The 80% tow rule. Where did it come from?

[purman]

Wayne,

What you say makes good sense and I can live with that answer.

[AlbertF]

Originally Posted by purman

I think this may be key " results could vary depending on the way you were using the vehicle."

Some TV may work better than others with the same tow capacity. when or when not maxing out the Tow capacity. As pointed out by Jack..

Also as Gene pointed out sway control and equalizing hitch is key.

And those guys in Canada have had very good success with setting up TV... No matter what people my think..

The manufacturers' numbers are recommendations. As the Swedish engineering student essentially said, there is no way they can anticipate different circumstances and combinations. In my experience, at 60 mph on a level highway a 5500 lb Airstream tows easier than a 1500 lb 6x10 enclosed cargo trailer. The Airstream also handles much better, and stops a lot more readily.

In the end, only results and experience will tell what works. Recommendations and ratings are only guidelines to ensure that people are generally safe, and that customer's expectations are generally met.

[Druupy]

You are missing the point.
You get an airstream to;
Look cool
tow fantastic, aerodynamic, independant suspension - with shocks.
and be COMFORTABLE, "did I say that out loud?"

Comfort.

I don't tow at 80% listed limit.

I tow at 50% listed limit.

The only thing I worry about when towing is someone looking at the rig for toooo long and driving into me.

If you have to wory about wether the tow vehicle will do the job,
"we ain't havin fun".

Yes, you can tow a 12,000# boat/trailer with a toyota pickup w/2000 cc motor.
Been there, done that.

Comfort while camping, and relaxation have the same meaning.

Yes, get a small van, pull a big trailer, but I don't think it would be fun.

The goal is fun, relaxation, enjoyment.

[carlvs]

We just picked up our first RV ever. I think we made the right choice to pick an AS.

I had a lot of concerns after I put my deposit down and before I picked up the trailer.

We too have the new model Toyota Sequoia with Tow package. We called with the techs from Toyota and they told us that the towing capacity was plenty to tow the AS 25FB international 09. Toyota told us the 80 % rule is an old wives tale. Even for us in the foothills in Colorado we could maintain the total towing capacity as our real tow capacity.

Now on the payload... when I started looking at those numbers... that really got me concerned. I have only ~1250 lbs available as my payload. My trailer hitch weight is ~800 which leaves 450 for my 2 dogs (125 lbs each) and my wife and myself.
I think my payload is at the 110/-20 level.

We had a Equal-I-zer installed but I think that didn't help. It seems that the ball was installed way low. They put in about 10 washers.. I'll go and re-install the thing myself before I will do any serious towing.

Anyway, we did make it home. Pulling our first ever travel trailer. All the way from Tampa, Florida to Littleton, Colorado (1900 miles). Most freeways we drove ~ 70 mph even over the mountains around Chattanouga, TN.

Our MPG dropped from 17.2 to 9.8 (no trailer to trailer).
We pulled ~90% of our max and 110% on the payload, and we did not feel that we were reaching our limits yet. The steep uphills the car was in 3rd and 4th gear but we were never forced to slow down because the TV couldn't pull it.

[ROBERTSUNRUS]

Hi, the 80% rule is an American invention; Americans tend to want to max out everything. My trailer will hold about 850 lbs of junk, but I know I will never need to carry that much weight inside of my trailer. People on this forum have stated that their trailer weighs at, or more, than it's rated GVWR. What are you carrying in your trailer? These must be the people who buy those cast iron cook wear sets at Camping World. Same with their tow vehicles, maxed out. I like the idea that I can't carry so much useless stuff in my trailer or tow vehicle. We don't need to carry six months worth of water and drinks with us. Bring about a weeks worth and stop at Wal-Mart and buy more on the road. I would like to know what people who have a 25'er that is rated 1,000 lbs higher than mine put in their trailer to max it out. Everything we bought for our trailer and many things we didn't had to do with it's weight.

