Measuring GCM

[SeanC]

Is there a certain methodology used by the department of transport to measure GCM?
Different methods can affect if you are legal or not.

Methods.

1. Vehicle and Trailered Load are measured separately as 2 unconnected units.
2. Measured separately as 2 connected units.
3. Measured as a single connected unit.

If the Vehicle is at GVM of 3000kg. The Trailered Load is at 3500kg maximum weight. GCM is 6500kg. Tow-ball weight is 300kg

1. Legal
2. Not legal GVM exceeded by 300kg tow-ball weight
3. Legal

Move 300kg from the Vehicle to Trailered Load.

1. Not Legal. Maximum Trailered Load exceeded by 300kg.
2. Legal
3. Legal

Remove 300kg from Vehicle but not transferred to the Trailered Load.

1. Legal
2. Legal
3. Legal

The only way to be legal in all cases is to be under GCM by the Tow Ball Weight.

Let’s not get into a debate about whether Land Rover allows for Tow Ball Weight in addition to GVM.
Let’s pretend the vehicle is say, a Land Cruiser.

[Odysseyman]

Seems like you’ve answered your own question…You can’t load the car to GVM and the trailer to ATM and then add towball weight.

They are likely to be weighed connected so the towball weight comes off the ATM of the trailer and goes on to the payload of the car. so you would need to have less stuff in your car to allow for the towball weight.

I’d be more worried about how far over those weights would exceed your maximum rear axle loading, remembering that 300kg on the ball adds around 450kg to the rear axle.

David

[Graeme]

Maximum GCM is stipulated for the tow vehicle and usually by the manufacturer, but can be reduced by the transport authorities at registration time, such as for trucks that are registered to tow only 1 trailer instead of multiple trailers. The actual GCM is the weight when the combination is driven onto a weigh bridge.

[Wojer]

Seems like you’ve answered your own question…You can’t load the car to GVM and the trailer to ATM and then add towball weight.

They are likely to be weighed connected so the towball weight comes off the ATM of the trailer and goes on to the payload of the car. so you would need to have less stuff in your car to allow for the towball weight.

I’d be more worried about how far over those weights would exceed your maximum rear axle loading, remembering that 300kg on the ball adds around 450kg to the rear axle.

David

Exactly, well highlighted.