Cadillac 2008 CTS - Manual (Page 351)

High-Speed Operation
{ CAUTION:
Driving at high speeds, 100 mph (160 km/h)
or higher, puts an additional strain on tires.
Sustained high-speed driving causes
excessive heat build up and can cause sudden
tire failure. You could have a crash and you or
others could be killed. Some high-speed rated
tires require inflation pressure adjustment for
high speed operation. When speed limits and
road conditions are such that a vehicle can
be driven at high speeds, make sure the tires
are rated for high speed operation, in excellent
condition, and set to the correct cold tire
inflation pressure for the vehicle load.
If your vehicle has 235/50ZR18 size tires, they will
require inflation pressure adjustment when driving your
vehicle at speeds of 100 mph (160 km/h) or higher
. Set the cold inflation pressure to the maximum inflation
pressure shown on the tire sidewall, or 44 psi (300 kPa),
whichever is lower. See the example following. When
you end this high-speed driving, return the tires to the
cold tire inflation pressure shown on the Tire and
Loading Information label. See Loading Your Vehicle
on page 4-22 and Inflation - Tire Pressure on page 5-67.
Example:
You will find the 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 44 psi (300 kPa).
5-69