Pontiac Aztek 2003 Owner's Manual page 113

Notice: Loading cargo that weighs more than
220 lbs. (100 kg) on the luggage carrier may damage
your vehicle.
When you carry cargo on the luggage carrier of a
proper size and weight, put it on the slats and distribute
the weight evenly. Then slide the crossrail up against
the rear of the load to keep it from moving. You can then
tie it down. Cargo containers must be loaded on the
crossrails only.
Don't exceed the maximum vehicle capacity when
loading your vehicle. For more information on vehicle
capacity and loading, see Loading Your Vehicle on
page 4-32 .
To prevent damage or loss of cargo as you're driving,
check now and then to make sure the luggage
carrier and cargo are still securely fastened.
Loading things onto the luggage carrier can interfere
with the performance of your XM™ Satellite Radio
System.
Your luggage carrier has release levers within the end
of each crossrail support.
2-37