Increasing Trailer Weight Capacity

[Salty Tricks]

Is it possible to boost a trailers capacity (e.g. 10%) by swapping the springs of each axle?

 

[bowman316]

Re: Increasing Trailer Weight Capacity

I don't know what that would do. It is all about what your tires are rated for. YOu could buy more heavy duty tires. Maybe bigger leaf springs

 

[Silvertip]

Re: Increasing Trailer Weight Capacity

The GVWR of a trailer is determined by a number of things. 1) tires, 2) springs, 3) axle, and 4) the frame. You need to determine what the axle capacity is as a starter. If the spindles have 1-1/16 outer and 1-3/8 inner bearings it is very likely a 3000 - 3500 pound axle. If it has 1-1/16 inner and outer bearings it is a 2000 - 2200 pound axle. The next question is how close to that number is your current total weight. Since you want to increase the capacity by 10% I suspect you are near or over the GVWR by about 10%. That means an axle change may be required. That then means you need to change tires and possibly the hubs, and very likely springs. Tire capacity is listed on the sidewall. The answer to your question though, is yes you can increase the capacity of the trailer -- but only if you consider all of the factors. Bigger tires and springs allow a heavier load but only if the axle can carry that load.

 

[Salty Tricks]

Re: Increasing Trailer Weight Capacity

Thanks for your responses, that does make it clear.

A follow up if I may...

I was told that trailer manufacturers understate their trailer caps by 10% is this a valid statement?

 

[Salty Tricks]

Re: Increasing Trailer Weight Capacity

see above

 

[marquette]

Re: Increasing Trailer Weight Capacity

about 10 yrs ago at the sportsman show i was looking for a new trailer for a 16ft alumacraft. basic boat with floor, 1 bench and 1 pedestal seat. i was looking at a spartan trailer that i beleive was rated at 1200lbs. i wasn't sure i felt that was adaquate. the sales man said well then buy the 1600lb trailer. isaid what is the differance because they looked identical to me. his answer was "tires" . as far as i could see he was right. the tires went from (i beleive this is the right designation) a load range "B" to a load range "C". there was only $75 difference in the price of the trailer so spartan couldn't do much for a $75 differance. so i don't know if trailer makers under rate there trailers but i think that they have similar groups of trailers sharing parts and what combination of parts they put together changes the weight rating. so if you have the bottom trailer in a group you can probably make some simple changes (tires & springs) and increase your weight rating but if you have the top of the group there probably isn't much you can do because they have already maxed the weight capacity. i have called spartan with questions about weight rating and they were very helpful. so maybe you should call the manufacture and ask them what you can change and how far you can go before you exceed the frame capacity.

 

[Silvertip]

Re: Increasing Trailer Weight Capacity

Marquette -- The trailer you just described very likely had a 2000# axle so it could be fitted with tires and springs for any GVWR between 1000 and 2000#. Without chaning the axle you can certainly change tires to any larger size -- provided the load you put on that trailer does not exceed the capacity of the springs and the axle, even though the tires may be good for something over 2000#.

As for under rating trailers, yes, it is probably done as a safety factor, just like bridge design. But the fact remains a trailer should not be loaded heavier than it's GVWR. GVWR by the way is not the weight of the boat. It is the weight of everything including the trailer, boat, motor, gas, gear and adult beverages.

 

[marquette]

Re: Increasing Trailer Weight Capacity

silvertip
i agree with you about the GVWR. but have you noticed boat trailer manufacturers don't often give the empty weight of their trailer like cargo trailer manufacturers. it's pretty hard to figure the GVWR without knowing the weight of the empty trailer. so i think most people look at a 2000# boat trailer and figure that is the weight boat (with gear) they can load on it.

 

[Silvertip]

Re: Increasing Trailer Weight Capacity

The real problem is not so much "owners" overloading a trailer as it is "dealers" selling trailers with marginal capability for the load. They are basically interested in getting a a "package rig" (boat, motor and trailer) out the door and if there is $100 or $200 more in it for them by fitting a lesser trailer under the boat that's money in their pocket. But I also agree that most owners have no idea what GVWR even means and don't know what proper tire pressure is or where to find it. Anyone can get trailer weight data by calling the manufacturer or simply going to a public scale and weighing it.

 

[marquette]

Re: Increasing Trailer Weight Capacity

i agree about the "package deal". and unfortunatly i think that with the current financial state of the marine industry i think we are going to see dealers selling all kinds of mismatched boats, motors and trailers just to get inventory out the door. this could be a time of great deals but a smart buyer will have to look very closely to make sure that the trailer is appropiate for the load it is carrying. and i am not sure we won't see some marginally matched packages directly from the manufacturers.

 

[109jb]

Re: Increasing Trailer Weight Capacity

From a practical standpoint you can certainly increase your trailers ability to carry a load. As stated before, you would need to asses the trailer frame capability along with what the axle, hubs, spring, tires, etc are able to handle and make modifications as necessary. Could get to be more costly than just getting a different trailer and selling the one you have.

Then there are the legal considerations. I know that in my home state, a manufactured trailer's maximum weight capacity is determined by the manufacturer and is listed on the registration and on the data tag that the manufacturer puts on the trailer. There is no way to arbitrarily increase this except by re-registering the trailer as a home-made trailer and setting the gross weight yourself. In my state there are no inspections for smaller home-made trailers so it wouldn't be much of a problem. In other states though it could be.

 

[69seabreeze]

Re: Increasing Trailer Weight Capacity

And if you ever get in an accident or something happens related to the trailer and your boat weighs more than the manufacturers rating, It's going to be your fault for overloading the trailer because the new leaf springs or axles or anything won't match up with the original GVWR.

 

[chiefalen]

Re: Increasing Trailer Weight Capacity

You could add another axle.

You could add another few leafs.

 

[flatboy]

Re: Increasing Trailer Weight Capacity

Everyone is right. I work at a suspension shop in south louisiana for 14yrs. now,most of the time we just run the next heavier spring than whats on the trailer or add an extra leaf to beef it up some.You have some room to go heavier,but you need to make sure what the axles are rated for(1400lb. springs on a 1200lb. axle)not a good idea..