GVWR, GCWR, & GVW

[clev]

Every time that I think I have a handle on these, they seem to explode in my mind. I know what each of the letters stand for, Gross Combined Weight Rating,........etc., and I know what they mean. What's confusing me, is the application of the ratings.

Example: My truck, 6.7 diesel, 3.55's, srw, has a GCWR of 23,500 pounds, a GVWR of 11.5k, and the truck weighs ~7.5k. If I have an 18.5k fifth wheel with pin weight of 3k, and drop the pin in the back of the truck, the truck now weighs 10.5k. The actual trailer weight after hook up is 15.5k. If the total rig was sitting on a scale, the total weight would be 26k. Is the truck overloaded? The 10.5 does not exceed the GVWR, and the 15.5k trailer does not exceed the max trailer weight of 15.7k pounds. Is the trailer weight, the weight as it's hooked up with the 3k sitting on the truck? Or, is it the total sitting weight of the trailer, unhooked?

[otrfun]

clev wrote:
. . . My position, and that of Curt who is a major hitch manufacturer, is that the 'towed' weight of the trailer is everything in and on the trailer, 'minus' the pin weight, because the truck is not towing the pin weight. So, with my example, the 18.5k pound trailer has a pin of 3k, and a 'towed' weight of 15.5 k. That has no effect on gcwr, and I know that.

The 15.5k you're referring to is defined as AXLE WEIGHT, not "tow(ed) weight". 15.5k of AXLE WEIGHT plus 3k of pin weight equals a trailer that weighs 18.5k (15.5k + 3k = 18.5).

It is not possible to calculate the GCWR of a truck/trailer combo and/or the GVWR of a trailer without knowing the sum total of the AXLE WEIGHT and pin weight of a trailer.

The gross AXLE WEIGHT rating (GAWR) and GVWR are clearly stated on each and every trailer manufactured. There is NO mention of "tow(ed) weight". Subtract the GAWR of each axle from the GVWR to arrive at the pin weight used by the manufacturer to calculate the trailer's GVWR.

If you're trying to use your definition of "tow(ed) weight" (in reality, AXLE WEIGHT) to calculate whether you're exceeding the TOW CAPACITY of your truck . . . it's not going to work because they mean two different things.

Manufacturers base their TOW CAPACITY ratings on the weight of the ENTIRE trailer---the sum TOTAL of the weight placed on the landing gear, king pin, or hitch, AND the AXLE(S) (AXLE WEIGHT).

[avvidclif1]

A good rule of thumb:
3/4T = <12k RV GVWR
1T SRW = 12-16k RV GVWR
1T DRW = 16k RV +

At 19k RV GVWR you are very close to F450 range.

Truck 11.5k GVWR, RV GVWR 19k = 30.5k GCVW

I don't know why you asked you have already convinced yourself it will work.

[tinner12002]

cmeade wrote:

clev wrote:
Thanks, KD4. I guess my biggest confusion was/is 'Trailer Weight". I know that trailer weight is what it weighs on a scale but I 'think' that is different than max tow weight. In my example, the trailer has a pin weight of 3k pounds and when that weight is transferred to the truck, the trailer, sitting on a scale would weigh 15.5k pounds, which is what the truck will actually be pulling. The 3k pin weight just gets added to the GVW, which is still well within limits. Anyway, do you see my confusion?

. The truck will be towing 18,500 trailer not 15,500 trailer!!

I would have to agree. Your tow rating is based on what your truck can pull regardless of where its hitched to the truck at...your drive axle is still pulling the total weight of your RV at your hitch point. Weight loaded on your truck makes no difference. You mentioned you could drive around with 3000# loaded in your truck...yes you could but your not putting pressure at your hitch point by pulling anything so that weight it irrelevant. As soon as you hook your truck to your RV and you start pulling you now have the total weight of your RV pulling against your hitch regardless of how much weight you have loaded on the truck, its still pulling that weight. Your truck still has to move it.

[cmeade]

clev wrote:
Thanks, KD4. I guess my biggest confusion was/is 'Trailer Weight". I know that trailer weight is what it weighs on a scale but I 'think' that is different than max tow weight. In my example, the trailer has a pin weight of 3k pounds and when that weight is transferred to the truck, the trailer, sitting on a scale would weigh 15.5k pounds, which is what the truck will actually be pulling. The 3k pin weight just gets added to the GVW, which is still well within limits. Anyway, do you see my confusion?

