GCM & BTC Upgrades

Legally increase your Gross Combination Mass and Braked Towing Capacity with full engineering certification — tow more, safely and road-legally.

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Related services

ATM upgrades →

Heavy vehicle engineering (VSB6) →

Vehicle modification engineering →

From the blog

What is a GVM upgrade? →

Understanding VSB6 →

Understanding the vehicle certification process→

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Servicing Northern Territory, Queensland, Western Australia, South Australia registered vehicles Australia wide

Frequently asked questions

How long does the engineering process take?

Timeframes vary depending on the complexity of the project and the documentation required. Straightforward inspections may be completed quickly, while more complex engineering assessments or custom modifications require additional analysis and documentation. Furthermore, difference in wait times are dependent on the regulatory body providing the approval. Each State and Territory has its own body, as does the federal system.

How much does a GVM upgrade cost?

Total cost = engineering certification +shop install. Engineering certification starts anywhere between $1,990 and $5,990 depending on your vehicle type, complexity, and whether there are type approvals available in your state or territory. Shop installs vary from $2,500 to beyond $50,000 depending again on type of vehicle and modifications required/desired. Call us to discuss.

Is your vehicle suitable for a GVM upgrade?

Possibly. It depends on the vehicle model, chassis, suspension, axle limits, brakes, tyres, and intended use. We review those factors to confirm whether a GVM upgrade is suitable and what certification is needed. See our GVM Upgrade Finder tool or call us to discuss.

How do GVM and GCM differ on your vehicle?

GVM is the maximum weight your vehicle can carry when loaded. GCM is the maximum combined weight of the tow vehicle and trailer together. A GVM upgrade may not change GCM. We can help you work out what applies to your setup.

Will a GVM upgrade increase my towing capacity?

Not necessarily. A GVM upgrade increases the maximum allowable weight of the vehicle itself, but it does not automatically increase towing capacity or Gross Combination Mass (GCM). Every vehicle has specific limitations, and these should be considered when planning modifications or towing heavier loads.

What information do I need to get a quote?

To provide accurate advice, we'll generally need:Vehicle make, model and yearVIN (if available)Registration state or territoryDetails of any existing or planned modificationsIntended use (touring, towing, commercial, etc.)Providing this information upfront helps us identify the most suitable engineering pathway and provide an accurate quotation.

What's the difference between pre-registration and post-registration GVM upgrades?

Pre-registration GVM upgrades are done before the vehicle is registered and are often part of a Second Stage of Manufacture (SSM). Post-registration upgrades are performed on already registered vehicles and may have different compliance requirements.

How much can I increase my GVM?

The amount you can increase your GVM depends on your vehicle's make, model, and structural capacity. A licensed engineer can assess your vehicle and determine the maximum allowable GVM.

Can I get a GVM upgrade after my vehicle is registered?

Yes, GVM upgrades can be performed on registered vehicles. However, the process and requirements may vary depending on your state or territory.

Does a GVM upgrade increase my GCM?

No, a GVM upgrade does not automatically increase your GCM (Gross Combination Mass). GCM is determined by the vehicle manufacturer and may require separate certification.

What is a GVM upgrade?

A GVM (Gross Vehicle Mass) upgrade increases the maximum allowable weight your vehicle can carry when fully loaded. This is achieved by modifying components such as suspension, brakes, and axles to meet higher load requirements.

Does a GVM upgrade affect insurance?

Yes, a GVM upgrade can affect your insurance. It's important to inform your insurer about the modification to ensure your policy remains valid.

Is a GVM upgrade legal in Australia?

Yes, GVM upgrades are legal in Australia, provided they comply with the Australian Design Rules (ADRs) and state or territory regulations. Certification by a licensed engineer is typically required.

Can I reverse a GVM upgrade?

Yes, a GVM upgrade can be reversed, but it requires re-certification to ensure the vehicle complies with its original specifications.

Does it affect warranty?

A GVM upgrade may affect your vehicle's warranty, especially if the modifications are not approved by the manufacturer. Check with your dealer or manufacturer for details.

Does it affect resale value?

A GVM upgrade can affect resale value positively or negatively, depending on the buyer's needs. Some buyers may value the increased capacity, while others may prefer an unmodified vehicle.

What modifications are normally required?

Common modifications for a GVM upgrade include upgrading the suspension, brakes, and axles to handle increased loads. Additional components may also be modified depending on the vehicle.

What is a GCM/BTC upgrade?

GCM (Gross Combination Mass) is the maximum legal weight of your tow vehicle and trailer combined. BTC (Braked Towing Capacity) is the maximum weight the vehicle can legally tow with a braked trailer. Upgrading both lets you tow heavier without exceeding factory limits — this upgrade applies to vehicles that already have a compliant, upgraded GVM in place.

