Well it's not about NEVER EVER, but rather it's about an acceptable speed. I don't subscribe to the Speed Kills nonsense, which you rightly ascribe to politics, as thinking that government logic to the end would see us all going back to early 20th century "the human body was not made for speed above 25km/h". Of course the nanny state won't be happy until we're all coddled in swaddling, as my wife likes to say.

Meaning, maybe trucks *should* be limited to 80! (and banned from the passing lanes, but that's just a personal peeve of mine). So should towing vehicles! Especially if transporting live animals.

You're also right about controlability, but that isn't just a function of physics, that's also a function of training and adaptive driving. Which admittedly are sorely lacking in Australia. (Having driven extensively over decades on 4 continents, I'm sad to state categorically that at the least Melburnians are amongst the worst drivers I've ever shared the road with ) Common sense is also absent - I just reamed a P-plater on a horse forum about wanting to know what SUV she should drive to tow her horses. A *P Plater*!

My point being that these vehicles quite obviously can safely tow according to the manufacturer's specifications in countries with higher speed limits but also with higher levels of training. So, it's as if the government recognises that Australians are horrid drivers and the only weapon they have in their arsenal is to muck about with the maker's ratings, as they either feel they have already lowered speed limits to what society will accept or can't be bothered to have a tiered system.

Oh well.

Quote Originally Posted by wai View Post
Yes, but then you would never ever allow any truck on the road either. Just look at the energy of a 38 tonne semi travelling at 100 km/h! Don't even think about looking at the energy in a B-Double ir a B-Tripple.

But friction is not just related to stopping, although the information from the authorities do allow a higher trailer weight if brakes are fitted. It is controlability that is also an issue. Even negotiating a corner is an issue as without sufficient weight in the tow vehicle can see the trailer push the tow vehicle wherever it wants to.

On the speed kills campaign, this is purely political. They show the dramatic consequences of travelling at 65 km/h instead of 60 km/h. But look at the difference between 40 km/h and 50 km/h. Speaking of 40 km/h, it amuses me when I see a bus with the lights flashing but doing 60 km/h. I am supposed to slow to 40 km/h while the bus carries on at 60 km/h. Other quirks are where you can have route busses travelling full with seated and standing passengers (no seat belts) at speeds of up to 100 km/h, or the inconsistent speed restrictions on learners and P platers, and minimum driving age.

So, there is a lot of politics involved, however there are compelling reasons to relate the trailer weight to the tow vehicle weight, and to require trailer brakes over a specified weight. There is also a compelling argument to limit the speed of a vehicle when towing to say 90 km/h, but can you imagine the outcry if that were to happen?