can't get the gvwr math to work

[tianna_veum]

I want to buy a Bigfoot 25C9.4SB and a short bed srw crew cab diesel to match. Everything I read says "gvwr gvwr gvwr - never violate your trucks gvwr!".

ok.

So, Bigfoot says their camper is 3K pounds "dry" but truck camper magazine says plan for 4K pounds to account for water, propanne and "gear".

Ford tells me a f350 short bed srw crew cab diesel has a max payload of 3.5K pounds with "a 150 pound passenger at each avaiable seating position".

Since I'm the only passenger, I figure the truck's max payload is probably closer to 4K pounds.

Is this to close? 4k camper on a 4k capable truck?

If so, then I can go for a gas engine instead of the diesel which buys me about 500 pounds. But, I would prefer diesel over gas.

Would appreciate advice.

tianna

[ardvark]

I guess the engine law has to do with pollution? Here in Tennessee when I go in to register my F350 they ask if I am commercial. I say no, just for my RV and that is the end of it. It is just another pickup. Until recently I didn't even get asked that.

It would be nice if there was some kind of uniformity, but I am sure that is wishful thinking. 🙂

[Kayteg1]

DOT laws vary between the states and are so murky, that even DOT officers have trouble answering the question.
But for example in California - pickup is vehicle below 11,300 lb (from top of my head) so anything with bigger GVWR should drive via scales. The requirement is historically ignored, but in last years the "revenue seekers" are making good reinforcing it.
Than if you have >= 15k GVWR you have to get new engine every 20 years regardless how you register it.
In "salt belts" not too many vehicles last 20 years, but on West Coast I still see 40 years El Camino and lot of other 30-40 years vehicles used as daily drivers. Sure requirement for new engine can junk 20 yo pickup, regardless how pristine it is.

[ardvark]

So you are saying, even if you are not hauling commercial, you have to behave as though you are, if your truck hits a certain GVWR? What is the weight at which they would be held to commercial (DOT) regs? Never heard that before?

[Kayteg1]

ticki2 wrote:

Kayteg1 wrote:
Some people need longer to get it than others 😉
It should not be too hard to understand that GVWR is taxable number, when axles numbers is real capacity and that is what we should observe.
Fact that those numbers make big difference might be confusing, but who pays taxes on what he actually earns?
For some earning $90,000 and paying taxes on $40,000 is not confusing at all.

If it were as simple as that states would charge according to axle numbers and make more money . Each state has their own formula for registration and taxes . Some make more sense than others. I find it interesting in these discussions that some feel that truck manufacturers GVWR is arbitrary but axle and tire ratings are absolute . Unless one has access to the engineering and testing data it's all guess work by the consumer.

But beware that we have maze of different laws that might apply here.
Rating pickups at their actuall GVWR - would put all duallies (and some SRW) into commercial laws. Meaning additional checks, driving via DOT scales, driver health certificate and in CA need to upgrade engine every 20 years.
Than who wants to pay the commercial registration fees?
Do you really want to go there?

[burningman]

But it’s not like we can’t see what the truck is made of.

[Bedlam]

If you understand that GVWR is a rating putting a vehicle into a particular classification and an identically equipped vehicle can have different ratings based on the buyer’s desired vehicle classification, you understand that GVWR has little to with safety limits. Axle ratings reflect capability better and are based on the weakest components making up that assembly. If you run 19.5” tires and rims, the typically lowest rated component is now stronger resulting in a higher rated assembly. If you take off OEM LT tires and replace them passenger tires or rims, you most likely degraded the axle assembly rating regardless of what is printed.

Blindly following the numbers as an absolute without knowing how they were derived or what is their purpose is the most unsafe practice I have read in these posts.

* Edited for readability

[ardvark]

I disagree.

First of all, the manufacturers do post a rating, but then they also post all kinds of numbers that seem to invalidate their rating.

And I think people are trying to explain why they do what they do in regards to weight when they choose to ignore the manufacturers' ratings. Isn't that what leads to these debates and discussions? Too much information rather than not enough?

If we got rid of all those extra numbers i.e. specifications, all end-users would have is one rating number to look at rather than however many.

[burningman]

ardvark wrote:
Your point regarding engineering data is a good one. In follow-up to that, it seems to me it would make things simpler if manufacturers published less data. If they simply said, this model truck is designed to carry this much weight and tow this much weigh, wouldn't that make everyone happy?

That is what they do.
All that’s going on here is trying to explain why most 2500/3500 trucks have lower ratings that what they’re actually perfectly capable of.

The rating number isn’t an engineering limit of the whole truck.
It’s mostly a number that places the truck into a certain defined category.

Many of us can’t help notice that some trucks are rated lower, like lots of 2500s, yet they have the same engine, transmission, and axles. Then you look at exactly what was changed on the higher rated ones and it’s either nothing or nothing much.

[ardvark]

Your point regarding engineering data is a good one. In follow-up to that, it seems to me it would make things simpler if manufacturers published less data. If they simply said, this model truck is designed to carry this much weight and tow this much weigh, wouldn't that make everyone happy?

I will say this. For a fair number of years I was very involved with the RV industry and I was much impressed with the volumes of data the manufacturers have about their products that they don't share with end-users. The old saying "you don't beat a man at his/her own game comes to mind".

[ticki2]

Kayteg1 wrote:
Some people need longer to get it than others 😉
It should not be too hard to understand that GVWR is taxable number, when axles numbers is real capacity and that is what we should observe.
Fact that those numbers make big difference might be confusing, but who pays taxes on what he actually earns?
For some earning $90,000 and paying taxes on $40,000 is not confusing at all.

If it were as simple as that states would charge according to axle numbers and make more money . Each state has their own formula for registration and taxes . Some make more sense than others. I find it interesting in these discussions that some feel that truck manufacturers GVWR is arbitrary but axle and tire ratings are absolute . Unless one has access to the engineering and testing data it's all guess work by the consumer.

[Kayteg1]

wnjj wrote:
After all the posts back and forth, the undecideds ultimately pick a side, don’t they?

Somehow I don't see owners carrying 10 foot campers on 6500 series trucks as that is what it would take to follow truck taxation ratings.

[wnjj]

ardvark wrote:
Doesn't seem like either side is winning does it?

Not sure winning is the goal and there’s no way to know who all you may have influenced that don’t post. After all the posts back and forth, the undecideds ultimately pick a side, don’t they?

[ardvark]

Doesn't seem like either side is winning does it?

[wnjj]

ardvark wrote:
I don't understand what feels to me like a need of some folks to convince others of the rationale behind their decision. What am I missing?

On one side some may try to convince because it can (in their mind) prevent an accident or injury so it makes it kind of a moral obligation.

On the other side some may try to convince because it can allow someone on a budget (or unable to change trucks for other reasons) to enjoy the camping lifestyle we all enjoy.