Hi Everyone,We have a 2011 Ford Expedition 4x4 with the Heavy Duty Trailer Tow package. A few relevant specs:Axle = 3.31Max Loaded Trailer Wt = 8,900lbsGCWR = 15,000lbsGAWR Front = 3,700lbsGAWR Rear = 4,250lbsGVWR = 7,135lbs (5,515 curb wt + 1,620 cargo max)So the question is...how heavy a loaded trailer can I safely tow? Adding the GVWR + Max trailer gives 16,035lbs...1,035lbs OVER the GCWR. However, it is very unlikely I will ever cram 1,620lbs of cargo in it. So, lets assume 2 adults (350lbs) + 200lbs cargo and the new GVWR becomes 6,065lbs and the new GVWR + Max trailer Wt = 14,965lbs. Very close to the GCWR.Is this a concern? Should I consider a 1,000lbs safety margin and limit myself to a 7,900lbs trailer? Should I allow 1,500lbs margin? Is this even necessary?Thanks in advance.Frank

The tongue weight of the trailer must be added to the 350# of people and 200# of cargo. Plus the weight of your trailer hitch/wright distribution hitch (+- 100#). You need to be looking for a trailer with a tongue weight that is 1000# or less once the trailer is loaded and ready for camping. Given that tongue weight should be about 13% of the total trailer weight you need to find a unit that is in the 7300# range, again loaded,ready to camp not published dry weight from an rv website.

The safety factor is included in the manufacturer's ratings. As long as you don't exceed the rated weights for any axle or total vehicle weight you are okay. As 8iron said above, you will probably max out on payload before you reach the "rated" trailer weight.

Sport45 wrote:The safety factor is included in the manufacturer's ratings. As long as you don't exceed the rated weights for any axle or total vehicle weight you are okay. As 8iron said above, you will probably max out on payload before you reach the "rated" trailer weight.Safety wise that might be true, but what those ratings DO NOT factor in is the comfortability and ease of how a TV handles the length, HUGE FRONTAL AREA, and wt of TTs. Do you want to arrive at your destination after 4 hours feeling normal or arrive feeling worn out, nerves on edge from fighting with how stable your combo was every inch of every mile. This very subjective area can't be easily quantified except thru experience with sufficient time behind the wheel. There can be a WORLD OF DIFFERENCE in a 30min. or 1 hr. trip to your local CG vs. a 4 or 6 hr drive to an overnight destination followed the next day by the same routine.Larry

If you want to know what you can tow, fill the truck with gas and take it to the cat scale. Get seperate front and rear axle weights..Also post the max lb your tires are at max psi..( on the side wall)

Tow ratings are not safety ratings per say. ONLY performance stds. IE what Larry is mentioning. I've towed 150-200% of a rigs tow rating with no issues from a safety standpoint. Meanwhile, a trailer that was 1/3 the max rating was loaded incorrectly, started to fishtail sway, and dang near took me off the road! This latter incident is what I would call a safety issue. This is solved with proper loading etc. But as noted by Larry, Frontal area is NOT a forced factor in ratings much. Meanwhile weight is. BUT, a rig at 15K lbs with 70sqft of frontal area, needs about 105hp to go 60 mph. Meanwhile, same rig with 90sqft needs 135hp. Same hp as a 25K rig with 70sqft! These numbers can also vary by plus/minus 30% depending upon the total aerodynamics of the rig too. I've had a rig rated to 16K gcwr, but it could not go up a 20% grade at 12K. Meanwhile, the rig with a gcwr literally 100 lbs LESS than its 8600 gvwr, went up the hill with at 12K. The latter had better low end grunt gears vs the one with over double the HP and 1/3 more torque!In 30 yrs of towing, I have found safety is the human factor, along with tow ratings, but one better know what the spec is the engineer that specs the tow rating is using vs my needs! That engineer usually has a lower expectation on some things than I do.marty

How Much Safety Margin to Allow...If Any? | Good Sam Community

Fast_Mopar
Explorer
Sep 19, 2014
wintersun wrote:
The question should be how much of a load can you safely tow and still stop the SUV and trailer in an emergency braking situation. My 1998 Tahoe was rated to tow over 7,000 lbs. but with a 3,000 lb. boat and trailer it took a country mile to come to a stop from 60 MPH and to me it was not safe for towing.

SUV's have a lot more body weight to deal with and I would want to upgrade the factory brakes with aftermarket components before towing anything close to the rated towing capacity.

I don't want to die because my trailer brakes malfunctioned and the tow vehicle's brakes were not able to handle the additional load.

Using this logic, nobody should tow more weight than their tow vehicle's payload.

