View Full Version : towing weight
10-21-2005, 07:56 AM
I Have a GMC 2500HD Shortbed 6.6 duramax/allison,manual says i can tow max 15,400 trailer with max 2500 hitch pin, trailer weighs dry and carry capacity 12,700lbs hitch pin weight is 2300 lbs, am I looking for trouble, will it do hills
I am not a fifth wheel person, but since none of them have chosen to answer, I will jump in and supply some information, based upon what I read and hear from those who do own one.
I think that the main issue is going to be the wheel base, as long as you stay under the weight limits. You will probably need one of the sliding hitches to be able to back into a tight space, without danger of hitting the trailer on the cab of the truck. Also, what I read indicates that you may well have handling issues with a short bed and a long trailer.
Since I have no expereince to base this information on, let's hope that those who do will join in!
10-24-2005, 08:05 PM
I'm no longer a 5th wheel person (or perhaps it will turn out that I'm not a 5th wheel person at the moment :-), but I'll attempt to provide some insight from when I was.
As Kirk says, the posts here seem to indicate that short wheelbase tow vehicles can have problems towing long 5vers. And short bed pickups definitely tend to have more problems with the trailer 'kissing' the truck in tight turns. An extended pin box and/or the sliding hitch can help reduce the latter problem. I am a big fan of long box trucks, so never experianced any of these problems myself.
Next, as towing up hills, diesel engines seem to be better than gas. So I would say that if the truck works fine on the flats, it will likely be adequate up the hills (even diesels may slow down some). It would probably be wise to have some kind of 'exhaust brake' to help going DOWN the hills. My gas engine was fine on the flats, but was not adequate going up hills, and that was with only 6000 pounds behind my 2500HD.
So the final area to look at is weight. First of all, do not put much stock in the 'dry' weight listed for the trailer. This may be the planned dry weight, or even the actual dry weight from the factory. However, it won't include anything added or changed by the dealer or previous owner. When shopping for trailer weight, use only the GVWR of the trailer, because that is the maximum weight it is designed for.
The only use for the 'dry' weight is to give an indication of how much stuff you can carry in the trailer, or CCC. This is GVWR - dry weight. If this is anywhere near not enough for you, make sure you actually weight the trailer empty before committing to buy it. And weigh it loaded for travel before setting off on a trip.
So how much trailer to get? I'm a bit leary of that 15,400 weight. In the past, at least, the claimed trailer weight is with a truck with no accessories installed, no cargo, no passengers, just a 150 pound driver and a bit of gas. Certainly you can use their numbers as a guide, because they probably won't outright lie to you, but it is wise to look for trailers with a good safety margin for the real world. For instance, you mention a 2500 pound pin weight, I think. You would probably need to subtract the weight of the hitch, and anything else in the bed of the truck, from that weight.
Really, the best way to figure out what you can tow is to take your truck, loaded with all gear and people just as it will be when you tow, to a scale and weigh it (front axel, rear axel and total weight). Now you can subtract the total weight from its GCWR (Gross Combined Weight Rating) to find out how much trailer you can REALLY tow. And subtract the rear GAWR (Gross Axel Weight Rating) from the rear axel weight to find out how much pin weight you can really have.
Note that pin weight 'tends' to be 10% to 20% of the trailer weight, and assume 200 pounds for the hitch unless you have the real weight. And the smart driver will try to stay as much as 20% under his ratings so as to never give even the appearance of being over his rating limits. Being over limit may or may not lead to accident, premature wear or breakdown, but does tend to attract attention from highway police in some states, and lawyers after any accident...
10-24-2005, 08:58 PM
thanks for your comments,the 15.400lbs is straight from gmc,and so is max 2500 pin weight right from manual, i weighed my my truck the way we would drive it pulling a trailer and it weighed 7500 lbs a hitch is 200lbs the tank was full and all my camping goodies were in it, my axles ratings are 4670 frt /6084 rear, i called the trailer factory factory and they gave me shipping weight of 13000 gvwr,not dry weight,they say pin weight is 2300lbs on the trailer i want to buy ,being new at this i dont trust myself to figure this out, you sure sound like you know what you are talking about of course when i spoke to gmc they said use 20%of trailer gvwr for pin weight, im lost
Pin weight is the amount of the trailer's weight that is directly in the bed of the truck. If you were to weigh the truck, with the wheels of the trailer completely off of the scale, the pin weight would show as a part of the total weight of the truck and that weight should not exceed the GVWR (gross vehicle weight rating) for the pick-up. Pin weight is designed into the trailer by where the axles are positioned and the location of the different items that are heavy, inside of the trailer. Such things as the fresh water and waste tanks locations will play a major part of that. Also, storage that is in front of the trailer's axles will also increase the pin weight. On the other hand, if you locate the tanks behind the trailer axles, due to leverage adding weight in them will remove weight from the pin and shift it to the axles. Another factor is what you put into the storage of the trailer and where that storabge is located. It is not a simple thing to determine and a wise owner will weigh everything when it is hooked to the truck and loaded for travel. Most designers base their weights on having the fresh water tank full and the waste tanks empty.
