Are They Meaningless? Tow Limits, Payload and Axle Load

[dznf0g]

"Okay, so we can say they are arbitrary but only one direction. They will not offer the option of a higher GVWR sticker. So sure, if you are buying used you might want to know if this was "de-rated". But the discussion is about 1/2 ton trucks and I doubt those are de-rated because the increased registration and taxes do not apply in that category. Am I incorrect?"

Yes, although, I think arbitrary or meaningless are not correct terms, as they seem blanket. I would say there are unique industry exceptions in a narrow product group.

"But in the example Andy used in the article there was no claim of de-rating via sticker. This was the maximum GVWR of the vehicle as sold. He set it up in a manner that exceeded this significantly under static conditions. It is what it is. I am happy that it handles well but hit a good bump at highway speed and you will be exceeding limits even more and in an dangerous situation if something breaks.

I get that it can be done, but those numbers are not arbitrary and they are set by people who designed the system. Strengthening the hitch assumes that the hitch was deliberately under-designed wrt the rest of the vehicle rather than deliberately set at that level as a weak link because the next weak link is more dangerous/expensive if it breaks. Go ahead and get an Audi engineer who set that limit to come on here and tell us that it is under-rated. Otherwise I will go with the specs. I don't know about you but I have a healthy respect for German automotive engineers, having owned a number of BMWs, Audis and Mercedes over the years for road and track use."

I agree. but it is well established here, by many posters, that that AS Dealer knows much more than most all the world's manufacturers. I have been emphatically told that several times.

[BayouBiker]

Originally Posted by jcl

I think it would be worth separating out the different types of ratings, limits, guideance, etc.

(snip...)

I think the bigger question is whether trailer weight should be considered the primary factor in what can be reasonable towed. It can be a factor, but there are many others that are not considered to the same degree. Trailer frontal area, side area, centre of gravity, suspension, profile, etc. Sure, these are often very similar for different models of Airstreams, and this is an Airstream forum, but we don't see qualifiers being expressed about a common tow rating applied to widely different trailers.

I agree, and maybe this is a way to better understand how and why opinions often diverge.

There seems to be no conflict about tire and axle load limits. I suppose it's because the purposes are well understood and the consequences are much more clear.

On the bigger questions, I see what you're getting at. We can both agree and many more will join us that trailer weight is technically not the most accurate way to express towing capability. It is an easy to understand and obtain number so it is useful for buyers. Do you have an idea about the range of variability around that number presuming it is an accurate technical limit. Do you have any suggestion about how one might determine the nature of the limit for any particular vehicle?

One complication is, for example, when the hitch is weak we can't safely conclude that is the primary issue because it is common engineering practice to match auxiliary components to the the weakest link. I recall a conversation on this site regarding a frustrated parts manufacturer with a bearings that would run indefinitely at no extra cost but the industry preferred one with a mean life of 150000 miles, presumably because they wanted the bearing to fail first.

In limited cases, there is a data available that reveals the primary source of the vehicle's towing limitation and then we can do better but this is rare.

[tjdonahoe]

Originally Posted by BayouBiker

It is common in the towing community to hear that towing and hauling load limits from the manufacturers are all over the place with little or no relevance to vehicle ability to pull a trailer down the road. You often hear the numbers are meaningless and you hear this from novices, those who are seasoned and experienced and some who are considered experts in the field of towing.

One group notably absent from this group are the engineers and technicians employed by vehicle manufacturers who directly determine, test and establish tow and haul ratings.

How can this be that there is so much disagreement outside of the pool of those who establish these limits?

The claims seem to get started by the large group of people who don't understand how the limits are established nor how to interpret the limits. Many who do have some understanding seem to prefer to perpetuate the rumors and myths for some reason or another. The rare Engineering expert (Collyn for example) comes along from time to time and tries to shed some light on the topic.

So this thread will once again attempt to discuss and explain the meaning of these numbers and why they seem to be all over the place with no obvious basis used to establish or apply them.

How many of them engineers ever towed anything. ?

[DewTheDew]

Originally Posted by tjdonahoe

How many of them engineers ever towed anything. ?

Likely all of them. It is, after all, their job.

[jcl]

Originally Posted by DewTheDew

Okay, so we can say they are arbitrary but only one direction. They will not offer the option of a higher GVWR sticker.

