If you look through the gallery in this article, you'll likely get the impression that we used towing with pickup trucks as an excuse to spend a day on the sand dunes in ATVs and touring Zion Park. You'd be 99 percent correct in that assumption. It turns out though, even for experts, towing is more than it appears.
We arrived in St. George, Utah and met with GMC representatives to talk about towing. After an early morning breakfast and debrief on the day's plans, we looked over the trucks and trailers and their intended cargo. The trucks were 2018 GMC Sierra Denali pickups with a 5.3-liter V8 or 6.2-liter V8 gasoline engine. The trailers were bumper-pulled, two-axle, flatbed vehicle haulers. On those trailers were two side-by-side all-terrain vehicles (ATVs) with either two or four seats, strapped down carefully to the flatbed.
We were given a crash course in towing, with the more expert of us being paired with less seasoned drivers. I personally hadn't expected to learn much at an event like this, expecting the tow portion to be fairly cut-and-dried as I've driven semi-trucks professionally and pulled trailers of all types behind vehicles of all sizes. My assumption was incorrect. Riding with someone who hasn't towed much before was an eye-opener.
The crash course from GMC included what types of trailer hitches are available on today's market, how they fit in a vehicle capability lineup, and why it's important to know the differences. A Class IV trailer hitch, for example, cannot pull the kind of load that a fifth-wheel hitch can. Further, just because a vehicle comes with a trailering setup doesn't necessarily mean it's capable of pulling the trailer you might want to pull. These things should be obvious, but many are unschooled in both the options for towing and in the weight limitations for any given towing system.
Trailer Weights and Knowing the Load
A trailer, for example, puts not only pulled weight (added vehicle weight behind) to the truck, but also adds cargo weight by pushing down on the truck's rear axle. The overall weight of the trailer and its cargo is measured versus vehicle towing capacity. Our Sierra 1500 Denali trucks, for example, have a maximum towing capacity of 9,300 lb (4,218 kg) in their lightest configuration and about 12,500 lb (5,669 kg) in their heaviest setup. Our trailers had about 6,500 lb (2,948 kg) of total weight to them (trailer and cargo).
The way weight is distributed on a trailer is very important. This is where "tongue weight" comes into play. Having 5,000 pounds of cargo, for example, is well within the parameters of the trucks we were driving, but if all of that weight is on the front of the trailer, it will have a teeter-totter (fulcrum) effect, pushing down on the "tongue" of the trailer, pressing down on the rear of the truck. That, in turn, lifts the front of the truck like a child's teeter-totter, pushing the front wheels off the ground, reducing traction and thus braking and steering control.
Optimally, the tongue weight of the trailer will be about 10-15 percent of the truck's weight. In our case, the truck itself weighed about 5,500 lb (2,495 kg) on its own. So a tongue weight of no more than 550 to 825 lb (249 to 374 kg) is optimal.
On paper, all of this sounds great, but in the real world, the logistics of measuring these weights is problematic. Most truck stops have a scale that can weigh individual axles as well as overall vehicle weight with a trailer. That's fine and dandy if those scales are readily accessible, but this is not always the case. An alternative is to make some measurements of your own.
On a level surface, measuring at the front of the pickup, without a load, from the trim (edge of the wheel well) down to the ground and then comparing that to the same measurement made with the trailer hitched up is a quick field method of adjusting tongue weights. If the measurement stays within a few millimeters and doesn't "lift" (increase) by more than a half an inch (1.3 cm), then the tongue weight is acceptable. This rule of thumb works with most pickup trucks, regardless of load carrying capacity.
Other trailering tricks include crossing the safety chains connecting the trailer to the truck so that they "cradle" the hitch itself. Thus if the trailer comes loose from the ball hitch, it will fall into that cradle rather than drag on the ground. A dragging trailer tongue can become a catapulted trailer quite easily on the highway. Testing trailer brakes (if equipped), lighting, and other items are fairly straightforward tasks, but are often overlooked trailer hookup requirements as well.
Towing and Engine Power
Our first tow was with the smaller-engined GMC Sierra 1500 Denali, pulling the loaded trailer out of the city of St. George and into the mountains to the east. We were headed towards Zion National Park, but driving through town to the highway took some time. In this stop-and-go situation, it was apparent that the truck's 5.3L was capable of the task, but a larger engine would have less trouble getting the load moving out of a light or up the on-ramp to the interstate.
In these situations, it is obvious why having more than enough to do the job is often confidence-building when towing. Once we stopped for a break and swapped drivers, my drive partner, Eric, helped establish this as he somewhat nervously took the wheel to continue our trip. I also began to learn that there is more to towing than I remember having to learn – largely because most of it comes naturally once it's been done regularly.
Turning corners when towing a trailer, for example, means watching where the trailer's axles will end up as you turn. The track for the trailer's tires versus the truck will vary depending on the length of the trailer, specifically the distance from the rear axle of the truck and the axles on the trailer. I showed Eric how to "button hook" a turn, leading the truck's nose straight into an intersection and turning at the last minute, rather than making the natural curve most car drivers tend towards. This maneuver pulls the trailer forward before turning it, shortening the trailer's track so the wheels don't smack into a curb or vehicle. This is best done slowly, which might make drivers behind unhappy with the time being taken, but it keeps trailer loads from shifting and mistakes from becoming disasters.
From there, a light foot on the throttle and brakes is key. Adding plenty of following distance to give room for stopping finishes the basic requirements for trailering. Then, in our case, having a navigator who can read the whole map and directions without getting distracted is also key. Which means I shouldn't be navigating because I'm terrible at it.
Fun times on the dunes
Once we arrived at the Coral Pink Sand Dunes in Zion Park, we parked our truck and trailer, unhitched the load, and unloaded the ATVs. A guide took us into the dunes to show us where we could go, what we could do, and to repeatedly tell us not to roll the ATVs over. I did my best to ignore that last bit. I did manage to make some people nervous as they watched, though. I will sum the ATVs on the sand experience up thusly: if you can get a chance to do this, go do it. Holy crap is it fun, and way better than the go-carts in the sand we used as kids.
To get back to civilization, we got back into a truck, this time swapping for a 6.2L monster, and drove through Zion Canyon. The drive is scenic, leisurely, and a whole lot of picturesque.
Product Page: GMC Tow Like a Pro
