Weight math

[winojoe]

Just rented a trailer for my first adventure and would like to ask the community to check my math

Tow Vehicle:

Before adding trailer:

Front Axle: 2820 lbs
Rear Axle: 2800 lbs

After adding trailer:

Front Axle: 2640 (-160 lbs)
Rear Axle: 3880 (+ 1080 lbs)
Trailer Axle: 3000

Calculated trailer weight: 3900 lbs (Combined vehicle+trailer weight minus the vehicle weight before adding a trailer)_
Published trailer dry weight 3075 lbs.

I'm towing a 2020 Rockwood Geo Pro 19FBS.

New 2020 Forest River RV Rockwood GEO Pro 19FBS Travel Trailer - Off Road Package!

Forest River Rockwood Geo Pro travel trailer 19FBS highlights: Single Slide Rear Bath Queen-Size Bed Outdoor Grill Come see just how fun and easy camping can be with this Rockwood Geo Pro travel...

www.parrisrv.com

The dry weight is 3075 lbs and the published hitch weight is 413 lbs

I'm trying to estimate the actual tongue weight. If my math is right the tongue weight is 900 lbs, this sounds way out of line with the 10% rule-of-thumb number I've seen many times.

The trailer is lightly packed. All the tanks are empty. Has the accessories to hook up water and power, and the grey black water hoses. Has 2 full propane tanks (on the tongue) and two car-sized batteries on the tongue. Has kitchen supplies (all plastic and cheap). All storage bins are empty, fridge is empty.

Is it possible that by keeping the tanks empty I'm actually making matters worse? If the water tank is behind the trailer's axle then a full tank would reduce the tongue weight.

In any case, 900 lbs tongue is way beyond the rating of my vehicle, I might have to return the trailer.

Is my math wrong, something isn't making sense.

 

[TheLooks]

What is the tow vehicle and what is the payload?

 

[winojoe]

What is the tow vehicle and what is the payload?

There is no payload, The tow vehicle is literally empty other than a full tank of gas (it was full in both measurements above). There were no occupants in the vehicle at the time I weighed it.

 

[TheLooks]

That is what you are missing. What is your vehicle rated to haul? Not tow. You as a passenger are part of the payload.

 

[winojoe]

That is what you are missing. What is your vehicle rated to haul? Not tow. You as a passenger are part of the payload.

I'm not sure what difference that makes. it is rated to haul 5000 lbs with a 500 lbs tongue weight. Now that this is known, I still can't compute the actual tongue weight.

 

[TheLooks]

My Ram 3500 is not rated to haul 5000 lbs. What is your vehicle?

 

[TheLooks]

Do not confuse haul with tow....

 

[Rich W.]

Take it to the scales and you’ll know for sure. Vehicle on the scale, trailer off, and weigh the vehicle with the trailer connected and disconnected. That will tell you the actual (real) tongue weight.

 

[Kevin D Pem]

Yes!! You have calculated right!!! Why the trailer you rented has a 30% tongue weight is beyond me!!!
The weight is the weight with or without a driver. The information you gave is overkill, so this can lead to over analyzing things.

If I built a trailer that only had the proper tongue weight when loaded, I would get out of the business of building trailers. "Return it!!!".

 

[TheLooks]

Good lord Kevin, you went straight to the excessive tongue weight. But you have no idea what he is hitching it to. And he won't say. And he does not realize what payload and towing capacity are. I was trying to gently educate once I had enough info. I could care less what his front axle and rear axle are unless I know his wheelbase and ability to carry a load. But in the end the advice is correct, return the trailer or buy something that will tow it.

 

[winojoe]

Do not confuse haul with tow....

Thank you. Haul is what you put in the back of the pick up (usually a pick up). Tow is a trailer.

 

[winojoe]

Good lord Kevin, you went straight to the excessive tongue weight. But you have no idea what he is hitching it to. And he won't say. And he does not realize what payload and towing capacity are. I was trying to gently educate once I had enough info. I could care less what his front axle and rear axle are unless I know his wheelbase and ability to carry a load. But in the end the advice is correct, return the trailer or buy something that will tow it.

Greetings. I know the stats. I'm reluctant to say the tow vehicle because this thread wll become something I really don't want it to be.

I found a trailer that was advertised as 3300 lbs. Yeah, really close to the limit. I was hoping the tongue weight would be approx 350 lbs and, while I'm cutting it close, I'm technically okay (maybe a bit over weight). When I took it to the scales, I got some weird numbers, but this was my fault. The weight tag I used for the unhitched weight was an old tag and incorrect. Once I found the correct weight tag - which includes modifications to my tow vehicle - then everything made sense

I attached the OEM stats to this response

Actual trailer weight: 3620 (not 3300) - a little over (3500 is OEM max)
Calculated tongue weight: 620 lbs - way over (350 lbs is OEM max)
Rear Axle weight: 3880 which is 330 lbs over OEM max (ouch)

So, maybe I'll look for a trailer with the axle more in the middle so the tongue weight isn't so out of proportion with the trailer weight. I hear newer single-axle trailers tend to have axles more towards the rear. Not sure I understand why, I suspect it's because Americans drive too fast when towing.

