how much wiggle room is in...

[MrUKToad]

Originally Posted by ROBERT CROSS

"....... It appears to me manufacturers design vehicles (both TV's and RV's) structure/axles/tires to a pre-determined maximum LOAD rating, which in fact is the GVWR on your door sticker."

Not necessarily so...at least not at Airstream.
Here is the weight & spec sheet from our Classic.

Notice the GVWR of the trailer and the weight rating of each axle.....

Bob

I read about that somewhere or other and that Canadian market Airstreams have higher rated axles (rated that is, they may well be the same things with a different sticker), but I could be just imagining that.

[ROBERT CROSS]

"It would be nice to think that there was some nice simple method, perhaps based on vehicle weight, by which manufacturers arrived at tow ratings but sadly that's not the case. Tow ratings are decided using factors such as customer demand, the needs of the marketing department and what the competition are doing rather than any mathematical or scientific method."

That could be changing...

Lets hope it's more realistic than the EPA mileage standards.

Bob

[HighFlying]

Some food for thought. I recently read about an RV owner who towing a trailer way over the towing capacity listed for his tow vehicle. He was involved in a accident due to not being able to stop and some people lost their lives. When the lawers got involved they went after the RV owner for involuntary manslaughter for being over the listed capacity of his tow vehicle. My point, just because you can do something doesn't mean you should.

[Friday]

I can tell you that if I am investigating a serious collision, the vehicles get towed to a secure location for mechanical inspection. I recently had a pedestrian get hit by an over-width cargo trailer - seriously injured. I guarantee, that if your trailer, tow vehicle, or anything bolted on - is going to be examined and compared to whatever Motor Vehicle Act Regulations apply.

It's great that Can-am does all these wonderful things... I'm telling you that if I take photos of your 'specialized' rig, and Nissan, Ford, or whoever says "Yeah, there's a reason we don't put class IV hitches on a Fiesta"... you're in trouble. If you're over weight, it's no different than a tractor-trailer accident where overloading is a factor... Maybe your insurance company still covers you, maybe they don't... that's not really up to me. But, if my final accident report points the finger at a vehicle defect that YOU created, how are you going to defend yourself?

What if someone has ended up dead? Are the people that set you up going to cover your liability? It doesn't matter if the rigging didn't cause the crash... it's just like having a wreck when you are drunk - the assumption is automatically that the drunk guy is liable.

There are lots of situations that are within the numbers, but are still unsafe... I just hate these types of questions... its the same as "How much over the speed limit before I get a ticket?"

There are limits and numbers. If you don't agree, fine, but if you get caught up - don't pretend you didn't know.

[dkottum]

Friday, with investigator, judge and jury like you around I think I'll just lock myself up in the house the rest of my life.

I wish these threads could have a complete discussion without some self-appointed legal beagle jumping in with dire warnings. Have we as (North) Americans always been burdened by this crap?

doug k

[MrUKToad]

Originally Posted by Friday

It's great that Can-am does all these wonderful things... I'm telling you that if I take photos of your 'specialized' rig, and Nissan, Ford, or whoever says "Yeah, there's a reason we don't put class IV hitches on a Fiesta"... you're in trouble.

I think that you're spot on but, as the determination of Tow Ratings (not the Axle or Gross Weight) has no basis in anything other than a whim, the manufacturer couldn't stand up in court and say that there was a reason why they don't put that Class IV hitch on, at least not one that had any meaning.

If we're talking GVWR or GAWR, both properly set and recordable figures, then they'd have a case. In my view.

[Friday]

Originally Posted by dkottum

Friday, with investigator, judge and jury like you around I think I'll just lock myself up in the house the rest of my life.

I wish these threads could have a complete discussion without some self-appointed legal beagle jumping in with dire warnings. Have we as (North) Americans always been burdened by this crap?

doug k

I'm not a 'legal beagle', I'm a cop... and I'm tired of the 'how close can I get to the edge' type of questions. You can get as close as you want, until you fall off.

This forum is full of people that tell the tale of how they've driven for 50 years and never had a problem. That is great. What you don't see is people relating many horror stories. I'm here to be a dose of reality because I'm the one that see's the 1 in 1000, or 1 in a million... and can say that sometimes the warnings come because of wisdom... not because some jack-ass thinks laws are 'a burden', except when they are the one wronged - then wait for the change in attitude.

I'm not even in that busy an area, and I've lost track of how many fatal accidents I've been to.

[Friday]

Originally Posted by MrUKToad

Of course, private vehicles are of little interest to the law makers as they have their sights fixed firmly on commercial operators, so unless you are obviously overloaded, it's unlikely that you'll get pulled over.

It is true... the most properly-equipped to check RV's are Commercial Vehicle Inspectors, who have access to portable scales and such. In this area, RV inspections are typically part of a combined enforcement day where many agencies will set up (usually at a weigh scale) and do inspections on all types of vehicles for the day. If it looks too heavy, it goes on the scale.

More typical things we want to see are functioning break-away devices, working brakes, and working lights. The compliance rate on all three of those together is usually around 50%... not great. It's usually the case where people have known for a long time that something isn't working, they just never get around to fixing it.

