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Old 12-29-2012, 07:38 AM   #1
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2012 Mercedes ML350 towing math/specs-for 25, 23 AS

I have a 2012 Mercedes ML350 and it pulls our 1967 Caravel wonderfully--like a dream. Problem is, my wife wants something newer and bigger. Probably the newer 23 ccd would work, but I'm in love with the 25FB.

The Math

2012 Mercedes ML350 AWD
Mercedes Placard on door pillar
Gross Axle Weight Rating: Front: 3086 pounds
Gross Axle Weight Rating: Rear: 3527 pounds
Gross Vehicle Weight Rating: 6283 pounds
Maximum Tire load 2149 pounds (listed on tire)
Combined weight of occupants and cargo should never exceed 1080 pounds (From Mercedes Tire and Loading information placard)
Pulling weight is 7000 pounds


From Mercedes Manual page 363 step by step instructions for calculating correct load limit:

Maximum combined weight of occupants and cargo= 1060 (from tire and loading placard)
Subtract combined weight of driver and passengers= 430 (me, my wife and my dog)
Equals combines cargo and luggage load available: 630
Subtract weight of luggage and cargo: 0 (I'll carry luggage and cargo in the trailer)
What's left is the maximum hitch weight I can carrry 630

Airstream weights
25FB empty weight 5550
25FB Gross weight (with cargo) 7300
Tongue weight 833

23FB empty weight 4700
23FB Gross weight (with cargo) 6000
Tongue weight 467

From these figures I find it difficult to see how I can pull a 25, but I see some on the forums who want to trade from a HD truck to a European diesel SUV?

Believe me, I'd love to keep the ML350 as it is a driver's dream and great vehicle when the AS is parked, but I can't see how. Can you?

Also, there's a fellow pulling a 25 or 27AS on Utube with a Mercedes GL320 Diesel? (does it have a slightly larger cargo capacity?) Can that be done safely? Will a WD hitch take that much weight off the rear of the car?

Help, I want to keep the ML, but for a 25 I may need something larger. And how about the 23? It looks like I could haul it OK. I'm just not crazy about the layout of the 23FB?
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Old 12-29-2012, 08:37 AM   #2
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The math exercise is what many fail to take in consideration, good job on the homework. The fact is many people to choose to ignore the math and manufacturers ratings. The guy you refer to on YouTube with the GL is Rich Luhr editor of Airsteam life, his GL is rated for 7500 lbs, 750 tongue weight. The Safari bunk has a hitch weight of 840 and totally empty dry weight of 6700 (gvwr at 8400), so he is over in all accounts when towing wet as well however it tows it well (however most have beefed up the hitch).

The biggest thing on the European SUV tow ratings is lower tongue rates that we do in the states vs. Europe. We typically use 15% of trailer weight as a guideline and the EU uses 8-10%. The thing that I keep thinking about is the Mercedes manual never mentions a equalizer hitch in the math, which technically does not hedge ratings but rather redistributes the weight to front axles but certainly makes a huge difference.

All of that said and I have a new GL 350 on order to pull my Safari 30! Going from a Suburban 3/4 ton with 8.liter . Interestingly they both have 455 ft lbs of torque.
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Old 12-29-2012, 09:15 AM   #3
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We went through a similar thing: We pulled our Safari 20' with a 2005 ML500. Was great. But we wanted a little more room in the car and might be going to a 25'. So we got a Dodge Durango. It's the same platform as the new ML, but a bit bigger and better towing numbers. We're very happy with it. And I can buy a $4 oil filter for it.
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Old 12-29-2012, 09:30 AM   #4
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I have an MB R class, the room inside is fantastic, and it is a great road vehicle. I am 6'7" and have plenty of room in the front and back seat (with the drivers seat all the way back)
Andy T (can-am) posted some pics from a setup he did with an R500 and a 34' triple axle. His comment was that the extended wheel base of the R combined with the short rear overhang make the setup work well.
The R class is being discontinued in the US after 2012, you might be able to get a great deal if it works for you.
I have not towed with mine yet, but just wanted to give you some food for thought!
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Old 12-29-2012, 10:17 AM   #5
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Mercedes GL 320 and 25 FB AS