For the one ton truck example and the 10,000 lb break point, true AFAIK. But in the context of a declaration that the GVWR represents the upper limit of the vehicle capability, that is the important and relevant direction.

Same with the import manufacturer who offers a pickup, and a minivan built on the same platform, but with a much lower tow rating. The conclusion is that the manufacturer, for a number of reasons, may choose to test and rate a vehicle at less than it’s capability. It doesn’t mean that we should all rush out and disregard all ratings as meaningless. But it also means that when a competent company develops, tests, and sells a suite of modifications to improve the towing performance of a vehicle, that we shouldn’t jump to the claim that it is impossible to do that because the factory ratings represent the upper physical limits of various relevant characteristics.

I also have great respect for the German engineers, particularly the ones who developed and tested my six BMWs. One of those vehicles was an X5. It had a 7700 lb tow rating in many markets outside North America, but was only offered with a 6000 lb rated receiver in North America. In researching the vehicle, I came across a no cost Euro option for a higher tow rating, around 8800 lbs as I recall. I am pretty sure it was just a decal, based on my review of the technical documents and parts books. Also, they don’t typically give away stronger springs and brakes. The higher upper limit on the decal would mean that the owner would need a more expensive vehicle license and registration. They would also have to keep log books, as a commercial operator, not a problem if one is already a commercial carrier, but unsuitable for recreational or private use. I am positive that the higher limit was tested to the TUV standard, since they said so. But they derated it for marketing reasons. The lower limit was the standard. The higher limit was on request. Then there was further dreaming when a product manager specified a 6000 lb receiver for the NA market. It is fair to assume IMO that the BMW product managers didn’t see a higher tow rating in North America as a marketing feature.

Another BMW SUV I owned had a payload sticker on the door jamb. It said the same as the brochure. Posters here insisted (sometimes stridently) that the real payload for my specific vehicle was less than the catalogue figure, due to installed options, etc. Pickup thinking. I found that all the examples I saw had the same label. What BMW did was take the worst case payload (GVWR - curb weight) and put that on all the decals. Totally legal. If one went and weighed the vehicle, it turned out the usable payload was higher than the decal. And when I replaced the rear coil springs, I found out that the GVWR varied as well. They tested to the higher figure, then derated for convenience. They simply didn’t see maximizing the published capability as important.

[DewTheDew]

Originally Posted by jcl

For the one ton truck example and the 10,000 lb break point, true AFAIK. But in the context of a declaration that the GVWR represents the upper limit of the vehicle capability, that is the important and relevant direction.

Same with the import manufacturer who offers a pickup, and a minivan built on the same platform, but with a much lower tow rating. The conclusion is that the manufacturer, for a number of reasons, may choose to test and rate a vehicle at less than it’s capability. It doesn’t mean that we should all rush out and disregard all ratings as meaningless. But it also means that when a competent company develops, tests, and sells a suite of modifications to improve the towing performance of a vehicle, that we shouldn’t jump to the claim that it is impossible to do that because the factory ratings represent the upper physical limits of various relevant characteristics.

I also have great respect for the German engineers, particularly the ones who developed and tested my six BMWs. One of those vehicles was an X5. It had a 7700 lb tow rating in many markets outside North America, but was only offered with a 6000 lb rated receiver in North America. In researching the vehicle, I came across a no cost Euro option for a higher tow rating, around 8800 lbs as I recall. I am pretty sure it was just a decal, based on my review of the technical documents and parts books. Also, they don’t typically give away stronger springs and brakes. The higher upper limit on the decal would mean that the owner would need a more expensive vehicle license and registration. They would also have to keep log books, as a commercial operator, not a problem if one is already a commercial carrier, but unsuitable for recreational or private use. I am positive that the higher limit was tested to the TUV standard, since they said so. But they derated it for marketing reasons. The lower limit was the standard. The higher limit was on request. Then there was further dreaming when a product manager specified a 6000 lb receiver for the NA market. It is fair to assume IMO that the BMW product managers didn’t see a higher tow rating in North America as a marketing feature.

