Towing a Trailer: has anyone solved the equation?

[ORshepherd]

I have read a few posts in various Volvo and Travel Trailer forums...but have not been satisfied at all with the answers....

How can you tow 3300lbs if you can't exceed 165lbs tongue weight????

I've been looking at trailers under 3500...but this doesn't make sense....If you can't exceed 165lbs tongue weight that puts your trailer at about 1650lbs...

and then there is this:
http://www.rvlifemag.com/component/k...mother-s-volvo

[apersson850]

What's the problem?
My XC70 specifies max weight on hitch 90 kg, max gross trailer weight 2100 kg.
You simply balance the trailer so that 2090 kg is resting on the wheels, 90 kg on the towing hitch. It's all a question about how you distribute the load on the trailer.

[ORshepherd]

I thought of that, but got this response from trailer forum:
You can shift weight in the trailer to reduce tongue weight, with adverse effect on towing safety.
Tongue weight generally suggested is 12-15 per cent of trailer weight ( loaded to go ). Some use 10 per cent as a guide, but the further you reduce it, the more likely you are to induce sway and end up as a statistic.

[apersson850]

I assume you are based in the US? Towing after cars is not too common there, compared to towing using pickup trucks. A pickup truck designed for towing usually have a rear axis design that's more heavy duty than what you see on a car. Thus I can understand that recommendation, as long as you stay with trucks.

However, if you overload the rear end of a car, you may induce instability in the car instead of in the trailer, ending up in the same report. As long as you make sure you stay around the upper limit of tounge weight for you XC70, you'll not see any instability problems with trailers up to the specified max gross weight. Provided the trailer suspension/shock sbsorbers are in good shape, of course.

This one works fine after my XC70.

[ORshepherd]

Beautiful!

Just at a first glance, I notice that the single axle on your trailer is centered in the body...most of the trailers here have that single axle back of center. I know next to nothing about all this, but I would assume that has a big impact on towing requirements! (yes, I am in the NW US)

[apersson850]

Yes, trailers sold here (I'm located in Sweden) typically are designed like that. The trailer on this image I've towed too. Heavy to pull and a lot of air resistance, but still no problem to move with the XC70.



My own cargo trailer is balanced the same way.



I guess you are referring to trailers like those that are designed to be towed by farming tractors. These tractors have very heavy duty rear axes, and also need the downforce to get enough traction to move the trailers on rough ground. Hence they have their axes shifted towards the rear. Like this one.

[ORshepherd]

Like these:

[apersson850]

I see. Well, it looks like they aren't designed correctly for being towed by a car. Looking at the chassie, they also seem to have a very simple axis and perhaps also lack brakes?

[apersson850]

As a side note, I just had some information exchange with a Swede who lives most of the time in Australia. They seem to be stuck in the same reasoning downunder, probably because the available trailers are of the same kind as those you can buy in the US. Instead of balancing the trailer so that the tounge weight doesn't exceed 100 kg, they have their axis center offset to give about 10% of the gross weight on the tounge. Thus they aren't useful for towing behind a car, but behind a farming tractor or pickup truck.
A balanced trailer requires a better chassie, or it will tend to wobble at speed. European trailers are designed to handle this.

[ORshepherd]

THey DO have electronic brakes...and the "egg" trailers are FIberglass....I could get away with towing a 13' ....