Carrying Capacity of Pontoon Trailers
What a boat weighs seems like a fairly simple subject.
When selecting a trailer it’s an important consideration. Every manufacturer states their boat weight in their sales literature and sometimes on the Certificate of Origin (title). But it’s sometimes not as simple as it seems. Boats are certified with the Coast Guard when a new model is introduced. The boat as it is configured at that time is weighed and that is the published weight for the life of that model. Over the years granite countertops, a 600 lb. captains stand or a 50-gallon fuel tank may be added, but the published weight remains the same.
Several years ago, when Barletta introduced their luxury pontons it was determined that their boats were sometimes as much as 1,000 lb. heavier than comparable luxury boats. Did Barletta really have that much more “stuff” in their boats? NO, everyone else had outdated weighs. This situation is being repeated with the new Alera and Evotti pontoons (2025). They are often considerably heavier than other boats, but it’s only because they were weighed and certified recently.
This is important not only for selecting the proper trailer but also figuring out if your tow vehicle is sufficient. A mid-sized SUV might be able to tow 3500 lbs. but if the boat weighs 4500 lbs. and the trailer weighs 1200 lbs. you may have a difficulty.
Trailer capacity is easy to figure, but different manufacturers rate their pontoon trailer capacity in different (often inaccurate) ways. Capacity is limited by the strength of the axles; the strength or rating on the spindles and hubs and then by the rating of the tires. A trailer with a 3500 lbs. axle can carry 3500 lbs. but the actual carrying capacity may be lower because of the rating of the tires. If the tires have a capacity of only 1300 lbs. (each) the pontoon trailer capacity is reduced to the lower capacity of the tires. (for a single axle trailer 2600 lbs.). There are other considerations, the strength of the frame and bunks, but these factors are difficult to determine. It’s easy to learn the true capacity of trailers. Check the rating, stamped on the axle and read the side wall of the tires. Some pontoon trailer manufacturers overate their trailers capacity. It’s a common practice to add 250 lbs. - 300 lbs. to the capacity because that could be the amount of tongue weight on the hitch and it might eliminate weight on the trailer. We don’t use that method. Our trailers have sufficient capacity that we don’t have to add factors that may or may not be accurate.
Carrying Capacity
Once you know the capacity of the pontoon trailer, you can arrive at the carrying capacity. This is the figure that you should be most concerned with and again, is sometimes difficult to determine. The carrying capacity is arrived at by deducting the weight of the trailer from the lowest capacity of the axle or tires. Our 120 single axle pontoon trailer has a 3500 lbs. capacity axle but the tires limit the capacity to 3320 lbs. The trailer itself weighs 700 lbs. (the weight is on title), thus there is 2520 lbs. of capacity left to carry a pontoon boat. See more about tires and carrying capacity here.
Our Trailer components
Axles on all of our trailers have a 3500 lbs. capacity. Single Axle trailers have 13” D range tires with a capacity of 1610 lbs. Super Duty & Heavy Duty trailers have 14” D range tires with a capacity of 2040 lbs.
Why should I care about overloading a pontoon trailer?
If you're not going very far and using your pontoon trailer infrequently you can probably get by with an overloaded trailer. It will wear the tires, burn up the bearings and the seals, but if you don’t use it much, failure will probably be the second owners problem. However if you tow frequently, tires will overheat and wear prematurely. Bearings will overheat and grease will dissipate more quickly than normal. The bearings will fail potentially scoring the axle and leading to a costly repair. This usually happens on the second day of your vacation and you will be broken down a hundred miles from home. (only kidding, but you get the point)
Loading Capacity
These two photos below illustrate the potential for overloading a trailer. It’s the same pontoon boat in both photos, it weighs about 4500 lbs. The tandem axle trailer on the left has the springs compressed almost to the point where the tires could rub the fenders. (about 1” away) The triple axle (6000 lbs. capacity) trailer could care less about the 4500 lbs. load, the tires are 3” from the fenders.
The tandem axle trailer above is overloaded on both axles. The triple axle trailer is overloaded on the front axle. The triple axle trailer can be fixed by sliding the boat further back on the trailer, but the tandem axle trailer shown above needs a triple axle to carry the weight.