VIC ROADS - Vehicle standards information - Guide to modifications for motor vehicles.
8. WHEELS AND TYRES
Replacement wheels and tyres may be fitted provided that they comply with the following requirements:
The width of any replacement rim must not be:
more than 25mm greater than the widest wheel specified by the vehicle manufacturer for that model or vehicle series; or
less than the width of the narrowest rim specified by the vehicle manufacturer for that model or vehicle series.
Rims, which have been widened, must have no more than one peripheral weld. All welding must be carried out in accordance with recognised engineering standards, and the rims must comply in all respects with specifications contained in the Tyre and Rim Standards Manual published by the Tyre and Rim Association of Australia.
The overall diameter of any replacement rim and tyre must not be:
more than 15mm greater than largest diameter tyre specified by the vehicle manufacturer for that model or vehicle series; or
more than 15mm less than the smallest diameter tyre specified by the vehicle manufacturer for that model or vehicle series.
Rim and tyre combinations must be in accordance with the recommendations contained in the Tyre and Rim Standards Manual published by the Tyre and Rim Association of Australia and have a load and speed rating equal to or better than that required by the standards for registration.
The wheels and tyres must not foul any part of the body, suspension, steering or brake components at any position of the suspension travel or steering movement.
The maximum allowable track increase is:
in the case of a front axle-25 mm;
in the case of a rear axle with independent suspension-25 mm;
in the case of other rear axles-50 mm; and
in the case of a motor vehicle manufactured with a combination of front wheel drive, McPherson strut front suspension and negative scrub radius steering geometry, no increase in wheel track is permitted unless specified by the vehicle manufacturer.
in the case of a motor vehicle fitted with a diagonally split braking system (i.e. one front wheel and opposite rear wheel on same hydraulic circuit), no change in the wheel track dimension is permitted.
Spacers between the wheel and hub are not permitted unless provided by the vehicle manufacturer as original equipment.
Wheel nuts must engage the thread of the wheel stud for at least the same length as the original wheel nut and have the same taper as the mating wheel stud hole.
The stud pattern of the replacement wheel must be the same as the original. Re-drilling wheels, hubs, drums, discs or axle flanges is not permitted. Wheels with slotted stud holes are not permitted.
Aluminum alloy wheels (mags) are acceptable provided they meet the above requirements and are legibly and durably marked to show compliance with one of the following standards:
AS 1638 Australian Standard
DOT Department of Transport USA
JWLT Japanese Light Alloy Wheel Truck and Bus
JWLTJapanese Light Alloy Wheel
JIS Japanese Industry Standard
KBA German TUV Certification
VIA Vehicle Inspection Association Japan
Repaired or damaged alloy wheels are not acceptable.
Unless im reading incorrectly, this says nothing about the size of the rim, just that it cant be any wider than 25mm and the diameter of the tyre cant be more than 15mm larger, if im reading inccorectly then can someone tell me please.