fus)
Wheels and Tires 257