Bigger tyres or replacement wheels
Compare dimensions and the evidence for your wheel and tyre fitment.
Modification compliance, made clear
Need to check a modification? MOD/CHECK it.
Source-linked vehicle modification guidance for owners, modifiers and authorised officers. Choose your jurisdiction, then compare original and modified specifications with published requirements to see when certification or further review may be needed.
Start here
Choose your jurisdiction
Start with the requirements that apply to your vehicle.
New South Wales
Choose a calculator
Start with a basic check, assess a vehicle system, or create an Inspection Mode record.
Light vehicles ≤ 4.5 t · Change jurisdiction in the headerQueensland
Choose a calculator
Choose the change you want to check. Read the scope and information needed before you start.
Light vehicles ≤ 4.5 t · Change jurisdiction in the headerNew South Wales
Choose a vehicle system.
Use an individual system check, combine wheels and suspension where they interact, or assess several live systems in one Inspection Mode record.
Prepare your information: View all system guides · Understand your result & VSCCS
What are you changing?
Find a starting point using words such as bigger tyres, lift kit, engine swap or window tint.
Choose a system below, or search for a modification.
Lift kit or suspension change
Start with measured height and suspension information. Tyre changes may also affect overall height.
Engine swap or performance change
Check selected engine and performance pathways and their supporting evidence.
Brake upgrade or replacement
Check the relevant brake modification pathway and installation evidence.
Steering, gearbox or driveline change
Review steering, transmission and driveline changes for the selected vehicle.
Seat removal, seats or restraints
Prepare the seating, restraint and mounting evidence for the change.
Towing, loading or a mass-rating change
Check recorded ratings and selected modification pathways. Queensland also compares actual loading.
Light bar, lamps or window tint
Check selected lighting, glazing and visibility requirements.
Camper conversion or body change
Prepare the body, chassis and installation evidence for the proposed work.
Adaptive controls or wheelchair access
Check the selected adaptation pathway and any individual design or approval needs.
Motorcycle bars, sidecar or trike changes
Read the selected motorcycle scope before checking dimensions or approval needs.
BASIC
Start basic tyre check →
Basic tyre diameter & width check
Enter the manufacturer references and fitted tyre to see the overall-diameter change in either direction, any width increase and whether either certification threshold is exceeded.
INSPECT
Start an inspection →
Multi-system Inspection Mode
Select every relevant live system, identify the subject vehicle once and produce a consolidated record that distinguishes assessed findings from systems not assessed.
MULTI
Start combined check →
Combined wheels and suspension check
Assess tyre, rim and suspension triggers separately, then calculate their combined effect on front and rear vehicle height.
Available now
NSW light vehicles · Selected checksComprehensive wheels & tyres
Detailed front and rear tyre dimensions, rim width, axle load evidence, wheel ratings, tyre category, speed rating and speedometer status.
Open comprehensive assessment →Suspension & ride height
Front and rear height changes, manufacturer specifications and assessed suspension-travel triggers.
Open suspension check →Engine & performance
Engine substitutions, displacement and power increases, forced induction, electric or hybrid changes, emissions, engine management, fuel-system and fuel-tank pathways.
Open engine & performance check →Transmission, driveline & steering
Transmission fitment, ratio and speedometer effects, drive-axle origin, driveline fabrication, added axles and steering modifications.
Open transmission, driveline & steering check →Seats & occupant protection
Guided checks for seats, seatbelts, anchorages, child restraints, seat removal, roll structures and pole-mounted cabin screens.
Open seats & occupant protection check →Braking systems
Guided checks for disc or drum arrangements, component substitutions, balance devices, service-brake controls and selected trailer-brake changes.
Open braking systems check →Vehicle ratings
Check proposed changes to vehicle and trailer mass ratings, including GVM, GCM, ATM and GTM, and the supporting documents you need.
Open vehicle ratings check →Body & chassis
Guided checks for structural body and chassis changes, towing and loading equipment, camper conversions, tow-truck work and road-rail equipment under VSI 06 Items 23–38.
