If you pull an empty (or nearly empty) utility trailer, you probably know the feeling of utility trailer bounce. It’s that bumpy jolting extra bouncing you feelin the tow vehicle as you drive. Sometimes it feels like the trailer is just bouncing away behind you, yet it’s not, but really it is.
What Causes Trailer Bounce?
The simple answer is the suspension is too stiff for the load. There are other parts to it, like load balance and the axle position, but we’ll get to those in a minute. Basically utility trailer bounce happens when there is not enough compliance in the system for the current load.
If your trailer is rated at 3500#, and you’re pulling it empty (maybe 500# trailer weight), then the suspension is not going to compress much over a bump. Instead, it bounces — and sometimes keeps bouncing because full tires are like basketballs on the ends of the axle.
Remember, a trailer suspension is a system that includes both the springs (or rubber with torsion axles) and the tires.
Amplification
To make matters worse, depending on trailer length and where the axle is placed, when the car goes up and down over a bump, that teeters the trailer like a teeter-totter. The mass of the trailer frame wants to keep moving even as the shock absorbers on the car are trying to smooth things out. Then, the trailer tires go over the bump and the mass of the frame is excited again. All of this jostling makes pulling the trailer somewhat annoying, if not disconcerting. (Read the details in “What Is The Right Trailer Tongue Length?“)
Pulling a trailer in a truck with a stiff suspension also amplifies the effect. And, if the trailer is quite heavy and/or long, that makes things worse too. Finally, the smaller the tow vehicle (compared to the trailer), the greater the effect.
So, is there a way to fix it? Can we make it go away?
Utility Trailer Bounce Solutions
The focus here is on utility trailers because they are often pulled empty, then full, then empty. They also have a large difference in load from empty to full, so it’s often called “utility trailer bounce”. It happens with other trailers too, and what you are feeling is not only bounce, but all the movements of the trailer. The bounce part is the topic of this page.
Can we fix it? The honest answer is NO. BUT, you CAN calm it down considerably!
Tire Pressure
The easiest way to reduce utility trailer bounce is to adjust tire pressure. By lowering pressure, the tires act more like a partially filled basketball and they bounce less. How much pressure? That depends on trailer weight, tire size, and tire type (trailer tires or automotive tires). In general, for an empty utility trailer, you can run half the normal pressure.
For one trailer I had with 225-70 R15 automotive tires, normal pressure was 35psi. Trailer capacity is 3500#, but empty weight is 600 lbs. When empty I ran 12-15 psi which smoothed things out superbly. Automotive tires usually require a little more pressure because they have softer side walls. Radials especially.
Please don’t take my word on it, experiment with your trailer. Try reducing by 10psi, then go down in 5 psi increments until the bounce is acceptable. It won’t go away completely, but it will change a lot.
With very low pressures you run several risks of tire damage, so don’t go too low. It won’t wear the tire more quickly when the trailer is empty, so that’s not a problem, but a big bump can cause other trouble. Also, if you’re taking the trailer to pick up a big load, make sure you also carry an auxiliary tank or pump — because you DON’T want to haul a load with low tire pressure.
Use this cool tool for inflating / deflating the trailer tires.
Other Options
There are some rubber inserts on some shackles that dampen some of the bouncing. They can be expensive, and limited in the effect they have.
If it’s practical, add a longer tongue or set the axles back some. These also reduce the bouncing you feel in the tow vehicle.
Torsion axles are a little better for bouncing than leaf springs, because rubber has a natural hysteresis. However, running empty you don’t deflect the torsion much (if any), so there is not much of an effect.
Also, tandem axles reduce bouncing some because they interact with each other to mitigate some of it. While it’s an option for some, it doesn’t work for all. Finally, there are other axle mounting styles like this Walking Beam Suspension that do a lot for bounce because the wheels counter each other.
Thanks for reading. If you know other options, please leave a comment below to share with all our readers. Thank you.
sir I read all your articles and understood most of it , I have a 5×10 utility trailer with wood on the floor I’m driving to texas, so my question is , if I place 80lb bags of cement in the center of the trailer in front of the tires but not to far to the front will this give me more stability, or should I place one bag all the way to the front and follow it to the center of the tires and stop there for better stability , also I’m going faster 65 to 70
Good questions. If the tongue weight — the force from the trailer tongue on the hitch ball — is in the area of 10-15% of the total trailer weight, it should be good. There is more than just weight balance in the stability equation, but that’s a big part of it. If you have a choice, like with bags of cement, then low and in one tight group is a little better for bounce (as opposed to spread out all over the trailer), assuming the weight balance is exactly the same. That said, it’s not really a factor so much with stability. Enjoy your trip.
