GMC 2001 Yukon XL Owner's Manual page 348

Inflation -- Tire Pressure
The Certification/Tire label, which is on the rear edge of
the driver's door, shows the correct inflation pressures
for your tires when they're cold. "Cold" means your
vehicle has been sitting for at least three hours or driven
no more than 1 mile (1.6 km).
If you have an 8600 GVW truck (2500 series) with
LT245/75R16E tires, you can improve your ride
comfort by reducing tire inflation pressure, but only
when carrying reduced loads. If you have a maximum
of 8 passengers, and 200 lbs. (90 kg) of load, you can
set the front tires at 40 psi (280 kPa), and the rear
tires at 50 psi (350 kPa). When using the reduced tire
inflation pressure settings, don't exceed the following
loading conditions: GVWR – 7900 lbs. (3583 kg),
GAWR FRONT – 3730 lbs. (1692 kg), GAWR
REAR – 4410 lbs. (2000 kg). When carrying loads
greater than 8 passengers and 200 lbs. (90 kg) and/or
when pulling a trailer, you must inflate your tires to the
pressure shown on the Certification/Tire label.
NOTICE:
Don't let anyone tell you that underinflation or
overinflation is all right. It's not. If your tires
don't have enough air (underinflation), you can
get the following:
D
Too much flexing
D
Too much heat
D
Tire overloading
D
Bad wear
D
Bad handling
D
Bad fuel economy.
If your tires have too much air (overinflation),
you can get the following:
D
Unusual wear
D
Bad handling
D
Rough ride
D
Needless damage from road hazards.
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