It felt good saving some money to buy a half-ton pickup that can actually tow more than the old ¾-ton that you traded in at the dealership.
It just didn’t make much sense to spend more to buy a new ¾-ton when you didn’t plan on ever towing much more than 10,000 lbs.
But then two weeks later comes the gut punch from the kid working the counter at U-Haul. While it’s true your truck is rated to tow over 12,000 pounds and you’ll be towing a trailer with a gross trailer weight of 7,200 lbs., it’s your truck’s curb weight that’s the problem.
Say hello to the old 80% rule which for years has served as a rule of thumb for determining towing thresholds. For U-Haul it’s policy and it’s applied it to vehicle curb weight to determine max towing. Visit their towing reservations webpage and give it a try. (Others simply apply the 80% rule to max towing. In other words, they don’t like to exceed 80% of the truck’s max tow rating.)
While your half-ton truck is probably more than capable of towing 7,200 lbs., its curb weight will keep it from being eligible to tow a 5,000 lb. vehicle on U-Haul’s tandem axle auto transport trailer.
Applying the math of the 80% curb weight rule is easy. Let’s say the curb weight of the pickup comes in at 5,000 lbs. The curb weight of U-Haul’s trailer with the vehicle is 7,210 lbs. According to U-Haul, the tow vehicle must “equal or exceed 80% of the combined weight of the trailer (2,210 lbs.) and the vehicle being towed (up to 5,290 lbs.).”
To apply the 80% curb weight rule, multiply the gross trailer weight (in this case 7,210 lbs.) by 80 and multiply that sum by .01. For our example, 7,200 x 80 = 576,800. Then 576,800 x .01 is 5,768 lbs.
The 5,000 lb. truck in this case fails to qualify for that car hauler because it does not equal or exceed 80% of the gross trailer weight. U-Haul’s tow dolly can’t be used because its max gross trailer weight for a rear-wheel drive vehicle is 3,900 lbs., or 1,100 lbs. under the 5,000 lb. vehicle we’d like to tow.
You can’t blame U-Haul too much here. In this age of nuclear verdicts where liability can turn into huge lottery-like judgements, companies have to protect themselves. Even if there was a waiver for you to tow beyond the 80% rule, it wouldn’t mean all that much in court.
What’s even more interesting is that Penkse and Budget only rent auto haulers for use with one of their trucks. No surprise there. They know their trucks and their capabilities.
But some no longer follow the 80% rule and here’s why. After the major OEMs adopted the J2807 towing standards set by the Society of Automotive Engineers (SAE) in 2014, a lot of towing aficionados began backing off the 80% rule. These tough tests, which OEMs helped to create with SAE and agreed to undertake before releasing max numbers, created what many feel to be dependable standards. Nonetheless, some in the towing world still prefer to adhere to the 80% rule.
Most of us who own ½-ton pickups, including me, probably won’t be inconvenienced much by a rental company’s equipment policy. The 80% rule is a reminder though of the importance of playing it safe while towing. I won’t forget a reader who said that despite the growing tow ratings among newer ½-ton trucks, he won’t tow anything substantial with them because, as he pointed out, they lack the weight, size, chassis structure and larger brakes of a heavy-duty truck.
In the 1980s, I was riding with a friend in the back of a pickup heading to Lake Powell, Ariz. The driver, my friend’s dad, was pulling a good-sized boat. Something caused him to swerve which sent that truck at an odd angle while that boat behind us suddenly became the tail wagging the dog. Thankfully, my friend’s dad pulled us out of a near disastrous jackknife though we were all pretty shaken up about it, especially my friend’s dad. While the fishing and scenery on my first trip to Lake Powell were amazing, I’ve also filed away that road trip as an important lesson. Towing can be a lot more challenging than it appears and so I don’t fault someone for wanting to follow the 80% rule if that’s what makes them comfortable.