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Trailers 101
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Don't know all of the lingo? Craig demystifies some of the nomenclature for those of us who don't eat, sleep, and breathe trailers.

Items below so far...

What are 'Rub Rails'?

What trailer lighting plug do I need?

What is a trailer brake controller?

Just added! Will my car fit????

What do all those letters mean? (GVWhat?)

What does full DOT stand for?

Why do tandem axle trailers need four wheel brakes now?

Why being legal is more important than you'd think!

What is a breakaway system?

What are LED lights?

What is a stake pocket? Do I need to buy D rings?

What is a VIN tag?

What is an MSO?

How does the M/T Tilt bed Work?

Here you go....
read away and get smarter than trailer dealers you'll meet!

First. If you read this and you still don't see an answer to a question, PLEASE! Click here to send me an Email and I WILL answer it. Plus, you will have helped grow this page by reminding me to answer another riddle of the trailer world for the next person who comes here to learn.

What are rub rails? 
Once again, when you are in the business as long as I am, you sometimes forget that what you think is common knowledge is unknown to the layperson. Forgive me for not explaining this sooner.

The rub rail is simply a steel strap that is fitted and welded along the side of the trailer to the outside of the stake pockets. This creates unlimited places to tie down along the side of the trailer, as illustrated with this strap being placed in between two left front side stake pockets on an 18 E/T tilt.

What Trailer Plug will I need? 
Tandem axle utility trailers... all models.
(Buying a single axle from us? Scroll down)
If you have any late model truck with a factory tow package, you most likely have the right plug on your truck already ... Here is a photo of the actual truck plug that our std tandem axle trailer lighting plug is designed to interface with.
This 7 pole lighting plug is the same design offered by Ford, GM, Dodge, Toyota and Nissan on their new trucks with tow packages. All are wired the same and will simply allow our trailers to plug in and work properly with no modifications.

The actual lighting plug on all of our tandem axle trailers looks just like this one ...

This is the plug equipped as standard on the following models ... HD flatbeds, Tandem SS and RS utilities, M/T, E/T and G/T tilt Speedhaulers, Hi Deck flatbeds and all Dump Box models. If the unit has brakes, this will be the plug we put on it ... period.

(Tech support sidelight here ... )
I had a customer who unfortunately had a rogue corn stalk grab his trailer lighting plug and pulled it, wires and all, out of our trailer plug. I created this diagram to help him rewire his plug and thought that it would be a good idea to put it on the site for future reference for all of our customers. This is how we wire ours to mate up to your OEM tow package truck wiring plug.

If you have any questions on this, don't be afraid to email or call me at 712-589-3100. Thanks ~ Craig

Single Axle Trailer Lighting plug ...
Hope that helps you get your brain around trailer lighting plugs. As always, email me or call me if you need more info.

What is a trailer brake controller? 
(and why do I need one?)
All I can say at this moment ... is THANK the LORD for the internet …
The smart folks at already did a really nice article all about these and you can read about it here.

Just for reference, here is an average electronic brake controller installed under the dash on a late model Chevy truck.

and here is a close up of a factory brake controller on a later model Tahoe.

Why do you need a brake controller? Well, that is best answered in the howstuffworks feature, above, but the short version is ... so you can control when and how hard your trailer brakes activate while you are towing.

Will my car fit? 

This question reminds me of the old Pink Panther movie, when Clouseau asks the German hotel manager if his dog bites. Didn't see it? Pretty funny ... here's a link to it on YouTube.

Anyway, back on subject – so, you have a lowered hot rod, race car, or some other ground-dragging machine that you want to load on a wood deck or aluminum car trailer, and you want to know if the nose is going to rub when climbing the tilt bed, or if it will high center as it climbs onto the deck on one of our ramp trailers. The answer is ... how low is your car? How much overhang do you have on the nose? How blue is the sky...? Here's a quick drawing to help you figure out the nose clearance issue.

