Axle weights limits vs. combined weight - What am I missing?

[Section8]

I towed my newly-purchased Avion 34V 200 miles from VA to my SC home this weekend. It towed like a dream, with the only noticeable difference being the truck's ride was a lot smoother and I had to push on the gas a little harder on the hills, but just a little. The truck never seemed to be under a strain at any time, engine temp ran about a "needle width" higher on some of the hills (and there were some fairly steep hills on the way home, but none that I would call a long grade).

Anyway, when I scaled the TV and trailer at the first oppotunity (an hour into the trip), I saw that my gross weight of 14,700 lbs was 1200 lbs over my TV's Gross COMBINED Weight Rating of 13,500.

Axle weights, however, were all below their limits by a good margin, and like I said above, the Amtrak car/Avion towed like a dream. What am I missing here?

Here are the weights from the CAT scale ticket:

AXLE WEIGHTS (vehicle ratings in parenthesis):
Front: 3,680 (TV rated at 4100 max. 3037 curb wt)
Drive: 4,280 (TV rated at 6084 max. 2452 curb wt)
Barge: 6,740 (Avion rated at 9500 max. Stated Dry weight 6940 lbs)

Gross: 14,700 (TV rated 13,500 max combined, 9000 max by itself)

For the record, I used a Husky WD hitch (rated 1000 TW/10,000 GW) and set it up as explained in many places on this site, and as described by the manufacturer. The bars were 800lb rated, and had a slight bend, just as I expected from all the instructions. The train car/Avion was perfectly level, and the TV's front and rear seemed to be loaded equally since their "loaded" heights were within 1/2" or less of their original "unloaded" heights (relative to each other).

Also, I shortened the chain on the bars by one more link, which took some effort (6th link from the bar), and reweighed:

Reweights:
Front: 3,800 (120 lbs more)
Drive: 4,100 (180 lbs less)
Barge: 6,780 (40 lbs more)

Gross: 14, 680 (20 lbs vanished somewhere - we did take a pee-break in between)

I suspect I was good/better-distributed before the adjustment.

Anyway, using all three of my brain cells, I can see that I am under the rated limits on all axles, under the gross (not combined gross) capacity of the TV (9,000 GWR), under the gross weight of the trailer and it's axles (3), yet i am over the TV's gross COMBINED weight. What am I missing? Better yet, what am I hurting?

(The TV is a '98 Chevy 3500 crew cab longbed, single rear wheels, 350 vortec engine, automatic w/overdrive, Draw-Tite receiver rated 1000/10,000 using a WD hitch.)

[driftless]

Section8, well presented data and question.
It would seem to me that your basic TV is surely enough truck to pull your trailer so I'm going to take a WAG (mostly because I want to be subscribed to this thread) and say the Max rating of 13,500# has more to do with the capacity of the power train and or braking system than anything else.
Hopefully you'll get some definitive responses to your question as it is a very interesting one.

[87MH]

Originally Posted by Section8

I towed my newly-purchased Avion 34V 200 miles from VA to my SC home this weekend. It towed like a dream...
Anyway, using all three of my brain cells, I can see that I am under the rated limits on all axles, under the gross (not combined gross) capacity of the TV (9,000 GWR), under the gross weight of the trailer and it's axles (3), yet i am over the TV's gross COMBINED weight. What am I missing? Better yet, what am I hurting?

(The TV is a '98 Chevy 3500 crew cab longbed, single rear wheels, 350 vortec engine, automatic w/overdrive, Draw-Tite receiver rated 1000/10,000 using a WD hitch.)

Good for you for weighing and posting your results - the limits, well, they are what they are as posted by the manufacturer. Just a guess, I would suspect your TV lacks a tow package or has a low ratio axle (3.42?).

One word of caution - don't pull with the OD engaged - I burnt my '95 Dodge 3/4 ton tranny (at 80,000 miles) while towing in OD - after a rebuild (and adding a tranny cooler) I have put 50,000 more miles on it (partial towing only) with no problems.

On the front axle - my opinion is that the "Best" WD setting is to restore the front axle weight to ALMOST the weight that was on it prior to dropping the tongue on the rear end.

Luck - if you want the PDF of the '99 tow ratings drop me a PM.

Welcome to the Forum!!! - I shall strive to NOT refer to your Avy as a "Stepchild" - they are great units, unfortunately, they do not have the widespread mystique that Airstreams enjoy. Bet you got a great deal on it.