Unfortunately, without some type of enforcement action... a lot of people wouldn't bother keeping their RV's in good repair... Lots of people will swap their licence plate off their boat trailer to their RV trailer, thinking it's not with the $50 a year for another plate... then come up with some BS story for insurance when their trailer gets wrecked and wasn't registered to be on the road.

Who pays? The rest of us.

[dkottum]

Friday, if you're tired of the questions and discussions stay out of them. I am also tired of you summing up reasonable discussions with certain liability, and dismissing those who question "law" as jackasses.

doug k

[mefly2]

Originally Posted by mack-in-nc

the various 'you can tow this' ratings?

My RV books all say that you do not exceed the GVWR. If it is 9300 lbs and you try pulling 9350, you are in deep do-do.

Okay but my Airstream book, "Airstream the History of the Land Yacht' by Bryan Burkhart and David Hunt shows Airstreams being towed by all sorts of vehicles...mostly mid size sedans, station wagons and pickup trucks of the 50s and early 60s (when most of the photos in this book were taken) but also, very early in the book, what appears to be a 19 footer or so being towed by what appears to be a 10 speed english bicycle of what we used to call the 'racer' type!" Now I am sure this was a stunt of some sort, but it does make me wonder..are Airstreams easier to tow that other trailers of the same size or is it that you truly can exceed the GVWR, even if it is not a great idea?

Wiggle Room ???
Very little if you have to talk to an insurance adjuster ... and jeopardizes safety of others sharing your roadway. From a former F/T Leo and Insurance adjuster. You really put yourself in an indefensible position ... maybe, just maybe, you won't get caught for a while; but my experience is that in the long run you will be the one who pays. YMMV

What a huge investment in AS, TV, and lives to put at risk with overloaded vehicles ... jmho.

[xrvr]

One can question the law all you want but it must be obeyed. If you do not like it then go through proper channels and get the law changed. Calling people names only makes your case for pushing the limits that much less realistic. We need to learn to be responsible for our own actions, and not try to rationalize out why we got [caught] when that time comes. jim

[noreen&sal]

I am a retired professional truck driver and had to deal every day with the aggrivation of weigh stations. But can you imagine the carnage on the roads if these weight laws werent enforced? Sal.

[Ag&Au]

Originally Posted by noreen

I am a retired professional truck driver and had to deal every day with the aggrivation of weigh stations. But can you imagine the carnage on the roads if these weight laws werent enforced? Sal.

Goverment is not the solution to our problems; government is the problem. Ronald Reagan

Hi Sal,

The sentiments expressed in the body of your post don't seem to me to match those expressed in your signature line.

What am I missing?

Ken

[Sodbust]

One can get by most of the time being over the GVW limits,, but that moment when some fool pulls out in front of you at 60mph is when that gray margin becomes very important..

After 120 years of making cars and trucks,, the companies have a good idea what works and what doesn't.. So the door sticker becomes ones Bible as such and should stay within the limits as much as possable..

Now if one watches what gets loaded in the trailer and what stays home is more important than most can see.. No one that I know ever totals up what they stuff in every shelf or corner or under the bed. I starts to add up real fast.

What got me,, was when I was looking at SOB trailers at the RV show last January how many trailers once loaded up with full holding tanks and fresh water and propane are with in 500 to 700 lbs of the load limits already!. It does not take very many cast iron skillets or bags of charcoal to reach that limit real fast..

My dear wife alone packs 150 lbs of hair shampoo and women things.. Main reason I gave up riding a motorcycle on long trips!

Sodbust

[mack-in-nc]

The phrasing of my original questions seems to led some folks in the wrong direction...so allow me to get in here with some clarification..

I have no intention of pulling a nine thousand lb plus AS down the road with a TV that has no business pulling more than ...say...seven or eight thousand...I shudder at coming down out of the Blue Ridge (or worse yet, the Rockies...) while wondering where my brakes went...

I am not trying or thinking of trying of circumventing the law...I am wondering if there is a 'built in' safely factor..."this thing can really tow 10K but let's say nine, just to be on the safe side.."

[Ag&Au]

Originally Posted by mack-in-nc

The phrasing of my original questions seems to led some folks in the wrong direction...so allow me to get in here with some clarification..

I have no intention of pulling a nine thousand lb plus AS down the road with a TV that has no business pulling more than ...say...seven or eight thousand...I shudder at coming down out of the Blue Ridge (or worse yet, the Rockies...) while wondering where my brakes went...

I am not trying or thinking of trying of circumventing the law...I am wondering if there is a 'built in' safely factor..."this thing can really tow 10K but let's say nine, just to be on the safe side.."

A few thoughts:
Everything involved in this equation should have been designed by a competent engineer. Sound engineering practice involves designing everything with a safety factor build in. Sound engineering management practice should involve not publishing the safety factor, because someone is going to say, "Well, if there is a 25% safety margin, then obviously I can use it up to rated+24% no problem.

Considering these factors, one should be able to safely use anything up to its rating. If it makes you feel better to leave your own safety margin on top of that, that is fine.

