Filed under: Technology & Camping
J2807 IS HERE
Twelve of us were sitting around a campfire. All guys – the girls were at another camper doing whatever girls do when they get together.
Now, guys on the other hand KNOW what they are going to talk about when they get together around a campfire – it is either football or trucks. Yea, TRUCKS – the ones we use to pull our campers up and down the highways, especially the oil burners that often grow an extra set of wheels and hips on the side of the truck bed.
We are all friends – at least I think we still are. Things are said that can sort of tick one or more of the guys off, but nobody gets really mad and upset enough to get nasty or go away mad. Ribbing another guy about his truck can get someone really riled up, but not as much as making fun of his dog.
Doug looks over at Mike who recently bought a Dodge diesel and says, “Why did you spend all that money on a puny RAM that won’t pull a greased string out of a mud puddle?”
Mike looks back at Doug with a smile on his face – knowing what is about to happen, “Just for the record Mister Gotta-Mechanic-Coming, the tow rating for my RAM is two-thousand more pounds than your Silverado.”
That’s when Elmer decides to join in the fracas. “Hey, both of you guys need to get a life – my Ford F250 has a tow rating that is higher than either one of you guys”.
Of course, Joe just has to challenge the big three with the stats on his Toyota – even if they don’t quite measure up to the big diesels Doug and Mike somehow maneuver into Wal-Mart parking lots. The Toyota is fair game for the F150 and 1500 half-ton gasohol fueled contingency gathered around the fire.
Before you know it, a heated (but fun) discussion has ensued with each of the guys giving opinions and product numbers.
But here is the rub – tow ratings for pickup trucks from the (now) big four – Ford, Dodge, Chevy/GMC and Toyota have actually been worthless for any level of comparison . The game has been to put the highest tow rating possible on a truck that the lawyers will allow. No one has ever truly understood how a manufacturer’s tow rating was determined and why it would be the same for towing across the flat lowlands of Florida at elevations under 500 feet and going up an incline on the Rockies at over 5,000 feet. Comparisons were no better than the taste of orange juice to grape juice.
But, the arguments and uncertainty of tow rating comparisons has come to an end with the introduction of the 2013 models from all four (actually five – Honda is in here too) of the full size pickup truck companies.
Welcome SAE J2807
J2807 is a testing standard that has been agreed upon by the Society of Automotive Engineers and the vehicle manufacturers. It took over five years to hash out the standards and implement them for all manufacturers. Yes, a few, like Toyota, did adopt early J2807 standards for their vehicle tow ratings.
Truck buyers now have a true apple juice to apple juice standard to compare one truck to another.
The new standards use timed acceleration on level ground and up a real-world incline while maintaining a specific speed. Air conditioners must be on and fluid temperatures must not exceed safe operating temperatures – all while pulling a trailer with a specified weight (weight depends upon vehicle class). Additionally, variations which may include understeer, trailer sway response, and braking either add or subtract points from a vehicle’s score which ultimately help to determine the manufacturer’s tow rating.
More information concerning the standards for J2807 are spelled out below and on the AUTOMOBILE web site. Another spot to check out for info is the GM web site, which also provided the image for the thumbnail photo.
Standard J2807 spells out test procedures and performance requirements that must be met for a manufacturer to assign a maximum tow rating to a particular vehicle. While various trailer configurations are suitable for these tests, the towed unit must provide a minimum specified frontal area starting with 12 square feet for a TWR below 1500 pounds, ranging to 60 square feet for a TWR exceeding 12,000 pounds. There are also specifications for how the trailer’s load is distributed on its axle(s) and how the attachment tongue is configured.
One major change from previous practices is what the SAE committee defines as Tow Vehicle Trailering Weight (TVTW). Unlike the past, a driver, a passenger, optional equipment purchased by at least one third of the customer base, and hitch equipment are now included in this calculation along with the base weight of the tow vehicle. Raising the TVTW figure automatically lowers the maximum permissible GCWR and TWR figures.
