Max Trailer GVWR for towing with AI 3500 EXT

[SWH]

Interested in possibly adding an AS trailer to pull behind the Interstate for extra sleeping/camping capacity for when we actually want to camp (we purchased our Interstate just for road trips, but really getting sucked in to the AS world).

I know that the max towing capacity of a new model AI EXT is 5000 lbs.

There are 5 models that come in at/below 5000 lbs:
- Basecamp
- Sport 16
- Sport 22
- FC/Intl 19
- FC 20

I think my favorite floor plan is the FC 20, but has a 5000 lb GVWR, the max for the Interstate.

Question is would you be comfortable purchasing a trailer that is at the max of tow capacity of Interstate, and if not what would you deem the max "conservative" weight to be, e.g., 4500 lb GVWR of FC 19 or Sport 22 okay?

Appreciate any advice and thoughts!

[SWH]

May also consider waiting to see the details on the new Nest coming out also... looks pretty interesting.

[Andrew T]

Instead of the FC 20 consider the 23' FB or 23D. They tow better due to the tandem axle. We have many customers who tow with sprinters, several tow 30' Airstreams, some race car trailers or horse trailers with no issues. We do strengthen the hitch receiver for larger trailers but it is a pretty good receiver for smaller ones. You need to use a weight distribution and set it up properly. Once done I think the Interstate handles better with the trailer on that without it.

Andrew T

[RandyNH]

As Andrew points out, that 5000lbs is probably the hitch capacity so if you wanted bigger you could probably beef it up, depending upon what your GCVWR is.

Your concern about the FC20 being at the limit, that 5K GVWR is the MAX for the trailer, which means that you won't be close to it dry and being that you have the AI I wouldn't think you would be completely outfitting the trailer with a full load of supplies too.

Back to a large trailer, there are definite advantages to having a dual axle trailer, so an Flying Cloud 23 with a GVWR of 6000lbs, might have an actual travel weight of below 5000lbs and be well within your capacities. It's all about the numbers.

[xrvr]

Remember the sprinter is close to its max weight after the camper conversion. Gvwr. So you want to tow an oversized trailer? Remember the accident here in Florida with the sprinter and airstream?

[Boxster1971]

Originally Posted by avionstream

Remember the sprinter is close to its max weight after the camper conversion. Gvwr. So you want to tow an oversized trailer? Remember the accident here in Florida with the sprinter and airstream?

Here is one report on that accident.
http://www.tampabay.com/news/publics...orough/2317909

The Interstate 3500 Sprinters have a GCWR of 15,250 lbs. That is total allowed for Sprinter and a trailer in tow. My 2013 Interstate runs about 10,700 lbs in normal travel mode. That would limit my allowable trailer weight to 4,550 lbs. The problem with running a rig overweight, which a lot of RVers do, is when you have an accident like the one reported above. The police and insurance company will no doubt investigate. If they determine you were running overweight if could be a problem.

Stay safe!

[SWH]

Thanks all. I thought the max weight wasn't entirely about safe handling and hitch capability but also what the sprinter mechanically is designed for, e.g., if you exceed ratings you run risk of damaging your transmission, engine, suspension, etc. I like the idea of dual axles but I'm conservative on these weight limits, and based on boxster's post sounds like a 22 sport at 4500 lbs max gvwr might be my best bet. At 3600 lbs dry weight I can keep it comfortably under 4500 lbs. And I get a full size shower!

[InterBlog]

The accident referenced does, indeed, involve a Sprinter and an Airstream trailer, but the Sprinter is not an Interstate, so it's difficult to determine the causal factors. Was the Sprinter upfitted, and if so, how, and what were its resulting operational parameters? Not only was it not an Interstate, the photos make it appear to be a low-roof Sprinter, so there's significant info missing in that case study.

[xrvr]

But it can't be ignored.

[73shark]

Originally Posted by SWH

Thanks all. I thought the max weight wasn't entirely about safe handling and hitch capability but also what the sprinter mechanically is designed for, e.g., if you exceed ratings you run risk of damaging your transmission, engine, suspension, etc. I like the idea of dual axles but I'm conservative on these weight limits, and based on boxster's post sounds like a 22 sport at 4500 lbs max gvwr might be my best bet. At 3600 lbs dry weight I can keep it comfortably under 4500 lbs. And I get a full size shower!

I think you hit the nail on the head. I also believe that any vehicle max tow weight is based on powertrain limits.