If however someone wants to gamble on operating in the space between the rating and the safety margin, they would be better off to take their money to Vegas and gamble to afford higher rated equipment.

Ken

[noreen&sal]

Originally Posted by w7ts

Hi Sal,

The sentiments expressed in the body of your post don't seem to me to match those expressed in your signature line.

What am I missing?

Ken

Example: keeping overweight-unsafe vehicles off the road=good. Doing an inspection on my rig just because you have a gun and a badge and holding meup for 45 minutes and the only thing you find is a burned-out backup light ON THE TRACTOR 40 feet from the tail end. $50. summons. Sal. PS the 10 most dangerous words in the English language: Hi, Im from the government. Im here to help you. Ronald Reagan.

[Protagonist]

Originally Posted by ROBERT CROSS

Tow ratings are decided using factors such as customer demand, the needs of the marketing department and what the competition are doing rather than any mathematical or scientific method.

As an engineer, I beg to differ with that last part. Automobiles are designed by registered professional mechanical and automotive engineers, who work exclusively with mathematical and scientific methods. I have never designed an automobile, but I understand enough about the process of designing machines to know that towing capacity is based solely on mathematical and scientific methods!

For example, let's take two vehicles. In this case, since this is the Airstream Forums, take new extended-length Airstream Interstate 3500 class B motorhome and the standard-length Airstream Interstate 3500. Both have identical engines (3-liter turbo-diesel), identical GVWR (11,030 pounds), and identical GCWR (15,250 pounds). They even have the same make, model, and capacity of hitch receiver. The towing capacity of the extended-length Interstate 3500 is only 5000 pounds; the towing capacity of the standard-length is 7500 pounds. One reason for this discrepancy is a mathematical and scientific principle called "moment of inertia." Because the extended-length Interstate 3500 has a trailer hitch that is 16 inches farther away from the rear axle, the effective tongue weight is magnified accordingly; although the actual tongue weight is less, its effect on the rear supension is the same as the higher weight closer to the axle. There are dozens of other factors that all come into play, and every single one of them can be calculated mathematically by someone who has the training and expertise to crunch the numbers.

By the way, this same issue of "moment of inertia" is one reason why a half-ton pickup can tow a fifth-wheel trailer that is so much larger than any pull-behind trailer it could possibly handle. The trailer tongue weight is directly over the rear axle, not several feet behind the axle.

Customer demand and marketing departments only affect towing capacity in one way: if brand X loses business to brand Y because of low towing capacity, then the ruling elite over at brand X will tell their engineers, "Design me a vehicle with towing capacity higher than brand Y." And, lo, in a few years, it will come to pass, but only at the expense of something else (like smooth rides) that had to be sacrificed to get the higher towing capacity.

[ROBERT CROSS]

"Automobiles are designed by registered professional mechanical and automotive engineers, who work exclusively with mathematical and scientific methods."

Protagonist


Agree fully.....

BUT sadly they are not marketed by said engineers.

SAE

Bob

[MrUKToad]

Originally Posted by Protagonist

As an engineer, I beg to differ with that last part. Automobiles are designed by registered professional mechanical and automotive engineers, who work exclusively with mathematical and scientific methods. I have never designed an automobile, but I understand enough about the process of designing machines to know that towing capacity is based solely on mathematical and scientific methods!

For example, let's take two vehicles. In this case, since this is the Airstream Forums, take new extended-length Airstream Interstate 3500 class B motorhome and the standard-length Airstream Interstate 3500. Both have identical engines (3-liter turbo-diesel), identical GVWR (11,030 pounds), and identical GCWR (15,250 pounds). They even have the same make, model, and capacity of hitch receiver. The towing capacity of the extended-length Interstate 3500 is only 5000 pounds; the towing capacity of the standard-length is 7500 pounds. One reason for this discrepancy is a mathematical and scientific principle called "moment of inertia." Because the extended-length Interstate 3500 has a trailer hitch that is 16 inches farther away from the rear axle, the effective tongue weight is magnified accordingly; although the actual tongue weight is less, its effect on the rear supension is the same as the higher weight closer to the axle. There are dozens of other factors that all come into play, and every single one of them can be calculated mathematically by someone who has the training and expertise to crunch the numbers.

By the way, this same issue of "moment of inertia" is one reason why a half-ton pickup can tow a fifth-wheel trailer that is so much larger than any pull-behind trailer it could possibly handle. The trailer tongue weight is directly over the rear axle, not several feet behind the axle.

Customer demand and marketing departments only affect towing capacity in one way: if brand X loses business to brand Y because of low towing capacity, then the ruling elite over at brand X will tell their engineers, "Design me a vehicle with towing capacity higher than brand Y." And, lo, in a few years, it will come to pass, but only at the expense of something else (like smooth rides) that had to be sacrificed to get the higher towing capacity.

I published this before. These are the words of named people in the automotive industry, not unattributed comments. As I said before, it would be good if engineering was used to determine tow ratings but at the moment, they are not.

The Numbers Game: Current Practice & The Ratings - Consumer Feature - Truck Trend