In the above drawing,
A is the exact point where your front tires meet the ground on the leading edge. Why is this measurement important? Because, as your car rolls up on the trailer, this will be the rise point -- when the wheel rises up, along with the nose.
B is the lowest hanging point on the front end of your car. It might be a spoiler; it might be the bottom of your radiator; only you can say.
C is the ground directly below the lowest hanging thing on the front of your car.
What you are trying to determine here is how many inches of rise per foot your car has, and drive-up to, before it makes contact.
Here is a quick photo tour of how to make this determination using a slick Ferrari 512 BB (NOTE! We don't make a std trailer that this car can load on without “just” touching that pretty nose on, if you loaded in on flat ground. Our customer always loads onto a curb or uses a couple of planks to ensure that his baby doesn't rub... (Actually, if we built a 26' long M/T tilt, it would clear, but who wants to tow a Ferrari on a 26' long trailer?)

So ... I hope this helps you get YOUR number in line … now for mine.

Rise per foot on some of our trailers?
18' 7,000lb GVWR tilt trailer (M/T or E/T same) 3.5" per foot of bed- length from tail
20' Tilt 3" per foot
22' 14,000lb GVWR 3" per foot
24' 14,000lb tilt 3" per foot.

So ... go measure, and I hoped this helped you plan a little better!

1. Alphabet Soup: What do all of those letter designations mean? 

Think it's weird, here? You ought to see what they make us do in Canada! (Yikes!)

GVWR: It's simply the term used for Gross Vehicle Weight Rating. What GVWR means is that this is the maximum amount of total weight this trailer can handle, including the weight of the trailer itself. If you are looking at one of our 18' M/T Tilt Speedhaulers in 7,000lb GVWR trim, it means that this trailer can carry a combination of its own empty weight and cargo up to a maximum of 7,000lbs. Since most trailers of this type weigh about 100lbs per foot of deck length (16' trailers will weigh about 1,600lbs, 18' trailers weigh about 1,800lbs and 20' trailers weigh about 2,000lbs), you must deduct that trailer weight off of the GVWR to find out what a trailer can truly carry on top of its own bed.

GAWR: This is the total capacity of the axles on a given trailer, Gross Axle Weight Rating. In most cases, including ours, the GAWR and the GVWR are the same. Some manufacturers will also add in the capacity of the trailer’s hitch, on top of the GAWR, and come up with a higher GVWR number. We choose not to, as everyone loads their trailers a little differently, and the coupler capacity is like a hidden bonus of weight-bearing capacity. Personal preference? Hey, we'd rather under-promise and over-deliver.

CWR: Coupler weight rating. On our single axle units, the 2" coupler is rated to carry a separate 700lbs of tongue load, on top of what the axles are rated to carry. Our 2 5/16" coupler, used on all tandem models, is good to carry a separate 2,100lbs of whopping load in excess of what the axles can carry.

GCVWR: (How about that for a long acronym?) This honey stands for Gross Combined Vehicle Weight Rating, which would add on the GAWR and the CWR for an overall nosebleed maximum amount of weight this trailer can carry. If you used this formula on our units, a std 18' M/T Tilt Speedhauler would have a GCVWR of 9,100lbs. (7,000lbs of axle capacity and another 2,100lbs of coupler load capacity)

We would rather err on the side of caution and hold our GVWR number as a good solid usable maximum weight this trailer can carry if you want it to last for the next 20-plus years. Remember, the heavier you load a mule, the shorter it will live.

2. What does Full DOT stand for? 

In our case, full DOT stands for the fact that any trailer with this designation is fully legal for use in all 50 States of the US, as well as all provinces in Canada. DOT means Department of Transportation (yes ... those guys in Washington, DC).


