Answering "How Much" Questions

[jerem0621]

Sorry for this long and wordy post... I am looking for some feedback on a little project I have been working on today. Kind of a sick day for me... so I have taken the down time to try and be productive.

One of the questions many people ask in the TT, Fiver, and TV's forums is how much can I tow? Really this is two questions in one.... How much you can tow (trailer weight) is directly related to how much can you carry (payload).

I have created some charts, in an effort to help some out with correctly answering, how much can you tow and carry at the same time.

After one arrives at an understanding that their vehicle must not only tow but must also carry the tongue/pin weight... the next question is... how do I know how big of a trailer I can tow without overloading my TV? After all the tow rating is often MUCH higher than how much payload the truck has available.

Now the charts, and I wanted to ask the forum if these make sense.. if they are useful... or should be scrapped?

Basically, you take your available payload and based on the rule of thumb 13% tongue weight for TT's or 25% pin weight for fivers you get an APPROXIMATE max trailer weight... of course if your tow rating is lower than what the chart says is a match for your available payload or your GCWR is lower then the LCD rules in this number games.

Here are the charts

How to calculate available payload



Travel Trailers



Fifth Wheels



Are these useful, worthless, can be improved?

Thanks for the feedback in advanced.

Jeremiah

[hawkeye-08]

Put a disclaimer paragraph to exclude the things that the tables do not work for...

[jerem0621]

Ron Gratz wrote:

blt2ski wrote:
Ron has a formula that works fairly well, probably 50-75% of the time for how much wt is pulled off the FA depending upon overhang etc. The issue I see with it, is it does not take into account the different spring rates of vehicles. OR if it has a self leveling system. These items in my experience do effect how much wt is taken off the FA. Some times a bit more, some a bit less. IT is a reasonably good start.

Actually, Ron has a formula which works quite well all the time -- as long as the measurements are properly made.

If you have scales data and vehicle dimensions which show that load removed from the front axle is dependent on spring rates, please post the information.
I have many scales data reports which show the formula is equally valid for SUVs and HD trucks.
Please refer to this post for details.

Ron

Thank you both for contributing these details!

Thanks!

Jeremiah

[Ron_Gratz]

blt2ski wrote:
Ron has a formula that works fairly well, probably 50-75% of the time for how much wt is pulled off the FA depending upon overhang etc. The issue I see with it, is it does not take into account the different spring rates of vehicles. OR if it has a self leveling system. These items in my experience do effect how much wt is taken off the FA. Some times a bit more, some a bit less. IT is a reasonably good start.

Actually, Ron has a formula which works quite well all the time -- as long as the measurements are properly made.

If you have scales data and vehicle dimensions which show that load removed from the front axle is dependent on spring rates, please post the information.
I have many scales data reports which show the formula is equally valid for SUVs and HD trucks.
Please refer to this post for details.

Ron

[blt2ski]

Overhang will be an issue with Type A and C motor homes. ALONG WITH many pickups with campers that the owners put extensions on the hitch, so they can hook up ORC trailers, many of which are surge brakes. This can be both enclosed or open trailers. Boats are another commonly towed trailer within the RV industry.

THere are probably a higher % of Surge brakes than one wants to think or believe. This potential issue needs to be thought about, if one is going to put together a "BEST practice Towing guide". Pintle hitches are probably not going to be found in any great numbers in the RV industry. Construction or related towing industries, probably a lot. But if someone in that industry is looking for "Best Practice towing", they might look at an rv site to get the info via search engines etc. So some of the issues within this type of towing, should at least be mentioned, or thought about!

One should also look at it from a legal prospective. A Type A motor home with a manufactures GAWR of 25K lbs, does not get to run down the road legally at 25K lbs. They only get 20K lbs on it! There are a few instances where upwards of 22K can be put an individual axel, not sure that would be in the RV industry.

If Jerome or anyone wants to put out guidelines, charts, excel programs etc, with this info, it should attempt at including many of the minor things that can make or break a person in how well they may or may not tow things within the RV industry! Assuming this is aimed at ONLY the RV industry.

Ron has a formula that works fairly well, probably 50-75% of the time for how much wt is pulled off the FA depending upon overhang etc. The issue I see with it, is it does not take into account the different spring rates of vehicles. OR if it has a self leveling system. These items in my experience do effect how much wt is taken off the FA. Some times a bit more, some a bit less. IT is a reasonably good start.

Marty

[LarryJM]

jerem0621 wrote:
Thanks for the feedback Marty..

How do we quantify this into terms that people can understand about the impact of overhang? Maybe just speak to the use of WD, This isn't really designed to be a how to adjust my WD hitch kind of instruction. I could simply link to the WD set up page.

But this issue of overhang... Hmmm.. Going to have to noodle that one for a while.

Thanks!

