Standard roof racks are not meant to carry heavy, wide loads, and can actually tear off at high speeds. Here's what you can do to prevent this expensive disaster.
Secure the leading edge of your roof rack cargo to prevent damage to the roof rack. Tie it down to a location under the front bumper—and reduce your speed.
Roof racks are great for moving lightweight cargo around town. Just secure the stuff to your roof rack and you're good to go. But if you're moving large, flat items like plywood or mattresses, you have to tie the load to the vehicle as well as the rack. A friend tied a mattress to his roof rack and took off for his cabin. As soon as he hit 40 mph, he heard “pop, pop, pop.” The “air lift” had ripped the rack mounting bolts right out of the roof (see photo). The body shop repairs cost more than the value of the mattress (and way more than a set of tie-down straps). You've been warned.