TECH - How to PROPERLY load your trailer

With all of the trailers I see on the road hooked to some moron's truck where the bumper is nearly dragging the ground there is so much weight forward or seeing the truck 'fishtailing' going down the road because the weight is too far back on the trailer, I just wanted to stick this up here during tech week. Hopefully it'll help someone, or if nothing else, its good info just to share.

So... lets begin.

You want to have the trailer sitting as close to level as possible when loaded - unless you are towing with something like a gooseneck hitch or 5th wheel on a ton dually truck - then all this info basically goes out the window.

Typical class III hitches have a max tongue rating of around 500#, but and a half ton truck will carry that much weight easily, but unless you know the center of balance of both your trailer AND the vehicle being towed, its hard as hell to openly 'guesstimate' where to load it.

I think I would consider myself (without patting myself on the back) an expert in this area (figuring center of balance) as I taught it in the USAF as both an Aircraft Load Planner and a Phase II Loadmaster. Its up to you whether you want to try it, so you be the judge.

To find the center of balance on a 2 axled vehicle, there is a simple formula you have to follow, and it requires you to know the weights of both front and rear axles.

The formula is REAR AXLE WEIGHT x WHEEL BASE
............................GROSS VEHICLE WEIGHT

This calculation will give you the center of balance from the center of the FRONT AXLE. In order to get the C/B from the front edge of the vehicle, you'll have to add on the front overhang (FOH), which is the distance from the center of the front axle to the furthest point forward on the car.

When it comes to measuring axle weights on something like a trailer, any pair of axles that are less than 48" apart are considered 1 single axle, and the point at which all distances are measured is the middle of the 2 axles.

With me so far?

Okay, now, you're probably thinking how you measure the weights on the trailer, since it has what is considered only 1 single axle, right? Well, the tongue on the trailer is considered the front axle, (unless it is resting on the jack, but that is an entirely different calculation and measurement in itself), so you have to do some extra work to find the weight of the front axle. In order to do that, you must follow these steps:

STEP 1. Weigh the rear axle ONLY on your tow vehicle. You do this, of course, by driving it onto a scale but driving the front axle off of the scale so that only the rear axle remains on the scale. It doesn't matter if the front wheels are 1" off of the scale, or almost the entire wheelbase is off the scale. The weight on the rear axle will be the same.

STEP 2. Next, weigh your entire tow vehicle. You'll need to know this weight for the next step.

STEP 3. Next, take your trailer to the scales with the tow vehicle you just weighed. Drive the entire tow vehicle onto the scale, but DO NOT drive the trailer onto the scale. The difference in the Gross Weight of the truck before you hooked up the trailer and AFTER you hooked it up will be the weight of the FRONT AXLE of the trailer. See, pretty simple, right?

STEP 4. Pull the entire trailer onto the scale and disconnect it from the truck. This will give you the GROSS WEIGHT of the empty trailer.

STEP 5. To figure the RAW (rear axle weight) of the trailer, subtract the tongue weight (you found this in STEP 3) from the GROSS WEIGHT of the trailer. Simple again, huh?

STEP 6. Measure the wheelbase of your trailer. This will be from the tongue all the way back to the center of the 2 axles. (works the same if there are 3 axles as well).

STEP 7. Do the calculations by plugging into the above equation the numbers you've just found, and this will give you the center of balance for your trailer. You'll also know exactly how much tongue weight you have when your trailer is empty as well.

I'll use my 18' car trailer as an example, with estimated weights.

My trailer weighs in at 2200#, with a wheelbase of 146" FFA. The FA weighs 300#, so that gives a RAW of 1900 pounds. So, plug those numbers into the equation:

.................. RAW (1900) x WB (146)
.............................GW (2200)

So, 1900x146 = 277400

Next, take 277400 / 2200 = 126.09 Inches/FFA

So, the center of balance (C/B) on my trailer is 126" FFE. It is just 20" forward of the center of my rear axles.

To find the center of balance on your car (or other vehicle you'll be loading), all you need to do is weigh one axle, and then once you have that calculation, you'll need to weigh the whole car. The calculations are the same. You can either add in the FOH (front overhang) or ignore it, and measure your center of balance from the FFA (from front axle) .