So, Would you feel comfortable pulling a late model 25'AS with the GL 320 bluetec diesel?
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Old 12-29-2012, 03:35 PM   #6
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I think a GL350 or older 320 would pull a 25 nicely with the added wheelbase on the GL over the ML.
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Old 01-01-2013, 09:53 AM   #7
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Manufacturer Weight Ratings on the door plate

I have a 2007 ML 320 CDI (built in October of 2006) and took it to the scales a few weeks ago after reading this forum to determine what is actually the towing story for my car. It has every factory option that was available when I ordered the car in the late summer of 2006. It was one of the first of the diesel engine models of this car built for the US market. There was no other stuff in the rear seat or cargo area. There is some reinforcing steel between the factory installed hitch and a rear frame member as installed by CanAM. The weight of this modification impacts the rear wheels as it is behind the axle and should actually counter balance a few pounds from the front axle.

With just me (around 225) and an iPod in the glove box, the front axle had only 145 pounds of load left.

My wife weighs in at about 130 and her purse weighs probably over 15 pounds. So, in theory we are at a maximum front axle load when she is in the car. I am not thin, but a couple of six foot plus chaps weighing in at 275 each would have the car legally overloaded on the front axle.

There was no mention in any sales literature of the time or by the selling dealer that only thin people could buy the vehicle to keep from overloading the front axle. There are plenty of fat Germans as well as big people in other locations in the world where this car is sold. The car was designed in Germany and the only fabrication plant in the world for this Mercedes model is in Alabama. The engine was assembled in Germany and shipped to the US.

The suggested payload would be exceeded if there were five passengers that weighed an average of over 235 pounds let alone their luggage.

I point to this weight capacity situation as many of the private vehicles on the road are really overloaded just from the passengers aggregrate weight let alone their "stuff" in the cabin and trunk/cargo space of the vehicle. Has any one heard of an insurance company denying a claim because the fat passengers and their stuff overloaded the vehicle which in the insurance company's mind contributed to the accident (claim avoidance procedure?).

Just asking!

I have chatted with folks that tow 30+ foot Airstreams with this model car with no issues. Interesting!

With my wife with purse in the car, the 39 gallon fresh water tank filled and the "stuff" in the trailer the front axle is overloaded by 55 pounds and the rear axle still has over 200 pounds of capacity. The Hensley Arrow hitch attached to the 25FB International has moved the tongue load appropriately.


I routinely loaded my airplane to the maximum allowable weight a large percentage of the time.

Many posts on this forum state you should not operate at GVW.

There is no warning in the Mercedes documentation I was presented at the time of purchase or in the owners manual stating the vehicle could not be operated at maximum weight all the time. Mercedes was willing to sell me a 100,000 mile extended full coverage warranty for the car. They obviously did not expect structural failures of the components from such operation or they would have put a disclaimer in the warranty policy.

I do not see us using the trailer for extended operations for may years as we are still doing a lot of international traveling. The Mercedes could fill the TV role until then.

YMMV
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Old 01-03-2013, 11:03 PM   #8
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Mercedes GL320 pulling 30 footer?

Ok, so I think the available cargo capacity of the GL350 would be about 1400 pounds.

Myself, my wife and my dog=440 say
leaving about 960 # for hitch weight and cargo

I know the 25FB's hitch weight is 833 or so. Add a WD hitch for some extra pounds. (not sure how much) How much is the 30's hitch weight?

So, anyway put the cargo in the trailer mid to rear.

And, you think we're ok with the GL350 and a 25 footer FB? Pretty close.

How about the 30?
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Old 01-04-2013, 06:42 AM   #9
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Quote:
Originally Posted by SafariSS View Post
The math exercise is what many fail to take in consideration, good job on the homework. The fact is many people to choose to ignore the math and manufacturers ratings. The guy you refer to on YouTube with the GL is Rich Luhr editor of Airsteam life, his GL is rated for 7500 lbs, 750 tongue weight. The Safari bunk has a hitch weight of 840 and totally empty dry weight of 6700 (gvwr at 8400), so he is over in all accounts when towing wet as well however it tows it well (however most have beefed up the hitch).

The biggest thing on the European SUV tow ratings is lower tongue rates that we do in the states vs. Europe. We typically use 15% of trailer weight as a guideline and the EU uses 8-10%. The thing that I keep thinking about is the Mercedes manual never mentions a equalizer hitch in the math, which technically does not hedge ratings but rather redistributes the weight to front axles but certainly makes a huge difference.

