Simple question on how much weight can a trailer tow safely

sporters78

Member
Aug 6, 2010
323
Stuart ,FL
Boat Info
2015 19 SPX
Engines
4.3 merc
If a trailer is rated at a maximum allowed weight of 3400 pounds up to what weight is considered safe to tow regularly?
 
Is this a trick question?

I'd say 3400 pounds :smt021
 
When I bought my jetboat 21 feet by 7.5 wide I had a choice of 2 trailers one with single wheels one with double wheels. Farmer friends (they have lots of waggons and RV trailers) told be to get the 2 wheel trailer. They said they do not load to max on small trailer rule for them was 70%. Idea is springs and tires at max rating are something waiting to break.
 
No, I think he thinks that the max is 3400 but can you haul that weight 100% of the time. The answer is yes. It's not like a duty cycle where you can only haul 3400 for say 20% of the time and anything less up to 100%. Trailer max weights are rated for 100% usage all of the time.

It is actually harder on the springs to run empty than full. When full the weight is distributed through the entire spring length. When empty the constant bouncing rides on the out part of the springs at the eyes or spring ends. This vibration is then transferred to the center of the spring bolt hole and cracks develop.
 
Fully loaded with gear and gas I'm close to the max limit, just making sure im all safe with this trailer as I'm not getting a solid answer from Marinemax and Brunswick for more then a month image.jpg
 
Agree with it being perfectly fine to trailer right at the max.

That looks like the packaged trailer that would of come with the 19SPX. The trailer is made by Shoreland'r. They make EXCELLENT trailers - I would even go as far to saying that they're somewhat overbuilt compared to most. Now, here's the thing with the trailers used under the SPX - there are different models (weight capacities) of trailers depending on whether or not the boat has a 4cyl, V6, tower, etc. If I was at the store right now I could tell you in about 2 seconds as we (dealers) were provided with a nifty little cheat sheet from Sea Ray for just this purpose. Give your dealer a call - you should be able to get your answer in less time than it took you to read what I wrote.
 
Dennis,
it took a more then a month for Marine Max and Brunswick to finally come up with an answer for me ( with no back up) so it's not quite so simple after a dozen emails and phone calls.originally searay called for a dual axle trailer with the 4.3 engine that has now disappeared from their website I guess from me complaining.
 
Well, I'd have to look at my notes at work to speak more about this. I don't understand why you weren't getting an answer - you should of - this isn't rocket science. But, let's add this up...

Base weight on the 19SPX is about 2,730lbs. A V6 weighs about 250lbs more than a 4cyl. One battery = 50lbs. Gas = 200lbs. Engine oil, etc = 25lbs (guessing on that one).

Total weight = 3,255. Leaving about 150lbs for life jackets, ropes, anchor, toys, etc -- which should be plenty. Did I miss anything? Do you have any other options?

Just out of curiosity, why were you speaking with Brunswick and not Sea Ray?
 
Dennis,
actually I was speaking to both Searay and Brunswick along with Marinemax as no one could come up with an answer .that is why I finally put it on the board and thankfully people like you have given me a good answer. image.jpgthank you again.
ps. The only thing that you missed was the two coolers on the boat and the stern anchor
 
You're welcome, Steve. I'm glad it puts your mind at ease. Enjoy the new toy - looks nice with the black bottom!

Nice doggie!
 
Like a pogo stick, right? I used to have a yellow lab that would jump the same way. Over and over -- boing... boing... boing.
 
If you look up your tire specs you’ll get part of your answer. Your tires, ST205/75R15D are going to have a carrying capacity of about 2,120# each. I didn’t look them up, so how do I know that? Your trailer label shows the axle rating at 4,240#. You would have to find out the actual design limits of each component on your trailer if you want to know more, but if you did you’d find the tire rating is the weakest/lowest link. Your trailer could/might be otherwise capable of an increased load but you’d have to pull teeth to find out about all the other components.

So how do you feel good about towing near max weight for your tire rating? Your tires are rated at that weight at their max air pressure. Don’t run them at a lesser pressure. If you want to make yourself feel better, at the next tire change go to the next higher load rating.

I’m of the opinion that the majority of trailer tire problems come from running at max or over their design weight limits. Where’s the proof? You got SeaRay and Shorelander setting you up with a trailer that’s pushing the tire limits, throw a few more items in your boat and you could be over. Add to that the fact that most folks never check air pressure let alone know what it should be and you often get ka-boom and much internet discussion on cheap Chinese junk tires.:smt043
 
While it's a simple question, there isn't a simple answer. There are s lot of factors. As Woody points out tire load is important.

First off trailer manufacturers work with safety factors, so a rating of X may mean the actual capacity is 1.15x X. They also have to assume that the tires they spec will be maintained. This means properly inflated, safe tread depth, and good sidewalls.

Bearing condition and axle end condition also play into this. The higher the load on the axle coupled with driven distance and the greater the forces resulting in higher temperatures at the axle end. The poorer the axle bearing condition and the faster the grease cooks off ending up in a burned axle (fused bearings, scored axle).

Finally, and this is critical with single axle trailers, you need to look at the towing vehicles tires. Up to half of the the trailer/boat weight can end up on the rear tires. If the towing vehicle is loaded the superimposed load from the boat can cause problems.

I personally wouldn't use a trailer that is nearly maxed out from day one. For the simple reason that even with safety factors age related deterioration will lead to reductions in capacity.

Henry


Sent from my iPad using Tapatalk HD
 
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Not to be contrary but I've run Oldskools trailer for 8 years and the PO since 89 on 5 lug 15 inch rims/class D tires and square axle. Max load weight is 3400 and Oldskool lists at 2800 dry and no cargo. Add in 34gal fuel (210lbs), second battery, misc coolers and stuff and I'm about 3200.

