Many caravanners have considered, or have had, a GVM (Gross Vehicle Mass) upgrade to their tow vehicles to increase load carrying capacity.

Is a GVM upgrade the answer?

YES, in many cases, it will allow the vehicle to carry more legal weight, if that is what you need for work or play.

The original manufacturer of your vehicle will set certain limits on the original vehicle’s weights. A Second Stage Manufacturer (SSM) can take that vehicle and remanufacturer it to include new higher GVM, GCM and braked towing weigh limits.

HOWEVER: – a GVM upgrade alone, doesn’t automatically upgrade your vehicles GCM (Gross Combined Mass). Some Second Stage Manufacturers (SSM) do offer GCM Revision, however the majority do not. So, check with the SSM before you commit to a GVM Upgrade. Vehicles vary.

In both cases (Original GCM or new SSM GCM) any additional load you put on the tow vehicle, even after the GVM upgrade, must come off what is left on the vehicles GCM allowance for towing. In fact, it will reduce the towing capacity because you are always limited by the GCM, as well as several other factors: Axle Capacities, Tyre Load Index, Rim Load Rating, Tow bar rating, ball mass rating and Towing Capacity. So, research and know all of your vehicle limits.

GCM is basically the tow vehicles GVM (Tow Vehicle total loaded weight) plus the weight of any trailer / caravan that it tows. However, many factors are considered by the manufacturer in calculating this figure. They included dynamic stability, drive line and drive train thermal capabilities, chassis design etc.

For example, you will note many vehicles have advertised 3,500 kg towing capacities however, they cannot tow that weight when the tow vehicle is fully loaded at the same time.

Lovells offer a 4,200kg GVM Upgrade and a 4,000kg Towing /GCM Upgrade for the Landcruiser 200, however, the GCM is capped at 7,800kg but still has an increase of 950kg on the original GCM.

Increase the tow vehicle’s GVM, and you may not be permitted to tow up to the original towing capacity to allow for both the new GVM and caravan GTM, to still equal the original unchanged GCM.

Lovells and several other SSM’s have undertaken SAE testing to enable the original towing capacity to be maintained even at maximum GVM. Lovells also offer Towing Upgrades which maintain the new towing capacity and new GVM Capacity…. But you are still limited by the GCM as noted above. Keep in mind though that many of the SSMs and original manufacturers for that matter, DON’T maintain the towing capacity and the towing capacity IS REDUCED to keep it within the GCM rated capacity).

So, you will need to do your homework on how it will affect your particular vehicle, and what is available for that vehicle, in your state and it will vary greatly depending upon whether your vehicle is new and not yet registered or already registered and ‘in service’. Shop around and ask all the questions. States regulations vary greatly so avoid random social media advice and check your own situation.

With many vehicles now having 3,500kg towing capacity, with 350kg weight allowed on the tow ball, that does not leave much left for driver, passengers, bull bar, vehicle tow bar weight and all other accessories plus the fridge, luggage, fuel and a boat on top etc..

The Toyota Landcruiser for example, has 610kg load capacity and if towing a van with a ball weight of 310kg that only leaves 300kg for all the above including driver and passenger
Many vehicles have less than this.

It is little wonder so many vehicles are overweight, and therefore unroadworthy on the roads. The Landcruiser is a popular and reliable tow vehicle (and I own one) but like all vehicles must be driven within either Original Equipment Manufacturers OR Second Stage Manufacturers specifications.

In my case I purchased a new Toyota Landcruiser 200 series and before taking delivery and initial registration, I had TJM Bundaberg, (A Lovells agent), increase the GVM from 3,350 to 3,800 kg, the GCM from 6,850 to 7,800 kg and the braked towing capacity from 3,500 to 4,000 kgs. The vehicle was then registered and insured noting the new compliance plates weights.

While I do not usually tow to that capacity, it does give me an increased safety margin and extra load capacity when carrying boxes of heavy brochures and stickers along with the usual ‘stuff’.

There is currently misleading information on social media and even some caravan industry blogs saying get a GVM upgrade to restore your towing capacity. This isn’t always correct and will confuse many risking fines for being legally overweight. So, check whether the SSM and GVM Upgrade kit you want to purchase offers this.

Always get the facts from a trusted source. Not all social media.is accurate.

More towing tips on www.truckfriendly.com.au
Stay safe everyone.

Ken Wilson


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