Axle rating and GVWR

[Rugged Brown]

Looking for some understanding of the correlation between Axle ratings and GVWR. I am looking at a new travel trailer with axle ratings of 3500 lbs. The GVWR has a published rating of 7495 lbs. Should this be of concern? My thoughts are that the axle ratings should exceed the GVWR.

[A32Deuce]

2 axles and tongue weight should equal more then gross weight. Tongue weight should be 10 to 15 percent of gross.

[Rugged Brown]

Originally Posted by A32Deuce

2 axles and tongue weight should equal more then gross weight. Tongue weight should be 10 to 15 percent of gross.

The tongue weight is 581 lbs and the UVW is 5857 .


3500 x 2 = 7000 + 581 = 7581 which is more than 7495lbs.


so it could be an issue?

[A32Deuce]

2 axles@3500 each is 7000 lbs. plus 585 lbs. tongue is 7585 total. So you are under with a little wiggle room and more if you don't max out cargo weight.

[pdqparalegal1]

You will have to weigh the trailer as loaded to travel. Axles rated to carry up to 3500 # each total 7000.

What does the trailer actually weigh? Weight will be distributed between two axles and tongue. what percentage on each can vary wildly.

You said the GVWR has a published rating of 7495 lbs. .Empty trailer should be less than that. That number is the MOST you should load it to.
What does the sticker inside the cabinet say? Is there another sticker outside with weight information?

Bottom line is the axles don't carry ALL the weight of the trailer. The hitch carries some.
Safe travels.

[xd40c]

Loaded trailer weight minus tongue weight is what will be on the axles. This must be below 7000.

[dlink9368]

Originally Posted by Rugged Brown

The tongue weight is 581 lbs and the UVW is 5857 .


3500 x 2 = 7000 + 581 = 7581 which is more than 7495lbs.


so it could be an issue?

I can guarantee that the tongue weight will be a lot more than the published weight. The published weight on my 21fbrs is 446 lbs. but actual weight is 720 to 780 depending on how it's loaded ... and that's with empty fw tank

[Blucruz]

Originally Posted by Rugged Brown

The tongue weight is 581 lbs and the UVW is 5857 .


3500 x 2 = 7000 + 581 = 7581 which is more than 7495lbs.


so it could be an issue?

We need to know your actual loaded axle and tongue weights ready to go and hooked to the tow vehicle before this question can be answered correctly.
I would expect your tongue weight to be higher than 581# if you were anywhere close to GVWR unless you have everything loaded to the rear of the trailer.

[Airdale]

The trailer manufacturer is required by law to provide the following information. GVWR, total GAWR and a recommended tongue/hitch weight. When their recommended tongue weight is added to the total GAWR, the sum MUST be greater than the vehicle’s GVWR.

When the vehicle is sold the tongue weight becomes the responsibility of the new owner. Balancing our trailer loads is our responsibility.

You can ponder the manufacturers tongue weight recommendations and doubt them. They were developed via a computer model. They will work but an owner would be hard pressed to match the method used to get a perfectly balanced trailer. Remember, all water is cargo.

[MR.M]

Originally Posted by Rugged Brown

Looking for some understanding of the correlation between Axle ratings and GVWR. I am looking at a new travel trailer with axle ratings of 3500 lbs. The GVWR has a published rating of 7495 lbs. Should this be of concern? My thoughts are that the axle ratings should exceed the GVWR.

Yes it should be . seems manufactures love to push the limits . don't listen to the tongue weight argument . it goes that the tongue is carrying 10 to 15 % of the weight and puts in within limits . that maybe fine standing still but once you're rolling down the road there are times the TT axles and tires are carrying all the weight and then some . also if you use a WDH that puts extra weight on the TT alxes as well . so bottom line it the manufactures need to start putting axles and tires on that can safely carry the full weight and then some cushion to boot

[A32Deuce]

Subtract tongue weight from gross weight. What is left is the axle weight. That is what you need for wiggle room, the amount that's excess after loaded. You added tongue weight when you should have subtracted.