A properly engineered GCM/BTC upgrade reinforces the vehicle's chassis, suspension, and towing components to safely handle the increased combined load, backed by an engineer's compliance certificate for registration. Our certification process includes finite element analysis of key components, full brake and ESC testing, and Davis Dam profile towing testing — followed by individual compliance checks on your vehicle before a mod decal and compliance paperwork are issued.

Without certification, towing beyond your factory GCM/BTC is not road-legal, may be uninsured in the event of a claim, and can fail a roadworthy inspection. Read our full guide on GVM vs GCM →

Upgrade options

Availability and target ratings vary by vehicle model and state - contact us to confirm.

Option 1 - GCM Upgrade

Increase your GCM rating on a vehicle with an existing compliant GVM upgrade.

Option 2 - GCM +BTC Upgrade

Combine a GCM upgrade with an increased Braked Towing Capacity for maximum touring flexibility.

Our process

Assessment

We review your trailer/caravan, intended load, and touring setup to determine the right upgrade path.

Engineering

Chassis and suspension components are selected and fitted to safely support the new ATM.

Inspection

The trailer is weighed and tested to confirm it meets the required standard.

Certification

We issue engineering compliance certification so your new ATM can be recorded on registration.

Related services

GVM upgrades →

Heavy Vehicle Certification (VSB6)

Vehicle modification engineering →

GVM Upgrade Finder Tool

From the blog

What is a GVM upgrade? →

GVM Upgrade Costs in Australia and What to Expect

Overloaded 4WD Legal Risks in Australia: Myths vs. Reality (2026 Guide)

Understanding the vehicle certification process→

Ready to upgrade?

Servicing vehicles Australia wide

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Get it certified right, the first time.

Contact KME Vehicle Engineering

A Guide to What is Allowed Around Australia...

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KME provides independent engineering advice and certification. We recommend solutions that are legal, practical and suited to what your vehicle is needed for.

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Frequently asked questions

NSW, Victoria, South Australia, Tasmania

Yes.These are allowed under limited circumstances.Usually this occurs as a result of a Second Stage of Manufacture, the common ways people refer to this are: Federal Approval or Pre-Rego. The way this works is: 1. A customer selects and purchases a vehicle - 2. The vehicle is re-manufactured according to the SSM 3. The vehicle is registered. The registration must occur after the re-manufacturing, thus the term Pre-rego.These kinds of changes are accepted by most jurisdictions, with the notable exceptions of QLD, WA, ACT and the NT. These jurisdictions do allow these under limited circumstances.

Northern Territory

No.The Vehicle Standards Office does not recognise any change in GCM from the original, first stage manufacturer. This determination applies to both in-service and SSM upgrades that purport to increase the GCM.

Western Australia

GCM Upgrades: Yes. The Department of Transport allows this under VTB 181A. Depending on the popularity of the vehicle type, we may need to wait until there are multiple customers before conducting the required tests.BTC Upgrades: No.The Department of Transport directs people to section 168 of the Road Traffic (Vehicles) Regulations 2014 where it says that only the manufacturer of the vehicle can define the BTC of a vehicle. The department's interpretation of this manufacture is the first stage manufacturer of the vehicle only.Refer to the DTMI FAQ page here for more details.

I have a LandCruiser but I don't know its GCM?

For many years LandCruisers were produced without a specified GCM. This value is specified by the Manufacturer. If the manufacturer does not specify it, then your vehicle does not have a specified GCM. Typically people will simply add the GVM and the BTC together to get a pseudo GCM (if these were loaded to their maximums, then you can't theortically carry anymore without exceeding either your GVM or BTC so it is crude, but it works). But this is not the GCM for the vehicle as it doesn't have one. Where people get into disagreement about this is when a vehicle has a GVM Upgrade, and then the question is, what is the new pseudo GCM. Is it the old pseudo GCM (original GVM + original BTC), or is it a new value (new GVM + original BTC). The truth is, it doesn't matter, as the vehicle does not have a GCM...To know if your vehicle has a specified GCM, it will be based on the age of the vehicle - see attached links for 2x 70 Series spec sheets - 1 from 2016 showing no GCM listed, and one from 2018 showing a GCM. You can look these up for Prados and the 200 Series as well.As a result of popular demand, we now conduct these assessments in person for a fee of $990. We inspect your vehicle thoroughly and then issue you with a vehicle placard and letter specifying your undefined GCM. This should avoid you any awkward conversations with vehicle enforcement officers across Australia.

Daly was a pleasure to work with and has a wealth of knowledge, which he is happy to share. He is able to explain ADR requirements in simple terms and is more than happy to help customers understand the pathway to certification.

Steve P.

Very professional and efficient service. Daly is very knowledgeable and obliging and a pleasure to deal with.

Duncan T.

I can't complain about getting my GVM upgrade the same day I asked and paid!! Too good to be true. Amazing service.

Jamie L.