This is a new trailer with 6 lug hubs which are good to 6000 LBS with. Bearing should be no issue here with these hubs other than annual maintenance. The tires can be upgraded to E-series that will give a 2830 rating at 80PSI however the D-series should be good for a couple seasons. UV damage is the bigger problem with older tires and side wall deterioration.

We can stand here all day and compare data but the long and short of it is that the trailer will carry the load, The hubs are 6 lug so wheel bearing condition is maintenance dependent and tires can be upgraded to E-series if the OP wishes. The trailer should also have a 2"X3"X7ga axle. The rated capacity for this axle is 3500LBS.

If any of these specs are incorrect concerning your trailer please let me know however your VIN should be as I have stated.
 
I too prefer not to be near max specs on my trailers. As Henry noted there is no room for deterioration or future upgrades. The other thing I wanted to add is a caution about cheap or low end trailers sold by manufacturers based on low cost not quality. These trailers likely have NO margin of capacity and are built with cheap components. Their builders sell them under many names and likely have little to risk by selling inferior equipment.

Please note, most reputable dealers and boat builders use reputable trailer builders.

If you are at the max I'd want to know how long before the salt water in Florida began to weaken the trailer as it appears to be a steel galvanized frame.

MM
 
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Not to be contrary but I've run Oldskools trailer for 8 years and the PO since 89 on 5 lug 15 inch rims/class D tires and square axle. Max load weight is 3400 and Oldskool lists at 2800 dry and no cargo. Add in 34gal fuel (210lbs), second battery, misc coolers and stuff and I'm about 3200.

This is a new trailer with 6 lug hubs which are good to 6000 LBS with. Bearing should be no issue here with these hubs other than annual maintenance. The tires can be upgraded to E-series that will give a 2830 rating at 80PSI however the D-series should be good for a couple seasons. UV damage is the bigger problem with older tires and side wall deterioration.

We can stand here all day and compare data but the long and short of it is that the trailer will carry the load, The hubs are 6 lug so wheel bearing condition is maintenance dependent and tires can be upgraded to E-series if the OP wishes. The trailer should also have a 2"X3"X7ga axle. The rated capacity for this axle is 3500LBS.

If any of these specs are incorrect concerning your trailer please let me know however your VIN should be as I have stated.
Well ah, hey...that's what I said.

This trailer sizing and tire performance is quite a interesting topic really, lots to consider for those that want to get into it. I'll use your example, Old Schools trailer. Simple things like the fact the OP runs in FL make a difference. That hot, sun beatin' down environment is a lot harder on tires than up north. Faster deterioration just sitting there along with a hotter running tire while going down the road. Add a few pounds of weight, run the tires below rated air pressure(which reduces load carrying capacity) and ka-boom in FL but maybe not in PA. I still say they've set him up with a border line rig. I've seen tire tips from manufactures that recommend the total capacity of a trailers tires be as much as 20% over the trailers loaded weight.:huh:
 
There's many good points brought out in the light above. One that I want to expand on is the notion of "cheap vs quality" trailers. That couldn't be more true. As I mentioned above, ShoreLand'r is by no means a second-rate company. They are top notch. In fact, from a retail standpoint, they sell for 30%-60% MORE than most other manufacturers. Sea Ray has been using ShoreLand'r as their trailer builder since 2001. They have been absolutely fantastic - in most cases, even mroe reliable than full-on custom trailer companies. ALL of the Shoreland'r trailers that come under a Sea Ray usually within a few hundred pounds of "max" when totally loaded up. That's the way they're designed. That's also why I mentioned they seem to be 'overbuilt'. Even their galvanized finish/process is better than most.

We have plenty of customers that come to us to buy a replacement trailer for boat X and opt for a less expensive route. We do carry some less expensive lines, but we don't carry anything "super cheap" as it's still going to be us that the customer comes back to if they have a problem. For the customer that is shopping price only, sometimes we lose a sale because of that - but I'll take that 6 ways to Sunday over dealing with ongoing "issues". Anything can have issues, but by far, there are much, much less of them with the ShoreLand'rs.

My point is, there are valid concerns brought up by the posts above - but rest assured, Steve, that Shoreland'r has done their homework and while you are close (or maybe even right at or a bit over) to the "stated" max, you are still well within the capabilities of that trailer. Given how many trailerable boats we've sold since 2001, I would be one of the first to know if there were issues with the Shoreland'r. They have truly been a fantastic line of trailers to have. They're one of those things that "just works".
 
Well ah, hey...that's what I said.

This trailer sizing and tire performance is quite a interesting topic really, lots to consider for those that want to get into it. I'll use your example, Old Schools trailer. Simple things like the fact the OP runs in FL make a difference. That hot, sun beatin' down environment is a lot harder on tires than up north. Faster deterioration just sitting there along with a hotter running tire while going down the road. Add a few pounds of weight, run the tires below rated air pressure(which reduces load carrying capacity) and ka-boom in FL but maybe not in PA. I still say they've set him up with a border line rig. I've seen tire tips from manufactures that recommend the total capacity of a trailers tires be as much as 20% over the trailers loaded weight.:huh:

I agree with all of your statement Woody. The only observation I would add is that up north trailers tend to sit for a longer period over winter lending to flat spots on the tires. I do pull my trailer every couple months just to rotate the tires.

You may remember my early post about blowing out to perfectly good "looking" Carlisle tires right down the center tread. Side walls held but the cords separated due to sitting.
BTW this was in WNC too.

Good points made be all and I'm not discounting anyones view when it comes to safety.
 

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