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All vehicle modifications must conform to the National Code of Practice for Light Vehicle Construction and Modification (VSB14). This document provides the technical requirements for compliance when modifying or constructing a vehicle.
NCOP11 Section LS Suspension and Steering provides the allowable limits for suspension lift.
For motor vehicles under 4.5 tonnes GVM, the fitting of tyres and rims must adhere to the specifications listed on the vehicle tyre placard. In some cases, such as basic modifications, the vehicle may be equipped with tyres other than those listed on the tyre placard; however, this must be in accordance with VSB14.
The Victorian Department of Transport and Planning (VicRoads), also provides additional guidance for modifications on passenger and light commercial vehicles, as well as an alternative to VSB 14 for four-wheel drive vehicles. This information is contained within Vehicle Standards Information sheet 8.