Jeremiah

Unfortunately as usual the two scenarios of pindle hitches and surge brakes are for the most part not found on TTs or those with TWs high enough for WDH considerations. They might be more common in the utility area, but are simply IMO not germane and therefore are more of a red herring here and just muddle the issue. I could be wrong, but IMO overhand has more to do as a consideration as it pertains to the TV WB and weight due to the longer lever effect with respect to YAW forces. The one case I can think of where this could become more of an issue is in the shorter WB old style now extended FORD Van when lightly loaded towing at it's tow limits or close there to.

Larry

[jerem0621]

Thanks for the feedback Marty..

How do we quantify this into terms that people can understand about the impact of overhang? Maybe just speak to the use of WD, This isn't really designed to be a how to adjust my WD hitch kind of instruction. I could simply link to the WD set up page.

But this issue of overhang... Hmmm.. Going to have to noodle that one for a while.

Thanks!

Jeremiah

[blt2ski]

Something you have not done, nor has anyone else that I have seen trying to do these calculators. Lets assume 4 or 5 equal gvwr tow rigs, all towing the same trailer, all have the ability to carry a 1000 lbs hitch/pin wt.

One is a 15 passenger Ford van. That very long overhang, 7-9' or so, this will take a bit of weight off the front,will swag say 400-500 lbs, added to the rear axel, potentially overloading the rear, causing some handling issues.....

A typical pickup, has around 5', so maybe 200-300 lbs off the FA, added to the rear, not as bad as the Ford van.....still some issues.

Some SUV's actually have a semi short overhang of 4', still better yet to a degree.

A rig setup initially as a cab and chassis, may have its hitch as little as 3' in front of the rear axel. Giving it the least wt added to the rear via wt off the front. Probably the best potential handling rig for a ball mount setup. This might be as little as 100 lbs or so off the FA. Reality, for a typical 8 lug truck, not an issue! Some of the 5 or 6 lug rigs, with softer suspensions, this drop, removal of weight off the FA may be more. Different legnth wheel bases can also effect how much is off the FA.

Then if you include a 5w/gooseneck right over the axe to just in front, you have 95-100% of the HW going to the rear, nothing taken off the front.

I know some will say with the ball mounts, that is what a WD system is for. BUT in some cases, a WD will not work. IE a pintle hitch. I have heard of one that might work. Surge brakes is another that is not normally recommended with a WD system. So these two rigs will have potential handling issues. Still under gvwr and maybe under an RAWR.

While charts etc are good, they do have places that will not always work if you look at just the numbers per say. While I realize I have probably thrown a monkey wrench in the program. One needs to keep things like this in mind when choosing a rig for a given trailer size etc, along with the basic numbers.

Marty

[jerem0621]

Thanks for the feedback!

I edited the above post so it is the final version... All I did was take out part where I was asking for an evaluation. I will hyperlink to the post above in my signature. I really appreciate all the feedback, and it's great to hear that it IS helping folks put the pieces together.

Thanks!

Jeremiah

[getontheroad]

This is a great way to explain this. I have looked at weight calculators in many different forums for both TT and 5vers. Sent a question on the forum just last week.

I NOW UNDERSTAND....You taught me something today...thank you for that!

No offense to all...the help and responses I received were awesome and I somewhat understood, but everything was still so confusing. A picture is worth a thousand understandings!

[jerem0621]

Thanks Barney, that means a lot to me.

Jeremiah

[BarneyS]

Jeremiah,
I have sent a message to the General RVing forum moderator about your thread. I suggested he probably should include it in our forum FAQ and it will probably be linked there in section 4b or 26 sometime in the near future. Good job and thank you. 🙂
Barney

[jerem0621]

Marquette, thank you for the feedback.

Yes, is seems that you have accurately read the chart. A 4000 lb fifth wheel will have about 800 - 1000 lbs of tongue weight...typically.

Thanks!

Jeremiah

[marquette]

I'm the guy you wrote the post for. I'm looking for a 5th wheel that a F150 can tow. For a little backgound we are looking to upgrade from our current camper which is a converted 6x12 V-front cargo trailer. Nothing special but has worked well for the last 5 years. The Scamp 19ft 5th wheel sounded good to us. We couldn't find a used one to look at so we drove up to the factory in Backus, Mn. to look at one. Nice people and very helpful but in the discussion about what truck can pull them the salesman said the one we had just looked at had about a 3000 lb dry weight. Whoa this is a long ways from the 2100 lbs in the brochure. 2100 lb doesn't include refrigerator, battery, bathroom, ect. But we decided to look for a used one anyway. However as we scouted online we found several 18-19 ft traditional 5th wheel trailers from the 1990's that are considerably cheaper than a used Scamp. From what I can tell from various online sites they have a appox dry weight of 3000 lbs and a gross weight of 3800-4300 lbs. If I am reading your chart right and the online calculator linked in one of the posts my 2001 F150 would be right on the border of safe giving no margin for safety. I took the 1500 lb cargo weight and subtracted me, my wife, 2 dogs, hitch, fuel, and 100lbs assorted stuff and came up with just under 800 lbs. 4000 lb gross trailer weight would have a 800 lb pin weight at 20%. Hopefully I missed something in my calculations and am wrong because if not that would make almost any 5th wheel impossible to safely tow with my F150. As I said in the beginning of my post I'm the guy you wrote the charts for. Either they are clear enough for a dummy to understand or you have your first dummy that couldn't understand them.