All of that said and I have a new GL 350 on order to pull my Safari 30! Going from a Suburban 3/4 ton with 8.liter . Interestingly they both have 455 ft lbs of torque.

Coincidentally, SafariSS, I called MB USA yesterday and asked about the tongue weight of the factory hitch.

The answer given to me about its capacity, was 600 lbs.

Be careful.
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Old 01-04-2013, 06:57 AM   #10
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Hitch weight

So, in other words, the GL would take the cargo weight, but the hitch might just break off!!

Can it be reinforced? Has anyone done that? What's involved?
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Old 01-04-2013, 07:16 AM   #11
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Restating part of my earlier post, in order to use any weight distributing hitch on the Mercedes factory installed hitch on either the ML or GL, it has to be reinforced or it could just twist off under the rotational loads applied to move weight to the front axle. My factory hitch was re-welded under a recall in late 2007 or early 2008, but this was not a reinforcement, just a repair for missing welding.

Thus the need for my 4,400 mile trip (took seven days with one day at their shop) from Phoenix, Arizona to London, Ontario to have my hitch reinforced properly by CanAm. They have done many of these reinforcement jobs on Mercedes with no issues. I have an image of what they did in my photo link. I arrived with the Hensley Arrow (the full sized hitch vs their smaller one since I have a 25FB International) straight stinger. They cut off about four inches of the 2" solid steel steel bar that goes into the vehicle receiver and re-drilled the locking pin hole into the appropriate location. They also slightly bent the stinger downward to preload the Hensley arms so they come under load sooner when adjusting the support arms.

This stinger modification brings the over-center locking nuts right up-to the rear bumper. I was unable to get the Hensley wrench onto the nuts, but I made a quick trip to Harbor Freight and I picked up a 21' Crescent wrench for under $25 and all works well.

The original post did not specify that the vehicle was a CDI (diesel) or gasoline. The gas v6 would would be way underpowered in my opinion. As a US customer, we are NOT allowed to have either the ML or GL built with the Mercedes 4.5L V8 diesel that is available to everyone else in the world market. That engine would be just the ticket for the GL, but highway milage is just under 20, not 27.5 like my 2007 ML.

Since my ML just passed 101,000 miles, their is no extended warranty to be compromised for modifications. While the warranty was in effect, the dealer made no comment about the movement of the air suspension air storage tank downwards about 1.5" to allow the new CanAm support to pass forward above that tank and be welded to a cross member.

The actual tongue weight of my 25FB on the scales is 1,175 pounds unhitched. When the 25FB is attached with me, my wife, and 80 pounds of gear in the rear end of the car, I am still not overloading the rear axle by 200+ pounds. The trip across the CAT scales allows one to set up the hitch properly.
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Old 01-04-2013, 07:55 AM   #12
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I'm reasonably comfortable with my current configuration. Reese Dual Cam, and the 23 FB with a tongue weight of 467(?) give or take.

I talked to Andy at CanAm, early on, and he advised a Hensley or a ProPride, with hitch reinforcement.

With that in mind, I have a son who lives in Dallas. I called a Dallas AS dealer and asked for their rec's on trailer hitch installation. I visited Joe's Hitch, in Dallas, and they said with the Reese WD, and my factory installed hitch, I should have no problems.

We've traved to the UP in MI and New Orleans. And have gone west to the North Rim of the Grand Canyon (going through many destinations in CO to get there), without problems.

Of course, if we were to move up in length, I would probably move up to a Suburban 3/4 ton, or comparable.
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Old 01-04-2013, 08:14 AM   #13
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Quote:
Originally Posted by murreywalker

Coincidentally, SafariSS, I called MB USA yesterday and asked about the tongue weight of the factory hitch.

The answer given to me about its capacity, was 600 lbs.

Be careful.
Are you referring to the GL or ML? The GL states in the owners manual it can handle 700 lbs.

The new 13 model GL has 455 lb ft of torque, same as my suburban 3/4 ton 8.1 which is more than adequate towing my Safari 30.
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Old 01-04-2013, 07:16 PM   #14
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Enough already with the numbers. You are not far from Can Am. Drive there with the Mercedes and have them reinforce the hitch a bit. Pick up a new 30' unit and keep your wife happy. And then go camping.

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