All modern trucks use the SAE (Society of Automotive Engineers) J2807 standard for determining the towing ratings and capacities. You may have heard about the J2807 standard before, but what does it mean in the real world. How do manufacturer actually validate their truck’s capability before they announce the big numbers?
We team up with Engineering Explained and visit the Ram trucks proving grounds in Chelsea, Michigan to learn out about and show you what it’s all about.
The J2807 is a series of tests or assessments that all truck manufacturers agreed to in order to rate the towing capacities. This is not a certification process always verified by a third party, but we get a rare opportunity to actually verify a lot of these tests. It includes several acceleration tests, braking tests, cornering maneuvers, and incline testing – all while towing a very heavy trailer.
The test truck available to us is a new Ram HD 3500 Mega cab dually 4×4. The Ram engineering team attached an approximately 30,000 lbs gooseneck trailer to the truck to demonstrate all tests. This is basically the currently stated maximum towing capacity for this 2019 Ram HD truck.
Acceleration tests include: 0-30 mph, 0-60 mph, and 40-60 mph runs. All manufacturers agreed on certain maximum acceleration times that a truck must meet in order to pass the evaluation.
The dually you see here with accelerated 0-60 MPH with a 30,000 lbs trailer in 28 seconds, which is well under the 35 second limit defined by the J2807 standard.
There are also two specific braking tests: 20-0 mph with and without trailer brakes enabled.
Next there is a parking brake hold test on a grade. The truck’s parking brake is asked to hold the truck and the fully loaded trailer on a grade of at least 12% with the transmission in neutral. The parking brake needs to handle this pointing up the grade and pointing down the grade.
There is also a cornering test that tests predictable understeer from the truck. The goal here is for the truck to push a little during a corner so that it always leads the trailer through a turn. If the truck was to oversteer (or the rear the end stepping out) – then it can lead to trailer sway and a dangerous situation.
There is also a quick steering adjustment maneuver that aims to induce trailer sway. The truck needs to handle trailer sway in a quick and predictable fashion.
All of this is helped by the standard trailer definition that is also part of the J2807 standard. The standard defines the trailer size, trailer tongue length, tires, and more.
Finally, the J2807 also includes the Davis Dam grade test. This an 11.4 mile stretch of highway in Arizona. The standard requires a truck to successfully complete the climb up this (on average 5% grade) without overheating on a 100 F day with maximum air conditioning enabled.
After a truck can successfully complete all these tests, then the towing rating can be finalized.
The video below shows and explain all this in more detail.
