Cadillac DeVille 2005 Owner's Manual page 339

If your vehicle has P225/60R16 97S or P235/55R17 98H
size tires and you will be driving at speeds of 100 mph
(160 km/h) or higher, where it is legal, set the cold
inflation pressure to the maximum inflation pressure
shown on the tire sidewall, or 38 psi (265 kPa), whichever
is lower. See the example following. When you end this
high-speed driving, return the tires to the cold inflation
pressure shown on the Tire and Loading Information
label. See Loading Your Vehicle on page 4-30
Example:
You'll find maximum load and inflation pressure molded
on the tire's sidewall, in small letters, near the rim
flange. It will read something like this: Maximum load
690 kg (1521 lbs) 300 kPa (44 psi) Max. Press.
For this example, you would set the inflation pressure
for high-speed driving at 38 psi (265 kPa).
Professional Vehicle
The proper inflation of the tires on your professional
vehicle depends on the type of tires on it.
•
If your vehicle has P235/60R17EL 103S size tires,
the cold inflation pressure is 41 psi (284 kPa).
•
If your vehicle has LT235/60R17E 112S size tires,
the cold inflation pressure depends on the vehicle
mass and should be determined by the vehicle
coach-builder. A tire and loading information label
provided by the final stage manufacturer should
be attached to the B-pillar on the driver's side of the
vehicle. If the final stage manufacturer's label is
not present, the coach-builder should be consulted.
Do not use the tire pressures indicated on the
General Motors label. These tire pressures are for
the incomplete vehicle and are not the correct
tire pressures for the completed professional
vehicle.
Operation at inflation pressures below this
recommendation may cause your tires to become
overloaded.
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