The tow vehicle must meet these level road performance criteria to merit a particular TWR:
•Acceleration from zero to 30 mph in 12.0 seconds or less in vehicles with single rear wheels.
•Acceleration from zero to 30 mph in 14.0 seconds or less in vehicles with dual rear wheels.
•Acceleration from zero to 30 mph in 16.0 seconds or less in vehicles with dual rear wheels and a GVWR over 13,000 pounds.
•Acceleration from zero to 60 mph in 30.0 seconds or less in vehicles with single rear wheels.
•Acceleration from zero to 60 mph in 35.0 seconds or less in vehicles with dual rear wheels.
•Acceleration from zero to 60 mph in 40.0 seconds or less in vehicles with dual rear wheels and a GVWR over 13,000 pounds.
•Forty to 60 mph passing acceleration in 18.0 seconds or less in vehicles with single rear wheels.
•Forty to 60 mph passing acceleration in 21.0 seconds or less in vehicles with dual rear wheels.
•Forty to 60 mph passing acceleration in 24.0 seconds or less in vehicles with dual rear wheels and a GVWR over 13,000 pounds.
Grade Launch Requirements
The tow vehicle must be capable of repeatedly moving from rest for a distance of 16 feet on a 12-percent grade in both forward and reverse directions. Five such launches must be accomplished within five minutes in each direction.
To merit a particular TWR, a vehicle must be capable of maintaining a minimum cruising speed while climbing the grade at Davis Dam on state roads 68 and 163 in Arizona and Nevada. This 12-mile-long run originating in Bullhead City, Arizona, involves grades that vary between 3- and 7-percent with an average over 5-percent. During this test, the minimum acceptable ambient temperature is 100-degrees F. and AC systems must be operating on the maximum cold setting with no recirculation and the blower at the highest possible setting.
Single rear wheel vehicles must be able to maintain an average of at least 40 mph on this grade. Dual rear wheel vehicles are required to maintain 35 mph or more here. Dual rear wheel vehicles with a GVWR over 13,000 pounds must maintain at least 30 mph.
To pass these hot-ambient-temperature, steep-grade challenges, there can be no vehicle component failures, no warning lamps, and no diagnostic codes alerting the driver. In addition, the tow vehicle cannot lose any engine coolant. The vehicle under test must be equipped with the lowest numerical axle ratio available from the manufacturer.
Standard J2807 specifies that an understeering handling attitude must be maintained up to at least 0.4g cornering without a weight distributing hitch. With a weight distributing hitch (which transfers vertical load from the tow vehicle’s rear wheels to its front wheels), an understeering attitude must be maintained up to only 0.3g cornering.
The test vehicle and trailer must stay within a 11.5-foot wide traffic lane during stopping tests. The parking brake must be capable of holding the rig on 12-percent up and down grades.
Stopping distance requirements from an initial 20 mph without use of trailer brakes are:
•In 35 feet or less with a TWR of 3000 pounds or less and no trailer brake requirement.
•In 45 feet or less with a TWR of 3000 pounds or less and a trailer brake requirement.
•In 80 feet or less for TWRs above 3000 pounds.
To assure that the tow vehicle’s structure is capable of towing a particular trailer load, standard J2807 specifies that no more than 5 degrees of permanent angular deformation at hitch attachment points is acceptable. Also, the highest experienced trailer hitch attachment force must be withstood for five seconds without significant loss of load (no structural deflection).
The SAE towing committee purposely defined the scope of this standard not to include brake fade and durability aspects related to the tow vehicle such as the endurance of chassis, powertrain, suspension, and brake components. Other SAE standards and each manufacturer’s own internal requirements instead address these towing issues.
If all requirements specified in J2807 are met, the tow vehicle manufacturer may state the following: This model meets or exceeds the tow-vehicle trailering requirements of SAE International per SAE J2807. All manufacturers are strongly encouraged to use this test for tow ratings beginning with the 2013 model year.
Well, shucks……. it looks like we will have to add another topic to the guys only campfire discussions to replace truck tow ratings. Any suggestions as to what?