I clearly know first hand what it feels like when trailer brakes fail. I blew right through a red light with my family loaded up due to this problem. Unfortunately, sometimes bad things happen.

Trailer brakes are designed to stop the trailer. Tow vehicle brakes are designed to stop the tow vehicle loaded to max payload (and some type of safety margin). A Ford F450 rated to tow 31,000 lb (or whatever the current number is) is not rated to stop the additional 31,000 lb - it is rated to stop the weight of the F450 plus the F450's payload.
wintersun
Explorer II
Sep 19, 2014
The question should be how much of a load can you safely tow and still stop the SUV and trailer in an emergency braking situation. My 1998 Tahoe was rated to tow over 7,000 lbs. but with a 3,000 lb. boat and trailer it took a country mile to come to a stop from 60 MPH and to me it was not safe for towing.

SUV's have a lot more body weight to deal with and I would want to upgrade the factory brakes with aftermarket components before towing anything close to the rated towing capacity.

I don't want to die because my trailer brakes malfunctioned and the tow vehicle's brakes were not able to handle the additional load.
blt2ski
Moderator
Sep 15, 2014
If you have to guess or do a best swag. You could use 15% of everything loaded goes to be, since you have a ball mount. But reality is that will not work depending upon the model of trailer you have. An front kitchen trailer may be a bit higher vs a rear kitchen vs a toy hauler may add very little hitch at, as the garage is over to behind the axles.
Reality is, best to weigh it and play from there.
Sirius33
Explorer
Sep 15, 2014
APT wrote:
Sherline offers a scale. There are other methods too.

Thanks - great links and advice.
time2roll
Nomad
Sep 15, 2014
Keep the trailer GVWR less than the tow rating. If every seatbelt is filled during transit you may need to go even smaller.
APT
Explorer
Sep 15, 2014
Sherline offers a scale. There are other methods too.

Every towing guide I have read recommends conventional trailers have 10-15% TW. RVers experiences suggest towards the higher of that spectrum, 12-15% is more stable. Maybe it's the high profile of both frontal area and sides, but those reporting 10% TW or less have more complaints about towing stability.

How to estimate? It's tough. As you know anything in front of the TT axles will increase TW. It should be proportional to the the distance between the ball and center of your two TT axles. A WDH changes that a little. Also, published dry weights often do not include typical and even mandatory options. Like my TT for example had something called a "Lightweight Package" which listed kitchen cabinets among other things. Kitchen cabinets certainly are not optional in a TT and they weigh something. As such, my TT came in with a yellow sticker as equipepd weight 300 pounds higher than brochure weight. Each brand varies, but it seems about 75% of them are higher by 150-500 pounds. Therefore, TW goes up too.

Then you have the things you put in. Many floorplans offer outside access storage in the front of the TT as well as inside cabinets in front and middle. So naturally that's where we owners store things.
Turtle_n_Peeps
Explorer
Sep 15, 2014
Sirius33 wrote:
Turtle n Peeps wrote:
The only way to know what the TW is, is to measure it when your trailer is loaded ready for your travel.

Weights and balances make all the difference in the world about how heavy or light the tongue weight is. I can change my TW a bunch just with the way I load my trailer.

I agree with the weights and balances bit 100%. How/where does one measure the TW? Who has a scale capable of doing that?

Here is a way to do it. Easy and cheap and simple. :)
Sirius33
Explorer
Sep 15, 2014
Turtle n Peeps wrote:
The only way to know what the TW is, is to measure it when your trailer is loaded ready for your travel.

Weights and balances make all the difference in the world about how heavy or light the tongue weight is. I can change my TW a bunch just with the way I load my trailer.

I agree with the weights and balances bit 100%. How/where does one measure the TW? Who has a scale capable of doing that?
Turtle_n_Peeps
Explorer
Sep 15, 2014
The only way to know what the TW is, is to measure it when your trailer is loaded ready for your travel.

Weights and balances make all the difference in the world about how heavy or light the tongue weight is. I can change my TW a bunch just with the way I load my trailer.
Sirius33
Explorer
Sep 15, 2014
APT wrote:
Your RV limit is likely payload or the 900-ish pound tongue weight limit. 900 pound TW means about 7k loaded TT, or 6k dry.

Thanks everyone for the great information. here is another question: as it appears that TW is key here, how is that calculated?

Let's assume that the published TW (e.g. dry) is 500#. I load 750# of stuff into the TT some of which is aft of and on the axles (therefore no impact to TW), the rest is forward of the axles and therefore add to the TW. Then you attached the weight distribution hitch which lightens the load on the hitch. So what's the real TW?

Is there some rule of thumb to calculate the TW?