Open body & chassis check →Mobility adaptations
Guided checks for appliances, adaptive driver controls, wheelchair or orthopaedic seating, access equipment, standards evidence and separate exemption status under VSI 06 Items 53–56.
Open mobility adaptations check →Mopeds, motorcycles & trikes
Guided checks for forks and handlebars, sidecars, frames and swing arms, motor-tricycle conversions, and tow couplings under VSI 06 Items 57–61.
Open motorcycle modifications check →Lighting & visibility
Check lamp fitting and switching, measured window tint, glazing evidence and driver visibility. See which issues need fixing and whether certification may be required.
Start lighting & visibility check →Queensland
Choose a vehicle system.
Use an individual Queensland check or combine wheels and suspension. Each result identifies the selected requirements assessed.
Prepare your information: View all Queensland guides · Official Queensland sources
What are you changing?
Find a starting point using words such as bigger tyres, lift kit, engine swap or window tint.
Choose a system below, or search for a modification.
Bigger tyres or replacement wheels
Compare dimensions and the evidence for your wheel and tyre fitment.
Lift kit or suspension change
Start with measured height and suspension information. Tyre changes may also affect overall height.
Engine swap or performance change
Check selected engine and performance pathways and their supporting evidence.
Brake upgrade or replacement
Check the relevant brake modification pathway and installation evidence.
Steering, gearbox or driveline change
Review steering, transmission and driveline changes for the selected vehicle.
Seat removal, seats or restraints
Prepare the seating, restraint and mounting evidence for the change.
Towing, loading or a mass-rating change
Check recorded ratings and selected modification pathways. Queensland also compares actual loading.
Light bar, lamps or window tint
Check selected lighting, glazing and visibility requirements.
Camper conversion or body change
Prepare the body, chassis and installation evidence for the proposed work.
Adaptive controls or wheelchair access
Check the selected adaptation pathway and any individual design or approval needs.
Motorcycle bars, sidecar or trike changes
Read the selected motorcycle scope before checking dimensions or approval needs.
MULTI
Live
Start combined check →Combined wheels and suspension check
Check selected wheel, tyre and suspension requirements together, including their actual combined height change.
Available now
QLD light vehicles · Selected checksWheels and tyres
Tyre dimensions, load and speed ratings, manufacturer references and documented wheel fitment.
Open wheels and tyres check →Suspension and ride height
Measured ride-height changes, retained travel, components and combined tyre/suspension height.
Open suspension and ride height check →Engine and performance
Engine replacements, performance changes, documented comparisons and emissions evidence.
Open engine and performance check →Driveline and steering
Transmission, axle and steering changes, installation records and interacting systems.
Open driveline and steering check →Seats and occupant protection
Seat changes and removal, restraints, anchorages and the finished seating configuration.
Open seats and occupant protection check →Braking systems
Brake components, complete manufacturer options, conversions and installation evidence.
Open braking systems check →Vehicle ratings and towing
Current ratings, matched travelling loads, trailer and hitch limits, and proposed upgrades.
Open vehicle ratings and towing check →Lighting and visibility
Lamps and switching, measured finished glazing, mirrors and the driver’s view.
Open lighting and visibility check →Body and chassis
Roof, wheelbase, body, campervan and chassis changes, with design and installation records.
Open body and chassis check →Mobility adaptations
Adaptive controls, selected mobility aids and the records needed for specialist assessment.
Open mobility adaptations check →Motorcycles and trikes
Selected motorcycle dimensions and equipment, plus structural and trike assessment routes.
Open motorcycles and trikes check →Each result covers the checks you select and the information you provide. Other modifications and the vehicle’s overall compliance need separate assessment.
Modification guides
Know what to bring to the check.
Manufacturer references, worked examples and the scope behind your result.
A result you can understand and verify.
01
Choose jurisdiction and scope
Choose where the requirements apply, then select an available calculator. You only enter information relevant to its scope.
02
Use the correct reference
Use the applicable manufacturer diameter, width and suspension specifications for the same vehicle variant.
03
See each reason
The result identifies each certification trigger separately and flags when more information is needed.
Standards & sources
Published requirements for your jurisdiction
Each assessment identifies the requirements, official sources, review date and limits of the selected checks.