Ford Expedition Owner's Manual page 203

Temperature A B C
The temperature grades are A (the highest), B and C, representing the
tire's resistance to the generation of heat and its ability to dissipate heat
when tested under controlled conditions on a specified indoor laboratory
test wheel. Sustained high temperature can cause the material of the tire
to degenerate and reduce tire life, and excessive temperature can lead to
sudden tire failure. The grade C corresponds to a level of performance
which all passenger car tires must meet under the Federal Motor Vehicle
Safety Standard No. 139. Grades B and A represent higher levels of
performance on the laboratory test wheel than the minimum required by
law.
WARNING: The temperature grade for this tire is established
for a tire that is properly inflated and not overloaded. Excessive
speed, underinflation, or excessive loading, either separately or in
combination, can cause heat buildup and possible tire failure.
TIRES
Tires are designed to give many thousands of miles of service, but they
must be maintained in order to get the maximum benefit from them.
Glossary of tire terminology
• Tire label: A label showing the OE (Original Equipment) tire sizes,
recommended inflation pressure and the maximum weight the vehicle
can carry.
• Tire Identification Number (TIN): A number on the sidewall of
each tire providing information about the tire brand and
manufacturing plant, tire size and date of manufacture. Also referred
to as DOT code.
• Inflation pressure: A measure of the amount of air in a tire.
• Standard load: A class of P-metric or Metric tires designed to carry a
maximum load at 35 psi [37 psi (2.5 bar) for Metric tires]. Increasing
the inflation pressure beyond this pressure will not increase the tire's
load carrying capability.
• Extra load: A class of P-metric or Metric tires designed to carry a
heavier maximum load at 41 psi [43 psi (2.9 bar) for Metric tires].
Increasing the inflation pressure beyond this pressure will not increase
the tire's load carrying capability.
• kPa: Kilopascal, a metric unit of air pressure.
2012 Expedition (exd)
Owners Guide, 1st Printing
USA (fus)
Tires, Wheels and Loading
203