Brand New Trailer - Axles Too Light for GVWR

[CaptainKirk14]

I am looking for some input for a friend. He is about to take delivery of a new Momentum Toy Hauler and I am sure the same situation exists with other trailers. The issue I pointed out to him is this: The trailer as advertised by the manufacturer states the GVWR is 16,500 lbs. The two axles are 7000 lbs each and the tires are rated at 3420 lbs. each so neither the tires nor the axles will handles this rig fully loaded. I've pointed him to the Bridgestone Duravis r250 as they are simply rock solid, but I am also telling him to have larger axles installed if the factory will not do it. Any input from you all would be great!

[Kenny kustom]

Usually, they account for the truck handling some of the weight.


2016 Sabre 36QBOK
2015 Ram 3500 CUMMINS

[donniedu]

The rest of that weight is calculated as hitch/pin weight.

[TURBS]

The truck hauls the missing weight in your calculations

Look at the pin weight number, that should be your missing weight.

All manufacturers do it the same.

The momentum that I looked up had a 3100 lb pin weight!



2015 Columbus 320RS
2008 2500HD Duramax
2015 nights camped "34"

[Mr Havercamp]

Originally Posted by CaptainKirk14

I am also telling him to have larger axles installed if the factory will not do it. Any input from you all would be great!

They won't, Grand designs lists all their toy hauler 5ers as having 7K axles. Interestingly the numbers do not work on one model, the 327M, which shows it being 50lb over although those website specs do not mean much, the yellow sticker does. The pin weight on all the others is more than 2500lbs so the numbers work. Barely with no room for a buffer other than the buffer that's already engineered into everything.

[CaptainKirk14]

Sometimes I have to relearn things I guess - I forgot about the pin weight! Jeeze. Ok. Well, that's that. Thanks guys!

[ependydad]

The part that annoys me is the tires don't add up to support the axle! THAT'S NOT RIGHT!

You shouldn't have 6,840 lbs. of carrying capacity on a 7,000 lb. axle. IMO, if there's still a warranty on this thing- he should have a case for going up in load capacity on the tires. If not under warranty, he should load it up and get individual wheel weights done. I did and found that I was overloading 1 tire and within 20 lbs. of maximum capacity on 2 others.

[WolfWhistle]

Mine is same-o same-o.. I try to tell people it isn't axles alone that determine GVW. But if you hit GVW before the tire rating is exceeded who cares. My axles 5200# tires 2540# trailer total gross on sticker 9970# less a TW of at least 1000#. 8970# net / 2 = less than 4500# on each axles / 2 (again) = 2250# each tire... Under all max ratings. That's the way it is; if want more they make more capable THs every day and a dealer would love to sell you one.
WW

[JPSPete20]

We purchased a trailer listed at 7000 pounds with two 3500 pound axles and a cargo weight listing of 750 pounds, exactly the listed hitch weight. It was our first RV and we did not pay enough attention to the specs. Simply filling the fresh water tank, adding the propane tanks and a spare tire left us with approximately 200 pounds. Adding food, clothing, bedding and other odds and ends quickly put us overweight. We burned up a wheel bearing a ruined an axle on the first trip major trip, but that was after the factory installed tires begin failing at 2000 miles. Forest River replaced the axle and tires under warranty. On a subsequent trip we burned another wheel bearing and fried the second axle. As we were on the road, we needed a quick replacement. We found a dealer that had a 5200 axle in stock. It would fit, but required that we upgrade to heavier six bolt rims. Later in the same trip, we hit a pot hole between Fairbanks and Anchorage which broke a rear spring and caused that axle to fry a bearing. We had the axle and rims and all of the springs replaced with a 5200 pound parts matching the previous replacement. The trailer now rides much better and we have a 3000 pound cargo capacity and no worries about how much we load up. We are not full timers, but take numerous short trips and one long one each year. We no longer worry about the running gear. We special ordered our trailer and added several options. I really wish that the manufacturers would offer heavier springs, axles and rims as a kit. It would costs less than doing it later and would save lots of grief for buyers.

[SuicideSaints]

To the OP, hitch/pin weight is taken into account as part of the load disbursement. Almost all trailers are specd to the limit, if you want a more capable unit you have to step in in price/quality/brand.

[AquaMan]

When everyone realizes that the GVWR is a CALCULATED figure of the GAWR + Pin/tongue Weight (and not reverse engineered), the world will be a better place and this conversation won't come up every week. As for 6840lb of tire load vs 7000 axle rating, that's something to contend with.

[D. J. Schuler]

It is very obvious no attempt was made to contact GD. GD is one manufacturer who will answer you statements ans questions directly by Email and phone. Go to their WEB Site to get the REAL FACTS. I gave up on FR and Jayco, both had standard answers - go to your dealer.
Yes, I am ordering a GD and contacted a service engineer directly about weights, furniture and structural questions. The engineer told me what changes I would see in my order, now I have a choice - what's on the lot or brand new. Try it you're be amazed or get everyone elses opinion.

[Airdale]

Axles are not built in increments that may be needed by a RV trailer manufacturer. Therefore, during the building process the trailer manufacturer has the authority from the DOT to set GAWR values to coincide with the specifications of the trailer to be built. Those GAWR values become the standard for that trailer and are displayed on the vehicle federal certification label.

The very minimum value for tire fitments is to have the ability to carry the vehicle’s GAWR. So, any of the ST235/80R16E tires would be disqualified for service on 7000# GAWR axles. However, the vehicle manufacturer can set those axles at a GAWR value of 6750# and satisfy the safety requirement requiring them to support the maximum weight that may be carried by the GAWR axles.

Owners looking at the trailer’s brochure or individual axle tag are looking in the wrong place. The only official axle load is the GAWRs listed on the certification label.

Here is a picture of a certification label of a trailer with 7000# axles reduced to 6750#.

http://www.irv2.com/photopost/showfull.php?photo=22027

NOTE: The ST235/80R16E is manufacture with three distinct load capacities, 3420#, 3500# & 3520#. Without wording in the vehicle owner’s manual or on the certification label about which load capacity tires to use they all revert to the lowest load capacity (3420#) making all of them unqualified for use on 7000# GAWR axles.

Another note: I have personally seen GAWR axles set at 5080# to accommodate ST tires with 2540# of load capacity.

[WolfWhistle]

Not sure what a service engineer is.... Sales engineer? Sounds like all the comments on this post pretty much agree. This site is for everyone and everyone is free to ask questions and give their best answers and or, opinions. Are we always 100% correct certainly not; but probably about as often as any GD employee would be... they have an agenda so don't bet your life on their answers either. JMHO.
WW

[Too Tall]

The OP has hit upon just how close to the limit these axles are running.

[W5CI]

a couple of hundred lbs wont make any difference, I just load up and head out.

[Kenny kustom]

Originally Posted by Too Tall

The OP has hit upon just how close to the limit these axles are running.

Meh. I've got 2 7k axles with a gross of 14 k and a 2 k pin.
Not that close.


2016 Sabre 36QBOK
2015 Ram 3500 CUMMINS

[WolfWhistle]

Engineering near a limit is not unique to the RV world.

[Too Tall]

I would argue that they are under engineered. It does explain why there are so many failures. I think the folks that participate in this forum are more savvy than most but there are many that don't have a clue just how little the margins are and consequently how overloaded they are.

[TURBS]

2 6k axles
14.3k gross
2400 pin


2015 Columbus 320RS
2008 2500HD Duramax
2015 nights camped "34"