Distance Trailer Towing without the Boat

[C-WEED]

One variable is the trailer itself. My I-beam aluminum (like many 18 wheeler flatbeds) will arch up in the middle like a giant leaf spring when empty. And then sag in the middle when loaded. I am sure this adds springy bounce when empty.

I think the greatest result will come from airing down the tires. But the four suspension points that are designed for heavy weight when unloaded make for a rigid spring board. By removing two wheels this would unload two stiff suspension points. Additionally it will increase the weight on the two remaining wheels and springs/torsion pivot points. In theory giving a softer ride.

Without seeing the trailer it is hard to say which tires to remove. I would think the front tires removed would be better for a longer wheelbase and ground clearance at the hubs. While not scientific I am waving my hand like the trailer bouncing down the road. And it seems like having the tongue elevated slightly high would pull the rear of the trailer down (at 70 mph) to the ground better when it bounces rather than level or tong low attitude. Once the boat is unloaded the tongue might be just about right. Maybe you can just flip your receiver over for an adjustment if needed. Tongue high would add clearance to the front hubs if the tires are removed as well.

One thing that wasn't mentioned was the tow vehicle. I assume 3/4 or one ton with the R-tug. Some weight in the bed (if a truck) would help smooth the empty trailer also. If you get a slight hop in the rear of the truck bouncing (Like an empty dually) it can then resonate between the hitch and the axle. Causing some serious ripple/vibration bouncing thru the whole trailer frame. Airing down the tow vehicles rear tires would be a big help as well for the empty run.

For the sake of science (and the rest of us) maybe some experimintation is in order?

I wouldn't even fool with the jack. Just loosen lug nuts. Pull trailer over two boards and in less than 5 minutes drop two wheels. John is already disatisfied with the empty ride on four wheels. If two wheels is worse just pop them back on. One more advantage. If you run any toll roads you might save an axle fee running two trailer wheels.

[Chester]

While I do have a small boat I used to drive trucks up to 101,000# GVW, more if the weigh cops weren't looking. Some technology has changed in the last 20 years but the basics are still the same. At least around here lift axles are considered a component of the suspension package, rather than overloads.
As far as common boat trailer suspensions, unless there is a walking beam equalizer between the springs chances are running with tires on one axle should work. Even with an equalizer it could be made to work without much work.
It would be a good idea to see if the brake drums or rotors need to be secured with the lug nuts or bolts when the wheels aren't used.
Going from two axles to one will *double the traction, three to one will *triple the grip, greatly reducing the potential of a skid. (*approximately) It can be suprisingly difficult to detect locked up tires on an empty trailer especially if one of the tires retains it's grip.
Tire cupping has been challenging tire and suspension engineers for decades. It is still a common issue on trucks and trailers even with the best equipment. Once started it can be impossible to arrest.