Diesel Tech Q&A: Tow-Rating “Recertification”

Ram 3500 towing a fifth-wheel trailer through a tunnel
Installing heavier springs and beefier shocks may make a tow vehicle handle bigger trailers more easily, but these upgrades don’t change the truck’s tow ratings or load capacities, as set by the vehicle manufacturer. Photos by Bruce W. Smith

MARCH 2019

Red letter Q

I am driving a Ram 2500 with a 3.42 axle ratio. I just bought a fifth-wheel that had a pin weight higher than the truck’s load limit. The dealer told me I could replace the coil springs with heavier duty coils and have it recertified, which I did. Did I do the right thing?
Thomas Paul

Green letter A

Coil spring installation in diesel truck.
Upgrading a truck’s suspension to higher quality shocks, coil-overs or heavier-duty springs can make a significant improvement in ride quality and handling, but these components do not affect the vehicle’s load or tow ratings. Those ratings are set by the truck manufacturer, and no modifications can change them.

Replacing the stock coil springs with heavier duty ones stiffens the ride and reduces sagging under a heavy load. But changing the springs doesn’t change the truck’s certified towing or load capacity. Despite what your Ram dealer told you, the only way to “recertify” the capacities of any vehicle is by going through the vehicle manufacturer and having them retest it, which will never happen.

Once a vehicle leaves the assembly line, its tow ratings and cargo capacities are set in stone, just like the VIN. And each vehicle cab and bed configuration could have higher or lower capacities, depending on the axle ratio, engine, transmission and tow package. Installing heavier springs, high-capacity hitches or bigger brakes, modifying frames or making any other modifications to the drivetrain, chassis and/or suspension will not change that particular truck’s limitations as set by its manufacturer.

Tow ratings for your particular make and model can be found in Trailer Life’s annual towing guides, https://www.trailerlife.com/trailer-towing-guides, as well as on Ram’s website, https://www.ramtrucks.com/towing-guide.html.

Towing Liability

Towing a trailer that is beyond the capacities listed by the manufacturer of the tow vehicle is putting yourself and others that share the road with you at risk. In addition, towing or carrying loads beyond those listed maximum limits opens the driver to all sorts of liability issues, should there be an accident, especially if injuries to other parties occur.

Whether a vehicle owner agrees or disagrees with the manufacturer’s listed limitations is a moot point. When a driver sees a speed-limit sign, it’s up to the driver to abide by it or not — and face the consequences when caught exceeding it. Towing a trailer that exceeds the “posted” weight limit for that vehicle is the same thing — and for much the same reasons. Government agencies that post speed limits have considered a lot of factors before reaching a speed they consider safe under normal road conditions for that particular section of highway.

Safety First

Ram 2500 with a truck camper towing a Bronco on a dolly.
Some RVers carry slide-in truck campers while towing trailers. Here’s where it’s crucial to weigh the vehicle and trailer to see how much weight is over each axle, and how those weights compare to the vehicle manufacturer’s gross vehicle weight rating (GVWR), gross axle weight rating (GAWR) for front/rear axles, and how much hitch weight the trailer is applying. Exceeding the manufacturer’s limits on any of those aspects pushes the vehicle beyond what the manufacturer considers its specified “safe” limits, which can be considered an act of “driver negligence” in court should an accident occur that injures others. It can also negate insurance coverage in such an accident.

In setting tow ratings and load capacities, vehicle manufacturers take into account a large number of factors as specified under SAE J2807, which dictates a strict standard of testing both at the manufacturers’ testing sites and out in the real world. Among those tests are emergency accident-avoidance and vehicle-control tests with a loaded trailer in tow. If the vehicle being tested doesn’t pass these tests in a manner deemed “safe” by the experts doing the driving and monitoring the data being transmitted to an array of test equipment, then the trailered weight is reduced and the vehicle retested.

For example, if a crew cab 4×4 shortbed diesel is rated with a maximum trailer-towing capacity of 14,500 pounds, then that means towing 15,000 pounds caused some serious concerns as to vehicle control during emergency lane-change maneuvers, emergency braking, towing long grades, hot-weather cooling or other testing factors.

Risky Business

That gets back to the liability aspect of towing above your vehicle’s specific load limits. Causing a serious accident while towing in a manner that doesn’t meet the vehicle manufacturer’s explicit equipment requirements and exceeds established limits opens the door for legal actions based on “negligence” against the driver of the tow vehicle. It’s not a good situation for any RVer to be facing.

