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Old 11-07-2003, 11:01 PM   #1
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2007 23' International CCD
Lapeer , Michigan
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calculating towing rates- warning- need mathmeticians!

I have done a search and found a lot of information on tow weights and wheelbase formulas, but still I have some confusion. I have tried to look up the necessary numbers and here is what I came up with.

I have an 2000 EB Expedition, 4x4, 5.4L, 3.55 rear axle ratio, 17" tires, and 119" wheelbase.

On the door it reads front GAWR 3500#, rear 4128; GVWR 7200#

The Ford manual says GCWR is 12,500# for this set-up.

Starting with curb weight, I start to lose it further. I have only the number I found doing a search that I found in an article for 2000 Expedition, it says4850#, but I saw in the threads that sounds light compared to what I saw there.

We are considering the 2003 25' ssd (or c) Safari. The weights on the sticker in the unit per sales associate read:

The weights are as follows: Empty weight 5289
Water 378
Propane 60
Personal gear 573

From the brochure the hitch weight is 680# and UVW is 4770 (no options) see weight from dealer above 5289# and 6300# is the GVWR.

We have the hitch provided with car and Reese weight distributing hitch (800# bars)and a Reese one side friction sway control.

I think we could do it. My husband thinks we can do it. I know some of you do and some of you don't. I was wondering if you would be so kind to help me with the actual numbers so I could see in black and white for myself (and understand) just where the strength or weakness lies.

I know the wheelbase formulas and that the 25' is closer to 26', but also read it cannot be applied to the largest of units so I thought perhaps it would not have to be applied to this size unit.

Right now we pull a 2001 26' low-profile Towlite that handles well through the mountains as we just returned from a three week, 6,000 mile trip from Michigan to Glacier Park MT, Banff Canada, Yellowstone and Grand Tetons WY. The Towlite weighs 4040# without options, my sticker is incorrect on final weight so I need to do some calculations, the GVWR is 5500# the hitch weight is 550# We thought we could pull 800# more.

(Don't they include gas in the curb weight when it says all standard fluids included?)


I have looked up an old truck scale paper that my husband did. I do not understand the numbers beside the gross weight which was 11620# The car and trailer were loaded and I can't remember if we had the bicycles with that time or not or how much water we were hauling. The confusing numbers to me are:

Steer axle 6940,
Drive axle 2380
trailer axle 2300

He may shoot me for saying this but I know he did it over and I could not guarantee we did it correctly.

So there it is. I understand the gist of the weight considerations and the total is easy but the tongue weight subtraction, and whether to consider the weight redistributed, and some others, etc., have got me lost.

Sure would like to have our first full profile unit, and don't feel it viable to purchase the smaller CCD, we are used to a 26' interior. But do not want to purchase a new vehicle either. We have traveled many extended vacations out west in both this unit and previously our 21" Towlite pulled by our Explorer, before Jayco1406, before 806-Probe.

Thanks for your help. Sorry I was so long at it but wanted all the info out there in case it was needed.

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Old 11-08-2003, 07:24 AM   #2
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1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
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Commercial Scales

"The confusing numbers to me are:

Steer axle 6940,
Drive axle 2380
trailer axle 2300 "

The combined weight sounds about right.

Speculation on my part:
What might have happened in this case is that both of the axels on the tow vehicle were on the "steer axel" weighing pad, and one axel of the trailer on each of the "drive axel" and "trailer axel" pads.

Some weigh stations have what appears to be up to 5 individual pad areas, but this is deceiving. Most public scales are set up to weigh only three axels at a time. The other two are dummy pads.
Other scales have only three pads in total.

The actual weighing areas are marked by black/yellow ticking on the sides of the working weighing pads.

Also, the scales are set up for 18 wheelers, where there exists a significant difference of length from where the actual steering axel is located to where the driver is located. The communications panel for driver/scale operator communication is positioned at a point on the extended steer axel pad such that both conventional tractor and cab over drivers may access the panel without leaving their rigs. This necessitates a relatively "long" steering axel weigh pad.