Another BMW SUV I owned had a payload sticker on the door jamb. It said the same as the brochure. Posters here insisted (sometimes stridently) that the real payload for my specific vehicle was less than the catalogue figure, due to installed options, etc. Pickup thinking. I found that all the examples I saw had the same label. What BMW did was take the worst case payload (GVWR - curb weight) and put that on all the decals. Totally legal. If one went and weighed the vehicle, it turned out the usable payload was higher than the decal. And when I replaced the rear coil springs, I found out that the GVWR varied as well. They tested to the higher figure, then derated for convenience. They simply didn’t see maximizing the published capability as important.

Can you please make any sort of rational assertion as to why, in a country with trailers and campers everywhere, BMW would choose to advertise a towing capability lower than possible? I mean, it's not like they have to make any changes. I cannot see a downside to using the proper tow ratings. It sort of fails Occam's razor. Sure, they could do it. But why would they do so? Does having a higher tow rating make it harder to sell an SUV in North America?

[dznf0g]

Originally Posted by tjdonahoe

How many of them engineers ever towed anything. ?

Well, as for the big 3, probably all of them in their personal lives. When I lived and worked in Detroit, at the Tech Center, everybody....including the engineers had more toys than one could believe. MI is a huge recreation state. TTs, boats, multiple place sled trailers, motorcycle and atv trailers, etc. Every Friday, they're all going north on I75 and every Sunday, they're going south. It's a sight.

[dznf0g]

jcl, what 10k breakpoint? I'm at a loss, unless I have already forgotten something. The only light duty breakpoint I can think of right now is an 8600# EMISSIONS and CAFE breakpoint. (US). Is this 10k some Canadian thing?

[DewTheDew]

Originally Posted by jcl

F

Another BMW SUV I owned had a payload sticker on the door jamb. It said the same as the brochure. Posters here insisted (sometimes stridently) that the real payload for my specific vehicle was less than the catalogue figure, due to installed options, etc. Pickup thinking. I found that all the examples I saw had the same label. What BMW did was take the worst case payload (GVWR - curb weight) and put that on all the decals. Totally legal. If one went and weighed the vehicle, it turned out the usable payload was higher than the decal. And when I replaced the rear coil springs, I found out that the GVWR varied as well. They tested to the higher figure, then derated for convenience. They simply didn’t see maximizing the published capability as important.

Note that no one is claiming payload on the sticker is absolute, but we are discussing GVWR. How would the GVWR vary?

[dznf0g]

Originally Posted by DewTheDew

Note that no one is claiming payload on the sticker is absolute, but we are discussing GVWR. How would the GVWR vary?

It is absolute for GM, at least. It is VIN specific.

[jcl]

Originally Posted by DewTheDew

Note that no one is claiming payload on the sticker is absolute, but we are discussing GVWR. How would the GVWR vary?

By VIN number, depending on vehicle consist.

[jcl]

Originally Posted by dznf0g

jcl, what 10k breakpoint? I'm at a loss, unless I have already forgotten something. The only light duty breakpoint I can think of right now is an 8600# EMISSIONS and CAFE breakpoint. (US). Is this 10k some Canadian thing?

No, not Canadian (ours is in kg)

The 10,000 lb break point is used to define LD and HD (for lack of a better phrase) by various jurisdictions. It isn't about the vehicle, it is about how the vehicle is used. The regulatory agency looks to the GVWR to decide what category to put the vehicle or operator in.

Some states use 10,000 lb GVWR to calculate vehicle registration, licensing, and sales taxes.

Some jurisdictions require a CDL over that point, for some specific uses

Tow truck vehicle licensing had a break point at 10,000 lb GVWR in terms of insurance requirements.

Some states use 10,000 lb GVWR as the point at which non-commercial operators must stop at highway weigh scales

Drug and alcohol testing rules in the US for commercial operators used the 10,000 lb GVWR category definition, as I learned today.

It is a case of the manufacturer's marketing arm saying, if we de-rate this on the placard, we can sell more to those who want to avoid the cost, complication, liability, (or justifiable rules, if that is one's view) for operating a vehicle with a GVWR over 10,000.

[bono]

This is how BMW manipulates GVW - they use the same round 500 kg payload (standard suspension, no airbags) across all models and add this to curb weight.

