Spread 6-8 dryer sheets out along the bottom of your bathtub, then place the oven racks on top of them. The anti-static properties in dryer sheets help remove the baked-on gunk from the metal racks. You can do this one at a time or do all the racks at once. Plug the tub and let the hot water run. Squirt in 1⁄4 cup (59 ml) of your everyday dish soap and agitate the water. Turn off the water when the racks are covered by several inches of water. If you are in a hurry, let the racks soak for at least 4 hours before moving on to the next step. However, letting them soak overnight will allow more of the gunk to be removed, which means less scrubbing. In the morning, or after 4 hours have passed, use the dryer sheets to wipe the gunk off of each rack. For especially stubborn stains, you may need to use a non-scratch scouring pad. Let the water out of the tub while scrubbing the racks, then rinse them with hot water. Dry the racks with a clean towel and then put them back in your oven.

Summary:
Set the racks on top of 6-8 dryer sheets in the tub. Cover the racks with hot water and add 1⁄4 cup (59 ml) of dish soap. Let the racks soak overnight. Use the dryer sheets to scrub the racks. Rinse and dry the racks before replacing them.