Can someone please help with trailer weights i.e. the relationship between MAM (maximum allowable mass), Max Axle weight and nose weight)

I've re-built an old braked trailer. The original weight plate has long since been lost so I need to make up the new weight plate for it.

• I know the trailer weighs 250 kg unloaded.

• I know the Max Axle Weight is 1300 kg (that's the specification of the suspension units that I bought, ie 1300 kg spread over both wheels. The mechanical strength of the rest of the trailer will allow for more than this however so I'm happy with a 1300 kg axle weight limit

• Assume I always will have a nose weight on the towball of 50 kg

My question is reasonably simple I hope.

I know MAM refers to the Maximum Allowable Mass i.e. the most the trailer can weigh when fully loaded (i.e. weight of trailer + weight of maximum allowed load). However when hitched to the car some of the weight of the loaded trailer is taken by the car, via the nose weight on the towbar. In my case I am assuming 50kg.

Ignoring the load rating of the tyres for a moment, when making up my trailer plate therefore can I say that the MAM is 1350 kg (ie the max 1300 kg that the axle can carry plus the 50 kg nose weight that is carried by my towbar and not by the axle?

ie my plate will show

Unladen weight: 250 kg

Gross weight (MAM): 1350 kg

Max Axle Loading: 1300 kg

(And so working backwards this means that I can put a max load of 1350 - 250 = 1100 kg in my trailer)

Or is the MAM dictated solely by the axle weight and mechanical strength of the trailer (whichever is lower) and so in my case the plate will read

Unladen weight: 250 kg

Gross weight (MAM): 1300 kg

Max Axle Loading: 1300 kg

(BTW Although not relevant to my question, my car's GTW and GW allow me to tow more than either MAM calculation)

Thank you to anyone that can help me clarify this

I'm reasonably sure that your MAM should be 1300kg - not 1350.

Not sure, but max axle loading should probably be marked as 1250kg.

The axles are already marked with their Max axle loading of 1300 kg. Plus I checked with the manufacturer whether this was for the pair or for each suspension unit. It's 1300 kg for the pair, ie one axle.

Can you please explain the mathematics of your answer?

I believe the nose weight should be disregarded when calculating MAM, as nose weight can be a variable figure, and MAM should indicate the maximum permissible safe load of the rig.

Given that I believe the MAM should be 1300, I subtracted your proposed 50kg nose weight from the MAM, as that would be what would be indicated in the unlikely event that you were put on the scales.

Edited 5 September, 20255 Sep by Warrior193
correction