[jerem0621]

A question that is often asked on this forum is how much can I tow?

While this question does not have a simple answer there are some tools you can use to help understand the variables to accurately answer this question for yourself.

I must warn you right off...many people are shocked to find that their tow vehicles can't safely tow trailers that may be under their manufacturers tow ratings. Be prepared for that reality...

The Lowest Component Capacity is the component in your towing system that runs out of capacity first... that is your real limit.

First, you need to do some homework... big time homework... and get familiar with a lot of terms and equipment.

Note: This should be REQUIRED READING for anyone new to towing (or to get freshened up on your terms and understanding)

Click on this Link to U-Hauls Towing Glossary and READ EVERYTHING... read every single link.. then read it again.. make sure you understand the concept of these terms and the equipment listed in this link.

Now... We need to find out how much your available payload for your vehicle is and how much your excess axle capacity is.

Determining Available Payload and Axle Capacities

Take a look at this chart and plug in your answers on a separate piece of paper



Now that you know how much payload you can carry in addition to your family we need to find out how much of a LOADED trailer you can tow with your current vehicle AND carry the tongue weight or the fifth wheel pin weight.. depending on the type of RV you prefer.

Remember, nobody tows an empty RV to the campground...FORGET about unloaded trailer weights in the Brochure... Add at least 1000 lbs to 1500 lbs to the unloaded weight of the trailer you are looking at.. that will give you a closer approximation to the loaded trailer weight.

Rules of Thumb

When Guesstimating travel trailer tongue weight or fifth wheel pin weight, without weighing the actual trailer we can use a "rule of thumb" to give us an approximation to the likely heaviest tongue weight or pin weight the trailer will have.

For travel trailers the rule of thumb generally is 13% of the LOADED trailer weight will be the trailer tongue weight

For fifth wheels the rule of thumb generally is 25% of the LOADED trailer weight will be the trailer pin weight

I will be the very first to admit that not all Travel Trailers have 13% tongue weight... some have 10%, some have 16% or more. Not all fifth wheels have 25% pin weight, some have 19% or 22%... etc. etc... the purpose is to give you a general idea of a likely weight of trailer you can safely tow without overloading your Tow Vehicle.

The charts below let you take your available payload... and/or your available rear axle capacity and see how large of a TT or Fifth Wheel you can tow AND carry the tongue weight using the above rules of thumb.

Travel Trailers



Fifth Wheels



Don't forget Your Gross Combined Vehicle Weight Rating(GCVWR)

This number should be in your owners manual.

Add your loaded vehicle weight and the loaded trailer weight that you are considering together. This number is the gross combined vehicle weight... is this number UNDER the number in your manual? Yes? GREAT!... No? You need to look for a lighter trailer that will fall under this Gross Combined Vehicle Weight Rating.

Need to know how much a trailer tongue/pin weight will be with a different %?

We have a chart for that 😉

and lost of disclaimers.. etc etc etc



Max Trailer Tow Rating

One situation that some operators run into, especially with dually, HD pick up trucks is that they have enormous amounts of payload... so using the chart above they could just about pull the moon...

Not so fast.... there is still the trailer tow rating...

so even with enormous payload ratings.. the trailer tow rating should be complied with.

Finishing Up

If you can tell from all the math and the numbers above the real limit to how much you can tow is the component that runs out of capacity first.

I will call it LCC (Lowest Component Capacity)

• If you run out of payload then this is the LCC
• if your rear axle runs out of capacity then this is the LCC
• if you run out of receiver capacity then this is your LCC
• if you run out of GCVW rating then this is the LCC
• if you run out of trailer tow rating then this is the LCC
• if you run out of tire capacity then this is the LCC

DISCLAIMER: This is free advise...I am not a professional trainer in any position to CERTIFY your rig as good to tow. Its YOUR job as the vehicle operator to ensure that your Tow Vehicle, Hitch, and Trailer all all matched together properly, maintained properly, and the rig is operated sensibly.

DISCLAIMER 2: ... You and ONLY You as the operator are responsible for the safe operation of YOUR vehicle.

Thanks and see you on the open road!

Jeremiah