One other thing - check the age of the tires - many active member of the Forum here swear on replacing the tires after 5 years. I had a three year old tire blow out last year - a thrown casing can cause an incredible amount a damage to aluminum skin.

[Section8]

Originally Posted by 87MH

Good for you for weighing and posting your results - the limits, well, they are what they are as posted by the manufacturer. Just a guess, I would suspect your TV lacks a tow package or has a low ratio axle (3.42?).

One word of caution - don't pull with the OD engaged - I burnt my '95 Dodge 3/4 ton tranny (at 80,000 miles) while towing in OD - after a rebuild (and adding a tranny cooler) I have put 50,000 more miles on it (partial towing only) with no problems.

On the front axle - my opinion is that the "Best" WD setting is to restore the front axle weight to ALMOST the weight that was on it prior to dropping the tongue on the rear end.

Luck - if you want the PDF of the '99 tow ratings drop me a PM.

Welcome to the Forum!!! - I shall strive to NOT refer to your Avy as a "Stepchild" - they are great units, unfortunately, they do not have the widespread mystique that Airstreams enjoy. Bet you got a great deal on it.

One other thing - check the age of the tires - many active member of the Forum here swear on replacing the tires after 5 years. I had a three year old tire blow out last year - a thrown casing can cause an incredible amount a damage to aluminum skin.

I don't know if it came with a tow package, either. But it does have 2 electrical tow hookups in the factory harness, a 4.10 rear with full floating axles, the hitch receiver was on it but I don't know if it's factory or not, and the tires are the "E" rated ones.

Most of the weight info I got on the truck was from a search of the vin# online. The Avion's info is from the original manual that came with it.

I did use overdrive whenever I was at speeds above the point where the tranny would shift back and forth, which it did not do most of the time.

The tires are now 200 miles/3 days old.

I don't mind being called a "stepchild" here with the Avy and all, I have felt very welcome here so far, and I know what you mean about the value thing; I was previously an Airstream owner.

[bryanl]

re: "Axle weights, however, were all below their limits by a good margin, and like I said above, the Amtrak car/Avion towed like a dream. What am I missing here?"

The combined rating (GCWR) is a wild guess based on assumptions about frontal area and other things. This is why the SAE is adopting a set of tests to help create better and more meaningful information about towing capabilities.

The issue of weight ratings creates a lot of heat as some think safety is directly involved, that being an ounce over a rating is a severe legal liability problem, that RV's get pulled over and ticketed routinely for being over ratings, that brakes will not be able to stop the vehicle and on and on. The FUD is ferocious.

The facts are a bit different. Each rating has its own importance (tire and wheel ratings needing most attention, for instance). Drivers can (and usually do) compensate for rig weight as needed. Your taking note of how your vehicle responds is what is needed for safe driving. Follow up with adjustments (including considering the OD precaution noted above), upping maintenance attention and inspection care, and so forth should take care of things.

This doesn't mean to ignore weight ratings but just to keep in mind they are ratings and not limits. There is no need to be obsessive about such numbers. Instead be reasonable and learn what they mean and what they do.

[Mikethefixit]

Section 8
Remember what chain link you used,I think you said 6 links and thats exactly what I use with my Reese DUAL CAM .The second weights look really great exactly proportioned as they should be. I bet it rode great ,it should have according to the weights,which look very similar to the weights I got when I scaled out Overlander Out.
You did good.
ROGER

[Jammer]

bryanl speaks my mind.

The "meaning" of the gcwr comes up in most RV forums from time to time. Some people believe it is a hard and fast limit.

I believe that there is a good deal of marketing involved. Tow ratings are one way the automakers encourage people to buy expensive power train upgrades.

Running heavier will reduce the useful life of the power train. Trucks with a higher gcwr are in theory built to withstand these stresses to a greater degree. We all make our tradeoffs.

Finally, Airstreams do tow better and safer than SOBs because of the rounded corners and the lower overall height. So if you're "safe enough" with an SOB right at gcwr then perhaps you're just as safe with an Airstream that is somewhat over gcwr.

[slowmover]

What an individual decides to do and what the rest of us should advise him to do on questions of hitch rigging & towing are two different things. It's just as reasonable to say to respect the manufacturer limits on GCWR (or other) as it is to advise respect on tire limits and the rest.

I've yet to see anyone tell me to exceed the tire ratings, but I can find a whole slew of them to tell me to tow heavy. None will explain the difference in principle, much less fact.