Originally Posted by Rugged Brown

The tongue weight is 581 lbs and the UVW is 5857 .


3500 x 2 = 7000 + 581 = 7581 which is more than 7495lbs.


so it could be an issue?

[A32Deuce]

Originally Posted by A32Deuce

2 axles@3500 each is 7000 lbs. plus 585 lbs. tongue is 7585 total. So you are under with a little wiggle room and more if you don't max out cargo weight.

7495 minus 581 plus 7000. That's your wiggle room weight.

[Airdale]

This is an excerpt from the standard, FMVSS 571.120, paragraph S10.2 which the trailer manufacturer MUST comply with.

"On RV trailers, the sum of the GAWRs of all axles on the vehicle plus the vehicle manufacturer's recommended tongue weight must not be less than the GVWR."


As I said before, once the trailer becomes the responsibility of an owner, so does the tongue/hitch weigh.

[A32Deuce]

What he was wondering about was the trailer gross was 7495 but the axles are only 7000 combined. He didn't realise the tongue weight of 581 lbs is subtracted and added the the tow vehicle capacity.

[Herk7769]

So how do you know?

Weigh your truck on a certified CAT scale loaded as you would going camping (Family aboard and a full gas tank) to get the steering axle and drive axle weights. First weight $12.00 Tell the attendant you are coming back for TWO re-weighs with the camper on.

If you are like me and the family hates the elephant walk to the CAT scale, then use ballast like a sand bag or two to represent their estimated weight.

Go back and get your camper loaded as you would be camping. Weight again THE SAME DAY. Re-weighs are $2.00 Leave the distribution bars on the trailer! This will give you the weight actually carried by each axle when you are traveling, BUT NOT THE TONGUE WEIGHT.

Get the new Steering Axle, Drive Axle, and Camper Axles weight.

Pull off the scale if there are trucks behind you; if not tell the attendant who will be listening for you to give him the "go ahead".

REMOVE the distribution bars from the trailer and drive back onto the scales! This will give you an actual tongue weight (the weight the tongue sees).

It is important to know the actual tongue weight; NOT the redistributed weight. The actual tongue weight is the weight the receiver and frame is going to carry and that is the truck's tongue weight limit in the books.

Get the new Steering Axle, Drive Axle, and Camper Axles weight with the bars off.

So now you have 3 weight tickets. What to do with them?

You should have the following numbers from the pillar of your truck.

FAWR - Front Axle Weight Rating (The MOST the front axle can carry)
RAWR - Rear Axle Weight Rating (The MOST the rear axle can carry)
GVWR - Gross Vehicle Weight Rating (The MOST that the sum of the axle weights can be)
GCWR - Gross Combined Weight Rating ( The MOST the sum of the axles in your combination can weight (Front + Rear + camper axles)

Camper GVWR - (The MOST the camper can weigh - the sum of the tongue weight and axle weights)
Camper Axle Weight - (the MOST each axle is rated for) NOTE: The Tire rating at the yellow sticker PSI MUST exceed the axle rating - usually not by a lot)

Gonna make up some numbers for a hypothetical truck and camper example. I will use my 2008 GMC 2500HD SWR Diesel for the truck numbers since I have them handy.

Truck

GVWR - 9200 pounds
FAWR - 4,500 pounds
RAWR - 6,048 pounds
GCWR - 24,500 pounds

NOTE: The sum of the axle ratings is NORMALLY more than the truck can safely carry. The GVWR is usually (but not always) the frame.

Camper

GVWR - 9,000 pounds
GAWR - 4,000 pounds Tandem (8,000 pounds total)

NOTE: A Travel Trailer's GVWR rating expects a minimum of 10% of the entire camper weight to rest on the hitch.

So, Off to the CAT SCALE.