Nice reading. Well written article. Thanks for this.
My dad wants to have a flatbed trailer that he can use to carry things when he goes camping. It was explained here that the trailer bounces when the suspension is too stiff. Furthermore, it’s recommended to go to trusted suppliers when planning to have a flatbed trailer.
Do u make trailers & what is the widest u make. Want to pull from state to state. Have a Ford F150.
We design trailers and we offer the plans for sale so you can make them. The widest legal for highway use is 102″ width (8’6″) state to state. Your F-150 has towing limits (total trailer weight and tongue weight), so build your trailer below those limits.
My husband want to get a utility trailer for his motorcycle, and your article had great tips to help stop the trailer from bouncing if this becomes and issue. I liked how you said to consider lowering the tire pressure so the tires act more like a partially filled basketball and bounce less. Thanks; I’ll share this with my husband if he gets a utility trailer.
I had no idea that a utility trailer could bounce when it’s empty because there’s not enough compression to keep it down. Right now I don’t have a trailer but I think that it would be important to look for one that is right for the loads you plan to carry. We like to go camping a lot so I’ll have to figure out what the weight of our equipment is and then look into utility trailers.
Hello and thanks for the info.
Would welding in some shocks help? My trailer is homemade with an old pickup axle on leaves.
Shocks are not often used on trailers, partly because the suspensions don’t move that much. However, a pickup truck has much longer springs, and they do move a lot more. If your trailer has the pickup truck springs, shocks might help a lot.
I doubled the length of my tow bar (was 4 ft and now is 8 feet long). I used the same tow gauge steel as the original tow bar and I’m now concerned there my be too much flex in the tow bar that could lead to excessive bouncing. I should have started with the type of trailer I have…it’s a small utility trailer with 48” bed and a max load of 1090 lbs. The trailer itself weighs 150 lbs ( just chassis) but I’ve build a wood box and floor for it so it now weights around 300 lbs. I’m wondering if there is a minimum gauge steel that should be used for an 8 ft tow.
PS. I have not yet pulled this trailer as I’m still building it.
Sounds fun. I don’t know of any standards to just apply — everything is based on the complex combination of material dimensions (width, height, wall thickness, length) and the loads, loading, etc of the trailer. For your situation, since the loads are pretty small, I’d say if it feels flimsy, that’s a very good indication that it is not enough. (However, that is not an adequate way to always decide what will work.)
I have a trailer for pulling up to 4 canoes that has a GVW of 1,200 lbs. The trailer itself weighs roughly 250 LBS and and a typical load is 60 to 100 lbs. It has a single axle with 13″ tires that have a maximum inflation of 60 lbs and a speed rating of 81 mph. I’ve dropped the tire inflation to 35 lbs but the bounce is still annoying and tiring. How much can I reduce the inflation before risking destroying the tires at prolonged highway speeds of 75 to 80 mph? Functionally, the trailer isn’t usable for long drives with the vibration from the trailer bounce. Thank you!
You’re right, there is some danger in reducing pressure a lot. That said, you probably won’t get much bounce relief until pressure gets down around 20 psi. I’d do an experiment. Reduce pressure until the tires begin to deflect a little. Not enough that they look like they’re going flat, but enough that they are not “hard”. Drive a short way and see if the bouncing is improved. If it is significantly better, then find some elastomer link adaptions for your suspension. Ife bouncing is not improved, then your load is probably too far back, or there is something else with the dynamics rather than the actual “bounce”. Immediately after driving your test, place your hand on the tires to see if they are hot. That will tell you more about what you can and can’t do with air pressure.
Thank you! I’ve never had a light trailer with a light load before but it has been ‘interesting.’
Are these drawings Engineer Approved & Stamped ?
The plans are fully engineered, but since most DIY’ers are not certified builders (especially as certified welders) and most do not purchase certified materials, there are caveats with respect to certification. I’ll point you to the FAQ “Are Your Trailer Plans Certified For Highway Use?” And for further info on “Stamped” I’ll point you to “Can You Give An Engineering Certification To My Design?“
We have a couple of light utility trailers that we use in our business suppling the car wash industry. When the trailers are loaded there is no problem with bounce, but once unloaded . . . say no more. So we tackled the problem using motor cycle type coil over shocks- which have a shorter stroke than most automotive shocks. We fabricated a simple flat plate to correspond with the existing U bolts under the trailer axle, welded on mounting points on the plates and on the trailer chassis, bolted everything together and hey presto – no more bounce. Now I’m thinking of making up a whole bunch of these and selling them as “No Bounce” trailer shock kits for DIY installation.