The Full DOT designation means different things on different trailers. In the case of our 2,990lb GVWR-rated single axle trailers, full DOT means that each trailer has the proper specifications, was built to meet certain benchmarks of quality, carries a federally registered VIN number (we'll get to that below, if you don't know what that is), comes with an internationally recognized MSO (read below), has the proper rated axle, wheels and tires, coupler, marker lights, tail lights, reflectors, safety chains, lighting system and trailer lighting plug to meet all of the standards set forth to be Federal Department of Transportation, legal to pull anywhere in North America. So, Full DOT isn't a very long phrase and gets WAAAAAYYY over-used in this industry. We can't speak for any other manufacturers out there, but when you see one of our trailers that says it is Full DOT ... it means that it REALLY IS FULLY Department of Transportation Compliant in all respects.

On our tandem axle 7,000lb GVWR units, in order to be fully DOT legal, all FOUR wheels have the proper electric brakes on them. We know that you are going to hear a million stories about whether you need brakes on all four wheels, so let us set the record straight ... in order to be federally compliant, any trailer with a capacity of 3,000lbs or greater MUST have brakes on every wheel that rolls on the ground … period.

3. Why do tandem axle utility trailers need brakes on all four wheels?  

Put brakes on all FOUR wheels! It's the LAW!

Read above! It's the law of the land ... really. Plus, remember that when an axle manufacturer builds a 3,500lb brake axle, he designs the brakes to stop a maximum of 3,500lbs. (Like you would expect!) So, if you have a trailer with tandem 3,500lb axles, and only one of them is a brake axle, you don't have enough trailer brakes to do the maximum amount of stopping power required to haul down a 7,000lb load. It's a safety thing ... and in this day and age, being safe means not getting sued, or worse. Read below.

4. Why being legal is more than not getting a ticket! 

More than a few years ago, one of my big parts vendors told me of a man who was paying the price for using a not-so-fully-legal trailer in the worst imaginable way possible.

The gentleman was a veteran trailer puller who was pulling a trailer he had owned for a few years. It was a 7,000lb rated dovetail car trailer with only one brake axle on it. The trailer was otherwise perfectly DOT legal, with all of the proper lights, chains, safety equipment, breakaway system, and all. But, it did have only one brake axle on it, which had not caused him any issues.

He was towing a classic car he bought at an auction back home, and his wife was sleeping in the passenger seat, when he left a green light in a larger city and was immediately T-boned by a drunk driver who ran the red light and hit his passenger’s door doing 70mph. The collision killed his poor wife immediately, and injured him pretty badly as well, but he lived, only later to find out what happens when insurance companies look at your rig.

Nothing about the accident had anything to do with whether he had enough braking power. He was barely doing 10mph, and was simply in the wrong spot at the wrong time, and the accident killed his wife of 22 years immediately, while injuring him. Now here is where it gets strange, aggravating, and a parable to buy your next trailer by.

This gentleman had a $2 million life insurance policy for himself, and another for his wife. When the life insurance company got involved, they discovered that his trailer was not fully DOT legal, because it only had one brake axle. They took it to court and fought hard and won ... since his trailer was not legal to pull, he was breaking the law at the time of his wife's death, and therefore ... they did not pay him a penny of life insurance.

So ... should you worry about being truly 100% legal when buying a new trailer?

We vote Yes.

Craig's common sense on proper brakes and breakaway systems:

I have a wife and kids, and I'll bet you have people you care about, too. I would never want to send out something that could injure or kill someone or their family members, and I hope that you wouldn't either. Whether you end up buying a trailer from me, or not, please make sure that it is safe, legal, and more than properly equipped to be safe under all circumstances ... or don't buy it.

5. What is a breakaway system? 

Good question! It's another item required to make your new trailer fully DOT legal if it is a brake-equipped unit. A breakaway system is simply a steel cable attached to a pull tether switch on your trailer’s tongue. The switch is powered by a small gel acid battery contained in its own little all-weather box in the tongue of the trailer. The small 12 volt battery inside sits and waits for the moment that your trailer comes unhooked while being towed at any speed.

If your coupler were to come uncoupled; your truck’s hitch, or the actual ball on the hitch broke; or if some other failure caused the trailer to come unhooked from the tow vehicle; the first thing that should happen is that your two safety chains will be hooked up, and the chains will catch your trailer and keep it from running loose and hitting someone.

