Need help figuring out why my rig is overweight

[jayspi]

Hey folks, this might be a weird question, but I need help figuring out why my rig is overweight. Let me explain.

We have a Grand Design Momentum 354M 5th wheel toy hauler. Here are the stats that matter:

• Dry weight: 13,400
• Pin weight: 2,700
• GVWR: 16,500
• Axle Rating: 2 x 7000
• Fresh water capacity: 157 gallons
• Fuel capacity: 60 gallons

Basic arithmetic tells us that with full fresh water and fuel tanks but nothing else, the weight is 15,211 pounds. That leaves us with 1,289 pounds for cargo.

The problem is, when we are fully loaded with cargo and full fuel and fresh water tanks, the CAT scales put me at a whopping 17,500 pounds (3,220 on the pin and 14,280 on the axles).

I know that CAT scales are reliable, but I still used 2 different ones to be sure. I also weighed the truck without the trailer attached so I could get an exact calculation.

Here's the thing, though: There's absolutely no way we have that much cargo. We use the garage for our son's bedroom. We don't have "toys." The heaviest things we have in the RV are our washer/dryer combo (150~ pounds), a cabinet we added in the garage (<200 pounds) and our mattress (100~ pounds).

Other than that, all we have are food, clothes, baby toys, and miscellaneous items like some camping gear and alpine skis. None of it weighs more than 30 pounds, and there isn't a lot of it. We aren't hardcore minimalists, but we don't like having a lot of stuff. We do regular purges of unneeded items.

I can see MAYBE having 500-800 pounds of cargo (after the items listed above), but there's no way that we have a total of 2,289 pounds (which is what we'd need to hit 17,500 pounds).

There's also no way that we have 14,280 pounds on the axles. The only things in the garage are the cabinet, washer/dryer, our son's crib, and some baby toys.

The only thing that I can figure is that I'm somehow using the scales wrong. However, I'm using the 3 boxes and getting weights for steer axle, drive axle, and trailer axle, so I don't think I've positioned it wrong.

Does anyone have any ideas?

[jayspi]

Ralph Cramden wrote:

jayspi wrote:

ependydad wrote:
I'd upgrade the axles.

My old rig was not a Grand Design, but another manufacturer who was proud of their "full 12" I-Beam" frame. I was running 1,000 lbs. over GVWR and maxed out on axles (7k axles). After 2 years of fulltiming, I ended up having a buckled frame.

If you're going to upgrade the axles, I'd suggest that you also upgrade the cross-member supports between the axles.

And regularly inspect the suspension and frame while using it.

I trust Grand Design's answer. I specifically asked them if the chassis could carry the extra weight and they said yes. The folks staffing that line really know their stuff. They aren't generic customer service reps.

That said, the dealer is going to double check that nothing else needs to be upgraded. He said the springs might need to be upgraded. I also asked him to look into the suspension.

Now that's a lot of faith in an RV manufacturer and high quality LCI frames. It may behoove you to at least consider ependy's advice. He has probably put more towing miles on a rig than anyone on this or most other RV boards.

That's why I said I'm having the dealer double check...

[Ralph_Cramden]

jayspi wrote:

ependydad wrote:
I'd upgrade the axles.

My old rig was not a Grand Design, but another manufacturer who was proud of their "full 12" I-Beam" frame. I was running 1,000 lbs. over GVWR and maxed out on axles (7k axles). After 2 years of fulltiming, I ended up having a buckled frame.

If you're going to upgrade the axles, I'd suggest that you also upgrade the cross-member supports between the axles.

And regularly inspect the suspension and frame while using it.

I trust Grand Design's answer. I specifically asked them if the chassis could carry the extra weight and they said yes. The folks staffing that line really know their stuff. They aren't generic customer service reps.

That said, the dealer is going to double check that nothing else needs to be upgraded. He said the springs might need to be upgraded. I also asked him to look into the suspension.

Now that's a lot of faith in an RV manufacturer and high quality LCI frames. It may behoove you to at least consider ependy's advice. He has probably put more towing miles on a rig than anyone on this or most other RV boards.

[jayspi]

BFL13 wrote:

jayspi wrote:

BFL13 wrote:
Perhaps between Grand Design confirming that trailer with those axles etc would be assigned the new GVWR if built that way originally, and the dealer certifying the new axles etc, were installed, they can get permission from whoever it is, to issue you a new sticker.

I didn't know that. That would be awesome. I'll ask them about it.

Thanks for letting me know.

I don't know that either! Just a suggestion to ask. I have heard that you can get a new GVWR if you pay for an inspector and all that, but I don't know any details or if you can do that in every jurisdiction.

I know that here, if you have a "home made" utility trailer, you have to do that to get a suitable GVWR or else they automatically assign a fixed low GVWR to it.

Thanks for clarifying, I misread your post 🙂

Either way, thanks for the suggestion. I'll look into it.