The J2807 "standard" has holes big enough to drive through. Being voluntary makes it even more meaningless. It won't be any help.

It doesn't sound to me like your all that far off. I'd not worry over it for awhile. Better to go through the TT brakes & tow-related wiring (make better than new); same for safety chains & breakaway plus some LED signal and brake lamps. Tires, shocks, suspension bushings, wheel alignment & balance plus welds would concern me more than slightly overweight on the list of things that might go wrong.

Given that the truck is old I'd go there next, with a plan of how long I'd keep it and attention to systems not just components. Wholly new systems trump piece-by-piece parts replacement any day. New parts, not rebuilts (unless selling). How's the timing chain?

You've done a very nice job in the opening post, and, as I was just PM'ng another Avion owner with a request for scale weights a few minutes ago and the rest: Thanks! as it may be my next trailer as well. The more comparisons I have, the better.

Show us some pics once it's cleaned up. Or not. But show us some pics and tell us about it.

[bryanl]

Let's not toss out the baby with the bath water ...

re: "It's just as reasonable to say to respect the manufacturer limits on GCWR (or other) as it is to advise respect on tire limits and the rest." -- blindly following anyone's recommendation or rating is foolish, IMHO. There is a very significant difference between how tire and wheel ratings are derived and how GCWR is derived and that difference, if you understand its origins, should guide you - not some blind adherence to some sticker.

re: "The J2807 "standard" has holes big enough to drive through. Being voluntary makes it even more meaningless. It won't be any help." -- if that's the number for the new SAE standard, I'd suggest that having specific criteria is much better than having none at all. Any standard has holes, which gets back to why you can't just take the numbers on placards and stickers as some sort of holy gospel.

[Jammer]

The essence of the difference between GCWR and, say, tire ratings, is that manufacturers frequently choose a lower GCWR for reasons of: product line differentiation (in other words giving people a reason to buy the big engine or the diesel), product marketing (don't want the vehicle to be perceived by the market as a utility vehicle. The Dodge Charger is a good example of this), controlling warranty expenses, or to control testing expenses.

None of this goes on with tire ratings. The tire carries what it says it can carry; exceed those ratings at your peril.

The automakers are not the almighty and the rating sticker is not the gospel.

[slowmover]

The automakers are not the almighty and the rating sticker is not the gospel.

At present you've no other guideline. If so, offer it up.

None of this goes on with tire ratings. The tire carries what it says it can carry; exceed those ratings at your peril.


How so? Tire ratings are often exceeded, see it constantly while at the landfill with other vehicles lined up not to mention on the highways.


blindly following anyone's recommendation or rating is foolish, IMHO. There is a very significant difference between how tire and wheel ratings are derived and how GCWR is derived and that difference, if you understand its origins, should guide you - not some blind adherence to some sticker.


Show us the published data from other sources (axle manufacturers) so that I may also exceed GAWR/GCWR as set by the vehicle manufacturer.

Any standard has holes, which gets back to why you can't just take the numbers on placards and stickers as some sort of holy gospel.

Control the questions and the answers are pre-determined. "Voluntary" means just that, ergo, meaningless. Published guidelines are all we have. A new set of badly done "standards" doesn't clarify our situation.

Same problem as above: what other source can you cite, authoritatively, that isn't simply your own, unverified opinion.

And both of you entirely missed the point being made: What you do, and what you advise others to do is an ethical question. Or do these not matter?

Defending your own decisions is your own business, it has nothing to do with how others should set up their hitch rigging or how they should be advised to do so.

If you want to be helpful, show us the scale receipts, manufacturer data, and the number of miles you've accumulated while overweight on the road. Then make your recommendations of how far over GAWR/GCWR based on that another person should set his.

I don't disagree that the "ratings" need work. I believe they are relative solely to the liability of the vehicle and RV manufacturers without proper, independent testing of what is reasonable, what is possible. Doesn't change that we are on our own once we decide to step beyond them. We any of us may need to defend the decision to exceed ratings, and you or I cannot defend anothers actions . . can we?

.

[xrvr]

20 pounds of fuel? zz

[ticki2]

Originally Posted by Section8

I don't know if it came with a tow package, either. But it does have 2 electrical tow hookups in the factory harness, a 4.10 rear with full floating axles, the hitch receiver was on it but I don't know if it's factory or not, and the tires are the "E" rated ones.

Most of the weight info I got on the truck was from a search of the vin# online. The Avion's info is from the original manual that came with it.

