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Thread: Axle Ratings < GVWR?
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03-24-2020, 07:59 PM #1
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Axle Ratings < GVWR?
So this could be a really stupid question so proceed cautiously....
I have a 2020 31MB, GD website lists the following specs:
UVW - 9778 lbs
GVWR - 11995 lbs
Today, I was under the rig looking for the axle information to order a suspension upgrade (Roadmaster Comfort Ride System w/shocks) fully expecting to see 7k axles. Nope, 5,200 lb Dexters... so the math on the axle ratings is 10,400 which is less than GVRW of the rig???
How does that work? is it GVRW - Pin weight = Axle load?
I'm sure it's "fine" but curious what the GD crowd has to say.... Would love your feedback on the Roadmaster if anyone has this setup
https://www.etrailer.com/Trailer-Lea...ils=.questions
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03-24-2020, 08:32 PM #2
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Marcy & Gary
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03-24-2020, 08:44 PM #3
Some people disagree the way it's designed, but the entire trailer weight will never be solely on the axles, some will always be either on the pin or the front landing gear. GD isnt consistent how they do it either, for example, my GVWR is 20k and I have three 7k axles.
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03-25-2020, 04:34 AM #4
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I think the question has been answered but there's always more to it. On my last 5th wheel the only way to load the trailer to GVWR without overloading the axles, was to have 25% on the pin. Grand Design sizes their axles a little heavier so you have a little more flexibility with loading.
While all of this works on paper, in my opinion, there is not enough margin above the component ratings to account for unusual loadings. That being said, GD is better than others.
For comparison, the combined axle ratings of a tow vehicle are usually higher than the GVWR.
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03-25-2020, 05:17 AM #5
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Just as you I was taken by surprise when I first saw this math slight of hand. I am one that believes that the axles should be able to carry close to or over the GVW. Using pin weight to allow for a lighter axle is degrading the suspension and undercarriage design. I caught this early on with another manufacturer's trailer that I was really interested in as it met a lot of my desires. I walked away from that one and started over with my new found requirements in hand. It really narrowed the field from there as it was more evident that most 1/2 ton towable 5Ws really aren't. My 260RD has 4400# axles and the factory weight is 7303# which I verified myself. I knew from my old TT that I generally carried about 1000# + of cargo. So that bought me to 8350# +/-. Even with the extra space, storage and new things I found I cannot live without I'm still below the 8800# the axles are rated for. I just consider the weight taken by the pin to be an added cushion and happy with that.
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03-25-2020, 07:39 AM #6
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My 2019 2800bh is in the over built category. It has a GVWR OF 7995 and two 4400 pound axles.
2019 2800bh
2018 Silverado 1500
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03-25-2020, 07:49 AM #7
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Unlimitedmatt.......Travel trailers generally fall in that way because I don't think the manufacturers can take into account a WDH taking part of the load. I wouldn't recommend it but you can elect not to use one so the entire load is on the trailer suspension. I found their weak link and also with 5Ws in previous models are the tire/wheel combinations. Most are at or under the rated GVW. I do believe this where not all but most travel trailer tires got their bad rap. Some did deserve it.
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03-26-2020, 09:02 AM #8
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Just to clarify a weight distribution hitch (WDH) on a travel trailer does not subtract weight from the trailers axles. For example if a travel trailer weighs 10,000 pounds and has a hitch weight of 1500 pounds these stay consistent regardless if a WDH is used or not.
A WDH can be viewed as levers that are attached to the rear of tow vehicle and lifted up, than secured to the tongue of the trailer. It redistributes the force back to the trailer tongue, but does not change the weight exerted on the axles. I verified this with my trailer, the weight on the axles remains consistent with the WDH connected or unconnected.
I wonder if this is the reason for some of the spring failures on some 5th wheel models, the calculation of pin weight reduced from the axle rating ends up with no margin for the forces generated from movement, which increases weight or force on these components as they move on the roadway.
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03-26-2020, 11:28 AM #9
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If you take your trailer to a scale, you'll see that the math does work. I've had my 351M weighing 16K lbs and neither of my 7K axles was overloaded. I know, it's kind of strange, but it does work out. That said, my 351 is rated, IIRC, to 16,800, I would have really preferred they set it up with 2 8K axles instead of 7Ks but.. It does seem to work fine as is, I'm just not a fan of loading things right "to capacity", I like to have wiggle room in there. Thing is, a 7K axle doesn't "break" at 7,001 lbs of load, there's already wiggle room in the 7K rating, so, I guess if it works, why worry about it, right?
My gooseneck dump trailer is done the same way, FYI. 16K rating with 14K worth of axles. It also seems to work fine, but, same commentary as above applies.
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03-26-2020, 05:49 PM #10
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