[BFL13]

jayspi wrote:

BFL13 wrote:
Perhaps between Grand Design confirming that trailer with those axles etc would be assigned the new GVWR if built that way originally, and the dealer certifying the new axles etc, were installed, they can get permission from whoever it is, to issue you a new sticker.

I didn't know that. That would be awesome. I'll ask them about it.

Thanks for letting me know.

I don't know that either! Just a suggestion to ask. I have heard that you can get a new GVWR if you pay for an inspector and all that, but I don't know any details or if you can do that in every jurisdiction.

I know that here, if you have a "home made" utility trailer, you have to do that to get a suitable GVWR or else they automatically assign a fixed low GVWR to it.

[jayspi]

BFL13 wrote:
Perhaps between Grand Design confirming that trailer with those axles etc would be assigned the new GVWR if built that way originally, and the dealer certifying the new axles etc, were installed, they can get permission from whoever it is, to issue you a new sticker.

I didn't know that. That would be awesome. I'll ask them about it.

Thanks for letting me know.

[BFL13]

Perhaps between Grand Design confirming that trailer with those axles etc would be assigned the new GVWR if built that way originally, and the dealer certifying the new axles etc, were installed, they can get permission from whoever it is, to issue you a new sticker.

[jayspi]

ependydad wrote:
I'd upgrade the axles.

My old rig was not a Grand Design, but another manufacturer who was proud of their "full 12" I-Beam" frame. I was running 1,000 lbs. over GVWR and maxed out on axles (7k axles). After 2 years of fulltiming, I ended up having a buckled frame.

If you're going to upgrade the axles, I'd suggest that you also upgrade the cross-member supports between the axles.

And regularly inspect the suspension and frame while using it.

I trust Grand Design's answer. I specifically asked them if the chassis could carry the extra weight and they said yes. The folks staffing that line really know their stuff. They aren't generic customer service reps.

That said, the dealer is going to double check that nothing else needs to be upgraded. He said the springs might need to be upgraded. I also asked him to look into the suspension.

[jayspi]

BFL13 wrote:
ISTR if you upgrade the axles and tires and whatever, you don't get a new, higher GVWR. There have been threads in the other forums related to all that and what different jurisdictions say about how to get a higher GVWR.

There is also something about GVWR in BC's rules if "they" ever wanted to weigh your trailer. ( Mostly they only do commercial trucks, but sometimes they do RVs, I gather.) So putting it all together---

If you are going to Alaska via BC and are over the sticker GVWR that might be a problem, but you have to check, because I cannot confirm what the real story is. Just thought it worth a mention, in case.

Meanwhile, it does makes sense to upgrade the axles based on the OP weights alone, where you are over, and are likely to be that way for many future trips.

Good point on the GVWR. I understand that you don't get a new GVWR after doing upgrades. It's kind of like adding air bags to a truck to give you more payload capacity. It doesn't change the truck's rating, but in the real world it makes a difference.

As far as traveling in the U.S. goes, I'll weigh the rig with the tanks empty and carry that printout with me. I'm not worried about the ability of our truck to safely tow 17,500 pounds. It's rated for almost 30,000 pounds of 5th wheel towing. So carrying the print out from the CAT scales would be purely for covering my rear.

Thanks for the tip about B.C. I didn't see them stopping RVs the last times we went to Alaska or Whistler, but I'll look into it before we go up again. I can dump some water through B.C. and fill up in the Yukon if necessary. The last time we went up we had problems getting fresh water since the pipes were still frozen. That shouldn't be an issue this year since we're going up in June.

[ependydad]

I'd upgrade the axles.

My old rig was not a Grand Design, but another manufacturer who was proud of their "full 12" I-Beam" frame. I was running 1,000 lbs. over GVWR and maxed out on axles (7k axles). After 2 years of fulltiming, I ended up having a buckled frame.

If you're going to upgrade the axles, I'd suggest that you also upgrade the cross-member supports between the axles.

And regularly inspect the suspension and frame while using it.

[jayspi]

rk911 wrote:
your 13,400 is the DRY weight, not the GVWR which is 16,500. your calculations on your fluid are close enough for govt work. I use 8.0-lbs for water and 4.0-lbs for LP but it's a distinction without a difference.

you're either using the scales incorrectly (hard to imagine) or you just have more stuff that you realize.

if this were me I'd go ahead and have the axles upgraded anyway but before I did that I'd unload everything and re-weigh. that'll give you a baseline weight (we used to call that the 'wet weight'. the weight of an otherwise empty RV with full fresh water, fuel and LP tanks). THAT will answer the question of just how much stuff you have added. I'd have the axle upgrade anyway just cuz.

See the latest post I made just a few minutes ago 🙂

Edit: Thanks for the help. I agree that the best thing to do is just upgrade the axles. I explain why in the last post.

[BFL13]

ISTR if you upgrade the axles and tires and whatever, you don't get a new, higher GVWR. There have been threads in the other forums related to all that and what different jurisdictions say about how to get a higher GVWR.