I did use overdrive whenever I was at speeds above the point where the tranny would shift back and forth, which it did not do most of the time.

The tires are now 200 miles/3 days old.

I don't mind being called a "stepchild" here with the Avy and all, I have felt very welcome here so far, and I know what you mean about the value thing; I was previously an Airstream owner.

Check your glove box for the vehicle options , any GM dealer can decode them for you . Z82 is the trailer towing package . According to the trailering guide for '98 the 3500CC 2wd with the 350 and 4:10 the max trailer wt is 7000# , the 4wd is 6500# . With 4:56 gears it is 8500# and #8000 respectively . Interestingly it does not list a GCWR . The RAWR of the axle manufacturers are usually much higher than the RAWR of the truck manufacturer . Interestingly the truck manufacturer rating almost always match the tire rating of the OE tires .As has been stated earlier There is much more behind the manufacturers ratings than engineering facts .

[Farmer Tom]

If you look at the manufacturers' specs you will find that the GVWR, GCWR and tow ratings don't make sense. Generally, the GCWR is less that the combination of the tow rating & the GVWR. But I don't think they intend these rating to be taken literally but to be used as guidelines in lieu of any other specs.

[Section8]

Wow. So many replies. Thank you.

Thanks in no small part to all your comments, and a lot of the words I made below, I have decided that exceeding the GCWR (combined weight) of my TV a little I will be OK. (If you can call 1200 lbs "a little.")

Probably.

Here is my reasoning, or my version of reasoning, listed more or less in order of importance in my decision. Comments are encouraged.

1. With the exception of "combined weight," ALL of the scaled weights were below the weight ratings of the TV and the Amtrak/Avion, and by a good margin at that. (Tongue weight is the only unknown here, since I did not measure it, but it seems to me that one could get a ballpark figure on that by comparing the weight on the hitched trailer's axles to the trailer's empty weight (mine was empty) with the difference between the two being the rough, ballpark, shadetree, guesstimated tongue weight, give or take. In my case the trailer's axle weights are just a few hundred pounds or less below the trailer's empty weight, so I would think the actual tongue weight is below the 1000 lb rating if the hitch and the TV when using a WD hitch). I have no idea if this is how you're supposed to think about stuff, but it's what happened when i did. I hope the rest of the list is shorter than this one.

2. The Drive-ability of the combination of TV and trailer. The TV road like a Cadillac and never once felt like it was straining -- or even working hard, for that matter. The Avion towed wonderfully, and appeared to ride even more smoothly on bumps and such than the TV, so maybe there is something to be said for Avion's independent suspension getup under there. It would have been easy to forget the trailer was back there at times.

3. I find it hard to believe that any Avion would build a travel trailer that could not be easily and safely towed by a properly hitched 1-ton pickup, particularly when one considers their target market and the fact that most of their advertisements for said trailer show it hooked up to a big family car (like a Cadillac or a Oldsmobuick or something), including illustration in the owner's manual.

4. I will be employing the "trailer" part of "travel trailer" way more than the "travel" part. It might get towed a coupla times a year, if that. (Well, at least until I retire. At which time, if my financial calculations are correct, I will be a 103. I'm really looking forward to that carefree life.)

5. I haven't come up with this one yet -- but I bet it won't be as important as the first three -- unless one of YOU kindly provide the text here. (Please?).


Regarding all of your replies/comments/suggestions (for which I am very grateful), I will try to fill in few blanks that formed on a couple of them...

The TV's option codes do not include Z82 (towing package) which, to me, explains why the "bare hitch" trailer weight capacity of my TV is 5000 lbs instead of 7000. (with a WD hitch, the capacity jumps to 10,000 lbs on my TV.)

As for the 20 lbs that vanished between first weigh and reweigh, I suspect that 20 lbs is probably an acceptable variation from one reading to the next on a scale that can read 150,000 lbs or more. It has been my experience (trucking) that 20 lbs is also the smallest increment on such scales. Both scale tickets were within minutes of each other and on the same scale.

Also, some of all that gross weight can be trimmed off a little on the TV end. The bed cap weighs 580 lbs (steel Reading toolbox type); there were two extra not-skinny people in the cab, a nice couple, who normally wouldn't be there (it's just me and the dog normally); I had five old cracked-all-to-hell radial tires in the bed (removed from the trailer). But, then again, if I were to remove all that (I think the nice couple left already) and then load up all my travel/camping/fishing "stuff" I think it would either be a wash or even heavier. Hmm.

