Towing a camper in the mountains: ratings that actually matter

A common way people end up with the wrong tow vehicle goes like this. They find a camper they love, look at its listed weight, find a truck or SUV with a towing capacity comfortably above that number, and assume they are set. Then they load the camper for a week in the mountains, put the family and gear in the vehicle, and head up a long grade on a warm July afternoon. That is when the numbers they did not look at start to matter.

Towing safely in Colorado is less about one big number and more about several smaller ones working together.

Dry weight is not what you tow

Trailer and camper manufacturers usually publish a dry weight, sometimes called unloaded vehicle weight. It is the weight of the trailer as built, typically without water, propane, batteries, cargo or dealer-installed options. Nobody tows a camper in that condition.

The more useful number on the trailer is its GVWR, or gross vehicle weight rating. That is the maximum the trailer is designed to weigh when fully loaded. You will find it on a sticker or plate on the trailer, usually near the front on the driver's side. Water tanks, propane, a battery, food, bedding, chairs, bikes and everything else add up quickly, and a loaded camper can weigh well above its dry weight.

When you compare a trailer to a tow vehicle, a cautious approach is to plan around the trailer's GVWR, not its dry weight. The best way to know your real loaded weight is to weigh the setup at a certified scale, which many truck stops and some landscape suppliers offer.

Tongue weight

Tongue weight is the downward force the trailer puts on the hitch. For conventional travel trailers, a commonly cited guideline is that tongue weight should be a modest percentage of the trailer's total weight; too little can make a trailer prone to sway, and too much overloads the rear of the tow vehicle. Check the trailer and hitch manufacturers' guidance for the specific setup.

The vehicle and the hitch each have their own maximum tongue weight. The lowest of those limits is the one that applies. Many larger travel trailers also call for a weight-distributing hitch, and some vehicles specify one above a certain trailer weight. The owner's manual will say.

Payload is the number people miss

Payload is how much weight a vehicle can carry in and on itself: passengers, cargo, accessories and the trailer's tongue weight. It is listed on a sticker in the driver's door jamb on most vehicles, usually as a statement that the combined weight of occupants and cargo should never exceed a given figure.

Here is why it matters. Say a vehicle has a generous towing capacity but a modest payload. Put four people in it, add a cooler and gear in the back, then add the camper's tongue weight. It is easy to exceed payload long before you reach the towing capacity. Over payload, the vehicle's suspension, brakes and tires are working beyond what they were rated for, and handling suffers.

There are a few other ratings worth knowing. GCWR (gross combined weight rating) is the maximum for the vehicle and trailer together, fully loaded. GAWR (gross axle weight rating) is the maximum for each axle. A careful setup stays under all of them.

Mountain grades and cooling

Colorado adds two things that flat-country towing guides tend to skip: long grades and altitude.

Long climbs on routes like I-70 put sustained load on the engine and transmission, which builds heat in the engine coolant and the transmission fluid. A tow package often adds cooling capacity for exactly this reason, such as a transmission cooler or upgraded radiator. Watch the temperature gauges on a long climb, and use the gear selection the manual recommends for towing so the transmission isn't hunting between gears.

Altitude matters too. A naturally aspirated engine makes less power as the air thins, so a setup that feels fine in Denver may feel noticeably weaker on a high pass. Turbocharged engines are generally less affected, though they still produce heat under load.

Going down is just as important. Long descents can overheat brakes if you rely on them alone. Use a lower gear or the vehicle's tow/haul mode to let engine braking do much of the work, and make sure the trailer's own brakes and brake controller are working and adjusted. Requirements for trailer brakes depend on trailer weight and state law, so confirm what applies to your trailer with the Colorado DMV or the trailer manufacturer.

Why ratings vary by configuration

This is the point we stress most with buyers. Two vehicles with the same name can have very different towing ratings. The rating depends on the engine, the transmission, the axle ratio, the drivetrain (2WD or 4WD), the cab and bed configuration on a truck, the wheelbase, and whether the vehicle has a factory tow package. A brochure figure is often the maximum for the most capable configuration, not for the vehicle in front of you.

So the right question is never "what can this model tow?" It is "what can this specific vehicle tow, as equipped?" The answer usually comes from the owner's manual, the manufacturer's towing guide for that model year, the door jamb sticker for payload, and the VIN-specific build information. Aftermarket hitches and accessories do not raise the factory rating.

When we list a vehicle, a towing figure appears only when we have verified it for that vehicle. If it matters to you, confirm it yourself for the exact configuration before you buy, and we will help you find the right documents.

A sensible checklist

Start with the trailer's GVWR, not its dry weight. Estimate tongue weight and check it against the vehicle's and hitch's limits. Add up passengers, cargo and tongue weight and compare that with the payload on the door jamb. Check the combined rating. Make sure the vehicle has suitable cooling and a brake controller if the trailer has electric brakes. Then leave yourself some margin, because mountain driving on a hot day is not the time to be at the limit.

If you are shopping for a tow vehicle, tell us what you plan to tow and where, and we will explain which kinds of vehicles fit and why. You can also browse vehicles currently available through ABC, and ask us to confirm the rating for any specific listing.