Rarely considered Tow Vehicle Limitations

[TucsonJim]

If you've been around trailers and fifth wheels long enough, you get pretty educated on GCWR, GAWR, GVWR, Payload, etc. But frequently we forget there are some other items to consider too. In the owner's manual for my 2016 F350, the following information is listed:

"Recommended Towing Weights Note: Make sure to take into consideration trailer frontal area. Do not exceed 60 feet² (5.6 meters²) trailer frontal area for conventional trailers. Do not exceed 75 feet² (6.9 meters²) trailer frontal area for 5th wheel and gooseneck trailers.


Note: Exceeding this limitation may significantly reduce the performance of your towing vehicle. Selecting a trailer with a low aerodynamic drag and rounded front design helps optimize performance and fuel economy.


Note: For high altitude operation, reduce the gross combined weight rating by 2% per 1000 feet (300 meters) starting at the 1000 foot (300 meter) elevation point."

For example, the Gross Combined Weight rating on my truck is 23,500 pounds. I frequently drive in the mountains at 7,000+ feet. At 7,000 ft, the GCWR is reduced to 23,500 x (7 x .02) = 20,210. For some of you with large heavy trailers or fifth wheels, you may be fine on GCWR at sea level, but under when it comes to towing at elevation.

Just something else to consider.

Jim

[RLK436]

I think their thoughts regarding the weight reduction is based more the loss of 2-3% horsepower per 1000 ft. rather than the weight capacity of the vehicle. With todays' turbo charged engines will you notice the reduction in power when towing at altitude? Maybe, but I doubt it . . .

[klenger]

The caution regarding altitude compensation would apply to normally aspirated gas engines, but not so much turbo-charged diesels. That's one of the reasons we choose to spend so much extra for a diesel in the west, especially in Colorado where you cross the continental divide at 11,000 feet any time you travel from the front range (Denver metro) area to the high country. Been there and done that plenty of times.

The 60 sq-ft frontal limitation also seems a bit restrictive. I'm guessing the frontal area of our 297RSTS is around 8' W x 9' H = 72 sq ft. Obviously the aerodynamic styling of the GD Reflection trailers helps. Another large factor in frontal area considerations is driving speed. Towing at 62 MPH vs 75 MPH will make a huge difference in performance and fuel economy, not to mention safety.

Finally, when climbing at altitude, combined gross weight plays a big role in performance, since you basically have to lift the GCW (17,000 lbs for me) as you climb, which is not a factor when towing on level ground. In my case, fully loaded, my GCW is 8300 lbs below the GCWR, so I've got lots of capacity there.

Good points in any case. Thanks for posting.