My tow vehicle is rated to tow 8,900 lbs and my trailer is rated at 6,300 lbs. And this is where I like it.

[ROBERT CROSS]

We surely pack differently when the objectives warrant.

We will be leaving shortly for two weeks of 'dock'n at the Lake, this requires a lot more "stuff" be included. Boat, motor, fishing gear, storage tents, generator, chairs, grill, etc..etc. Thankfully some of this "stuff" can be put in the Burb, which is still under it's load carrying rating. Under these circumstances we are at or above the GVWR of the AS. I would feel a little more comfortable had AS installed 4000lb axles rather the 3500's. (GVWR of the Classic, 7300lbs). The mitigating factor here is these trips are usually under 1500mi round trip.

On sightseeing excursion's we are well under the GVWR of the coach. I would assume this is true for most of us.

Different strokes for different Streamer's.

[Road Ruler]

Many years ago up in Northern Ontario 5 guys hooked up their trailer and gear, piled in the cab of their pickup truck, and started out down the highway.

It was a tight fit with those 5 burly guys and the driver had trouble handling the rig.

He finally pulled over. They drew straws and the looser got tossed out on the side of the road and got left behind.

Now with only 4 guys in the cab (80%) there was room enough to carry on in relative safety.

Sorry folks, getting married in a a couple hours and getting a little punchy..lol

[Boondocker]

I do not know where that guideline came from, and I do not claim to be a gear head. Having said that, here is why I think it is a good idea.

To start with, I am pretty sure that the towing capacities are determined under fanciful conditions (sea level, flat, no need for sudden stops, ect). So it might be the case that under optimum conditions, you can safely tow the payloads advertised.

On the other hand, I tow well above sea level (less O2 = less power), in somewhat less than even terrain. All to often this involves starts that are up steep inclines, and stops on the other side. It can involve sudden stops for wildlife or maneuvering around bikers. Add to this, weather conditions can further add to the challenge. Even at lower elevations there are challenges. On the plains winds can be an significant challenge. When I was towing with my 91 F150, it was not uncommon to be reduced to 40-45 mph ON THE FLATS by wind. Even with my powerstroke (which incidentally is WAY over powered for the job) I notice the wind.


So, while it is sort of true that you can get the maximum tow rating out of a vehicle under optimum conditions, real world towing presents less than optimum situations. Traveling with marginal equipment exposes you to increased chance of mechanical failure. Its like heading out on the road with exactly the amount of money needed for food, camping, and entrance fees; you technically have enough money- provided absolutely nothing goes wrong. I have traveled with a marginal tow vehicle, and with marginal money. In my opinion, it is far, far better to have more vehicle capacity and more money than actually required for a trip planned on the margins.

[purman]

Originally Posted by carlvs

We just picked up our first RV ever. I think we made the right choice to pick an AS.

I had a lot of concerns after I put my deposit down and before I picked up the trailer.

We too have the new model Toyota Sequoia with Tow package. We called with the techs from Toyota and they told us that the towing capacity was plenty to tow the AS 25FB international 09. Toyota told us the 80 % rule is an old wives tale. Even for us in the foothills in Colorado we could maintain the total towing capacity as our real tow capacity.

Now on the payload... when I started looking at those numbers... that really got me concerned. I have only ~1250 lbs available as my payload. My trailer hitch weight is ~800 which leaves 450 for my 2 dogs (125 lbs each) and my wife and myself.
I think my payload is at the 110/-20 level.

We had a Equal-I-zer installed but I think that didn't help. It seems that the ball was installed way low. They put in about 10 washers.. I'll go and re-install the thing myself before I will do any serious towing.

Anyway, we did make it home. Pulling our first ever travel trailer. All the way from Tampa, Florida to Littleton, Colorado (1900 miles). Most freeways we drove ~ 70 mph even over the mountains around Chattanouga, TN.

Our MPG dropped from 17.2 to 9.8 (no trailer to trailer).
We pulled ~90% of our max and 110% on the payload, and we did not feel that we were reaching our limits yet. The steep uphills the car was in 3rd and 4th gear but we were never forced to slow down because the TV couldn't pull it.

