I've read a few post from a search, but they don't answer the questions. I am just trying to learn a little more and making sure that I and others think about their weight. Doesn't the GVWR and GCWR change? Before everybody posts all no's. Example, I've been reading the 2001 and 2004 towing and rating guides, and they show if you have 17" wheels deduct 500#'s GCWR and Max trailer ratings. If you have the new 18" wheels deduct 500#'s. So if my truck came with 16" wheels and I put 20" on by extrapulating the numbers I have to reduce my GCWR and trailer rating by 2000#'s.
I have a '98 f150 supercab 4x2 shortbed 4.6lt 3.55lsd with factory tow pkg & 265/75r16 tires(max load 2600#) its GVWR is 6000#. If I go buy the 2001 ratings they are showing 6600#'s the v-6's are only listed at 6000# and all 5.4 w/3.73 list 7700#. How with 40 extra hp and 1 size up in gears did the GVWR increase 1700#? Are not the f150 trucks basicly the same? My 92 e150 conversion van 351w and 3.55 rates 900#'s more than my truck. I'm saying Ford changes the numbers according to engines,gearing,tires,and springs. If we change something on our trucks shouldn't the ratings change also, up or Down? Don't everyone get upset, I didn't say if I install a supercharger I can pull a 40' fiver with triple slides. I was thinking using the Ford ratings as a guide line on a stock truck and adjust the ratings(within reason) down or up if changes to the truck are made. My personal belief is a '03 and older f150 the GVWR should not exceed 8000# no matter what you add and the GCWR shouldn't exceed Ford's Max of 13500# the reason I chose that number was that was the highest for an f150 and the lowest starting point of a super-duty. The opposite is also true; installing larger tires, larger wheels or a lowered suspension with lighter springs would decrease the capacity a lot as well. What do you guys think?

 

There are a lot of factors that determine tow ratings. The 5.4L uses a larger rear end than 4.2/4.6 which helps explain the 1700 pound difference. Going up by wheel size is not proportional, like 500 pounds per inch. Take a look at the SuperDuty HD w/ 20" wheels, for example. Wheel/tire size and load ratings, springs, axle ratio and diameter, brakes, tranmission, frame, and a few more things all factor in to determining the tow rating. You should not exceed it, no matter the mods because you don't know by how much you have increased or decreased that rating.

IMHO, the tow rating is almost arbitray because most people find towing about 80% of their trucks ratings is the comfortable limit for them and their tow vehicle. Also, most people max out the GCWR 1000-2000 pounds before the tow rating.

 

I think you have a good handle on it. There's all kinds of things that make a rig better or less suited to tow with. Don't forget the tranny size, the size and type of breaks, and tire load ratings(for tounge weights) can have an impact also. It's actaully a pretty complicated subject. I'm still trying to figure out if changing my rear gearing (4x2) to 4.10 from the 3.55 would benefit me any in the towing dept.

 

Don't get hung up on 16", 17", 18" wheels etc. What matters is tire diameter. A tire with a larger diameter is like going to a higher speed rear gear, not good for pulling.

 

GVWR (Gross Vehicle Weight Rating) is not the 'tow rating' of the truck. It's what the max amount the truck can weigh all by itself.

My truck has a GVWR of #6250. Your's is #6000. By 2001 they had rasied what the physical truck can weigh to that #6600 (I think that's probably for the Super Crews). The #7700 is a payload option for the F150 and makes it like a "light duty" F250 of sorts....

Now, GCWR (Gross Combined Weight Ratings) is the combo of the truck and trailer weights. This is what techincally varies depending on drivetrain combo and such. This is also just a number tossed out there for the most part..... With the F150, you will probably exceed either your GVWR or GAWR (Gross Axle Weight Rating) before you exceed your GCWR anyway. (well, I did... )

When the manufactures come up with their actual "tow rating", it's based off of the trucks curb weight subtracted from it's GCWR. It's really a weight that you will never be able to achieve because your truck will weigh more then it's curb weight the moment you step inside.... Think of that white fleet truck with zero options and a single #150 driver.... That's what's figured for the curb weight....

So, for every pound you are over your curb weight, you will have to subtract a pound from it's 'tow rating' For your 1998, your "tow rating" is about #7000..... Well, that sounds all fine and dandy, but you also have a GCWR of only about #11500, so that means for every pound your truck weighs more the #4500, you have to subtract a pound from that "tow rating"... Oh, and still not exceed either your GVWR or GAWR at the same time... You can't just pick the rating you want and forget the others...

In my case, I have a 'tow rating' of #7700... Ok, great... But, I hitch up my #4500 fully loaded travel trailer and I've reached my trucks GVWR of #6250 (the trailers tongue weight is only #550, but I have some other 'stuff' in the truck and I don't weigh no #150!! (I did when I was in 9th grade!!). I figure my truck weighs around #5500 before I load it up for a weekend trip.

Anyway, look for travel trailers with a GVWR (the most it can weigh) of no heavier then #6000 and you should be ok.... I do very well with my trailer at a GVWR of #5000, but I have the 5.4, so that makes my towing comfort level even that much more enjoyable...

Good luck!

Mitch

 

You won't increase your tow limits or ratings, but your truck will have an easier time of pulling said weight.

 

There are several factors that come in play as mentioned, final rear gear ratio being a big one. I see and here alot of people talking about towing and rear gears. When I see people with trucks who choose to put on larger than OE tires, I always wonder if they re- geared to support those big tires, my guess is most don't!
When a manufacture puts the ratings and specs on the door, they spec the final rear ratio with a set tire size. So for example my 97's axle rating is 3.55:1 final rear gears with 235 70 R 16 tires. If I up the tire size to say 255 70 R 16 (approximatly 1 inch taller) then I have effectivily lowered my final rear gear ratio (lets say to around 3.45:1......this is a guess) this directly effects performance, and more importantly for those of us who tow or haul, you will notice a difference in usable power.
My guess is that when a dealer offers a tire size option to get bigger tires, they don't automatically adjust the final rear gear ratio, am I right?
When I here people complain about towing ability/performance of their truck, one of the first question I want to ask is, how big are your tires you are running.
Anyway, just my 2 cents, it seems one of the first mods people do is put on bigger tires, and most people probably don't the effect that one thing alone can have on towing performance, and even gas milage.

 

I've been thinking in terms of easing the long term wear on the tranny. I still haven't gotten a tranny temp guage, so I think I need to take that step first to see where that is. My wife has gotten this bug she wants a sporty luxury touring sedan (i.e BMW/Mercedes) and that doesn't really leave room for my original plan of upgrading to a 250/350 any time soon. We don't pull that often but when we do, it can be a longish kind of trip. Anyway, when I get around to it I'm going to ask over at rv.net and see what comes up there on what I should do. Maybe just keeping it out of overdrive when I tow will be sufficient along with regular fluid changes. Research research research. It never ends.