What is Tongue Weight And Why Does It Matter?
Whenever a trailer is towed, there are various physical forces at play. There is the forward force of the trailer as it gets pulled. There is resistance that the trailer offers due to its weight and wind resistance. There is also a downward force that the tongue of the trailer exerts on the hitch. Tongue weight is the static downward force that a trailer tongue exerts on the ball of a tow hitch.
This downward force plays an enormous role in safely towing a trailer. If it is too light (not heavy enough), the trailer is prone to swaying as it is pulled. Trailer sway is a big reason for trailer accidents, especially when loads are towed at high speeds.
Too much tongue weight (too heavy) forces the ball down, placing an unbalanced load on the rear (and consequently, lifting the front of the truck). Since most trucks are front-wheel drive models, you can see how that might force the tow vehicle to have less contact with the road. The heavy weight on the rear tires can make the trailer “push” the tow car (or truck) rather than the pulling force you want with a tow. Too much weight adversely affects steering around corners and braking distances, which is never good in an emergency situation.
What is the Proper Trailer Tongue Weight?
The accepted rule is that for trailers towed by a ball hitch, the proper tongue weight should be at most 10-15% of the weight of a fully-loaded trailer. For example, if you are hauling a 2500 lb trailer loaded with 2000 lbs of equipment or furniture, you should have a tongue weight of 450 - 675.
How Do I Calculate Tongue Weight?
There are several ways to determine the tongue weight of a tow vehicle and loaded trailer.
Commercial Truck Scales
The easiest way to measure tongue weight is to take your truck and fully loaded trailer to a truck scale. You should ensure that your truck is full of fuel and the trailer loaded. Drive your truck onto the scale with the trailer attached so that all four wheels of the truck are on the scale (but not the trailer). Record the weight.
Then unhook your trailer, and repeat the process without the trailer’s weight on the hitch ball. Record the total. This figure is your Gross Vehicle Weight (GVW). Subtract this amount from the number of the truck and fully loaded trailer attached. The difference between the two figures is the actual tongue weight of the trailer.
Tongue Weight Scale
Most trailer companies make dedicated tongue weight scales that can measure the load being exerted on the ball. Some ball mounts are made with built-in scales. There are many different kinds, but a simple one will cost around $200 - $250. (For an example, click on this link from etrailer.com).
Since most light-duty trailers have less than 300 lbs of tongue weight (the limit of a home scale), sometimes a bathroom scale can be used. However, this method requires a little more work.
- Make sure that your trailer is loaded and on an even surface
- Use cinder blocks or the jack stand to position the tongue to standard tow height.
- Place the bathroom scale under the level coupler so that the coupler or stand sits in the center.
- Ensure the coupler is set to a level and a normal tow height (you might need to make an adjustment).
- Record the tongue weight.
What if the Trailer Tongue Weight is Too Heavy?
If, after measuring, you find that the tongue weight of the trailer is too heavy, then you need to adjust the load. Move part of the load to the rear of the trailer. (Most experts agree that 55-60% of the load should be centered over or in front of the front axle of the truck).
Often, you only need to do a little rearranging to bring the weight into line by moving some of the heavier items closer to the rear. You want to be sure that you center heavy items over the axles and secure everything so it doesn’t shift during transit.
Conversely, if the tongue weight is too light, move a heavy item or two closer to the front so that it is positioned directly above or in front of the trailer’s axle.
What if Rearranging Items Doesn’t Correct the Tongue Weight?
If you don’t achieve enough weight reduction by rearranging items, there are a couple of options.
Get a Bigger Tow Vehicle
Any time you tow, you should ensure that the tow vehicle (truck, SUV, or car) can tow the weight you are pulling. Many vehicles just can’t pull much of anything. While the standard towing capacity of the ½ ton pickup or large SUV might be upwards of 7,500 lbs or more, many smaller SUVs and sedans can only tow 1500 - 2500 lbs. If your trailer is more than this, you need to find a buddy with a larger truck.
Lighten The Load into Two Trips or Two Trailers or More
If your tongue weight is too much, try lightening the load by taking heavy items in more than one trip. Removing some of the items will lighten the load, make the vehicle with the trailer safer, and ensure everyone will get to the destination in one piece. (This scenario is especially true if you haul things like furniture or building supplies locally).
Modify the Hitch
Many manufacturers and trailer stores can help you determine what class hitch you need to move your trailer, boat or camper. In addition, they can sell you a weight distribution hitch that helps distribute the weight of the tongue more evenly over the four wheels of the tow vehicle. They often have stabilizing bars designed to carry more tongue weight and provide more stability when towing a heavy load.
About THE AUTHOR
My name is Matt and I've been around cars all my life! I have owned and worked on many different classic vehicles, so I started this site to share my experiences. If you're new to classic cars, then this website is for you.Read More About Matt Lane