1. The Lighter the Better
Most minivan roof racks are designed for carrying lightweight objects -- like skis, small ladders, well-secured aerodynamic cargo containers (like those offered by Thule) and other light loads.
2. Mind the Center of Gravity
Putting heavy boxes, bulky luggage and other weighty objects on your roof will raise the center of gravity of your vehicle, which could increase the chances of a rollover during emergency maneuvering or in the event of an accident.
The National Highway Traffic Safety Administration (NHSTA) also encourages drivers to follow auto manufacturer guidelines for roof rack usage.
3. Strap and Secure
Improperly secured roof cargo can also fly off and strike vehicles travelling behind you, sometimes with tragic results.
Remember: Only put lightweight objects on your roof rack, secure cargo properly with tie-downs and strong cord, and consider purchasing an aerodynamic cargo container if you plan on using your roof rack to frequently carry light loads.