 

[Rosy]

Greetings. I know the stats. I'm reluctant to say the tow vehicle because this thread wll become something I really don't want it to be.

I found a trailer that was advertised as 3300 lbs. Yeah, really close to the limit. I was hoping the tongue weight would be approx 350 lbs and, while I'm cutting it close, I'm technically okay (maybe a bit over weight). When I took it to the scales, I got some weird numbers, but this was my fault. The weight tag I used for the unhitched weight was an old tag and incorrect. Once I found the correct weight tag - which includes modifications to my tow vehicle - then everything made sense

I attached the OEM stats to this response

Actual trailer weight: 3620 (not 3300) - a little over (3500 is OEM max)
Calculated tongue weight: 620 lbs - way over (350 lbs is OEM max)
Rear Axle weight: 3880 which is 330 lbs over OEM max (ouch)

So, maybe I'll look for a trailer with the axle more in the middle so the tongue weight isn't so out of proportion with the trailer weight. I hear newer single-axle trailers tend to have axles more towards the rear. Not sure I understand why, I suspect it's because Americans drive too fast when towing.

If a manufacturer quotes the (dry) tongue weight of their trailer as 350 lbs, you can bet the real world tongue weight is going to be much heavier than that even before you've loaded up the trailer.

 

[MemoriesByTheMile]

It sounds like you have calculated tongue weight.
Your idea of putting more weight in the back of the trailer would help reduce tongue weight. Typical tongue weight targets given by the experts is 10%-15%.
A weight distribution hitch could also help transfer some of that tongue weight to the front axle, but is not always allowed or recommended by tow vehicle manufacturers. Some tow vehicle manufacturers will provide different tow and tongue limits when using a weight distribution hitch (WDH).

 

[Kevin D Pem]

Good lord Kevin, you went straight to the excessive tongue weight. But you have no idea what he is hitching it to. And he won't say. And he does not realize what payload and towing capacity are. I was trying to gently educate once I had enough info. I could care less what his front axle and rear axle are unless I know his wheelbase and ability to carry a load. But in the end the advice is correct, return the trailer or buy something that will tow it.

Yes!!! I get it! Renting is not the same as buying, and in the end the rental company is liable for mismatching!!! Maybe the poster will share his information, he did run across the scales after all!!!

 

[Kevin D Pem]

If a manufacturer quotes the (dry) tongue weight of their trailer as 350 lbs, you can bet the real world tongue weight is going to be much heavier than that even before you've loaded up the trailer.

Heaver yes but 300 percent? The trailer has to be towable empty, and clearly that one is not!

What comes to mind is the claim that equalizer systems are the cause of frame failures, clearly in this case the cause would be the build!!!

 

[Rosy]

Heaver yes but 300 percent? The trailer has to be towable empty, and clearly that one is not!

What comes to mind is the claim that equalizer systems are the cause of frame failures, clearly in this case the cause would be the build!!!

I agree there's something off with this trailer. I'm just thinking that OP is unlikely to find a travel trailer with a loaded tongue weight less than 350 lbs and, if he did, I'm not sure I'd want to tow it with any vehicle.

Maybe the OP needs a boat.

 

[Bigblockyeti]

Instead of calculating the tongue weight, why not actually measure it? You need only a 4' length (or greater) of 4x4, a bath scale and a brick just barely taller than the bath scale. A simple 5:1 ratio will be well within the limits of the bathscale and give you a number that's pretty darn accurate. I understand not wanting to disclose a 4 cylinder SUV but if it meets specs, don't worry about it. FWIW, if it were my owned tow vehicle, I would do this infrequently, if it's leased, drive it like you stole it (or poured a bunch of money into a vehicle with zero equity at the end). A cooked transmission 15K miles after it's turned in is someone else's problem.

 

[Voyageurs]

Our tongue weight decreases as we load the trailer. Almost all the storage both inside and outside is behind the rear axle. So are the two 6 volt AGM batteries. But our trailer is a European trailer built under license in the US. Lighter hitch weights are common there.

Our loaded weight with full fresh water is 3385 pounds.

Our loaded hitch weight with fresh water full is 340 pounds. The water affects it a tiny bit but the tank is pretty much over the axle.

2022 T@B400. Tow vehicle is a tesla model Y. Excellent well balanced combo. No need for a weight distribution hitch.