Now, the good news. Most public scales at truck stops charge 8 bucks for a weigh, but only one dollar for each subsequent "reweigh" within a 24 hour period.

This means that for only a fraction more than a "gross", or total weight, the conscientious Airstreamer can get individual axel weights AND individual tire weights to establish proper vehicle and trailer loading for a safe trip. For individual tire weights (split axel), on the second trip through the scales, leave one tire just off to the side of the scales. This should put the other set of wheels pretty much in the middle of the scale pads. Weigh in the same manner as in the first time through, but with only one wheel of each axel on the weigh pads, subtract the known wheel weight from the total axel weight, and you have weights for each individual wheel.


"Suck it up, spend the bucks, do it right the first time."

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Old 11-08-2003, 07:44 AM   #3
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It appears do-able to me. The number you want to be concerned with is the CGWR. If it is, in fact, 12,500 lbs., you should come in under it.

But not by a lot. Again, using your figures, if the delivered weight of the Safari that interests you is ~ 5,300 lbs. then expect to leave for a trip at about 6,000 lbs. The empty weight of your Expedition can be determined by a visit to the truck scales, but somewhere around 5,000 lbs with full gas and driver sounds about right. Add passengers and assorted gear and it may well push 6,000 lbs.

I do think you may find the 5.4 liter V8 / 3.55 combination a bit anemic in the mountains, but otherwise should be quite acceptable.

Those wheelbase formulas are, of necessity, rules of thumb. They don't factor in the relative weights of the tow vehicle and trailer, the track (width), the size or type of wheels, or the suspension involved, all of which are important.

I pull the same size trailer with the same hitch, albeit with a longer wheelbase extended cab pickup, and have to say that control has never been an issue.

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Old 11-08-2003, 08:22 AM   #4
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2003 25' Safari
Eden Prairie , Minnesota
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We tow our 25 Safari SS with a V8 Explorer. The GCWR of the Explorer is 11,600, but we must subtract 500 for the third seat/rear heat & air. The empty weight of the Explorer is 4500. With the trailer at gross I can only carry 11,100 - 6,300 = 4,800 - 4500 = 300 lbs in the Explorer! We don't load the trailer to gross, so it's not quite this bad.

However, the Ford owners manual states that the towing capacity should be reduced 1% for each 1,000 ft of altitude!

Overall, towing with the Explorer has been fine. I suspect that your Expedition will work well too.
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Old 11-08-2003, 08:42 AM   #5
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I applaud you for doing this research. 87MH gave you some good info on the scales. I'd also carry a broom pole so the driver can get back into the truck, after making sure the axles are as close to centered on the scale platforms as possible, and seated normally in the driver's seat, using the pole to push the button.

Fuel the truck up, load it with the passengers and cargo you'll have in it when towing, and take it to a CAT scale or other certified scale to get its front and rear axle weights. Personally, I'd also install the hitch head in the receiver, and throw the spring bars and friction sway control if you have one, in the rear of the truck before weighting. THAT's what you need when doing these calculations. Without it, you're missing the most crucial info for them.
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Old 11-08-2003, 10:07 AM   #6
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I have towed a 27 foot safari with an Expedition and a Hensley hitch for over 25000 miles---not one problem. I have the 5.4 liter V8 and , of course, tow without overdrive. On flat highways at about 65 my rpm is about 2700. With overdrive,which I can do--but don't-- the rpm is about 2300.

I have towed over the Rockies and through the Ozarks. There is some engine strain, but not much. I would be hard pressed to claim that you need much more of a tow vehicle for my rig. Plus, the trailing is fine. The wheelbase and hitch combination are more that adequate to control the trailer when you need to manuver quickly. The Expedition has great brakes than can handle the trailer when you might have the trailer brakes set to lightly.

I do not load the trailer too much, and usually have the tanks empty except for about 1/3 of the fresh water tank.

I am pretty confident with all the stuff I carry in the Expedition and the trailer that I am close to the GCVW. But , as I said, this combination has worked very well for me.

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