“If I were counseling a business owner, I would say the manufacturer’s guidelines detail what the applicable standards are, and a reasonably prudent person needs to follow those standards to avoid liability,” said Anthony E. McNamer, partner in the Portland, Oregon, law firm McNamer and Company. “If you don’t follow the towing guidelines clearly set forth by the manufacturer, then it’s going to be very difficult to argue you were being reasonable.”

Several years ago an RV owner asked a similar question and mentioned that he didn’t know his truck’s tow rating or the actual weight of his big fifth-wheel, thinking the ads he saw on TV touting a 20,000-pound towing capacity covered all the bases. I had a chance to talk with another attorney at that time to get his take on the “I just didn’t know” defense related to towing liability issues.

Dean Holleman, vice president and managing attorney of Boyce Holleman and Associates in Gulfport, Mississippi, said, “Any person who tows a trailer would be responsible to know that the towing vehicle has certain limitations that should not be exceeded. If the accident is caused by the vehicle being used to tow something it was not designed to tow, this could be an act of negligence by the driver, and under the theory of negligence that person most probably would be held liable,” Holleman said. He added that, while some vehicle owners may argue the tow ratings and proper setup of their vehicle isn’t clearly noted in the owner’s manual or easy to find on the manufacturer’s website, “most vehicles do have proper warnings and posting of limitations of towing weight.”

That type of straight-up legal advice should make any RVer that is towing a trailer take notice. It’s the tow vehicle driver’s duty to make sure that (1) the trailer weighs less than the maximum loaded weight as specified by the vehicle’s manufacturer for that specific vehicle configuration, and (2) the towing vehicle is properly configured with the correct equipment for the trailered weight. If either of the above is neglected or disregarded, it could lead to an insurance company denying accident coverage and open the door to a lawsuit by others involved in a towing-related accident.

Getting back to the question of “recertifying” a vehicle to tow a heavier weight, you’d have to actually go back to the vehicle manufacturer to have that done, and it would have to pass J2807 certification testing.

Ram 1500 and 2500 page from 2019 Trailer Life Guide to Towing.

Truck manufacturers list load and towing capacities on their websites, and dealers have copies of the same information. Trailer Life consolidates manufacturer-assigned tow limits and publishes them in its annual Guide to Towing. As this page from the 2019 Guide to Towing shows (above), the Ram 1500 and 2500 tow ratings vary between vehicle configurations. Note that manufacturers occasionally make specification changes during the model year, so be sure to verify the capabilities of any vehicle you’re purchasing. Ram’s website is the most up-to-date source of information for tow limits on its trucks: https://www.ramtrucks.com/towing-guide.html.

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Bruce W. SmithA respected automotive and RV journalist and longtime Trailer Life contributor, Bruce W. Smith has held numerous editorial titles at automotive and boating magazines, and authored more than 1,000 articles, from tech to trailering. He considers his home state of Oregon a paradise for RVing and outdoor adventure.

Read More: Diesel Tech Q&A

See Related Column: RV Clinic


  1. Don’t rely on the Trailer Life Guide to Towing. It was published before some of the 2019 data was available from the manufacturer. The towing guide does note that in these cases it is publishing 2018 data. There are significant differences, however. For example: for a Ram 3500 SRW Crew Cab, Turbo Diesel, 6 speed transmission, the towing guide is publishing the the 2018 trailer weight limit as 17,200. Ram has now published the 2019 data for the same vehicle as 20,370.

  2. Thanks for explaining that truck manufacturers will have a list of load and towing capacities on their websites. I’m trying to learn more about diesel fuel so I can make the right choice for my new vehicle. Your tip about load and towing capacities should yield a lot of valuable info.

  3. Daphne: The benefits of a diesel far outweigh its additional cost compared to a gas truck for towing a trailer. I have had both and will never go back to a gas pickup. Take a trip to an RV campground and talk to owners of both. You will leave convinced.

  4. A related question: You would weigh the tow vehicle with the trailer connected to see the true load on the truck and compare to its GVWR. But how do you weigh the trailer to compare to its GVWR? If you weigh the trailer by itself, or alternately add the trailer wheel load to tongue load, then that is the “total weight” of the trailer, BUT you have counted the tongue weight twice — once on the truck and once on the trailer. How do you weigh the truck/trailer and compare to GVWRs without having to count the tongue weight twice?