Truck (loaded for camping) Only

Steering Axle Drive Axle Trailer Axle(s)
4,160 3,600 0

Total weight 7,760 pounds

Truck Plus Camper (WITHOUT BARS)

Steering Axle Drive Axle Trailer Axle(s) Combination
3,960 4,820 7,400 16,180

Camper Axles = 7,400
Gross Truck Weight w/camper = 8,780 pounds

Subtract truck w/o camper from truck w/camper = tongue weight.
8,780 - 7760 = 1,020 pounds

Camper weight = Tongue weight + axle weights
7,400 + 1,020 = 8,420 pounds


A properly loaded travel trailer's tongue weight will fall between 10% (tail heavy) and 14% (Nose heavy). The optimum for minimum sway is 12% of total camper weight on the tongue. Tail heavy trailers (less than 10%) will sway like crazy and can become unstable when passed by trucks or hit with a cross wind. Nose Heavy trailers will tough to steer due to weight being removed from the steering axle and will be a handful in a panic stop; having a tendance to swap ends.

In this case, 1020/8420 = 12.1% a perfectly loaded trailer

So that's why you need a weight distribution system to distribute that tongue weight OFF the rear of the truck and ONTO the steering and camper axles.

Truck Plus Camper (WITH BARS)

Steering Axle Drive Axle Trailer Axle(s) Combination
4,460 4,320 7,700 16,180

NOTE: With the weight distribution bars installed, SOME of the 1,020 pounds is moved OFF the rear axle and distributed to the steering and camper axles. In this case

200 pounds was distributed from the REAR axle and is now carried by the Front Axle and 300 pounds was distributed to the camper's axles.

NOTE: The the WD bars ON, you STILL need to make sure your axles ratings are not exceeded.

I hope this helped you.

For the math majors out there, I hope I did not screw up the "hypotheticals". I wanted the numbers so show as an illustration of HOW to do it; not an actual weight distribution scenario.

[Rugged Brown]

Thanks for all the great responses. I can always count on FRF to get the best info.


To offer some clarification of my concern, at this point I am not interested in towing or carrying capacity of the tow vehicle. I am just interested in the ability of the axles/springs to hold up to the weight of the camper. So here is my take away from your responses.


The GAWR of 7000 plus the published weight of the tongue of ~580 lbs will give the weight holding ability (new term WHA, remember I coined this term ) of the camper ~7580 lbs. The GVWR of the camper is 7495 lbs. Assuming that I loaded my camper to the maximum GVWR, this leaves only 85 lbs of wiggle room. To me, the GAWR is insufficient for the GVWR of the camper.


A further disclosure is that the product I'm considering is the Grand Design Imagine 2500RL. I know its not a FR product, but I have owned FR in the past, I'm a long time member of this forum and I always come her for the best information. HERK and some of the other guys and gals may remember from being a regular contributor a few years ago.

[HUNT N FISH]

Originally Posted by Herk7769

So how do you know?

Weigh your truck on a certified CAT scale loaded as you would going camping (Family aboard and a full gas tank) to get the steering axle and drive axle weights. First weight $12.00 Tell the attendant you are coming back for TWO re-weighs with the camper on.

If you are like me and the family hates the elephant walk to the CAT scale, then use ballast like a sand bag or two to represent their estimated weight.

Go back and get your camper loaded as you would be camping. Weight again THE SAME DAY. Re-weighs are $2.00 Leave the distribution bars on the trailer! This will give you the weight actually carried by each axle when you are traveling, BUT NOT THE TONGUE WEIGHT.

Get the new Steering Axle, Drive Axle, and Camper Axles weight.

Pull off the scale if there are trucks behind you; if not tell the attendant who will be listening for you to give him the "go ahead".

REMOVE the distribution bars from the trailer and drive back onto the scales! This will give you an actual tongue weight (the weight the tongue sees).

It is important to know the actual tongue weight; NOT the redistributed weight. The actual tongue weight is the weight the receiver and frame is going to carry and that is the truck's tongue weight limit in the books.

Get the new Steering Axle, Drive Axle, and Camper Axles weight with the bars off.

So now you have 3 weight tickets. What to do with them?

You should have the following numbers from the pillar of your truck.