[dznf0g]

Originally Posted by jcl

No, not Canadian (ours is in kg)

The 10,000 lb break point is used to define LD and HD (for lack of a better phrase) by various jurisdictions. It isn't about the vehicle, it is about how the vehicle is used. The regulatory agency looks to the GVWR to decide what category to put the vehicle or operator in.

Some states use 10,000 lb GVWR to calculate vehicle registration, licensing, and sales taxes.

Some jurisdictions require a CDL over that point, for some specific uses

Tow truck vehicle licensing had a break point at 10,000 lb GVWR in terms of insurance requirements.

Some states use 10,000 lb GVWR as the point at which non-commercial operators must stop at highway weigh scales

Drug and alcohol testing rules in the US for commercial operators used the 10,000 lb GVWR category definition, as I learned today.

It is a case of the manufacturer's marketing arm saying, if we de-rate this on the placard, we can sell more to those who want to avoid the cost, complication, liability, (or justifiable rules, if that is one's view) for operating a vehicle with a GVWR over 10,000.

Hmm, as far as I know, and states do vary, most of what you state is for commercially registered vehicles only. Again, in the 12 midwestern states I covered, 10k was never an issue, and I never saw any derating of gvwr. HP in big diesels, yes.
Also HD in the light duty world.is a marketing term for a beefed up option in a light duty truck.
Industry wide:
Light duty = 1500 - 3500
Medium duty = 4500 - 6500
Heavy duty = 7500 and up
When was the last time you saw any recreational trailer or 5th wheel or motorhome at the DOT scales or pulled over by DOT patrols....except those with the placard on the side, indicating they are a commercial delivery service?
DOT has no jurisdiction over non-commercial trucks and combinations.
I believe CDL is required at 16k, or in some cases a gcwr of 16k, when a trailer is used. Again commercial only.....or carrying 16 or.more passengers.
Yes, registration fees are based on gvwr sometimes. In many farm states, higher gvwrs are LESS, as farmers vote.
I think it is a non- issue here and we are drifting.

[jcl]

Originally Posted by DewTheDew

Can you please make any sort of rational assertion as to why, in a country with trailers and campers everywhere, BMW would choose to advertise a towing capability lower than possible? I mean, it's not like they have to make any changes. I cannot see a downside to using the proper tow ratings. It sort of fails Occam's razor. Sure, they could do it. But why would they do so? Does having a higher tow rating make it harder to sell an SUV in North America?

Sure, but it will take quite a few paragraphs.

TL/DR version - they did have to make changes. The Euro hitch wasn't legal here. They had to spec a new one from an outside fabricator. They chose a rating for that new design. It wasn't the same as the vehicle rating.

We have to go back to 1999. The Euro sport utility hadn't been invented yet. Sure, there were Land Rovers and so on, but they were more utilitarian, and less sport. Acura was first IIRC, but not Euro. When BMW introduced the X5, they took a lot of flak. Loyal BMW fans decried the move, this was the end of the brand, they were becoming a truck company (it is a stretch to call an X5 a truck, but so it went). All of this by way of explaining that BMW customers didn't tow. It wasn't part of the DNA, at least to BMW. They were wrong, as it turned out. But BMW hadn't offered hitches in North America for their other products. When you went to a dealer and asked about towing, the answers were even worse than currently seen at dealers for NA trucks, which apparently are intended for towing. BMW didn't help with users who wanted to wire in a brake controller. It was out of scope for them. I recall sharing the pin out diagram for the lighting control module, with a brake light pin identified, and a supplier source for a BMW compatible plug so people could build their own trailer brake wiring harnesses. It was risky to wire to the actual brake lights (multiplexed wiring). And you couldn't use the brake pedal switch, as it was a special sensor without an off/on. We were before wireless controllers, so that wasn't an option. All of this was worked out outside BMW. They didn't see themselves as being in the trailer brake game at that time. Probably since they didn't use electric trailer brakes in Europe, and the North American BMW functionaries didn't appear to be product design engineers. When contacted, BMW struggled to respond. Tow mirrors (clip on) were not offered, although they were available from BMW in Europe. Some imported them privately. I travelled regularly to the UK, and recall bringing X5 items back from time to time. There was no tow rating for the X5 in the US or Canada; it wasn't in the owner's manual, or online technical literature, or door jamb (this was pre-2007 regulations). There was a decal in the hitch receiver kit, and a warning that you needed to stick it on the receiver when you mounted the hitch.