    • Hi, Jim. I believe you could weigh the truck and trailer together to get the combined truck and trailer weight. Then disconnect the trailer and weigh the truck by itself. The trailer weight could then be calculated by subtracting the truck weight from the combined weight of the truck and trailer.

  5. On top of that great topic, driving at night, your headlights are facing up off the road because you are overloaded in the truck bed. I see so many RVers with shortbeds really sag down in the back towing 40- to 44-foot trailers. I drive a 2003 Dodge Ram 4×4 2500 diesel.

  6. Absolutely excellent article! I have known this information for decades! However, not enough people ever look into this stuff. For instance, I just upgraded my fifth-wheel when with the Morryde IS system. Now, I had them put on 8K axles and eemove my 7K axles. Even though I upgraded the axles with disc brakes. My certified trailer weight is 16,500 GVW! I can never exceed that amount, even though my larger axles would support more weight. People don’t realize that if you are found to be overweight by law enforcement and you have an accident, chances are VERY good your insurance will NOT cover the accident, putting you on the hook for the whole deal! NOT GOOD! Too bad more people don’t pay attention to safety issues!

  7. What is hilarious is some of the toy haulers featured in the May 2019 issue are shown hooked up to an SRW truck! Those toy haulers are way too pin heavy for an SRW!

  8. Every truck or car has a federal compliance tag on the vehicle itself. It will list the vehicle’s weight, what the vehicle weighs at the curb, filled with gas, oil and water. It will also list a Gross Vehicle Weight (GVW), which means vehicle, driver, passengers and anything else in the vehicle at time of operation. This is what the vehicle needs to be registered at. If the GVW says 6,000 pounds, you cannot put a 6,000-pound plate on your truck without facing a ticket if your truck weighs 6,213 pounds when you roll across a scale. It will also have a Gross Combined Vehicle Weight (GCVW) which applies to towing. This is figured by truck, driver, poassengers and anything else plus the Gross Vehicle Weight, trailer, supplies, gas, fresh water, black and gray Waters, food and clothes. The combined weight of truck and trailer shouldn’t exceed the GCVW of the truck nor the GVW of the trailer. The trailer too will have a tag that will show trailer weight and the GVW which again includes everything you’re taking with you. If you’re involved in an at-fault accident, your vehicle maybe scaled, and if your vehicle looks heavy and the police have been trained what to look for in that aspect, you may get stopped and invited to cross a scale.

  9. You can register certain trucks as commercial and/or modified (upfitted) in some states but still drive as personal use — no federal DOT registration required. This legally changes the weight limits allowed for that vehicle.

  10. What I find interesting is that trailer manufacturers will put in two 5,200-pound axles on a unit that has a 13,000-pound trailer weight.

  11. First, let me tell you how much I appreciate your annual towing guide and the fact that it is available online going many years back. I can’t imagine what horrible experiences I might have had without access to your excellent guides. I went through the guides for my target years to ensure that I’d have a truck that could do the job. That’s how I wound up with my 2011 GMC Sierra 3500 HD Crew Cab diesel dually to pull my Heartland Cyclone 4200. I would agree with your assertion that there’s no reliable way to ensure that a truck’s rating can’t be “fixed” by adding stuff. But I can tell you that even if your truck is rated as able to pull your RV, you can do things to make it perform better. I upgraded to a more powerful turbo and had an tuner installed to give me a range of power options (stock, economy, towing, street and performance). As a result, I can more easily pull the RV through the mountains.

  12. Thank goodness! Someone has published what I have been saying all along. Just because your truck says “HD” does not mean you can tow whatever you want. Read – read – read the owner’s manual and know what the limits for towing with that vehicle are. This is the only way to be safe. It is the only way to avoid a liability suit. Please, keep yourself and others safe on the road and don’t overload!

  13. It’s a real eye-opener for many RVers when they roll across CAT scales and get actual numbers on how much weight they are towing and what the combined weight is of their tow vehicle and trailer. It’s also an education to have the truck weighed sans trailer. Most tow vehicles are heavier than their owners surmise.

  14. I liked that you said that one thing to consider when youo are looking into buying a trailer is to make sure that your vehicle will carry the weight correctly. I have been thinking about getting a camping trailer for my family but I have been worried that my SUV wouldn’t be able to carry it. I will be sure to research the weight capacity for my hitch and vehicle so that I can be sure to purchase the correct trailer.


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