. The truck will be towing 18,500 trailer not 15,500 trailer!!

[wilber1]

clev wrote:
Wil, I've explained as best I can and I also read the Trailer Life article to which you reference. I give up. But, if you go back through and read my responses, perhaps you'll see that the horse has been dead a long time.

I didn't reference a Trailer Life article but do what you will. I really don't see what Curt has to do with this, Curt builds hitches, not trucks.

[clev]

Wil, I've explained as best I can and I also read the Trailer Life article to which you reference. I give up. But, if you go back through and read my responses, perhaps you'll see that the horse has been dead a long time.

[wilber1]

clev wrote:
Wilber, maybe I wasn't clear. I am familiar with gcwr and know it is the total weight of the truck and the trailer with all passengers, equipment, and fluids. I've said that since the beginning and yes, I'll be a little over gcwr recommendations. It's the towed weight that we disagree on. And no, I have not said you can pull any weight. According to the specs for my truck, it has a payload capacity of 3790 pounds (directly from Ford) and it can tow 15,700 pounds; max, that's it. My position, and that of Curt who is a major hitch manufacturer, is that the 'towed' weight of the trailer is everything in and on the trailer, 'minus' the pin weight, because the truck is not towing the pin weight. So, with my example, the 18.5k pound trailer has a pin of 3k, and a 'towed' weight of 15.5 k. That has no effect on gcwr, and I know that.

Curt is using its "towed" weight to determine its own hitch ratings. That has nothing to do with the truck's ratings which are the truck manufacturers problem and which Curt could care less about because they didn't make the truck.

So I don't know what you are getting at. If you add your truck's 11,500 GVWR to your max tow rating of 15,700 you come up with at combined weight of 27,200, so just what does a GCWR of 23,500 mean to you?

As I pointed out, Ford (and Ram, not sure about GM) use J2807 to determine their tow ratings and GCWR. To use your own extreme example, if you are towing a 15,700 lb 5th and dump another 3000 lbs in the truck bed, that will have a direct effect on whether your truck can meet the criteria of J2807.

[clev]

Beverley&Ken wrote:
Quote " Fact: the trucks specs will allow up to 3700 pounds on the rear axle. I'm good on everything except gcwr. I'll have to load very carefully. "
Is that 3700 pounds the rear axle rating , which would include the weight of the truck,(box, fuel, suspension etc, hitch and cargo) or is it the cargo carrying capacity not counting whats all ready part of the truck?

Ken

According to my door tag, the rear gawr is over 7k and fawr is over 5. The payload is 3790, and the 20" tires are rated for 3750 each. My truck is good with everything but gcwr which I'll have to be careful with. I know that I cannot change gcwr, but airbags, Bilstiens, trannie cooler, plus a few other mods will help with towing; and the trailer's Kodiac's will help with stopping.

[clev]

Wilber, maybe I wasn't clear. I am familiar with gcwr and know it is the total weight of the truck and the trailer with all passengers, equipment, and fluids. I've said that since the beginning and yes, I'll be a little over gcwr recommendations. It's the towed weight that we disagree on. And no, I have not said you can pull any weight. According to the specs for my truck, it has a payload capacity of 3790 pounds (directly from Ford) and it can tow 15,700 pounds; max, that's it. My position, and that of Curt who is a major hitch manufacturer, is that the 'towed' weight of the trailer is everything in and on the trailer, 'minus' the pin weight, because the truck is not towing the pin weight. So, with my example, the 18.5k pound trailer has a pin of 3k, and a 'towed' weight of 15.5 k. That has no effect on gcwr, and I know that.

[JIMNLIN]

CALandLIN wrote:
I think the best way to look at your weights is to place a safety zone on them. The truck’s GVWR is 11.5K. That’s it’s maximum safe weight allowance from it’s manufacturer. Anything above that is going to be speculative. Same thing with the GVWR for the trailer and the entire rig’s GCWR.

just a point here on GVWR...... Ford may choose any GVWR they want up to the sum of the fawr/rawr.
Also on Fleet Ford website on every page in their weight rating specs for all their trucks in paragraph #4 says;


4) Gross Axle Weight Rating is determined by the rated capacity of the minimum component of the axle system (axle, computer-selected springs, wheels, tires) of a specific vehicle. Front and rear GAWRs will, in all cases, sum to a number equal to or greater than the GVWR for the particular vehicle. (snip).