BMW simply couldn't understand what all this towing discussion was about. It went on for years. I was part of a grassroots support organization. There were specific BMW discussion boards for the X models, active from 2002. That was where the expertise was. Until the discussion board got so big, that BMW lawyers asserted their right to control all web presences with X5 in the name. X5World became XOutpost. It still exists under that name.

The Euro X5 hitch, developed by BMW engineers, and rated for 7700 lbs, was not legal in North America. It was a "swan neck" style, permanently attached at that time. The 50 mm ball was part of the tow hitch. There was no place to attach a safety chain separate from looping it around the tow ball. So, BMW NA had to come up with a solution. They decided to hire a local steel fabricator to build hitch receivers for them. They were not factory parts, they were only sold through the accessory parts channel at dealers (so they didn't have to keep them around for 15 years of service support, but I digress).

A BMW functionary in BMW NA hired that steel fabricator. The spec was for 6000 lbs. I suspect not because they wanted to derate it, but because 3500 kg didn't translate well. I suspect that 6000 lbs was seen as a convenient, and altogether sufficient number, but I don't know that for sure. BMW called it a Class IV hitch. I think they looked up hitches, found a reference to 6000 lbs being Class IV, and said, that will do. The unibody mounting part of the kit used the Euro design, which was rated higher, and that is likely why the factory X5 E53 hitch mounting was so overbuilt. When CanAm referred to the early X5 hitch as being built like a one ton, they weren't talking about the vehicle, but rather the welded fabrication that mounted to the vehicle. They were right.

The fabricator built the kits. BMW didn't even have an installation guide, they included a publication in the box that actually showed the swan neck hitch, and installers had to figure out which parts they had to mount, and which parts weren't applicable. My 2003 X5 included a carry spot (under the rear floorboard, cut out of the foam liner) for the swan neck. Nobody could figure out what went in it at first.

Over the years, they got better. They published a correct installation guide. They added towing references to the manuals. They put a rating on the door jamb (well, they had to, but at least they followed the rule). They added a rear view camera and gave it a connect view so it pointed down when you were hitching. They upgraded the transmission in the 6 cylinder, from a 5 speed to a stronger 6 speed, and then matched the towing rating of the V8 model. By the time the next generation model came out, the tow ratings had risen. I think they saw market opportunity by that point. It was the 2007 model. The new model even had a wiring diagram for a brake controller in the online tech literature system.

When BMW came out with the X3, in 2004, they applied what they had learned from the X5. Lots of improvements, including to the AWD system. The X5 got bigger in 2007. So did the X3. My 2007 X3 was virtually the same physical size as my 2003 X5. It had 40 more hp. Better brakes. Better solo handling. A stronger unibody. And it was offered with a 3500 lb Class 3 hitch receiver in North America (also derated from the X3 in Europe). So I don't think they learned that part. They looked up hitch classifications, and chose that one. I spoke to CanAm about the X3 towing. They advised I would be fine with an AS27. A friend was towing a 27 with a RAM 1500 Ecodiesel. I had more hp, better brakes, better handling, and 400 lbs more payload. I think of the X3 of that generation as being very similar to the current Audi Q5, which is the subject of some current debate here.

Occam's razor says the simplest solution is the most likely. IMO, they weren't malicious. They weren't trying to downplay the towing capability. They just didn't know. There is abundant evidence to support that premise, some of it recounted above. It was a whole new market. Seen through the lens of North American pickup manufacturers, who these days compete to outdo each other on tow ratings, it seems silly. But it was different back then.

[jcl]

Originally Posted by bono

This is how BMW manipulates GVW - they use the same round 500 kg payload (standard suspension, no airbags) across all models and add this to curb weight.

I don't have the chart handy, but that is virtually identical in concept to the GVWR variability on the X3. I recall one of the questions for GVWR then was if the vehicle had the panoramic or regular sunroof. Weight impact.