[Boxster1971]

Originally Posted by InterBlog

The accident referenced does, indeed, involve a Sprinter and an Airstream trailer, but the Sprinter is not an Interstate, so it's difficult to determine the causal factors. Was the Sprinter upfitted, and if so, how, and what were its resulting operational parameters? Not only was it not an Interstate, the photos make it appear to be a low-roof Sprinter, so there's significant info missing in that case study.

I didn't intend to imply it was an Interstate and it's not a case study, just a brief news report. I did find another story with a few more pictures.

http://www.tbreporter.com/traffic/hi...crash-injures/

I don't think it was a low roof Sprinter. From the photos it looks like a high roof with a collapsed roof. It is a 2008 Dodge 2500, based on single rear wheels. It has a roof fan/vent and blue/gray swirls on the sides. Likely some form of conversion van, not necessarily an RV. The 2500 Sprinter has a GCWR of 13,550 lbs and trailer limit of 5,000 lbs.

I'd treat this story as a reminder that towing a trailer combination that is likely close or over the rated limits can be hazardous.

There is a full thread on this accident on another part of Airforums.
Another accident...

http://www.airforums.com/forums/showthread.php?t=164380

[Andrew T]

I was towing one day when it was very windy so running 55 in the right lane. A fellow passed me in a first generation Jeep Grand Cherokee doing about 70 MPH. just ahead of me he dropped a tire onto the left shoulder wheeled it back onto the road spun around sideways and went off the road backwards into the Median. He wasn't towing anything, just driving beyond his capability in a somewhat unstable vehicle. Had he been towing something everyone would of course have blamed the trailer.

In the interstate accident there is no way to know enough about it to know what the cause was. It sounds like the driver did not notice the traffic stopping and had to drive into the guardrail to avoid it. I don't think it would matter what his tow vehicle was the outcome would have been the same as it likely would have been had he not been towing.

I can tell you that an Interstate connected properly is a more stable tow vehicle than most of the pickups people tow with.

Andy

[Boxster1971]

Andy - it's not an Interstate accident. I agree with you that vans make good tow vehicles. I towed a 27 foot Airstream chassis with a Ford E-350 van before I got my Interstate. But it is still important to keep your rig within the design limits.

That picture you posted above with Sprinter 2500 towing a 34' triple axle Airstream trailer is likely overloaded. Do you have the weight numbers for that rigs combination?

[Andrew T]

I drove that combination to the Region 1 Rally in Prince Edward Island and was pretty pleased with it.

With 5 people in the van with both water tanks full etc. the weights were 3780 front axle, 5360 drive wheels and 8520 trailer. GAWR was 3800 front 5300 rear and 8900 Trailer. So we were over the rear axle rating by 60 pounds but well under the tire ratings.

Andy

3780 5360 8520 0 17660

[rostam]

For comparison purposes:

We have a GL 350 Bluetec (that weighs around 6000#) and tow a 26' Avion that also weighs around 6000#. So, we pull a total of 12,000# with a 3.0 Liter Turbo Diesel V6 with 210 HP and 400 lb-ft of torque. I have lots of reserve capacity as far as axle ratings are concerned and some reserve capacity as far as GVWR is concerned. I am very happy with GL's performance, even in the Appalachian mountains, going up and down 10% grades in summer with close to 100 temperature.

AI has the same 3.0 liter Turbo Diesel V6 as in GL, but its de-tuned (I assume for longevity) and only produces 188 HP and 325 lb-ft of torque. I understand how we evaluate a tow vehicle is subjective, but looking at the numbers I find it difficult to believe how AI with a weaker engine compared to GL could tow 17,500# comfortably/safely/consistently.

I understand that different folks have a different definition of what an acceptable performance is or how important following the manufacturer ratings are. Based on my experience, and just by comparing numbers, I would bet that most people would be much happier staying within the 5000# tow rating of AI.

[Andrew T]

Hi Rostam

The combination in the picture actually had less power than the current Sprinters. The reason it works though is that at lower RPM's where you do most of your driving the power output is similar. The ML does not get its extra power until you wind it up further.

Attached is an article I wrote on the combination at the time it gives a better indication of the performance etc.

Andy

Over the years we have set up several Class B Motor homes as tow vehicles for a variety of trailers, for many people this creates a very versatile RV combination. They can often be combined with everything from cargo trailers and boats to a travel trailer for children or guests to stay in. It can give you the on road experience of a motorhome and the versatility of a travel trailer in one package.