The truck makers GVWR isn't a drop dead number as far as safety as evident of Fords F350 SRW trucks can have a 10000 GVWR or a 11500 GVWR in the same exact truck when we look at Fords same weight rating spec pages.

Axle/tire load numbers are the biggest safety numbers for carrying weight.

The 6.7 and that big auto sure won't have any issues towing its tow ratings and more.

[Beverley_Ken]

Quote " Fact: the trucks specs will allow up to 3700 pounds on the rear axle. I'm good on everything except gcwr. I'll have to load very carefully. "
Is that 3700 pounds the rear axle rating , which would include the weight of the truck,(box, fuel, suspension etc, hitch and cargo) or is it the cargo carrying capacity not counting whats all ready part of the truck?

Ken

[wilber1]

clev wrote:
Hi wilber; no, I'm not saying it, I'm quoting it from Curt's web site but I do agree with them because it makes sense to me. If the truck is within specs and carrying part of the trailer weight, then it is towing the remaining weight. And I think the word 'towing' and max towing weight is being misinterpreted. I interpret it as the truck being able to carry a certain amount of weight, AND tow a certain weight. As a radical example, if I dropped a 3000 pound weight in the bed of my truck, I could drive around all day with that weight and still have the capability of towing/hauling 15700 pounds. And you are correct on the gcwr. I'm not sure what my status will be until I get the trailer and get it weighed.

I don't agree at all. They are saying you can two anything you want as long as you don't exceed the trucks GVWR. If that is the case, why publish GCWR's at all? Why publish tow ratings? GCWR means Gross Combined Weight Rating. Total weight of loaded truck and trailer. Just because you move some of the weight from the trailer to the truck doesn't mean it magically disappears.

Ford uses SAE J2807 to determine tow ratings and GCWR.

Here are the main test methods trucks would be measured on as per J2807:

Cooling capability on a long highway upgrade modeled on the Davis Dam grade on Arizona SR 68;
Launch and acceleration performance on a level road and a 12 percent upgrade;
Combined handling performance – understeer and trailer sway;
Combined braking performance – stopping distance and parking brake-hold on grade; and
Structural performance for the vehicle and hitch or hitch receiver.
New calculations for trailer weight ratings: In addition to the performance standards, SAE J2807 also uses a specific set of assumptions to calculate maximum trailer weight ratings:

Ford's own charts say "maximum loaded trailer weight", not trailer weight minus hitch or pin weight.

If you actually are 26,000 lbs you would be 500 lbs over Ford's GCWR for your truck. Not enough to worry about IMO and not illegal but still overweight according to Ford.

[john_bet]

clev wrote:
Thanks, KD4. I guess my biggest confusion was/is 'Trailer Weight". I know that trailer weight is what it weighs on a scale but I 'think' that is different than max tow weight. In my example, the trailer has a pin weight of 3k pounds and when that weight is transferred to the truck, the trailer, sitting on a scale would weigh 15.5k pounds, which is what the truck will actually be pulling. The 3k pin weight just gets added to the GVW, which is still well within limits. Anyway, do you see my confusion?

I reality your truck is pulling the whole load, as in, the truck and trailer combo called GCVW. The engine,trans,rearend has to work very hard to move the kind of weight you are considering. The more weight the harder the work.

[clev]

Thanks, tinner. The gvwr of the tlr is ~19k pounds. That's why I used an excessive weight of 18.5k in my initial post. I've been doing this for 40 years and am very careful about loading, and always take it to a weigh station. The tlr will have the Mor-ryde individual wheel suspension with Kodiak disk brakes. Short of a total brake failure, stopping shouldn't be a problem.

And, I don't know how others are pulling these big rigs. Mine is set up to tow the max that Ford offers without being a dually. My 3.55 gears are all that's available with srw; 3.73's are for dually's. Yet, I see the big three, 350's and 3500 towing these huge 5's. They have to be way overloaded.

[tinner12002]

SanMarMor wrote:
Trailer weight is trailer weight. Part is sitting on the axles, part is sitting on the hitch. But you're pulling, and stopping, the full trailer weight.

Mark

Yes, full trailer weight, could be as much as the GVWR of the RV which no one has mentioned.