10-26-2005, 07:53 PM
Salvatore, Kirk gives a good definition of 'pin weight'. As you can imagine, it will tend to vary with the way the trailer is loaded, so I'm concerned that the 2300 pound figure may be low at times. I'm also surprised that GMC gives a maximum pin rating; they didn't do that for my 2001. In any case, 2300 pounds seems a bit too close to 2500 pounds for comfort.
When you weighed your truck, was the hitch in it? Did you get a weight for just the rear axel in addition to the weight of the whole truck?
Find out your GCWR (Gross Combined Weight Rating) for your truck (should be in the manual, or try your dealer or GMC). This is the maximum the truck and trailer together can weigh. Subtract your 7500 pounds (or 7700 pounds if the hitch was not in when you weighed) from the GCWR and that will be the maximum GVWR of the trailer. It would be wise to back off of this trailer weight as much as 20% in case you ever add more passengers/gear/accessories to your truck and just more safety in general. I think you'll find that 13000 pounds may be marginal.
Subtract the 7500 (or 7700) pounds from the GVWR of the truck (usually on the drivers door post) This will tell you how much additional weight (including pin weight) you can add to the truck. This may be where that 2500 pound pin weight limit came from.
Also, subtract the rear axel weight from 6084 (also subtract 200 pounds for the hitch if it was not installed when you weighed) which will give you another, possibly lower limit on pin weight, since you do not want to exceed the axel weight rating any more than you do the GVWR of the truck. Again, whatever the maximum pin weight you come up with, it is safer to back off around 20% to allow for variances in loading the trailer and adding stuff to the truck.
In closing, you will often find that pin weight is the limiting factor rather than trailer weight, for pickup trucks anyway. If you can't find the 5ver you like with an acceptable pin weight, you might see if a comparable travel trailer is available. They have a much lower pin weight (a few hundred pounds I think). There is a hitch by Pullrite which claims to make a TT tow as well as does a 5ver.
10-27-2005, 09:06 AM
Hi John, thanks for info,the 2500 lbs came from my owners manual it said max trailer weight 6600 V8 diesel 3.73 rear 15,400.5th wheel weight tounge weight 15-25 of trailer weight 2500 lbs max, it at the bottom of the page in the mainual page 4-66, i called gmc they said total weight max trailer and truck max 22,000,i found a montana we like with toungue weight of 1825lbs, dry and carry weight total with all factory options 12,285lbs. when i scaled my truck i had 2 passengers ,full tank and hitch weight ,barbie, tools, wheel chocks etc,trailer spare tire, weighed 7300.now this is the part i dont understand, the 15 -25% if iuse 15%of total trailer weight its 1842lbs if i use 25%it 2457lbs, what is the better #s?. am i o/k with these numbers? HELP
10-27-2005, 10:08 PM
Salvatore, first things first. Now that we know the GCVW (22,000) and the truck weight (7500 from your earlier append), we can get a good feel for the maximum trailer weight; that is, 14,500 pounds. This differs from what the book says, because you have 900 pounds of additional people and gear you want to carry in the truck. That Montana weight of 12,285 should be acceptable (15% safety margin) as long as that is the GVWR of the trailer and not the dry weight.
Now as to pin weight. The first step is to get the GVWR of your truck (on the drivers door post) and subtract the 7500 pounds travel weight from that. This is the absolute maximum weight the trailer can add to the truck. Next, get the weight on the rear axel of the truck, loaded for travel, and subtract that from the GAWR of the rear axel. That is the absolute maximum weight the trailer can add to the rear axel of the truck. The lesser of these 2 values is your true maximum pin weight.
Tounge weight is the same idea as pin weight, although it is more often used for travel trailers, and pin weight is more often used for fifth wheels.
The 15% to 25% of trailer weight is an ESTIMATE of pin weight. For greatest safety, you will want to use the 25% value. The dry pin weight is interesting, but since you won't be towing the trailer dry, is not a major factor in this decision.
Lets say that your true pin weight from above turns out to be 2050 pounds (I arbitrarily guessed that 1/2 of your 900 extra pounds would be applied to the rear axel, and subtracted that from the 2500 GMC rates the empty truck at). Now the trailer pin weight, loaded for travel is likely (BUT NOT GUARANTEED) to be 1842 to 2457 pounds. If it is close to 1842, you are good to go; if it is over 2000, you will be over at least one of your vehicle ratings.
Since this case is a close call, one thing you can do is find the dry weight of the trailer, and see what percentage the dry pin weight is of that to give an indication of the percentage this particular trailer is running at. And when you load it, try to put the stuff in to maintain that percentage.
Whatever you end up with, make sure you weigh the trailer, the truck, the truck rear axel and the total package loaded to go before setting out on any trips.
11-30-2005, 08:13 PM
I have never towed a 5th wheel, however, I have towed a number of gooseneck utility trailers with extremely heavy loads. I suggest that you go with excess tow capacity rather than bump up against the other side. Believe me, it will make for a much more relaxing experience going down the road. Check with the state police or state patrol in your home state. Unfortunately, states are not consistant about that how they regulate this. I would also check with my insurance company. It would seem that if there is any question about capacity of the tow vehicle compared to the trailer, it might be a good excuse for them to not pay in case of an accident.
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