OP, your “idea” about WDH isn’t bad, per se, it’s that you have incomplete information, misleading information, and lack information. (There’s more to it than I’ll sketch below).
First is, incomplete. Once the hitch is closed it is no longer a hitch. It has become a steering component
. This is true with any articulated vehicle. How well the steering responds is DIRECTLY at issue.
Second is, misleading. Belief that the automakers place your well-being above their profit is foolishness. SAE has published papers on towing dating back to 1965
(Bundorf) and we’ve quoted them around here. There are also those of us with close to fifty-years experience with this. We find it defies belief that SAE J2807 is suddenly concerned about over and under-steer issues they somehow missed for a half-century. In fact the holes are big enough to drive your RV through it.
The latest guidelines you appear to reference are quite handy in eliminating from consideration better tow vehicles than pickups (themselves the least stable vehicles sold . . but highly profitable). “Tow ratings” mean next to nothing when the majority of vehicles arent even tested.
Nor does that testing place the needed premium on steering & handling & braking.
Not does it take into account the problems of adverse winds (mainly, but not always, crosswinds). TTs are NOT comparable to other trailer types.
“How” the testing is done is at issue. What determines articulated rig stability. Foremost is that tires stay on the ground DESPITE maneuvers. (Where a pickup is a penalty by every measure, and WORSE when towing). The revised guidelines cure a next to non-existent problem while exacerbating existing serious ones.
Then, the lack of information. Starting with a numerical baseline as you’ve done is the right course. Your TARE weight should represent the load seen with driver, max fuel and any and all gear kept permanently aboard. To the day you sell it. This is your adjusted empty weight. The published shipping weight is now invalidated.
The TARE weight is the scale values versus the manufacturer axle/wheel/tire ratings. The legal limits. (Tow rating &. payload capacity have no bearing in law). Note the difference from scale reading to maximum allowance. Get this reading.
The series you did above is okay, but it needs the following:
1). TV loaded as if for camping trip. All passengers and gear aboard both vehicles. Full propane & fresh water in TT. No changes between weighing.
All gear in the TV must be secured against movement in any direction
. And, that the weight in the bed is on or ahead of the axle tube centerline.
The TT must be dead-level according to a carpenters level placed across the door threshold once hitched. (Can’t ignore this. It’s black::white. Must be corrected).
Start that day by getting cold tire pressure readings before vehicles move. On arrival at CAT Scale (phone app handy) start by topping off fuel tank.
2). Cross the scale hitched.
3). Drop the trailer and do a second pass.
That’s the basic without WD. With a WD hitch one crosses with hitch tensioned, then hitch relaxed, and then solo.
To get more detailed, weigh the four corners of the TV by getting first port and then starboard tires just off of scale when solo.
With the TT, you’ll need to ask the Scalemaster (fuel desk) for a tandem axle “split” (directions in manual kept at that desk).
A). The TV tires are to be adjusted according to Scale values. The vehicle manufacturer has a high & low number. Inside that range you may consult the tire industry Load & Pressure Tables for the tire type and design to get a close match. One DOES NOT use pressures beyond this to “tune” combined vehicle response. The maximum amount of tire tread contact in all directions is critical to stability.
B). TT tires are always to maximum sidewall pressure.
This is where one starts. How it drives in this condition is the baseline. Trailer dead level. Tires according to book. All gear properly stored & secured. Representative load in both vehicles.
The real test is a double emergency lane change at speed. A solo pickup can’t do it adequately at 55-mph. Towing, maybe fifty, but only then with a Hensley-patent WDH
. It comes after others.
So your first set of tests is braking distance. Solo and hitched. In above condition. The well-sorted rig will come to a complete stop sooner when towing.
The second set is how well the trailer brakes — alone — slow the rig to a stop.
Anyone burdened by typical trailer drum brakes knows that the first tests are a one-shot affair. There will not be any reserve capacity from the drums.
The important test of TT brakes is one we hope is never used. An out-of-control sway event. Oscillation. The single cure is SIMULTANEOUS manual maximum application of TT brakes and FULL ENGINE THROTTLE. Nothing less. It’ll be over in under three seconds. You control or you roll.
The second is on knowing the relative highest speed from which the TT brakes REALLY perform. 30-mph if you’re lucky, but 15-20 is more likely. (Most of us use this kind of test to choose brake controller settings for loose and wet pavements).
double lane change is best with an observer. As you’ve no hitch-based antisway, I wouldn’t exceed 25-mph the first time. (In fact I wouldn’t do it all with your rig).
Conversely, I can do this maneuver starting from the travel lane to the right onto the shoulder and whipping the wheel out to the median and then back to the travel lane — on the throttle — at nearly 60-mph with my 18k, 63’ long rig. All day long
. Ask yourself how it is that rig at nearly double the weight and 50% longer is so much more capable (in signature).
