GMC 2005 Envoy Owner's Manual page 305

What is the worst time for this? Wet ice. Very cold snow
or ice can be slick and hard to drive on. But wet ice
can be even more trouble because it may offer the least
traction of all. You can get wet ice when it is about
freezing, 32°F (0°C), and freezing rain begins to fall.
Try to avoid driving on wet ice until salt and sand crews
can get there.
Whatever the condition — smooth ice, packed, blowing,
or loose snow — drive with caution.
If you have the traction assist system (TAS), it will
improve your ability to accelerate when driving on a
slippery road. But you can turn the TAS off if you ever
need to. You should turn the TAS off if your vehicle ever
gets stuck in sand, mud, ice, or snow. See If Your
Vehicle is Stuck in Sand, Mud, Ice or Snow on
page 4-42. Even though your vehicle has TAS, you will
want to slow down and adjust your driving to the
road conditions. Under certain conditions, you may want
to turn the TAS off, such as when driving through
deep snow and loose gravel, to help maintain vehicle
motion at lower speeds. See Traction Assist System
(TAS) on page 4-8.
If you do not have TAS, accelerate gently. Try not to
break the fragile traction. If you accelerate too fast, the
drive wheels will spin and polish the surface under
the tires even more.
4-39