[jcl]

Originally Posted by dznf0g

Hmm, as far as I know, and states do vary, most of what you state is for commercially registered vehicles only. Again, in the 12 midwestern states I covered, 10k was never an issue, and I never saw any derating of gvwr. HP in big diesels, yes.
Also HD in the light duty world.is a marketing term for a beefed up option in a light duty truck.
Industry wide:
Light duty = 1500 - 3500
Medium duty = 4500 - 6500
Heavy duty = 7500 and up
When was the last time you saw any recreational trailer or 5th wheel or motorhome at the DOT scales or pulled over by DOT patrols....except those with the placard on the side, indicating they are a commercial delivery service?
DOT has no jurisdiction over non-commercial trucks and combinations.
I believe CDL is required at 16k, or in some cases a gcwr of 16k, when a trailer is used. Again commercial only.....or carrying 16 or.more passengers.
Yes, registration fees are based on gvwr sometimes. In many farm states, higher gvwrs are LESS, as farmers vote.
I think it is a non- issue here and we are drifting.

I agree with you on LD and HD, it was shorthand. I worked at a Ford dealership many years ago, and delivered trucks from the original Rangers to F series to C series to L series to CL series. I drove professionally after that (fuel tanker and tow truck) with what the US calls a CDL, in my case a Class III (unlimited GVW) with an air brake endorsement.

I think the rules related to GVWR vary widely throughout the US. I know the Canadian rules, I don't know as much of the detail of the US rules, but I know they exist.

A quick investigation showed:

Mississippi has variable sales tax on retail sales of new vehicles over and below 10,000 lbs
Maine says any vehicle over 10,000 lbs has to stop at all scales, including non commercial.
New York has different tax rules above and below 10,000 lbs GVWR
Washington State doesn't let anyone with GVWR over 10,000 lbs drive in the left lane, or HOV lane, whether commercial, private, or RV

And so it goes.

Yes, we are drifting. None of this matters in terms of whether a vehicle is commercial or not when towing an Airstream. The original point was that GVWR can be varied (downward) by the manufacturer when the vehicle is built, and isn't always related to vehicle capability. Sometimes it is just convenient to vary it. For the reasons noted above, among others.

Cheers

Jeff

[dznf0g]

Originally Posted by jcl

I agree with you on LD and HD, it was shorthand. I worked at a Ford dealership many years ago, and delivered trucks from the original Rangers to F series to C series to L series to CL series. I drove professionally after that (fuel tanker and tow truck) with what the US calls a CDL, in my case a Class III (unlimited GVW) with an air brake endorsement.

I think the rules related to GVWR vary widely throughout the US. I know the Canadian rules, I don't know as much of the detail of the US rules, but I know they exist.

A quick investigation showed:

Mississippi has variable sales tax on retail sales of new vehicles over and below 10,000 lbs
Maine says any vehicle over 10,000 lbs has to stop at all scales, including non commercial.
New York has different tax rules above and below 10,000 lbs GVWR
Washington State doesn't let anyone with GVWR over 10,000 lbs drive in the left lane, or HOV lane, whether commercial, private, or RV

And so it goes.

Yes, we are drifting. None of this matters in terms of whether a vehicle is commercial or not when towing an Airstream. The original point was that GVWR can be varied (downward) by the manufacturer when the vehicle is built, and isn't always related to vehicle capability. Sometimes it is just convenient to vary it. For the reasons noted above, among others.

Cheers

Jeff

Jeff, I still say I never saw nor heard of any LD vehicle at gm with any lowering of gvwr.
Think about it, there are no LDs with a solo gvwr near 16k. If you are running a commercial combination you couldn't haul much below 16k....heck, my 1500 Silverado plus my AS is 17,400 gvwr.
There are options for lower gvwr 4500 series to keep them below 16k. But it is a lighter rear suspension. Again, think about it. If a commercial interstate light bulb manufacturer wants to stay below 16k, but need space, they need a big box truck...but they can't stand a harsh stiff ride. Thus less spring in back. It's NOT a label only option to skirt the law. If they want to haul twice as many light bulbs, they choose the hassles of cdl and there are many graduations up the gvwr scale, with hardware differences in all.

[dznf0g]

I have an idea, let's circle back around to gvwr and payload are not meaningless nor arbitrary.
Who's up?

[DewTheDew]

So despite Andy calling the GVWR arbitrary in a 1/2 ton pick up, and jcl digressing about heavy duty GVWR, I still say it is not arbitrary. They did not pull the number out of thin air.