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Old 03-10-2008, 06:02 PM   #1
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Please Check My Math

I’ve been reading the Airstream forums for several months to figure out the best AS and TV for me and my dog. A big “thanks” to everyone who’s shared comments on late model ASs and TVs. We’ll be travelling Central and Southern California, and the Southwest. After going back and forth, over and over, I’m thinking a standard 25’ Safari SE (solar, awning package, A/V upgrade, no rear panoramic window, no galley skylight, 15,000 air conditioner, and a Ford F-250 6.8L V10 (crew cab, standard box with cap, 4wd, 4.10 axle ratio) will be best for us.

I’m trying to figure out how to calculate the towing capability for this combination, specifically how much cargo could be carried in the AS and the TV with their specifications and certain basic assumptions. I’ve done my best to search the forums for a generic formula, and haven’t come up with anything that I completely understand. I'm hoping that those of you who know how the pieces fit to this puzzle will check my attempt and please point out any assumptions or logic that isn’t correct. It would be nice to have a basic formula for determining tow capability where different values and assumptions could just plug in. I found a couple of spreadsheets on other websites but they were not clear to me. According to what I did, there is a maximum cargo of 275 lbs. for the AS and 990 lbs. for the TV. I hope you can see how I came up with these figures:

25' Safari SE
GVWR (Total allowable weight of the trailer, options, batteries, fluids and cargo) 7,000

UBW (Unit Base Weight):

Trailer 5,065

Options (solar, awning package, A/V upgrade, no rear panoramic window) 350

Batteries 75

Fluids (fresh water, propane) 275

Tongue Weight 860

Hitch 100

Maximum Cargo in Trailer 275


Ford F-250 6.8L V10 (Crew Cab, Standard Box, 4WD, 4.10 Axle Ratio
Gross Combined Weight Rating, GCWR (total allowable weight of the truck, the trailer, the cargo in each, fluids and occupants) 20,000

Unloaded Vehicle Weight, UVW (curb weight, with options and fuel):

Curb Weight 6,520

Options (including cap) 500

Fuel 180

Total Unloaded Vehicle Weight, UVW 7,200



Gross Vehicle Weight Rating, GVWR (includes weight of vehicle, optional equipment, driver, passengers, cargo and tongue) 9,600

Vehicle Base 6,520

Options (including cap) 500

Driver 180

Passengers 300

Tongue 860

Maximum Cargo in Truck (limited by Rated Maximum Payload) 990

Rated Maximum Payload (includes optional equipment, driver, passengers, tongue and cargo) 2,830

Gross Vehicle Weight, GVW 9,350

Axle (Front/Rear) 5,250/6,200

Maximum Rated Trailer Towing Capacity (Includes the weight of passengers, cargo, tongue and options) 12,500

Thanks for your help!
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Old 03-10-2008, 06:15 PM   #2
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hi bum...

very good start.

couple of errors i see...

the trailer tongue weight is already counted in the ubw..

so it doesn't count (again) against carry capacity.

the hitch mass is technically carried by the truck once hitched, n with spring bars adjusted....

those 2 adjustments will increase the ncc estimate significantly, but you will still need to WEIGHT the rig to be sure....

a/s lists the ncc at 1900+ lbs (not counting fluids) so 1000 lbs for personal gear is a reasonable estimate.

-also why get the 4.10 rear axle? you've got plenty of power without it.

over all that looks like a great combo and you are wise to do this tally in advance....

cheers
2air'

let me spend more of your money!

on the trailer options side, leaving OUT the skylight is a good idea and sadly they charge EXTRA to do this...

you might consider vista views in locations that aren't part of the stock package (like in the bed room) or up front...

the vista views add light (but not as much heat as a plastic skylight) and the perception of head space...

also consider 2 fantastic fans or replace the crappy bath vent fan with one...

and the full AWNING package. this adds useable outdoor space, rain protection and shades/cools the window areas!!!
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Old 03-10-2008, 09:35 PM   #3
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2air makes some good suggestions, I especially like adding the Fantastic fans.
IMO every trailer should come with an awning.
Dave
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Old 03-11-2008, 06:10 PM   #4
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Hi 2air and Fyrzowt,

Thank you for your replies.

Glad to see my errors since I hoped the AS cargo was light.

Prefer the 3.73 rear axle but the Ford "build it" site shows the V-10 available only with 4.10. I'll have to check with the dealer.

Planning on awnings on all 4 sides with one long awning street-side if available.

Didn't know vista views could be added in the bedroom!...great idea since I don't want a pano back there.

Up-to-speed on dual fans but hadn't thought of using the second to replace the bathroom vent...good to get rid of the crappy stuff; speaking of which would like the dealer to put in a porcelain toilet, Shurflo 4.0 water pump, and filament step light replacing LED...caught the light thing in one of 2air's posts!

Thanks again, and look forward to your posts on all subjects.

Joe
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Old 03-11-2008, 08:34 PM   #5
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I think you'll also find that you seldom travel with a full tank of water. It doesn't hurt to -- it actually helps as it lowers the center of gravity but you have to expend energy to move the extra weight and with gas @ $3.40 or thereabouts.....

mike
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Old 03-11-2008, 08:36 PM   #6
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Joe,

You can order a 1-piece ZipDee for the street side as either a window awning, or if you want maximum room for outdoor stuff.... a second patio awning! The rail is already there from Airstream, so adding the full patio set-up is no big deal!.............Just a few more $$$$$$$$$$$
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Old 03-11-2008, 09:03 PM   #7
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hey bum!

ordering is such a blast!

are u ordering the truck too?

the integrated brake controller works really well, so make sure it's ordered IF you want it.

you may be stuck with the 4.10 rear, but they have about 5-6 options listed in the super duty parts sheet.

the other IFFY thing on the weight list is the a/s listed tongue weight...

that's an estimate and doesn't include full lp gas tanks, so add 50-100 lbs to their guess.

ultimately you will need to weigh it. that extra weight cuts into the truck payload, but you still have reserve...

normally i'm a fan of led lights (the tail lights and NEW led marker lights rock!)

the step light just isn't very bright, perhaps a better bulb will be available soon?

yep, vista above the bed, wish i'd done this....

extra light AND at that height very private. craftsman did this last year on his 25? classic, and likes them.

the issues with the bath fan are the lid is very wimpy, and the fan is tiny and no rain sensor.

so i'm gonna have mine replaced soon with a base model fantastic fan with rain sensor...

i use the shower a lot and want something that will really suck the steam out...

like lew notes u can use a patio awning on the street side, but in tight campsites it won't open easily....

a long regular window awning on the street side is a GREAT idea, since it will keep the skin cooler in full sun.

and you are getting solar too? nice. most of us like having some sun juice.

are you planning to use a generator ever?

if so there is a 'generator prep' option which includes a 2nd 30 amp outlet on the FRONT near the tongue....

this is nice because IF you wanna use the gen near the tongue (or in the truck) a short cord can connect to the trailer...

it also means you can place the generator front or back, depending on campsite and neighbors...

so many options, have fun spec'ing your hut and ride!

2air'
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