No.
A GVM upgrade does not change how much weight your vehicle is legally allowed to tow, as it does not increase the Gross Combined Mass (GCM). However, owners do need to understand that any weight added to your vehicle, whether you have a GVM upgrade or not, can have an effect on how much you can tow.
Towing trailers heavier than 3000kg is always going to be a struggle with more than just a driver in a completely un-accessorised vehicle. What it does do is help with managing trailer ball weight so you still have a reasonable payload on the vehicle itself; this is of most benefit for trailers in the 2000 to 2500kg weight spectrum.
Curb Weight |
GVM |
Payload |
GCM |
Tow Capacity |
Trailer |
Trailer Ball |
2500kg |
3000kg |
500kg |
6000kg |
3500kg |
2500kg |
250kg |
Without a GVM upgrade, the vehicle weighs 2750kg (curb weight plus trailer down ball weight) before adding any 4WD accessories, luggage, fuel or even the driver! Add two adults (~150kg) plus a full tank of fuel (~70kg) and you have just 30kg to spare before you are over GVM (2970kg). In this same scenario with a 300kg GVM upgrade, you would have 330kg of additional payload on the vehicle, and would still be within your GCM limit.
At GVM, your vehicle will weigh 3300kg + a 2500kg trailer sits comfortably 200kg under your vehicles GCM.