Wayfarer
Northeast Alabama
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Looking at getting a toy hauler. When looking at axle weights on 2-axle trailers I am concerned about the numbers. For example, looking at a Grand Design 351M, the GVWR is 16,800 lbs. Assuming a 20% hitch weight that would be 3360 lbs. 16,800 - 3360 = 13440 lbs on the axles. Two 7000 lb axles equal 14000 lbs. 14,000 - 13,440 = 560 lbs "margin" left on the two axles. What if you load the trailer to max but end up with less than 20% hitch weight. This just seems like the toy hauler is marginal for 7000 lb axles. This is true not just for the Grand Design but for other two axle trailers I have looked at.
This has got me looking at 3-axle tailer though I really don't want a 41 foot hauler. Most 3-axle trailers have a 20,000 GVWR so the 3-axles (7000 lbs each) alone could carry the weight and still have a 1000 lb "margin" not even counting the hitch weight.
Am I over looking something here? I know you could upgrade to 8K axles but the manufactures seem OK with 7K axles.
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jdc1
Rescue, Ca
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It's 13,800 (UVW) minus 2,785 (pin weight). That leaves you with over 5,000 for payload.
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fj12ryder
Platte City, MO
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I'm not really sure I understand your concern. Are you thinking you'll overload the trailer and exceed the GVWR? OTOH, if you do hit the GVWR, you most likely will be over on an axle because both axles rarely weigh exactly the same, so one could be light and one heavy. I have a triple axle and I have a difference of over 500 lbs. between a couple tires.
Howard and Peggy
"Don't Panic"
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Wayfarer
Northeast Alabama
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jdc1 wrote:It's 13,800 (UVW) minus 2,785 (pin weight). That leaves you with over 5,000 for payload.
You never tow the RV at the UVW. I always assume the GVWR when doing calculations.
Tom
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Wayfarer
Northeast Alabama
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fj12ryder wrote:I'm not really sure I understand your concern. Are you thinking you'll overload the trailer and exceed the GVWR? OTOH, if you do hit the GVWR, you most likely will be over on an axle because both axles rarely weigh exactly the same, so one could be light and one heavy. I have a triple axle and I have a difference of over 500 lbs. between a couple tires.
I am concerned about overloading the axles as you described. I feel there is not enough margin with 7K axles and 16.8K GVWR or even a little less than the GVWR.
Tom
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Second Chance
Wherever...
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nineback wrote:fj12ryder wrote:I'm not really sure I understand your concern. Are you thinking you'll overload the trailer and exceed the GVWR? OTOH, if you do hit the GVWR, you most likely will be over on an axle because both axles rarely weigh exactly the same, so one could be light and one heavy. I have a triple axle and I have a difference of over 500 lbs. between a couple tires.
I am concerned about overloading the axles as you described. I feel there is not enough margin with 7K axles and 16.8K GVWR or even a little less than the GVWR.
Tom
On the Solitudes, Grand Design is now offering a factory upgrade to 8K axles and disc brakes (with LR H tires). You might check and see if the same option is available on the Momentums.
Rob
U.S. Army retired
2020 Solitude 310GK-R
MORryde IS, disc brakes, solar, DP windows
(Previously in a Reflection 337RLS)
2012 F350 CC DRW Lariat 6.7
Full-time since 8/2015
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Huntindog
Phoenix AZ
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Second Chance wrote:nineback wrote:fj12ryder wrote:I'm not really sure I understand your concern. Are you thinking you'll overload the trailer and exceed the GVWR? OTOH, if you do hit the GVWR, you most likely will be over on an axle because both axles rarely weigh exactly the same, so one could be light and one heavy. I have a triple axle and I have a difference of over 500 lbs. between a couple tires.
I am concerned about overloading the axles as you described. I feel there is not enough margin with 7K axles and 16.8K GVWR or even a little less than the GVWR.
Tom
On the Solitudes, Grand Design is now offering a factory upgrade to 8K axles and disc brakes (with LR H tires). You might check and see if the same option is available on the Momentums.
Rob It is. I just got my 398M
Three 8K axles/ Cooper LRH tires/ disc brakes.
GVWR went from 20K to 21K (limited by the 21K pinbox)
The brakes alone are well worth it.
Huntindog
100% boondocking
2021 Grand Design Momentum 398M
2 bathrooms, no waiting
104 gal grey, 104 black,158 fresh
Full Body Paint, 3, 8K axles, Disc Brakes
17.5 LRH commercial tires
540 watts solar,
2020 Silverado High Country CC DA 4X4 Big Dually.
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arhayes
Texas
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First, I think you will find the pin weight on a loaded TH will be much higher than 20%. My GD 380TH 2 axle actual weight is 19,400lbs with a pin weight of 4,250lbs. That means the 2 8k axles are carrying 15,150 lbs. They have done so just fine for 6 yrs and 52,000 miles.
I have only been involved with RV ownership for those 6 years, but have never seen anyone post that an axle has failed. I’m sure it can happen....I’ve just not seen it. YMMV.
Alan and Kathleen
2015 Grand Design Momentum 380TH (RVD2)
2014 F350 6.7L Diesel DRW (Stormtrooper)
2012 Honda Goldwing NAVI/ABS (Land Speeder)
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Mike134
Elgin
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nineback wrote:
Am I over looking something here? I know you could upgrade to 8K axles but the manufactures seem OK with 7K axles.
Nope the trailer manufactures cut it that close. My TT has a GVWR of 7700lbs with 2-3500lb axles. When I called they said the remaining load is carried by the tongue. Wasn't there a rock song about living in the edge?
2019 F150 4X4 1903 payload
2018 Adventurer 21RBS 7700 GVWR.
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Wayfarer
Northeast Alabama
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Interesting. The current Grand Design RV in your weight range are 3-axle. They have a 17000 lb TH with 7K axles. I've looked at Road Warriors and others and anything above 17K is 3-axles. Your pin weight is 22%. With the 8K axles you still have almost 1000 lbs in "margin". That is much better than the 560 lbs on the trailer I used as an example. I wish dealers would put 8K axles on the larger 2-axle RVs now.
arhayes wrote:First, I think you will find the pin weight on a loaded TH will be much higher than 20%. My GD 380TH 2 axle actual weight is 19,400lbs with a pin weight of 4,250lbs. That means the 2 8k axles are carrying 15,150 lbs. They have done so just fine for 6 yrs and 52,000 miles.
I have only been involved with RV ownership for those 6 years, but have never seen anyone post that an axle has failed. I’m sure it can happen....I’ve just not seen it. YMMV.
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