If for some reason, your safety chains did not hold the load or came unhooked -- then the trailer would begin to separate from the two vehicles. At some point, the pull tether (which should be hooked to the truck somewhere other than where the safety chains are attached) would hit its max length, and as the trailer kept going, the switch would be pulled by the pull tether.

At that exact moment, all 12 volts inside of the breakaway battery would immediately charge the magnets inside of the trailer’s brakes and lock all four wheels up, bringing the trailer to very short and safe stop before it could get loose and do any damage to others.

So, bottom line is this ... a good, properly working, and properly set up breakaway system that is able to activate the proper brake system is the last bit of insurance you, and anyone who may be near you will have, when the worst thing that could happen does happen! It's common sense at its best ... don't save $100, now, and find out it cost you a life, later.

6. What are LED lights? 

Want to learn all about how LED Lights Work? Check out this page at

Great question! LED stands for Light Emitting Diode and it is a cool piece of technology, indeed. Able to light up like a light bulb, but without the use of a filament, this new light design is actually a tiny little computer board inside of each light that excites gasses inside of a glass enclosure, which makes it light up and glow.

Why don't I put them on standard for every trailer? Well, for many reasons. First, it is still a reasonably new technology and, therefore, still a pretty pricey item for what it does. Second, it can be hard to find replacements when needed, which puts you in the position of deciding whether to find the proper replacement unit before towing, or towing illegally and unsafely. And third, because of the first two reasons, it really is an extravagance on a trailer that costs $1000-$2500.

I still like bulb lights because they work well, are cheap to replace when broken -- and there isn't an auto parts store or WalMart in America where you can't find a new one right away. Those who frequently use trailers know that lights get hit, knocked off or just torn up a lot as you use them, and I believe that when it comes to the choice of looking cool or making something cheap and easy to use, I am really learning in my later years that cheap and easy outrank cool every time.

We put 10 stake pockets like this on each 16 HD Flatbed and 18' Tilt Trailer! As the trailer gets longer, you get more pockets!7. What is a stake pocket and do I need to add D Rings on a trailer to tie my car down? 

Last question first ... No, you do not need to add anything to any of our trailers to tie things down. Each trailer comes with built in D-Rings (any of our SS series utility trailers), Numerous tie down points (as on our RS Rail Sided Utility Trailers) or Multiple Stake Pockets that are to be used as the most secure point for tying down cars or anything else on your new trailer.

8. What is a VIN tag? 

Simply put, a VIN tag is a Vehicle Identification Number that is registered with the Federal Department of Transportation and carries on it a truly one-of-a-kind number that only your trailer will ever use. VIN tags are found on any type of motor vehicle, and allow that vehicle to be traced back to its original manufacturer, and also track down the owners, if necessary, in case of a theft.

With a 17 digit alphanumeric series of digits, the possible combinations for creating unique VIN numbers counts into the 5 quadrillion range … so that is a LOT of possibilities. And the one on your new trailer is totally and completely unique and will never be replicated again.

See what you learn when you read stuff?

When you get a new trailer from us, you will also receive a written copy of the 90 day/5year/10 year warranty system that comes standard on every Hull Trailer we sell, but, more importantly, you will receive an MSO.9. What is an MSO? 

MSO stands for Manufacturer’s Statement of Origin, and it is a document that is printed on a very special bank note paper (so it can't be easily forged) and tells your local Department of Motor Vehicles office what type of trailer you are licensing, its VIN number, who built it, when, where, how much it weighs and who you bought it from.

Simply put, an MSO is the very first “Title” for your new trailer.

10. How does the M/T Tilt work? 

The short answer to this is “Very well.” (Sorry -- had to stick that in there!)

The basics of the unit are this: It is a channel steel frame, flatbed car trailer designed to allow the tail of the trailer to lower to the ground to load and unload, instead of relying on removable ramps to gain access to the loading area of the trailer.

Whether you have additional questions about our flatbed trailers, or you need a quote on dump trailer prices, call us at 712-589-3100

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