I tow with the same TV, make sure your ball in the right height. If it's not the equalizer won't work like it should. Find out the tongue height of your trailer and start there. Most trailers are 19.5 inches, well mine is... after the new axles.

I also have no problems pulling and have never seen the transmission temp gage or water temp gage go up, even pulling the mountains in 100+ temps in Ca and NV and UT.

[richinny]

i think it came from a person that was trying to give a guide "rule" for a condition that has hundreds (maybe more) of variables. you also have to consider the provider of the information. a truck manufacturer it trying to sell as many vehicles as possible. the person paying for insurance claims would likely underestimate the towing capacity.

it might be like speed advisory signs in that limits are for the best of conditions. if anyone is the author of the rule, let us know!

[Gene]

carlvs, check out this thread about Equalizer hitches, especially posts 13 and 14.
http://www.airforums.com/forums/f464...ort-34484.html

Then if you don't have the instructions, download them from the company website and you can call them and talk it over with an engineer. I took a long, long time trying to understand the dynamics of that system and too many hours adjusting it. It was a real pain figuring and doing, but the trailer rides much better. The dealer did a poor job setting it up. The height of the ball is tricky—Airstream in its owner's manual recommends one height, Equalizer's instructions another. The Equalizer people will now recommend equal height in relation to the tongue connection—I found that too low. Ball height determines (mostly) how level the trailer is; other adjustments determine weight distribution. It is a dynamic process and to get everything "perfect" is impossible for most set ups. A level trailer is more important than perfect weight distribution (i. e., equal compression of front and rear truck suspension) and getting the bars parallel to the tongue. It's a puzzle with many variables to adjust. In this thread, posts 153, 156-157, I described my experience: http://www.airforums.com/forums/f42/...s-47817-2.html

It's best to do it yourself because over time you may have to readjust it or reinstall for another truck or trailer. Or, if someone else does it, you have to watch them to make sure they do it right. Dealers have little incentive to spend the time to get it right.

Jason brings up another point—watching the engine and transmission temp gauges to determine what's happening under the hood. Like his, mine never change with one exception—I think the engine temp. moved maybe 10˚ to the hot side of center. But that was on Vail Pass when I was driving too fast, probably in a hurry, and the gauge was still pretty much in the middle. The point is, some vehicles have better cooling systems than others. I was reading the other day how certain Chevys have a small transmission cooler behind the bowtie—the bowtie restricts flow. How to fix this was far more complicated than I would have thought. Unfortunately, I have no idea where or what thread it was in. So, you have to read a lot to figure out cooling needs and after a while may be able to identify which vehicles have chronic cooling problems.

Tow ratings could be fine until that big engine overheats or the transmission fluid starts boiling off while going up a long, steep grade.

I've learned a lot since I got into this and will still be learning for years to come. It isn't only 80/20 or 85/15 or whatever rule or recommendation, but cooling, hitches, how much cargo you carry, and how you drive the thing.

Gene

[AlbertF]

Originally Posted by Road Ruler

Sorry folks, getting married in a a couple hours and getting a little punchy..lol

Congratulations to you and your bride!

[truckasaurus]

I kind of assumed it was tied in to Pareto distribution somehow.

Pareto principle - Wikipedia, the free encyclopedia

If there are 100 units of towing allowed then by never getting into the "risky" top 20 you are somehow able to relax more. On the other hand, to me, it's like saying 95% of car accidents occur when tire tread is down to 5%, that may be the case but it doesn't hold true that the low tire tread caused the accident.

So what I'm saying is that 80/20 is just a common ratio that is applied to many things and it's about as accurate as saying restaurants spend 80% of the budget on steak and 20% on potatoes, there's some basis for the statement but it's far from accurate.

[Freeheel]

I wonder if there is any implication on auto insurance or personal liability if you tow close to or above any of your vehicles stated capacities?