Understand that the trailer tongue is a lever
. And that scale values are static. The dynamic forces at play while at speed aren’t simply right-left, or up-down, but are rotational. That TW force can increase X10 depending on factors past what the two vehicles are doing. Pavement camber, pavement smoothness and wind loads are just the start.
A WDH spreads those forces from one point to three. From ONLY the Drive Axle to Steer and Trailer as well. You might say it cuts the tops off the spikes off the rise in force were it graphed. And you’d be right. As it isn’t the pounds of a static weighing at issue, it’s the percentage of distribution along the whole of the rig.
The typical integrated WDH has up to a few hundred pounds of sway resistance. The original is still the best of this (obsolete) type, the REESE DUAL CAM Strait-Line.
The only types worth consideration are the Jim Hensley patent design: the Hensley Arrow (and Cub) built under license, or the revised patent design, Pro Pride. The advantage of a fifth wheel type hitch, but also CANNOT sway.
The selection of TT, TV and hitch are equally weighted. Screw up one, and it screws up the rest. Screw up two, and you’re part of the 95% who’ll never know what a well-sorted rig is like. And have increased their chances of a loss-of-control accident.
Talk of skill is laughable. Don’t go there.
Risk reduction is the name of the game. Equipment comes first. Verification. Second is in the hitch rigging and associated acquired values. Then testing.
Annual confirmation is also basic.
Driver skill is little more than best habits. From trip planning to highway vehicle minimum spacing. Risk reduction, again.
It really doesn’t matter that you can run 80-mph under ideal conditions. You can’t maneuver nor can you stop.
Trailer-based electronic antisway is faster than vehicle OEM. Trailer anti-lock disc brakes are also a worthy upgrade. Both through TUSON.
Pickups are bottom feeder tow vehicles. The worst. But there are upgrades which are helpful. A rear Panhard Rod will keep the rear axle centered under the body. High quality aftermarket shocks are worthwhile. And polyurethane anti-roll bar bushings a cheap upgrade. A Hensley-type is pretty well mandatory. As an Airstream will stay upright longer than a pickup. The pickup IS the weak link.
Pickups are outside safe operation while towing above 60-mph. Solo, above 65. (And those are a stretch, so long as nothing goes wrong.)
With or without WD the first order of business is the shortest possible hitch shank. Order one undrilled. (Yes, one inch makes a difference). This same approach for any hitch type.
As noted by others, your TW may not be what you currently think. Where it genuinely is lower than 10%, the rear axle can be lowered using bar stock.
Don’t be so quick to believe initial impresssions about your. rig. A WDH WILL make your rig easier to drive. It will add a slight amount of anti-sway even if not an integrated design. They aren’t hard to use. The cheapest ones in price when when well-set add stability.
As before it’s a trio: TV, TT and hitch rigging. Three equal parts.
Your trailer type
demands WDH. It isn’t trailer weight that counts for much. It’s the TT sail area that does.
And also as above: there’s detail on every point not discussed.
Your easiest start is two-fold: The book by Fred Puhn, “How to Make Your Car Handle” covers the basics well enough as a layman’s reference that you’ll understand SAE & Airstream consultant Andrew Thomson’s published writings & videos.
He’s taken what the rest of us learned since 1967
and formulated decision trees about what works & why. His family RV dealership (Can Am RV; London, ON) has set more than 10,000 trailer rigs. He posts here as Andrew_T. Read his posts and threads from the beginning. All of them. See the dealer website for more.
Some random guy on the Internet indeed knows more than you. Or Fords “Engineers”. With experience to back it. And a choir of those of us not today’s new guys who believe ten years “experience” with only a pickup and bad hitch rigging is worth hearing.
The default AS rig down the highway is a pickemup with the AS bouncing along on the front axle.
You could take my word for it — I’m third generation with this trailer type the past fifty years, and drive commercially the past dozen — and do your tests accordingly and be ahead.
Or you can educate yourself by reaching farther.
The point to owning an Airstream is to vacation. Chase shirt-sleeve weather. With the drive itself being uneventful. Slow enough to enjoy the scenery. In a rig capable of basic safety (meaning it reacts closely to what you’re used to: the solo vehicle). The family car was and is still the best choice. As the vast majority of miles are solo. For this the AS was designed. A low COG, independent suspension and truly aerodynamic travel trailer hitched to a 4,000-lb, 122” WB fully independent suspension low COG car (with short rear overhang) is the benchmark. Everyone else is adding BandAids.
At the very least fix the present shortcomings. Verify, Record, Test. Then Confirm.