Generally setting up a class “B” for towing has a special set of challenges. One challenge is to be sure the van has enough load capacity to carry the trailers hitch weight. Class B’s usually are pretty close to load capacity on the back axle so a good way to handle the hitch weight is to fabricate a very solid hitch receiver that can transfer a good portion of the hitch weight to the front wheels of the van which improves stability as well.

This summer we took a trip to the east coast with five Airstream families that we have traveled with for many years. My Mother wanted to join us along with our two teenage daughters. Mom wanted her own space and the girls stay up a lot later than I do so we decided to tow with a Class B to give us a third private sleeping area. Since we would be towing a34’ Airstream the question was which class B to use. The Ford based van would do the job from a power perspective but I have towed with them and am pretty familiar with them so there was not much to learn there.

I really wanted to try out the 3.0 Litre Diesel Sprinter chassis on a longer trip. However most of the Dodge Sprinter/Mercedes class B’s are built on a 22’9” 170” Wheelbase van, This wheelbase is only 8” shorter than a lot of 30’ Class A motor homes once had. The long wheelbase is great for highway stability but it does necessitate the need for some additional space for maneuvering combined, with a 34’ trailer it would not be the best combination to get in and out of campsites. As well the single wheel back axle is pretty much maxed out for weight capacity and due to the length and wheelbase it pretty much impossible to transfer much weight to the front wheels so it is not a viable candidate for a 34’.

Last year Pleasureway introduced a class B they call the Accent model on a shorter 19’4” 144” wheelbase Sprinter chassis. Though this van is much shorter and lighter it has the same weight capacity so there is plenty of margin to carry some hitch weight and it is short enough to achieve weight transfer. As it was even with the 34’ Airstream attached and 5 of us in the van we were fine with weight capacity. This seemed like the ideal pair.

The first step was to put 1200 kilometers on the van to break it in gently. Running at 90-100 KPH with gentle use of the accelerator the Assent was able to run an impressive 27.6 miles to the Imperial Gallon or 10.3 litres/100km.

We added reinforcement to the standard hitch receiver and removed the rear mounted spare tire. With CAA and E range truck tires loaded well below their maximum limit I have never considered a spare all that mandatory but if you really felt one was a necessity there is space to mount a winch bracket underneath where the generator option would normally be positioned.

All Sprinters have a 3.0 Litre V/6 Diesel producing 154 HP which sounds very low these days but what makes this engine shine is a very flat torque curve of 280 torque from 1200 right through to 2400 RPM. Combined with the 5 speed transmission there are no flat spots between gears. Some people think this is the same drive train as the Blue Tec used in the M G and E class Mercedes vehicles which is also a 3.0 Litre. However the Blue Tec is a completely different system it produces 210 HP at 3800 RPM and 398 Torque from 1600-2400 RPM it is also mated to a 7 speed transmission but this drive train is substantially more expensive and no more economical.

Though you can never have too much power the 154HP Sprinter drive-train is a remarkable performer. With the 34’ Airstream attached and 5 of us in the van with all our stuff. Two fresh water tanks full and propane in both vehicles etc. the combination weighed 17660 lbs. I expected to do most of my towing in 4th gear but it tows the Airstream quite effortlessly in 5th gear and even climbs moderate grades without shifting down. In 4th gear at 100 KPH most normal grades are easily climbed, the 8-9% grades in northern New Brunswick needed third gear at 85 Kilometers per hour which is more than respectable. One of the units in our group was impeccable 1991 Airstream 35’ Classic motor home with a Pre-Vortex fuel injected 454 with 230 HP. I would guess that it would be pretty equal aerodynamically and almost as heavy yet performance on hills was about the same. On one very steep hill in a campground I wondered if the Sprinter actually had enough power it started vibrate while trying to climb the hill and was bogged right down in speed. For a second I wondered what was going on and then I remember the traction control switch. I turned it off and it took off up the hill climbing it quite easily. There was no real traction problem, the system just seems to be overly sensitive but as long as you can turn it off that is not a problem.

Towing fuel economy was very good for the size and weight of the combination the averaging 16.8 MPG for the trip and as high as 17.8 MPG on some tanks at a 100 KPH.