FWIW we've managed to shed enough weight on our rig to get from >100% of our GVWR (I'm embarrassed to say ) to about 85% and that's that absolute best I can do. The biggest single change was removing our Leer canopy for the summer which amounted to a whopping 340lbs weight savings and an immediate and noticeable improvement on overall driving performance. So I'd say that every bit certainly counts.

[87MH]

Originally Posted by CrawfordGene

...Jason brings up another point—watching the engine and transmission temp gauges to determine what's happening under the hood. Like his, mine never change with one exception—I think the engine temp. moved maybe 10˚ to the hot side of center. But that was on Vail Pass when I was driving too fast, probably in a hurry, and the gauge was still pretty much in the middle. The point is, some vehicles have better cooling systems than others.....Tow ratings could be fine until that big engine overheats or the transmission fluid starts boiling off while going up a long, steep grade....

On the subject of "stock" tranny and water temp gauges on 2000 to current Ford products, (at least the HD and Excursion lines), the gauges are little better than idiot lights.

It is often said (on Ford product related Forums) that you can only believe three indications on either gauge:
cold, normal, and too-late-you've-already-toasted-it.

Many of the Ford forums participants who regularly tow have installed digital type readouts that give a real up-to-the-second readout of the temps in question. There is no doubt that the algorithims that Ford builds into the stock gauges are not giving a true linear reading of the actual temps in the tranny or the water system.

Anyone who is "on the edge" on towing capacity (80%+ ???), or towing in really tough areas should certainly consider aftermarket gauges. Just to the West of Houston there are multiple 7* grades that will test an engine/tranny setup in the 106* weather we are currently enjoying.

Bottom line - you cannot believe the stock gauges for accurate instantaneous readings.

[87MH]

Originally Posted by Freeheel

...FWIW we've managed to shed enough weight on our rig to get from >100% of our GVWR (I'm embarrassed to say ) to about 85% and that's that absolute best I can do. The biggest single change was removing our Leer canopy for the summer which amounted to a whopping 340lbs weight savings and an immediate and noticeable improvement on overall driving performance. So I'd say that every bit certainly counts.

Every bit certainly does count, and the only way to know exactly where your starting point is to go to a CAT scale early morning on Saturday or Sunday (slowest days - here in SE Texas, anyway) and drop an Andrew Jackson on an accurate weigh and a half a dozen or so reweighs. Doesn't take all that long to do, a couple of hours at the most, and besides knowing how much more water you can afford to carry (or how much "stuff" you need to part with) you can get an accurate measure on three or four "link" take-ups on the weight distribution bar chains.

After getting individual axle weights on the unhitched trailer and Tow Vehicle (TV) it's easy to position the hitched vehicles to get subsequent total weights on the trailer axles (trailer axle pad) the rear TV axle (driving wheel pad), and the front TV axle (steering axle pad) while adjusting the weight distribution bar link chains between weighings. You have to drive on and off of the CAT between subsequent weighs so that the scales can re-zero.

It will probably take two separate weighs to get an accurate weight on the trailer's individual axle and the hitch - the CAT pads are spaced such that I have not even able to get close to getting all three weights from one weigh on any scale I have weighed on. Remember to position the jack such that the hitch is exactly the same height when standing free as it is when you have the weight distribution bars cinched up to your "normal" towing set-up.

I have been amazed on numerous occasions how much heavier cars, trucks, and trailers are than their "published" weights. We can speculate here until the proverbial chickens come home to roost in the trailer on how appropriate a tow vehicle is (or isn't), but until an accurate weight is taken on the actual hitch-up it is....just speculation.

[Gene]

Originally Posted by Freeheel

I wonder if there is any implication on auto insurance or personal liability if you tow close to or above any of your vehicles stated capacities?

That's a good question. Suppose your insurance policy—that contract you only get after you bought the insurance and never read, and if you do read it, you aren't really sure what it says—says you must inform them you are towing something with your truck, or makes a vague statement you must inform them if you are doing something different. I don't know what my policy says either, but we bought trailer insurance from the same company, so they are on notice. Best to check your policy.

