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Attaching a trailer to a vehicle seems like a pretty simple task, but there are safety factors to consider before hitting the road. Whether you haul a trailer often, or just occasionally, every time you hitch something up to be towed by your truck, there are best practices to follow.
When towing, trailers should be level to improve stability, braking performance, and ground clearance. A level trailer will prevent poor towing characteristics, like sway, and uneven tire wear. If a trailer level is not possible the next best option is to have the trailer nose down a little.
Adjusting the trailer to be level is important for safety. Traveling with an unlevel trailer can create a dangerous situation for yourself and other drivers on the road. Plus, the wear and tear it causes can create expensive repairs. Let’s talk about why you don’t want to travel with a trailer that isn’t level.
Why A Trailer Should Be Level When Towing
There are several reasons why a trailer should be level while towing including better towing characteristics, even tire wire, ground clearance, and proper braking performance. No matter what type of truck or trailer you have, it is always the best idea to have a level trailer.
Note: For ease of reading and clarity I’m going to refer to the vehicle towing the trailer as a truck. I know you can tow a trailer with a car, SUV, truck or a motorhome but for simplicity and instead of saying the vehicle doing the towing, I’m just calling everything a truck.
For ideas on moving your trailer without a truck you can check out these unique solutions.
Better Towing Characteristics
How well your vehicle handles the road while towing a 7000 lb aluminum box is greatly affected by whether your trailer is level or not while towed. Stability and aerodynamics of the trailer are important factors in road safety and not letting your trailer control your truck.
Stability and Sway
In many cases, trailer stability is synonymous with sway prevention. Sway gives the vehicle doing the towing an out of control feeling. The trailer will start swinging side to side (i.e. fishtailing) and can take the truck along with it. Trailer sway is responsible for the majority of trailer accidents.
Weight distribution is the leading cause of trailer sway. When there is too much weight added to the rear of the trailer, the front end gets lighter. The same goes for too little weight added to the rear.
If your trailer is nose up when connected to your truck, i.e. the back of the trailer is lower to the ground than the front of the trailer, the center of gravity of the trailer is too far back making it more susceptible to sway. This makes the trailer acts like a pendulum while the vehicle is moving, causing it to swing side to side.
To make matters worse the trailer may even be pulling up on the hitch reducing the amount of traction the rear tires of the truck have.
Conversely, a nose down trailer, i.e. the front of the trailer is lower to the ground than the back, can cause the rear of the vehicle to sag while lifting up the front. This reduces the traction of the front tires, which gives you less steering control.
Trailer sway can occur even when your trailer is level but is much more likely to occur in an unlevel trailer. Other common causes of trailer sway include:
- Poor trailer design
- Too much weight
- Side winds
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Aerodynamics and Fuel Economy
A level trailer is a more aerodynamic trailer. Trailer manufacturers design their trailers to be level when towed so the aerodynamics have been optimized for a level towing positon.
Aerodynamic trailers get the best gas mileage. If the front of the trailer is too high, the air will catch underneath the trailer and cause lift, which slows the vehicle down and uses more gas for the trip. We are all trying to improve our gas guzzlers fuel efficiency as much as possible
Good ground clearance is important for everyone towing a trailer. Even if you live somewhere where there are few bumps and dips in the road we all run into those awkward driveways with big dips.
Without proper ground clearance, you run the risk of damaging the bumper of your trailer or your jacks if you are nose high. If you are nose low then you could damage the tongue jack. All of which could be costly repairs. A properly weighted, level trailer will have plenty of ground clearance.
An unlevel trailer will put extra weight on one axle rather than an equal weight distribution between all of the axles. Obviously, this will cause excessive tire wear to the tires that have more weight on them.
If your trailer is nose high, you may notice your rear axle tires being more “flattened” than the front. This could lead to the rear axle and tires being overloaded. The same is true for nose low with the front axle and tires being overloaded.
Along with excessive weight, uneven weight can cause extra heat on the tires. Extra heat and more weight on one tire can cause a tire blowout while on the road. It is always a good idea to have a jack and a spare on hand in case of any mishaps.
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Learn more about the main causes of tire blowouts in our article, Why RV Tires Blow Out and How to Prevent It
If the weight distribution of the tires is off because of an unlevel trailer, the tires will be touching the ground at different pressures. When there are different pressures in the tire, it is possible that it may affect the braking performance of the vehicle.
When your trailer is sitting too high or too low in the front, one set of tires may not have good contact with the road. When you hit the brake and don’t have good contact with the road, your tires may skid and provide poor stopping power.
This also affects the braking ability of the truck since if the trailer is too high at the front it may be pulling up on the back of the truck preventing the rear truck tires from having good contact with the road.
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Affect of Leveling on Different Trailers
Basically, there are two types of trailers, single-axle trailers, and multi-axle trailers. These two types of trailers are affected a little differently by being unlevel.
Single-axle trailers are less sensitive to being level since there is only one set of wheels to worry about. You are less likely to see uneven tire wear and blowout due to leveling issues. Also, most single axle trailers aren’t equipped with auxiliary brakes so the braking performance of the trailer will not be a factor.
Both trailer types will still see issues with stability, aerodynamics, ground clearance, and braking of the truck as mentioned above.
How to Tell if Your Trailer is Level
Now that we know why your trailer should be level when towing we need to learn how to check if it is level when hitched up.