Some think the Sprinter vans would be unstable due to the tall narrow look of them but they actually handle quite well. Despite the narrow appearance the track is actually 1” wider than the other vans and the rear suspension stance is 5” wider. Even on some of the back roads in PEI which are covered in frost heaves the Sprinter was quite poised and never felt overly top heavy. The rack and pinion steering certainly helps here. Strong crosswinds have some effect but no more than you feel on some SUV’s. The previous generation sprinters had 225/75R x 16” tires and but this one has moved to 245’s which are not necessary for load capacity. Switching back to the 225 would give some additional steering precision, power and fuel mileage, if was towing something less aerodynamic than the Airstream it would be a worthwhile change.

Pleasureway adds Air bags to the rear axle and though they may be helpful on the longer van this one worked best with them set at minimum pressure there was just not enough weight to make them necessary. Once we figured that out the ride quality was quite good with a little bounce in the rear seat at times but overall nothing severe. Pleasureway has to make the quietest motor home on the road there is rarely any hint of a rattle or squeak in the interior. The only sound was an occasional rattle from the huge sliding door. The swinging side door on the Ford and GM based vans is much more user friendly for a class B. Other than that the van was flawless without a single repair needed or a single quality glitch discovered on the entire trip.

Caption for the Buick picture:
When you take a trip with a few combinations it is a great way to compare performance and mileage one of the other 34’ Airstreams was being towed by a Buick Enclave which I have written about previously. When we filled up at the same time the Buick would take 1-2 litres less than my combination. Though the Buick is lighter and much more aerodynamic it is still 4WD and it does not have the benefit of a diesel engine. As well it was the best performer easily able to leave mine or the Suburban/ 34’ combination behind on the hills. The Cadillac 3.6 Litre and 6 speed combination is a very impressive drive-train and fortunately it is available in a wide range of GM Vehicles.

[InterBlog]

I may have just located the ultimate time-waster. In searching for information on how Sprinters tend to deform in a variety of crash scenarios (re: low roof / high roof question), I found this thread called "Poor Sprinter" on Sprinter Forum. A comprehensive photo collection of crushed, crumpled, smashed, and otherwise ruined Sprinters, with a good dose of deadpan humor.

[Boxster1971]

Originally Posted by InterBlog

I may have just located the ultimate time-waster. In searching for information on how Sprinters tend to deform in a variety of crash scenarios (re: low roof / high roof question), I found this thread called "Poor Sprinter" on Sprinter Forum. A comprehensive photo collection of crushed, crumpled, smashed, and otherwise ruined Sprinters, with a good dose of deadpan humor.

The Sprinter Forum is full on Sprinter crash threads. Here is the most recent.
https://sprinter-source.com/forum/sh...ad.php?t=55292

A sad deadly case where occupants survived the first collision with an overturned truck trailer only to be crushed by another truck that plowed into the wreckage.

[Boxster1971]

Originally Posted by Andrew T

I drove that combination to the Region 1 Rally in Prince Edward Island and was pretty pleased with it.

With 5 people in the van with both water tanks full etc. the weights were 3780 front axle, 5360 drive wheels and 8520 trailer. GAWR was 3800 front 5300 rear and 8900 Trailer. So we were over the rear axle rating by 60 pounds but well under the tire ratings.

Andy

Andy – thanks for posting the numbers for that 34’ Airstream and Pleasureway Sprinter combination. I applaud that you know the weight on each part of this rig. It is good to know that you haven’t exceeded the axle or tire limits – that should make it reasonably safe from total structural failure.

But you must realize that this rig is rolling down the road significantly overloaded. The 2500 Sprinters have a GVWR of 8,550 lbs. and you were running at 10,140 lbs. Also, the Sprinter 2500 has a GCWR of 13,500 lbs. and you were running at 17,660 lbs. You are also towing a trailer at 8,520 lbs. that is well beyond the 5,000-lb. towing limit of the 2500 Sprinters.

The GVWR and GCWR are based on many factors beyond the axle and tire capabilities. Here is a good article from Truck Trends a few years back that explains the determination of weight ratings pretty well.
http://www.trucktrend.com/news/163-0910-truck-towing-capacity/

You might see this as an ideal pair – but it is another overweight RV and has the potential for problems. The Sprinter 2500 brakes and uni-body structure might be up to this kind of overload.

Stay safe.

[Andrew T]

Hi Mike

Your math is out by 1000 pounds. The weight on the axles of the van totals 9140. An easy mistake to make. The reason we can exceed the GVWR without overloading the van is that when towing we can transfer weight to the front wheels. On a solo van as it is loaded weight is removed from the front axle. Likely why these vans handle better with the Airstream on than they do solo.

Andy