If you're considering purchasing a vehicle for towing heavy loads, such as an RV or heavy equipment, you'll need an understanding of the vehicle tow rating and how to determine how much weight you can actually tow.
Vehicle Tow Rating and Capacity
Many people use the phrase "vehicle tow rating" and "vehicle towing capacity" interchangeably. The towing capacity of a vehicle is defined by the manufacturer, based on how the car or truck was made and the strength of the materials it is made of. Keep in mind that towing hitches and trailers also have their own towing capacity, so while you're calculating your maximum weight limit, always keep the lowest rating in mind and never surpass that weight.
Look Up Your Vehicle Tow Capacity
Since the tow rating depends on the manufacturer, you'll first need to find the towing capacity of your vehicle model. There are plenty of resources to find that, if you don't have your manual or if you're looking to purchase a new vehicle that can tow the weight that you need.
- HowStuffWorks provides a useful table that lets you click through to the make and model of your vehicle to learn what the manufacturer tow rating is.
- Edmunds publishes an annual list of the top vehicles for towing, along with the tow capacity.
Calculating How Much You Can Tow
If you think it's as simple as looking up your vehicle's tow capacity and then piling as much onto your trailer without exceeding that maximum weight, think again. There are many other factors to consider when you're towing very heavy loads:
- Every vehicle has a Gross Vehicle Weight rating that shouldn't be exceeded. The tongue weight of any trailer adds to the overall gross vehicle weight of your car, combined with any cargo and passengers that you have in the vehicle. When you're towing a very large trailer, you need to know the tongue weight of the load so that you don't overload the vehicle itself and surpass the gross vehicle weight rating, which could be very dangerous for you and your passengers.
- Each trailer hitch has its own limits on the maximum gross vehicle weight rating that it can safely handle. When you purchase a large trailer, such as an RV, the hitch should be rated appropriately for your vehicle.
- Most trailers distribute the weight of the load across both the trailer and your vehicle, adding to the tongue weight. Make sure you understand the GVWR for the trailer, in addition to the tongue weight you'll be applying to your own vehicle.
To safely calculate the maximum weight of your trailer, you would need to subtract your vehicle's weight from its gross weight rating, as well as the rear axle weight from the weight rating. This will provide your maximum tongue weight. Your maximum tongue weight should only be 10 to 15 percent of the overall weight of the trailer.
Play it Safe
Do the calculations above sound confusing? There are many factors that go into calculating safe towing limits, and many people focus on staying below 80 percent of the maximum towing capacity to play it safe. However, if you need to carry heavier loads, you can still remain certain you're playing it safe by using the Changing Gears calculator. This tool takes all of the maximum ratings for your vehicle (which you can find in your manual), and will determine the maximum weight that you should tow.
It is important that you understand and follow the maximum towing capacity, because overloading a trailer can cause any of the following unsafe conditions to occur:
- The vehicle won't have enough power to accelerate, which can eventually damage your drive train.
- Side winds, high speed, and other vehicles can cause "snaking" of the trailer, where it move from side to side as it tries to match the motion of your tow vehicle.
- The worst case is that your hitch or the towing hardware will fail and cause catastrophic damage or an accident.
Know the Limits
The best approach, when you need to tow large loads, is to carefully study all of the ratings for your vehicle. When you are shopping for a trailer or a hitch, make sure the retailer you buy from understands your vehicle limitations and sizes the trailer and hitch accordingly. Taking precautions before you head out on your trip will save the trouble and headache of dealing with a breakdown. The ability to tow cargo and supplies is a luxury. Making sure that you size your loads safely will ensure that you can enjoy that luxury for a long time.