To start you should be parked on level ground. Eyeballing the ground to see if its more or less level is good enough as long as the ground is following the same trend. For example, if you are parked at home and your driveway slopes towards the road, this is okay as long as the trailer and truck are both parked on the same slope, don’t let the front wheels of the truck be on the road,
If you want to be picky, grab a long level, at least 4ft, and place it on the ground to check. Take note of where the bubble is so you can compare it to the reading you’ll get on the trailer.
There are two ways you can easily check your trailer’s level, one is using a small torpedo level and the other is using a tape measure. Both checks should be done with a fully loaded trailer and truck like you would have for normal use. This included some sort of fluids in your water tanks.
Your trailer should be within 1 inch of level or 2 degrees.
Using a Level to Check Trailer Level
With your trailer connected to your truck AND the trailer fully loaded like it would be while traveling, place a level on the tongue of the trailer.
If the ground is close to level then you want the bubble to be centered within the lines on the torpedo level. But the bubble does not have to be perfectly centered. It is safe to be about 2 degrees out of level.
On a bubble level, this means your bubble can be touching or slightly past the line. The line on the bubble level indicates a 2 percent slope or a 1/4 inch per foot, this works out to about 1.2 degrees.
You’ll want to flip your level over so the side that was touching the tongue is now facing up and confirm your level reading. If you are getting a different reading you should check your level on a known level surface to see which side is accurate. Or buy a new level.
If your ground was not level, you can still check your trailer by comparing the level reading you took of the ground to the reading on the tongue of the trailer. Otherwise, you’ll want to use the ground clearance check below.
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Using Ground Clearance to Check Trailer Level
Again, have your trailer connected to your truck and have both loaded for travel and parked on a fairly flat and level surface. This is also the method you will use if you have a fifth wheel.
Using your tape measure, measure the distance between the bottom of the frame of your trailer and the ground at the front and rear of your trailer. These two measurements should be within about 1 inch of each other.
If you have a small trailer you’ll want this difference to be less than an inch. If you have a long trailer then you have more wiggle room so you can be a bit over an inch.
It is also a good idea to level from side to side as well. Check the ground clearance at all four corners of your trailer and compare the two front measurements and the two back measurements.
You’ll want your trailer to be pretty close to level from side to side so less than an inch difference. Of course, how level the ground is from side to side will need to be considered as well.
How to Level Your Trailer
In a perfect world, your trailer will be level the first time you hook it up to your truck. Unfortunately, this is a not so perfect world so let’s talk about how to level your trailer for towing.
Again, it is best if you are on level ground to level your trailer. The easiest place to start is with redistributing the weight in your trailer. If you are too nose down try moving some gear to the back fo the trailer. Too nose up? Move what you can forward in the trailer.
This might be enough to get your trailer level but if not, you’ll need to invest in a new hitch to either raise or lower the hitch. Below I’ll explain how to find the right hitch for your truck and trailer.
To raise your hitch you’ll need a rise ball mount. “Rise is the distance the ball platform is set above the top of the shank.” (source)
To lower your hitch you’ll need a drop ball mount. “Drop is the distance the ball platform is set below the top of the shank.” (source)
Since you are already connected to your trailer start by measuring the distance between the top inside edge of the receiver on your truck and the ground. The receiver is the square metal tube bolted to the underside of your truck. Write this value down, let’s call it R1, we’ll need it later.
Now you’ll need to disconnect the truck and the trailer. With the two vehicles separated measure again the distance between the top inside edge of the receiver and the ground. Write down this number too and call it R2. Subtract R2 from R1 to find the squat.
Squat = R2 – R1
Squat is the amount to drop or sag that occurs in a truck’s suspension due to the weight of the trailer on the hitch. If your truck is self-leveling with airbags or a similar system then there shouldn’t be much squat to account for but it’s still good to check.
Now before you take your trailer measurement you will need to level your trailer using the tongue jack. Use the level check or ground clearance check above to confirm your trailer is level. Then, you will measure the distance between the bottom of the coupler and the ground, write this measurement down as C. The coupler is the part that goes over the ball and connects your trailer to your truck.
Subtract the coupler height from the receiver height to find out how much hitch rise or drop you need. If you had some squat to account for then you will need to add that back to your rise/drop equation. Round your number to the nearest whole number to find the size of rise or drop ball mount. A negative number will mean you need a drop ball mount and a positive means you need a rise ball mount.
Rise/Drop = C – R2 + Squat
The video below provides some simple diagrams on how to find the proper rise or drop for your trailer hitch.
If you tow multiple trailers with different rise and drop levels, there are adjustable hitches that will give you the flexibility to raise or drop the ball mount as it is needed.
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What if You Can’t Level Your Trailer?
There is always the off chance that no matter what you do you can’t get your trailer level. You’ve done your calculations, tried different ball mounts adjusted the weight distribution and nothing you do gets you within that 1 inch of level.
In general, if you can’t level your trailer, it’s better to be a little nose down. Of course, there are multiple factors that can affect this so you should consider your specific situation.
One factor that is very important to this decision is tongue weight. If you are well within the allowable tongue weight of your truck then you adding a little more weight to the tongue and having your trailer a little lower in the front is your best option for sway prevention.
If your trailer has a too heavy tongue weight and is nose up then you need to seriously consider a lighter trailer or a heavier truck. Having an overloaded truck is very dangerous and can lead to a serious accident.
You should also be mindful of how full your black, gray and fresh water tanks are. Changing the level of fluid in these tanks can change the center of gravity of your trailer and affect how level your trailer is while towing.