March 29

Matthew Scyoc

# Towing Capacity

Introduction

What is Towing Capacity?

Limiting Factors

Trailer Classes

How is Towing Capacity Calculated?

# Introduction

Towing capacity is the maximum amount of weight that your vehicle can tow when pulling a trailer. It is determined by the vehicle manufacturer. The maximum towing capacity must always be observed in any towing situation. Exceeding this capacity, or towing more weight than your vehicle is rated, is extremely dangerous.

# What is Towing Capacity?

Image Source: https://en.wikiloc.com/

Towing capacity is something that SUV manufacturers brag about and discuss in detail, but what does it really mean?

The towing capacity of a vehicle is a fairly simple concept, but it can often be unclear. Finding the exact towing capacity for the vehicle you are looking for is sometimes more difficult than finding the vehicle itself.

To start, let’s take a look at what exactly the towing capacity is. Simply put, the towing capacity of the vehicle is the maximum weight that your vehicle is capable of towing safely. The maximum trailer weight is another way to refer to the same concept. Basically, answering the question, what is the heaviest trailer my vehicle can tow? Each vehicle is classified into specific trailer classes.

Any vehicle with a factory installed hitch is required to have an established towing capacity for that vehicle in that specific equipment package. Since different trim levels have different weights (additional features may add more weight than you think), each trim level will have a different trailer rating.

# Limiting Factors

Image Source: https://www.carfax.com/

There are many factors that limit the amount a vehicle can tow. First is the vehicle’s engine. The vehicle needs to have enough power to be able to tow without forcing itself to dangerous levels. Torque is more important than power in this determination. The old tribute is that torque is how far a brick wall can go through, while power is how fast it will hit you. And when you tow, you want to be able to get through a brick wall and well beyond that.

Next, the rest of the vehicle’s drive train must be able to pull the extra weight of a trailer. The transmission takes a beating when towing. The added friction, and therefore heat, can wreak havoc on a transmission that has not been properly prepared for towing. Transmission coolers and more robust components are essential when towing heavy loads over long distances.

Brakes and suspension are also key factors when towing. Braking is paramount to safety, don’t tow more weight than your vehicle can pull! Anyone who has experienced brake fade can attest to the terrifying feeling that a brake pedal drops to the ground without having to stop the vehicle. Suspension is also an important factor. Overloading the suspension can cause a vehicle to rock back and forth to dangerous levels, which could tip the vehicle over at high speeds.

# Trailer Classes

Image Source: https://www.carfax.com/

There are five classes of trailer weight gain at each step. Each class is typically associated with a certain type of vehicle.

For example, Class I is generally installed on small cars and crossovers like a Kia Forte or Chevy Trax, as it only has a capacity of up to around 2,000 lbs. About the size of a small jetski.

Class II is for midsize sedans and crossovers, such as a Toyota RAV4 or Honda CR-V, and can handle the slightly higher weight, up to about 3,500 lbs. Class III is typically seen in vehicles such as small trucks and SUVs.

Examples include vehicles like Chevy Colorado or Toyota 4Runner. Class III has a capacity of up to 6,000 pounds. Small boats and campers usually fit within this class.

Class IV is reserved for full-size trucks and SUVs, such as a Ram 1500 or Chevy Tahoe, and has a capacity of up to 10,000 pounds. This will tow a larger boat or caravan and even some smaller car carriers.

Lastly, the V-class hitch has a capacity of up to 12,000 pounds and is found on heavy-duty trucks like the Ford F-250 or Ram 2500.

# How is Towing Capacity Calculated?

Image Source: http://pechlimoinc.com/

Manufacturers take all factors into account when determining towing capacity. The power / weight ratio is important, as are the vehicle’s heat dispersion capabilities. The manufacturer ensures that the rating is below the thresholds that the vehicle is capable of supporting, ensuring the operational safety of the vehicle, as well as your safety!

The trailer rating can also be determined on your own. The Gross Vehicle Weight Rating (GVWR) is the maximum loaded weight that a vehicle is capable of supporting. This weight includes the wet weight (empty weight that includes fluids) of the vehicle with all cargo, occupants, luggage, cargo, etc. The manufacturer determines the GVWR. Once GVWR is determined, you must determine the tongue weight (TW), the downforce exerted on the trailer hitch by a loaded trailer. The weight of the tongue is added to the GVWR of the tow vehicle, limiting the amount you can add. The weight of the tongue is typically 10-15% of the gross trailer weight (GTW), the weight of a loaded trailer. Determining your maximum towing capacity will depend on the weight of the tongue and GVWR of your specific vehicle.

# Conclusion

A vehicle can only tow as much weight as determined by the vehicle manufacturer, be it a truck towing capacity, SUV towing capacity, or other vehicle towing capacity.

Manufacturers, including trailer manufacturers, often provide a number of different weight classifications that are designated by various acronyms.

Matthew is owner of Sunglass.io. He employs a close-knit group of engineers to develop the technical content on the site, but is passionate about everything engineering. Matthew loves the future of 3D modeling and wants to push for more helpful, useful tools for the engineering community. Feel free to reach out to him directly on the Contact page or on LinkedIn!

Matthew Scyoc