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-   -   Question regarding GVWR (https://www.airforums.com/forums/f463/question-regarding-gvwr-7351.html)

joshua32064 10-19-2003 01:19 PM

Question regarding GVWR
 
I have a question regarding GVWR. Let's say that you purchase a trailer that has a factory weight of 5,745 pounds and has an additional allowable weight of 1,555 pounds. From my understanding, the GVWR would be 7,300 pounds.

Let's say you purchase a trailer that has a GVWR of 7,300 pounds. From everything that I have read on the forum, your tow vehicle should really be capable of pulling 9,000 pounds.

Here is my question. What if your tow vehicle isn't capable of pulling 9,000 pounds but only 7,700 pounds shall we say. As long as you don't put 1,555 pounds of extra things in the trailer, shouldn't you be OK? From what I have read, if we know that fluids, gasses, etc., will weigh approximately 600 pounds. Wouldn't someone with a 7,700 tow capacity be capable of pulling a 28' trailer as long as they did not bring a TON of stuff? 5,745 pounds plus 600 pounds is only 6,345. That's also assuming that you would always have your trailer fully loaded with fluids, etc.

Is it cutting it to close? I look forward to your answers.

jcanavera 10-19-2003 02:10 PM

My '01 27' Safari had a GVWR (7,100 I think) which was higher than the tow capacity of my old half ton Chevy van (6,500). I did have the Safari weighed with my normal complement of food and clothing. According to the weight sticker, the Safari's unloaded weight was 5,500 lbs. With my normal load it came in at 6,000. I never towed with liquid in the holding tanks or freshwater tanks.
Since I didn't load the trailer beyond this point I was quite satisfied that the trailer did not exceed my towing capacity.

The other consideration you have to take into account is the GCVWR (gross combined vehicle weight rating) of your tow vehicle. This is your tow vehicle with full fuel tanks, passenger load, plus other stuff in that vehicle, plus the weight of the trailer with its normal load.

All manufacturers supply this rating in addtion to the vehicle's towing capacity. In this situation it doesn't matter if the trailer comes in within your vehicle's tow rating if the GCVWR is exceeded. The end result is a shortened life for your tow vehicle and its components.

Jack

RoadKingMoe 10-19-2003 06:37 PM

Cutting it close, when relying on "tow rating" or "tow capacity," will almost always result in overloading. These are specs calculated by subtracting the curb weight of a base vehicle from the GCWR (see below). From the tow rating must be deducted the weight of options, passengers, and cargo, and often fuel in the tow vehicle itself. This is something buyers often ignore when focusing on "tow rating."

Your tow vehicle has to do two things.

PULL it's own weight, and that of its fuel, passengers, cargo, the weight of the hitch, and the total weight of the trailer. The tow vehicle's Gross Combined Weight Rating (GCWR) is what's important here. It's largely determined by the amount of engine power and gearing, up to a point. The further you are below the GCWR, the better the tow vehicle will perform on hills and in mountains.

CARRY it's own weight, and that of its fuel, passengers, cargo, the weight of the hitch, and the tongue weight not distributed back to the trailer axles by the hitch. The tow vehicle's Gross Vehicle Weight rating is what's important here. It's largely determined by the frame, spring, axle, brake, and tire strength; however, even if these components are all exactly the same as those on a higher rated vehicle, the GVWR of a particular model may be lower for marketing and/or licensing reasons. Tow ratings totally ignore this aspect, even those for fifth wheels, where hitch weight is about double that of a travel trailer.

When selecting a trailer for a specific tow vehicle, there's no substitute for fueling the specific tow vehicle up, loading it with all the people and cargo that will be in it when towing, and taking it to a CAT scale or other certified scale, and getting it's actual weight. This can even be done during the test drive of a potential tow vehicle when trying to select one for a particular trailer.

Subtracting the tow vehicle actual weight from the GCWR and GVWR will give the maximum trailer weight and maximum tongue weight. Both weights have to be below that which would put the vehicle below its two ratings.

Gross Axle Weight Ratings for the tow vehicle front and rear axle are also important, even more so than the other two, but if GVWR is not exceeded, it is usually possible to distribute the load so as not to overload one of the axles.

My advice is to forget "tow rating" and "towing capacity."

joshua32064 10-19-2003 07:17 PM

Thanks for the responses. Very helpful stuff!

Silvertwinkie 10-19-2003 07:30 PM

Here my situation to compare....

The '96 LT1 Impala SS has a GVWR of about 5386. It has been given from the factory a 5,000 lb tow capacity (has mechanical heavy duty fan/cooling). The GCWR would then be 10,386lbs. In my case currently the Bambi is about 4500lbs GVWR. So I am under the GCWR.

However.....

I am upgrading to the Safari SS which is the same weights as the 25' CCD SS.

Now the car weighs with a full tank, gear, dog and girlfriend about 4975 lbs and the Safari SS has a GVWR of 6300lbs, so taking into account the hitch weight I am going to be over my GCWR by over 1,000 lbs.

Is it sane to do it? Yes and no. Not the best thing, however, let me add that the car was rated with 2.93 gears and I have upgraded many components on the car. I'm increasing the gears to 3.73. Also added cargo coils and stiffer shocks. Add to it I have the 1000lb weight bars and I feel that the car can do it.

Let me also say that the car has the same displacement, trans, etc that the '99 Silverado 1/2 ton has. It's really only missing the meatier center frame section.

So to me it's a calculated bet. :) If I had a less robust engine, trans or gears, I most likely would not attempt the Safari. :)

Eric

wingfoot321 10-19-2003 08:14 PM

Joshua,

Thought I would give you my trailer numbers to test your thought process.

29' Sovereign Dry weight 5300 lbs / 700 hitch wt. according to A/S website.

Actual scale weight: 6680 lbs. (hitch 605 lbs of the scale wt)
- includes awnings on both sides + a/c
- includes steel propane bottles 25.4lbs x 2
- includes propane 30lbs + 7 lbs.
- includes 2 batteries
- includes pots, pans, dishes, cleaning liquids
- includes dry/canned food except for refrig. perishables (75lbs)
- 3 empty holding tanks
- includes all misc. such as axe, grill, hoses, elec drill, flashlights, charcoal, lighter fluid, a/s manual, extra 30amp cord
- includes clothes, coats, shoes, shower kits, towels, etc.
- includes, sheets, blankets, sleeping bags, umbrella, rain gear

My point is that even without liquids, the gvwr comes up pretty fast.

Silvertwinkie 10-19-2003 08:57 PM

Wingfoot,

For grins do you know what the GVWR is for your coach? This is just so that I have a reference point as to how loaded your coach actually is from the 6680 to the max it's suppose to have..... Also, of the 6680 if I read you right, you are including the hitch weight in that figure, correct?

Thanks,

Eric


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