These calculations apply to just about every vehicle out there, except for tracked vehicles. They are the easiest of the bunch. To find the center of balance on them - say a tank - just square it up to a telephone pole laying on the ground, and drive over it. When the tank rocks forward, that is the CB.

IF you have any questions, or aren't clear on any single part of this, just ask me and I'll be glad to explain further.

AS for where to load the car on the trailer once you have located the CBs for both the car and the trailer, I'd place the CB of the car about 5-6" or so forward of the CB on the trailer. This should load it out perfectly for you to tow. With a trailer setup like mine, if I were to exactly center up the CB of the loaded vehicle and the CB of the trailer, I would have EXACTLY 300# of tongue weight. Loading it a few inches forward loads the tongue a bit heavier, but not so badly that it affects handling of my truck.

Always remember - proper loading prevents your sphincter from grabbing ahold of the seat involuntarily!

 

Can't we just see pictures??

 

also show some ramps that are not to heavy to lift !

but will still take the weight ,

I mostly move 2000 pound cars and use 2x10s 8ft long which work OK but would break with a full size car

Beaulieu

 

I guess being a smartass is better'n being a dumbass....

 

thanks Goztrider for the info. I found it helpful but also a bit too technical for my trailer experiences. I have been putting cars trucks and about anything else you can imagine on my car trailer for over twenty years.Yes there have been a few times that it was loaded with too much or too little tongue weight. But my standard rule of thumb for loading a vehicle on a trailer is to pull it forward until I see the tow vehicle drop a little in the back and that usually provides decent tongue weight.

 

hahaha

 

Nice post, a little confusing unless you read it thru a couple of times.
My comment to other readers is take note as high speed and running the down hill with a badly loaded trailer will find you out every time.
Does not take much weigh loaded wrong or over hang past the trailer body to get you into serious trouble.
Surpisingly the down hill does not have to be so steep to catch you out.
If you get into that situation do not go for the brakes, try letting it run out by just backing off the gas.
Then once you have changed your shorts you will know what I mean!

 

When we races the spring shop told us before you hook up the trailer measure the heigth of your rear bimper, then hook up the trailer and load the car. move the car till you have 1 to 1-1/2 inch of drop on the rear bumper.

We use that method for years with out any problem.

jim h

 

Not if you place concrete blocks under them.

 

I've never had a scale when I've picked up non running projects. Math and formulas are fine for theory but not out in the field. That's where experience comes in. Just as life teaches lessons that can't be taught in books.

 

You got to use something to bring the next project home and haul off the disgaurded junk. Stuff doesn't always fit in the box of a truck. Gene

 

I have always used the method hoarder1212 mentioned. Never had a problem as long as I used a good trailer. I've made the mistake a couple of times of borrowing a bad trailer that no matter how you loaded it it never would pull right. It sure makes for a long trip home.

Up until a few years ago if I needed to haul something I had to borrow a trailer from wherever I could find one. I have a two friends who would let me use their trailers but the problem with that was either some one else was using it or the previous person screwed the trailer up in some way and I'd have to spend time fixing it before I could use it. Then there were times when I went to use a trailer and the ramps were some where else and I'd have to chase across town to get them. I solved all those problems three years ago. I bought a brand new trailer with a tilt bed. It was the best purchase I ever made. I've even made money with by hauling a couple of my customers projects to their customers' location.

 

Trailering a project or parts home is an entirely different thing than trailering your hot rod instead of driving it.

 

You guys are forgetting that this was posted my a school teacher. I think a math teacher at that!~

 

I feel, that the information of correctly loading a trailer should not be shared. It is like taking a final exam in a high school class. NO coping is allowed. Everyone does their own thing ...yet it sure makes for some wild stories when things go wrong. I have heard tales of some crazy stuff that happens when pulling a trailer when things go south.

Of course I am just joking, take heed of the advice here. I am paranoid of pulling a loaded trailer.

