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Standardized tow ratings coming
Posted on June 4th, 2012 • by David Zatz
Not long ago, there was a small scandal over certain carmakers using different methods for coming up with their advertised horsepower ratings, leading to an agreement among all automakers to use specific SAE standards. Companies modified their advertised horsepower up and down — usually down, especially among the Asian contingent — as a result.
A similar effort was to be implemented by the 2012 model year for tow ratings, which have been criticized by some for their apparently arbitrary — and certainly variable by company — standards. This would put all the automakers in the same boat, and while some might suffer at first, they might benefit later. More to the point, it will help customers to know whether they can really tow that 10,500 pound load safely and without undue problems.
At Ram, an engineer wrote, “Most of our products would rate significantly higher if sold by other manufacturers. ” Other insiders suggested that Dodge / Ram has tended to use more conservative ratings, and at least one direct competitor has tended to use looser ratings.
According to Automobile, Standard J2807 requires tests to use a towed unit with a minimum frontal area (that varies by weight), with specifications on load distribution. The Tow Vehicle Trailering Weight (TVTW) now includes the weight of a driver and passenger, options chosen by at least a third of buyers, and hitch; that lowers the published GCWR and TWR.
Acceleration on level roads are spelled out, in terms of 0-30, 0-60, and 40-60 mph times; depending on whether the tow vehicle has single or dual rear wheels, and a gross weight rating of over 13,000 pounds, allowable 0-60 times can be from 30 to 40 seconds. There are grade launch rules (repeatedly going from a stop to 16 feet away, forward and reverse, on a 12% grade), and highway gradeability rules (using a 12-mile run with an average 5% grade and minimum allowed outside temperature of 100 degrees F — with air conditioners on maximum). Trucks must maintain at least 30 – 40 mph on this grade depending on class with no failures, warnings, or diagnostic codes and no loss of coolant, and the trucks must have the lowest (numerical) axle ratio available.
The rules also specify handling and braking requirements, and structural rules for hitch attachment points. The standard does not include endurance of truck components otherwise, or brake fade.
Legally, SAE can only enforce the rules through the use of its trademark power; only companies that follow them can say that the model meets or exceeds the tow-vehicle trailering requirements of SAE International per SAE J2807.
Standardized tow ratings coming
Posted on June 4th, 2012 • by David Zatz
Not long ago, there was a small scandal over certain carmakers using different methods for coming up with their advertised horsepower ratings, leading to an agreement among all automakers to use specific SAE standards. Companies modified their advertised horsepower up and down — usually down, especially among the Asian contingent — as a result.
A similar effort was to be implemented by the 2012 model year for tow ratings, which have been criticized by some for their apparently arbitrary — and certainly variable by company — standards. This would put all the automakers in the same boat, and while some might suffer at first, they might benefit later. More to the point, it will help customers to know whether they can really tow that 10,500 pound load safely and without undue problems.
At Ram, an engineer wrote, “Most of our products would rate significantly higher if sold by other manufacturers. ” Other insiders suggested that Dodge / Ram has tended to use more conservative ratings, and at least one direct competitor has tended to use looser ratings.
According to Automobile, Standard J2807 requires tests to use a towed unit with a minimum frontal area (that varies by weight), with specifications on load distribution. The Tow Vehicle Trailering Weight (TVTW) now includes the weight of a driver and passenger, options chosen by at least a third of buyers, and hitch; that lowers the published GCWR and TWR.
Acceleration on level roads are spelled out, in terms of 0-30, 0-60, and 40-60 mph times; depending on whether the tow vehicle has single or dual rear wheels, and a gross weight rating of over 13,000 pounds, allowable 0-60 times can be from 30 to 40 seconds. There are grade launch rules (repeatedly going from a stop to 16 feet away, forward and reverse, on a 12% grade), and highway gradeability rules (using a 12-mile run with an average 5% grade and minimum allowed outside temperature of 100 degrees F — with air conditioners on maximum). Trucks must maintain at least 30 – 40 mph on this grade depending on class with no failures, warnings, or diagnostic codes and no loss of coolant, and the trucks must have the lowest (numerical) axle ratio available.
The rules also specify handling and braking requirements, and structural rules for hitch attachment points. The standard does not include endurance of truck components otherwise, or brake fade.
Legally, SAE can only enforce the rules through the use of its trademark power; only companies that follow them can say that the model meets or exceeds the tow-vehicle trailering requirements of SAE International per SAE J2807.