There is also something about GVWR in BC's rules if "they" ever wanted to weigh your trailer. ( Mostly they only do commercial trucks, but sometimes they do RVs, I gather.) So putting it all together---

If you are going to Alaska via BC and are over the sticker GVWR that might be a problem, but you have to check, because I cannot confirm what the real story is. Just thought it worth a mention, in case.

Meanwhile, it does makes sense to upgrade the axles based on the OP weights alone, where you are over, and are likely to be that way for many future trips.

[rk911]

your 13,400 is the DRY weight, not the GVWR which is 16,500. your calculations on your fluids are close enough for govt work. I use 8.0-lbs for water and 4.0-lbs for LP but it's a distinction without a difference.

you're either using the scales incorrectly (hard to imagine) or you just have more stuff that you realize.

if this were me I'd go ahead and have the axles upgraded anyway but before I did that I'd unload everything and re-weigh. that'll give you a baseline weight (we used to call that the 'wet weight'. the weight of an otherwise empty RV with full fresh water, fuel and LP tanks). THAT will answer the question of just how much stuff you have added. I'd have the axle upgrade anyway just cuz.

[Cummins12V98]

fj12ryder wrote:

Cummins12V98 wrote:
"I have been to a number of RV factories and never seen a scale."

Take the DRV plant tour in Howe, IN

First pic at end of production. Second pic at factory one year later for warranty work.

So were the first weights wrong? Or have you actually added over 2 tons of "stuff"?

We have added almost 5k of "STUFF". That includes 20 gallons of water or so and full propane and the 6500 GEN.

[jayspi]

maillemaker wrote:

What isn't helpful are posts questioning why I would have our tanks fully loaded, suggesting that I don't know how much our personal items weigh, or assuming we're rookies.

I'm not sure why people automatically make these assumptions when they add nothing to the conversation.

Welcome to rv.net. I have said many times before this forum is one of the most hostile "help" forums I have ever encountered.

It seems like half the replies want to tell you why you're an idiot.

Anyway, I'd believe the scale. If you really want to know how much your rig weighed when you bought it, take everything out of it and go weigh it. Then compare that with what the dealer said it weighed.

Steve

To be fair, this forum has been extremely helpful in the past. There have been some really helpful answers/suggestions in this thread too.

I might just be over-sensitive since we deal with unsolicited advice so much with our vlog :).

Anyway, good news and bad news, then more bad news and more good news.

The first bit of bad news is that I still don't know why we're 1,000 pounds overweight. At this point I think the weight on the sticker by the propane door is wrong. I explain why below.

Here's some good news, though. I called Grand Design and the dealer and got some definite answers.

First, Grand Design says that the weight on the sticker by the propane door is the weight as it rolls off the line AFTER all the dealer options are added. If the dealer ordered a generator then the weight on the sticker includes that. Same for an additional A/C, etc.

So I called the dealer and he said he didn't add anything after he ordered it.

According to the sticker by the propane door, the weight when it rolled off the line was 13,461. That gives us 3,039 pounds of cargo to work with.

So here are my calculations. Somebody correct me if I'm wrong:

1. 1303: 157 gallons of water
2. 378: 60 gallons of gasoline
3. 60: 14 gallons of propane
4. = 1,741 pounds

1. 148: Washer/dryer
2. 200: After market cabinet
3. Mattress: 150
4. = 498 pounds

Total = 2,239 pounds

13,461 + 2,239 = 15,700

16,500 (GVWR) - 15,700 = 800

So, we have 800 pounds left over for clothes, food, and miscellaneous items. Incidentally, that's exactly what I said I thought the upper limit of our cargo was in my OP. I based that off the cargo in our last 2 rigs.

However, the scales how us at 17,500, so we're still 1,000 pounds off somewhere. I've gone through our rig at least 5 times these last few days, and I just can't come up with that much weight. We've got 1 closet of clothes, 1 cabinet of baby clothes and associated items, some baby toys, 2 pairs of alpine skis, a propane firepit, a few tools, a small bin of camping gear, a small bin of winter clothes, food, and kitchen items. That's it.

The only thing I can figure is that the weight Grand Design put on the sticker by the propane door is incorrect.

That's the second bit of bad news.

Now for the second bit of good news...Grand Design said that the weak point on the rig is the axles, and if we need to be over the GVWR then we can upgrade them.

So I called the dealer (he's a friend and I trust him to do us right) and he said he can't imagine spending more than $1,000 to upgrade the axles. He is going to do a little research and see if any other components need to be upgraded, like the tires and springs. He's going to write us up a quote.

Until then, we just won't fill up our fresh water tank. That won't be a problem since we won't be boondocking a lot for the next couple of months.

I might eventually empty out the rig just to see if the scales match the weight on the sticker. However, even if it doesn't, I think I'll upgrade the axles anyway. Grand Design tries to go with twin axles when possible on their Momentum 5th wheels, which I like. However, the flip side is that you're putting a lot of weight on two axles. Upgrading them will give me more peace of mind, especially when we tackle the Alcan.

So, I think I have the answers I need and a plan of action. Thank you guys for all the help 🙂