 

Gotzrider knows his stuff no doubt. It figures though that some guy out in Oklahoma would be the one to have this trailer loading all figured out in detail. (that's a compliment)

 

This is funny, because just yesterday my buddy showed up at my shop with a car on his trailer with just 2 straps, one in front and one in back, It made me think of the time another friend of mine used just 2 straps on a 50 merc. Rolling chassis. Well it came lose rolled of the trailer at 70 mph on highway 101, drifted across 3 lanes of traffic and hit the center divide. USE 4 STRAPS PEOPLE!

 

Wow...seems kinda complicated (although I do admire your effort) to load a trailer.

IMO...simple way is to just load the trailer until the bed of the truck goes down a few inches.

All you need is a few hundred pounds of tounge weight to pull it correctly.

Besides, I don't have a cell phone, so I can't calculate anything.

 

I've used bathroom scales on a steel milk crate to load Uhauls before and it has always worked. Just go for the magic tongue weight number and the real heavy shit goes over the axle. For heavier trailer loads, use 2 bathroom scales side by side with a steel plate between them. Just applying a little lo-tech junkyard technology.

Bob

 

When you are able to finally drive your FED or dedicated race car on the street, then come talk to me.

While I agree, it's still a good idea to know where the CB on your trailer is located, even when estimating where you are putting an unknown load on the trailer. I guess the big thing here is that you could use this more for those single axle trailers that pull a dragster, or something along that line.

Hey, its all about being safe.

You're right Bentley, I am a math teacher. However, I learned this as basic stuff with my USAF job in Air Transportation. I could teach it better with pictures, and even better in person, but at least with the information posted everyone can see it.

Up until that last part I was getting ready to throw up my WTF kind of answer!

Thanks for the compliment. I've been victim (of my father I should say) of having a trailer improperly loaded and have it toss me forward, jack knife the truck and trailer, throw the battery out of the battery box and across the engine compartment ('56 Chevy pickup) and pretty much scare the shit out of us both!

This'll possibly be my next Tech post. Basically, *IF* you know what you're doing, you can get enough restraint out of straps - but just how much?

I had to learn how to do all of this with a pencil and piece of paper - no calculator! Only once I understood it all, then I could use the calculator.

Thing is, the same basic principles are used to calculate the loads on an 18 wheeler loaded and unloaded, as well as how to properly balance even the largest civilian and military aircraft.

As always, take it for what it is worth.

 

Thanks for sharing, never thought about finding & permanently marking the trailer's natural balance point. Good idea

 

There's also a small scale of higher or lower tongue weight (always within the safe limits of the hitch, and the rear suspension of the tow car, of course.
Higher center of gravity on the trailer needs slightly more tongue weight (2,000 lb. Model T needs more than 2,000 lbs. of 4 × 8 plywood sheets stacked flat).
Higher centralized weight distribution of load can use less tongue weight (2,000 lb. cube of uranium right over the axle needs less than a 1000 lb. cube at each end).

If it's not your car, ask (and check) if there are any extra parts, spares, etc. in the car or trunk - if just left there for storage these also become bombs (a Kennedy machinist's chest in the back seat will go right through a convertible top) in an "incident".

Biggest single factor left out:
"How much air are you running in the trailer tires, vs. the rear tow tires?"
"What???"
This can also be used to "tune" lock-up point of electric brakes where you don't have all 4 tires the same type on the trailer.

If your tongue weight is too high, or rear springs too soft your shocks will get really hot after a few miles and stop working. If they're too hot to touch (with a fairly smooth road) you need to back off your tongue weight somewhat or the shocks won't do anything - it's not a "cure" but it's the only thing you can do under way.

 

I was once brilliant enough to haul a '67 Cadillac Hearse with a short bed 76 Ford pickup. I knew nothing of weight and balance or CG or any of that "fancy" stuff. I thought "hook it up and go!" About the time the tail got to wagging the dog at 60MPH, I found religion and messed my boxers at the same time. I was lucky that my old man had told me to stay away from the brakes in a situation like that, but it took a good half mile to calm that trailer down. I found an exit, rolled to a stop, lit a smoke and whimpered like a girl scout in a bear trap for about 15 minutes. Needless to say, my top speed after that was about 35 all the way home. Thanks for posting the formula here. I'll print it and tape it to the garage wall for future reference.

