How to Handle Towing a Heavy Load Downhill? [Ask TFLtruck]

2015 ford f-350 dually crw king ranch extreme towing tank up incline
2015 Ford F-350 Power Stroke

Today’s question has to do with controlling a heavy trailer when towing downhill.

What is the safest way to tow a travel trailer downhill in a F-350 automatic diesel in regards to transmission settings, speed, etc? It’s a 40-foot fifth wheel.


The beauty of the newest heavy duty trucks is the added capability and driver assistance technologies to make any heavy towing job easier. All 2015 model year heavy duty turbo-diesel pickup trucks can be configured with an exhaust brake from the factory. The exhaust brake restricts exhaust gases and uses the engine to slow you down. Of course, the automatic transmissions are smarter than ever and offer grade shifting feature to help with the downhill.

Simply, turn on the “Tow/Haul” mode on the transmission, enable the exhaust brake (if available), and the truck will help you maintain a safe speed down the hill. Of course, you may need to apply the brakes from time to time to stay under or at the speed limit. You just want to avoid riding your brakes all the way down. This brings us to trailer brakes.


It is very important to check that your trailer brakes are working properly before you tackle the big hill or any towing task. Plug-in the trailer’s electrical connection and check that all trailer lights are working. Then test the trailer brake gain setting and test the brakes in a safe and flat area, like a parking lot. Set the gain setting to 5.0, slowly drive forward, and apply the brakes. You should just feel the trailer brakes. If they grab too hard, turn down the gain.  If you cannot feel any help from the trailer, then turn up the gain. You can also test the trailer brakes by squeezing the manual override on the trailer brake controller.

Of course, you also need to make sure that the truck and trailer sit level together and that you are within your payload, max towing, and GCWR weight limits.

Happy towing!

Here is the 2015 Ford F-350 towing the WWII Half-track up the Ike Gauntlet extreme towing test.

Take a look at this towing comparison for more details about towing heavy weights up and down grades.