2004 Subaru Outback Owner's Manual - Page 353

Driving tips Trailer hitches F 60% 40% 50% 50% HS8021BB F: Front Never drill the frame or under-body of your vehicle to install a commercial trailer hitch. If you do, dangerous exhaust gas, water or mud may enter the passenger compartment through the drilled hole. Exhaust gas contains carbon monoxide, a colorless and odorless gas which is dangerous, or even lethal, if inhaled. Also, drilling the frame or under-body of your vehicle could cause deterioration of strength of your vehicle and cause corrosion around the drilled hole. The tongue load can be adjusted by proper distribution of the load in the trailer. Never load the trailer with more weight in the back than in the front; approximately 60 percent of the trailer load should be in the front and approximately 40 percent in the rear. Also, distribute the load as evenly as possible on both the left and right sides. Be sure that all cargo is firmly secured to prevent a change in weight distribution while driving. Do not modify the vehicle exhaust system, brake system, or other systems when installing a hitch or other trailer towing equipment. Do not use axle-mounted hitches as they can cause damage to the axle housing, wheel bearings, wheels or tires. Choose a proper hitch for your vehicle and trailer. 8-34