Also, I agree my '98 chevy is getting older, and good maintenance is critical. I tend to stay on top of maintenance pretty well, as a matter of habit -- I am 50 yrs old and have never owned a new vehicle. Probably never will. I tend to bargain hunt (as in "cheapskate"). My TV sold new in '98 for around $24,000. I have roughly 2100 bucks in the truck right now. Beleive me, if I knew how to do math I would tell you how much difference that is, and how much I probably saved. (I bought it used. It was cheap because the PO was having a hard time selling it even though many looked. He was having a hard time selling it because he "upgraded" it by swapping doors with a donor truck that had the power windows and locks he desired, which he did a very good job of installing, except he couldn't figure out where to hook up all the new wiring where there was none before. So, all the harnesses were just lying in the front floor like a bed of snakes under your feet. Obviously, the power windows and power locks were "non-functioning" -- which is kinda hard to quietly slip in to a good sales pitch. He was frustrated and tired of "fooling with it." I made an offer. Two days work to fix. It's a great truck. (Disclaimer: not all my transactions go this well. Actual mileage may vary.)

As for showing you folks some pics of the Avion when I get her cleaned up; I will take some and post them. But, honestly, there's really nothing to clean up. Or to redecorate. Or to substantially modify that would be an improvement. I mean, I'm all happy the interior is in such pristine condition (the outside could use a wax job/skin lube), but at the same time it is somehow a little unsatisfying to not really be able to improve on it by doing "re" stuff to it (-model, -build, -store, -paint, -pair, -vamp, -condition, -place). There's a lot of perfectly good, rewarding re's going to waste in my opinion.

I know... I could just re-lax and enjoy it.

After I take the pictures of course.


Comments always appreciated.

[slowmover]

It all sounds good to me. Look forward to pics and problems/solutions as they occur and are settled, temporarily or permanently.

[Section8]

At some risk to myself and others within range, I started thinking again. About this GCWR thing, I mean, and the numbers not adding up, and also about hot dogs because it is near lunchtime.

Here's what oozed out:

1. The TV's GVWR is 9,000 lbs and the TV's Max Trailer Weight capacity is 5,000 lbs (with a "dead weight" hitch).

B. When I add these two together with a brand new crayon, I come up with a total of 14,0000 lbs, which, keeping in mind that I gradjiated from a gubmit public school, is exactly almost the same as the TV's GCWR of 14,500 lbs.

3. Therefore, I can positively conclude that I am wondering if the GCWR doesn't take into acount the use of a WD hitch, which, when employed, jacks up the TV's max trailer weight to 10,000 lbs (which I am way below).

4. I wish I had some mustard.

So, does that make more sense? How about any sense?

[ticki2]

Originally Posted by Section8

At some risk to myself and others within range, I started thinking again. About this GCWR thing, I mean, and the numbers not adding up, and also about hot dogs because it is near lunchtime.

Here's what oozed out:

1. The TV's GVWR is 9,000 lbs and the TV's Max Trailer Weight capacity is 5,000 lbs (with a "dead weight" hitch).

B. When I add these two together with a brand new crayon, I come up with a total of 14,0000 lbs, which, keeping in mind that I gradjiated from a gubmit public school, is exactly almost the same as the TV's GCWR of 14,500 lbs.

3. Therefore, I can positively conclude that I am wondering if the GCWR doesn't take into acount the use of a WD hitch, which, when employed, jacks up the TV's max trailer weight to 10,000 lbs (which I am way below).

4. I wish I had some mustard.

So, does that make more sense? How about any sense?

The 10000 # trailer weight is for a 7.4l engine with 4:10 gears , is that what you have ?

[Section8]

Originally Posted by ticki2

The 10000 # trailer weight is for a 7.4l engine with 4:10 gears , is that what you have ?

Hi ticki2.

The TV is a '98 Chevy 3500 crew cab longbed, single rear wheels, 5.7/350 vortec engine, 4.10 gear ratio, automatic w/overdrive, Draw-Tite receiver rated 1000/10,000 using a WD hitch. The truck is rated for 10,000 lb max trailer weight with a weight distributing hitch; 5,000 lb max trailer weight without a WD hitch. There's some more detailed weight-rating info on this rig in the original/first post of this thread.

[TouringDan]

Section 8

Congratulations on your new Avion and welcome.

I agree with your assessment and also with Driftless's take on it. I think it probably comes down to accelaration standards set by GM. As long as you are well under the axle ratings, I think it is a non problem.

Dan