Tow-Ball/Trailer-hitch Downward Load Requirements ????

[Bugatti]

A post on weigh bridges (boat/trailer weight), got me into tow-ball downward load mode. I would have put this post there but it is probably a topic all on its own.

I have a Skimmer and the weight at the wheels (axle) weighs in at about 800 kgs. I remembered measuring the tow-ball/trailer-hitch with a set of Bathroom Scales at the time and it came in at 90 kgs (downward load). That was with the boat setup as I would normally set the boat up for fishing. This is with gear and eskies stowed away, some in the cabin and some by the helmish area.

It got me thinking (yes, it did hurt), as I have done some minor modifications to the trailer and boat since then, so I thought (yes, that one hurt too) best check it again. This time the boat was empty (just out of laziness) so the reading at the tow-ball/trailer-hitch would be reading lighter than what it would if the boat was set up to go fishing. So the reading at the tow-ball/trailer-hitch would be the absolute lightest it would ever be.

It came in at just over 70 kgs this time (downward load)

My tow-bar is rated at 2300 kgs but that is fine, I haven't caught a fish that big so well under that with about 800 kgs + 70-90 kgs.
Plus my tow-bar is rated at 230 kgs downward load, which the trailer easily comes in under that.

Now , , , , talking to a mate, we were both thinking (yet again, my thinking pain came on , , , , but all good this time, I took a dose of PanaDaniels and it seems to have alleviated the thinking pain), that is, if there is a road rule, trailer rule that is required to be met as far as tow-ball/trailer-hitch downward load. All as we could find was a suggested rule of thumb that states that the downward load should be between 7-15% of total weight of trailer (& boat) combined.

With wheel weight at 800 and tow-bar downward load being 70 (total weight of 870 kgs), that rule of thumb equation comes in at 8% of total weight.


Does anyone know what the legal road rules requirement is?

Cheers, Bugatti

[Nude up]

The only rule that you need to comply with is the towball down load figure that is in your vehicles hand book or the limit placarded on your tow bar if non genuine

[frozenpod]

Sounds like the downball weight is about perfect.

10% is thee rule of thumb for a single axle trailer. I read an article years ago where they did extensive testing and found single axle trailer towed best at 8%.

[Bugatti]

Sounds like the downball weight is about perfect.

10% is thee rule of thumb for a single axle trailer. I read an article years ago where they did extensive testing and found single axle trailer towed best at 8%.

Sounds good. I like towing a twin axle but not manoeuvring them about when they are off the car. But a single is a good trade off, as, a single is what came with the Boat.

I had a tyre blow on my single axle Skimmer trailer while travelling on the highway at about 100 km/hr. I rarely go over 100 km/hr when towing on the highway, I don't see any need for it, and the safety of my family in the car means more than 5 minutes saved PLUS I'm crappy at playing "eye spy" so the not going over 100 helps my chances. (ps. my kids are 15 & 17 now, and they still haven't clicked that I do the Dorky Dad really well plus let them win).

Oups I digressed, so popping a tyre on the highway, I was quite impressed with myself controlling it, mind you, my a$$ went about a 9.5 on the Sphincter Scale. So as a result, I made a few mods. First I put truck tyres on the trailer. I also extended the draw bar, which mad it a dream to tow.

But yeah, thanks, sounds like I'm in the ball park.

Cheers, Bugatti

[Bugatti]

The only rule that you need to comply with is the towball down load figure that is in your vehicles hand book or the limit placarded on your tow bar if non genuine

Thanks Nude up. Surprisingly some wouldn't know the towing capacity of their tow-bar, which doesn't necessarily mean it is as high as what the vehicle is capable of, depending on the tow bar. And even fewer would know the downward load capacity.

Glad to hear I'm not breaking road rules , , , , well not with the trailer hitch weight, that is.

Cheers, Bugatti

[saph]

Dont go over the ball weight and it will be fine and if you do be ready to have a loss of trailer and needing a new car since you will bend the chasis right in the middle like some giant splitting it apart.

[skronkman]

I don't know of any rules for ball down weight WP except for not exceeding your car hitches rating. 10% is the rule of thumb as you say. Too heavy and you'll feel it I'm the steering and suspension will sag, also hard to move it around on jockey wheel. Too light and your trailer won't tow properly, it will dance around from side to side behind the car and be dangerous. You'll also upend the boat and trailer and smash your skeg into the ground when climbing over the transom!

I can't tell from the photo if you have brakes on that tailer. You're over 750kg loaded so you're legally required to. Also, if your trailer axle takes the Holden style bearings then it's likely the axle is only rated to 750kg as well.