FAWR - Front Axle Weight Rating (The MOST the front axle can carry)
RAWR - Rear Axle Weight Rating (The MOST the rear axle can carry)
GVWR - Gross Vehicle Weight Rating (The MOST that the sum of the axle weights can be)
GCWR - Gross Combined Weight Rating ( The MOST the sum of the axles in your combination can weight (Front + Rear + camper axles)

Camper GVWR - (The MOST the camper can weigh - the sum of the tongue weight and axle weights)
Camper Axle Weight - (the MOST each axle is rated for) NOTE: The Tire rating at the yellow sticker PSI MUST exceed the axle rating - usually not by a lot)

Gonna make up some numbers for a hypothetical truck and camper example. I will use my 2008 GMC 2500HD SWR Diesel for the truck numbers since I have them handy.

Truck

GVWR - 9200 pounds
FAWR - 4,500 pounds
RAWR - 6,048 pounds
GCWR - 24,500 pounds

NOTE: The sum of the axle ratings is NORMALLY more than the truck can safely carry. The GVWR is usually (but not always) the frame.

Camper

GVWR - 9,000 pounds
GAWR - 4,000 pounds Tandem (8,000 pounds total)

NOTE: A Travel Trailer's GVWR rating expects a minimum of 10% of the entire camper weight to rest on the hitch.

So, Off to the CAT SCALE.

Truck (loaded for camping) Only

Steering Axle Drive Axle Trailer Axle(s)
4,160 3,600 0

Total weight 7,760 pounds

Truck Plus Camper (WITHOUT BARS)

Steering Axle Drive Axle Trailer Axle(s) Combination
3,960 4,820 7,400 16,180

Camper Axles = 7,400
Gross Truck Weight w/camper = 8,780 pounds

Subtract truck w/o camper from truck w/camper = tongue weight.
8,780 - 7760 = 1,020 pounds

Camper weight = Tongue weight + axle weights
7,400 + 1,020 = 8,420 pounds


A properly loaded travel trailer's tongue weight will fall between 10% (tail heavy) and 14% (Nose heavy). The optimum for minimum sway is 12% of total camper weight on the tongue. Tail heavy trailers (less than 10%) will sway like crazy and can become unstable when passed by trucks or hit with a cross wind. Nose Heavy trailers will tough to steer due to weight being removed from the steering axle and will be a handful in a panic stop; having a tendance to swap ends.

In this case, 1020/8420 = 12.1% a perfectly loaded trailer

So that's why you need a weight distribution system to distribute that tongue weight OFF the rear of the truck and ONTO the steering and camper axles.

Truck Plus Camper (WITH BARS)

Steering Axle Drive Axle Trailer Axle(s) Combination
4,460 4,320 7,700 16,180

NOTE: With the weight distribution bars installed, SOME of the 1,020 pounds is moved OFF the rear axle and distributed to the steering and camper axles. In this case

200 pounds was distributed from the REAR axle and is now carried by the Front Axle and 300 pounds was distributed to the camper's axles.

NOTE: The the WD bars ON, you STILL need to make sure your axles ratings are not exceeded.

I hope this helped you.

For the math majors out there, I hope I did not screw up the "hypotheticals". I wanted the numbers so show as an illustration of HOW to do it; not an actual weight distribution scenario.

Excellent Post!

FWIW - I would add that, in my experience, a lot of people also do not understand the importance of the axle weight ratings on the TOW vehicle and even though being in compliance with the combined weight rating and the gross weight rating they are actually close to, or overweight on the TOW vehicle rear axle. Even with a WD hitch you might be overloaded on the TOW vehicle. Everything one puts in or on your TOW vehicle adds weight on the rear axle. Camper shells (..with boat or kayaks on top), bicycles, generators, firewood, extra tools, loaded ice chests, grandkids, dogs all add to the cargo weight. Then add in the trailer tongue weight (even with a WD hitch) and you may have just exceeded the rear axle weight rating.....

[JohnD10]

Not too mention that just because a vehicle has a tow rating of, let's say 10,500 pounds, DOES NOT MEAN that you can or should buy a trailer that weighs 10,500 pounds!