 

WOW! That's a lot of interesting info Gozt.
When I built my trailer in 1983 it was for a specific Rally Car and I set it up so that you ran the front wheels right up to the front rail on the trailer. This was the perfect balance point for tongue weight and stops the front of the car from going any further in a panic situation. It served me well for in excess of 100,000 miles of towing those race cars all over the country. When I got out of rallying and started Off Road Racing my Ranger Race truck sat in exactly the same place for proper tongue weight. Since those days I have towed everything from a Model A to a 460 powered 56 Fairlane to an F1 truck and ALL of them end up in the same place. It might not be exactly where the math would come out but close enough that I have never had a "situation".
And I have the ticket from "Middle of no where Texas" that shows that my little trailer goes straight as an arrow with a 1984 Corvette race car (back in 84) at just over 100mph.

 

Its funny you say that. I was just up in Vacaville a few months ago picking up a '61 Starliner. I strapped the car down but only had one on the front. This old timer said, you need 2 on there, use this one and meil it back to me. I told him it would be alright but he insisted I take it. So we put the other strap on the front. We head out over to my buddies house and on the way down this overpass we hit one of those "Holy shit, where the hell did that whoop-dee-doo pothle come from" potholes. It made the frontend of the Starliner bounce violently. When we got to my buddies house, the strap i had originaly put on was just laying on the trailer. I about crapped my pants. That car would have come off the trailer if that second strap hadnt been there. Thats one lesson i learned from an old timer that ill NEVER forget.

 

Cut all the hi tech, if you build the trailer correctly from the start you don't have to go into all that rocket science stuff! I retired 5 yrs ago from the manufacture & repair trailer business after 25 yrs. & all you need to know is simple trailer math, whatever length of trailer bed, measure 60% from front of structure to centerline of axle(s) for proper placement. Tongue should be 42 inches from ball to front of structure for perfect towing & backing up response.------Now that was easy huh?---------Don

 

Duece Daddy, I have had experience with a tongue extension on a trailer that was 40" from ball to ball. I carried an 11 1/2' camper plus pulling the trailer. I hauled it all over like this for 8 years without a problem. It was very easy to back and I seldom took it off even when I didn't have the camper on.

 

Late post, I know, but had to share what happened this morning.<p> A good friend of mine relocated to Charlotte this morning. I helped her load her 12 ft. Uhaul last night. She calls me @ 9 am, saying she couldn't go over 42 mph without fishtailing, and just Jack Knifed her Toyo SUV on I 85 north, stopping with the trailer in the right lane, and her in the left.....blocking both lanes. Luckily, no one was close behind, and as she came to her senses, a Sheriff was already on scene, tapping on her window, with his patrol car stopping all northbound traffic. He backed her vehicle onto the emergency lane, and followed her to the next exit. I met her there to check on her, and come to find out, after I left last night, she decided to pack all off her College books in the rear of the trailer....to the roof ! <p>So take heed to the title of this thread ! It's a miracle she or no one else were seriously hurt or killed this morning ! <p>I took her books to the Salvation Army...she can "live" without them.

 

What if your loading a C-130..., C-141..., C-5...??? Hahaha... great tech... I've been accused of overstrapping and calculating every trailer and airplane in the U.S. Military... and I'm happy to say that not one single mishap occured on my shift!

 

I was Phase II certified to load C141s for awhile, and was also a certified loadmaster for many years as an Air Transportation Specialist in the USAF. IF it went through Air Force Air it went through us.

I overstrap and tie down things myself, and have never had anything come loose or break down on me when it comes to the loads I put on any trailer. It does scare me though to see how some of these trailers are loaded and equipment tied down on them.

I remember awhile back I was in a walmart parking lot and had noticed a beautiful Mustang fastback on a trailer - obviously going to a show. The guy had a total of 4 straps on it - the type that you can pick up at Harbor Freight for $10 for a pack of 4! Rated around 1000# each. $30-40K car held down with $10 worth of straps.