Having trouble understanding tow ratings.

[homelessduck]

My truck has a gvwr of 8800lbs. This means that the truck,passengers and cargo should not exceed this weight, correct? That obviously does not leave much room for towing. If you exceed this weight is that technically illegal ? Or do they just check that your trailer isn't over weight?

 

[laserjock]

I have been told you add your trailer GVW to your truck and that is the max. However, you have to watch your tongue weight as that adds to the truck weight. There are published tow ratings somewhere. If someone would like to teach a DOT legality course on this I'd love to see it. I've been told a lot of things by a lot of people. I think it also varies widely state-to-state as to how things are enforced.

 

[snicklas]

No, that's how much the truck, cargo, passengers and tongue weight shouldn't "legally" go over........

There is a GCVW (Gross Combined Vehicle Weight) which is the truck, as listed above, and trailer.....

For Example (Since I actually have these numbers):

My 03 Excursion has a:

GWCR (Gross Weight Combination Rating) of 20,000 LBS

Maximum Trailer Weight of 11,000 LBS

So some simple math means the truck can weigh 9,000 LBS.... (Truck Curb + Passengers + Cargo + Tongue Weight)

Looking at the same chart for the 6.0 Powered Trucks, the max Combo for all of them is 20,000lbs, but the max trailer weight varies depending on the vehicle, transmission and trailer type (obviously mine will only do bumper tow).........

Take a look at the charts starting on Page 14 (This is a 6.0...FYI):

http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/0360l6d1e.pdf

Closest I could get for the IDI trucks was for a 96, and it doesn't list the diesel in the charts (That's in the diesel suppliment which I don't see)

http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/96f23og1e.pdf

Starting on Page 229.... list all gassers from a 4.9 RCSB F-150 through a 7.5 F-Superduty. For close numbers, I would look at the 7.5L listed truck

If you scroll up from Page 229, it even lists the axle and engine codes.....

 

[homelessduck]

Thanks guys ! Looks like the GCVW max for my truck ( truck in sig ) is only 12k.. ouch. If it were 4.10's it would be 17k. The truck weighs about 6600 lbs. So that leaves me with a towing capacity of less than 6k. Obviously it will pull more than that, but I'm just looking for the legal numbers. I need to legally pull roughly 10k lbs.

 

[The Warden]

Thanks guys ! Looks like the GCVW max for my truck ( truck in sig ) is only 12k.. ouch. If it were 4.10's it would be 17k. The truck weighs about 6600 lbs. So that leaves me with a towing capacity of less than 6k. Obviously it will pull more than that, but I'm just looking for the legal numbers. I need to legally pull roughly 10k lbs.

Scott hit the nail on the head as far as far as explaining the difference between GVWR and GCWR. With that having been said, as I understand it, GCWR is not a legal designation in the same way that GVWR is; note that our trucks don't have a GCWR listed on the door jamb sticker, while GVWR and GAWR for both axles ARE listed.

It was explained to me that engine horsepower plays a much larger role in determining GCWR than spring and axle loading does. This is why 460 trucks have higher GCWR's than IDI trucks; same with why 4.10 trucks have higher GCWR's than 3.55 trucks that are otherwise identical (including having the same GVWR). So, with a big caveat that I will explain in the next paragraph, if the engine will comfortably handle the weight without overheating, I'd go for it

WITH THAT HAVING BEEN SAID, you need to ensure that the following conditions are met:

1. The trailer has brakes meant to stop the weight; if the trailer has factory brakes, don't exceed the trailer's GVWR. Also make sure you have a good trailer brake controller in the truck and that everything works. If your trailer doesn't have functioning electric brakes (I'm not a fan of surge brakes, but they're better than nothing), I wouldn't go over the truck's GVWR for the entire combo; that way, you don't risk having too much load for your truck's brakes, particularly in an emergency.
   
2. While you want good weight distribution on the trailer, you don't want the tongue weight to add enough weight to the truck to exceed the GVWR, the GAWR for the rear axle, or the load rating on the rear tires. If you can't meet those requirements without having too much weight on the back of the trailer, the trailer's too heavy.
   
3. Check the laws in your state; in many states, if you're towing a trailer that weighs more than 10,000 lbs, you need a Class A CDL.

Hope that helps some