Show Notes for Podcast Episode #9
The Principles of Overlanding :: Payload
We introduce our new series called the Principles of Overlanding, where Matt and Scott do the deep dive on cornerstone topics related to vehicle-based adventure travel. This first topic is payload, one of the most-often misunderstood and abused factors of overland vehicle preparation.
Real payload requires research, purchasing a vehicle that meets your needs for hauling and towing. The popularity of full-size vehicles like this RAM is because of the tragic payload numbers of most North American specification mid-size trucks and SUVs.
The Principles of Overlanding was inspired in part by Ray Dalio's book: Principles Life and Work
Matt reinforces that payload is most often caused by the conflict between needs and wants. It is feasible to travel around the world for a decade off of a motorcycle, that means it is entirely feasible to do the same in a vehicle with a limited payload. Just pack less stuff.
GVWR: Gross Vehicle Weight Rating is determined by the manufacturer, and is the sum of both curb weight and payload.
GCVWR: Gross Combined Vehicle Weight Rating is also determined by the manufacturer, and is the sum of both GVWR and the trailer towing capacity of the vehicle.
Payload: This is the most critical number, and is GVWR minus the curb weight. Payload includes full vehicle fluids, but not passengers. As a result, just four or five adults can exceed the total payload of many SUVs.
Roof Load Rating: The dynamic roof payload capacity, as determined by the manufacturer. Most SUVs have a 120-160 pound capacity. The 200 series land cruiser has a 400 pound+ roof capacity, and the new 2020 Defender is 370 pounds.
Sprung weight: The weight of the vehicle structure and components supported by the suspension.
Unsprung weight: The weight of the tires, wheels, axle, and suspension components not supported by the suspension.
Rotating Mass: Typically the weight of the tires, wheels, and brake/axle components. The heavier this mass, the more difficult it is for the vehicle to accelerate the mass or stop is (braking)
Reciprocating Mass: Typically the weight of the tires, wheels, and brake/axle components as they more up and down over uneven terrain or road surfaces.
SAE J2807 is the method that OEM engineers use to come to these numbers:
Primary factors that determine payload (there are many others not listed)
1. Axle and bearing load rating
2. Wheel and tire load rating
3. Spring rates and shock valving
4. Braking performance (effectiveness and heat dissipation)
5. Engine and transmission cooling effectiveness
In the end, payload is really about safety. Safety for you, your family, and others on the road.
It is really about safety, and not just for you, but everyone else on the road.
For improved safety and performance, we do not recommend exceeding 85-90% of the GVWR. Less is even better.
Consider the legal ramifications like fines, citations, denied insurance claims, and even criminal negligence if it can be determined that the vehicle was willfully overloaded and resulted in the death or dismemberment of another motorist or pedestrian.
If you plan to ship your vehicle internationally, know the regulations for compliance with GVWR. Australia is particularly stringent.
Keep an eye on what you do not use after a few trips, and don’t feel ashamed to remove it from your vehicle.
So, what do we do about it?
By the right vehicle
Take less stuff…
Modify only as required, and find items that perform multiple functions, and are lighter
Position the load properly
Weigh your vehicle as it is being modified
Remove unneeded OEM parts (like third row seats)
Deduct the weight of the items you remove
Consider a trailer for families