If you hit someone and any allegation can be made that towing had a contributing effect, that someone or their insurance company may be looking into if you were doing so safely. This will be more likely to happen if there's a large claim. Your own company may be checking into this in a no fault state or if they have to defend you.

So, for ex., Airstream recommends repacking wheel bearings every 10,000 miles or every 6 mos. or 1 year (depending where you read it) and it's 11,500 miles and you haven't adjusted the brakes either. A bearing meltdown or unadjusted brakes may cause an accident. An overloaded trailer or overtaxed TV could be blamed too.

The 80% rule, recommendation or myth might show up too. So a situation could develop where the plaintiff's lawyer will find some expert willing to testify the 80% thing is gospel and you also beat your wife. Your lawyer will find an expert to testify your truck will pull Mt. Everest, the brakes were perfect and your wife beats you.

Gene

[InsideOut]

I think the 80% rule of thumb is to protect those who are thinking of buying a trailer on the edge of their towing capacity based on the "book specs" of the trailer & TV. They haven't had a chance to take anything to the scales before they jump in and many never do. Alot of us (myself included) didn't have a clue when we were newbies getting our first trailer.

Two things I have since learned:

1) The book spec of the trailer does not include any options added - like propane tanks with gas, water in your water heater & fresh tank (not to mention grey/black at the end of a trip), A/C, awnings, spare tires, television, microwave, modifications, etc.
2) The book spec rating on the tow vehicle is when the vehicle is brand new, w/o wear & tear already accumulated and it's perfectly tuned up. Especially if an older TV is your first...I doubt it will be 100% up to spec, running perfectly -

For both these reasons the 80% is a good buffer IMO.

Our original 7yo TV was rated for 5000 lbs. - our trailer's book spec said it weighed 2890 lbs...we should have been fine. Our trailer actually weighs in at about 34-3500 lbs when on a road-trip. (I've never weighed it at the scales empty, but I'm sure it's not under 3000 lbs.) We were fine as long as there were no grades involved. However, it wasn't long before we got really tired of putt-putt'g up the mountains at 35mph. Could the TV move the trailer up a mountain, yes...but I wouldn't really consider it an adequate tow vehicle. Very frustrating.

Like others have said...the 80% is just a "rule of thumb" - only you can determine your own tolerances - but when talking with newbies & others with "who knows what" TV, 80% the accepted recommendation I am comfortable with.

Shari

[Gene]

I agree with Shari that newbies don't know much and neither did I. I tried to learn from the Forum and that helped a lot, but there's always more to know. I think the point about how TV's decline in ability over time is a good one and how weights of trailers loaded can be a lot more than we are told. I think the 80/20 thing is a good starting point and of course, everyone makes their own decisions. I'd still like to know how the number was established and whether there was long ago an objective analysis that led to it.

Gene

[slowmover]

80% is bull.

Another way to look at it is also simple: Limited travel miles in a years time is one way to decide on a "lesser" vehicle; a 1/2T over a 3/4T truck for example.

And don't listen to those who get twisted panties over climbing long steep grades at WOT at 40 mph for twenty minutes. The engine will be fine and so will you. Traffic now or traffic in the 1960s is an irrelevancy if you have NUMBERS to verify your hitch rigging (Solo & loaded TV & TT weights as a start) and have a well-inspected pair of vehicles. That's all we did then (many traveled with an empty trunk in the TV, for example, back then so as not to overburden the rear suspension).

Keeping lane-centered is the only real criterion; travel speed is a function of safe operation. The Interstate is 45 mph and there may be times one has to travel at that lower speed for a limited period.

80% is for those too lazy to be responsible, IMO. No numbers, improper loading, etc. Just take the time to get things right. A fulltimer has the luxury of spec'ng everything to that one function. The rest of us work with our compromises.