NSW Rims and Tires Information:
ADR 24 CEASED TO HAVE EFFECT: 1 January 2005.
Re: Accuracy of Speedometer & Legal Rim/Tire Combinations
http://www.rta.nsw.gov.au/registrati...vsi09_rev4.pdf
Up until July 2006 the Australian Design Rules required new cars to have speedos that are accurate to within 10% of actual speed when traving over 40km/h. The current Rules disallow under-reading, and permit over-reading by up to 4kmh + 10%
Wheel/Tyre Combinations:
When selecting your combination, you must take into account your stock recommended rim/tyre combination from Honda/Car Manufacturer.
This information can usually be found on a Placard found on the inside of the Driver Side Cabin Door.
In NSW you may only have an increase of less than 10mm of your TOTAL DIAMETER. That is, the length around your wheel + tyre.
Example: (Ru$ki's Original Post)
For the purpose of an example, a vehicles' stock wheel and tire combination is 185/60/14
Said vehicle can legally use 205/35/17
- The rolling diameter is decreased by 0.3mm
Because: the speedometer is 0.4% faster and as a result, if the Speedometer is reading 60km/h your actual speed is 59.42 km/h.
This vehicle cannot legally use 205/40/17:
- rolling diameter increased by 18.2mm
Because: the speedometer is 3.2% slower and as a result, if the Speedometer is reading 60km/h your actual speed is 61.92 km/h
Wheel / Tyre Combination Calculators
These tools will help you calculate what diameter your wheels and tyres are or will be, and also tell you how much difference there is on your speedometer.
http://www.chris-longhurst.com/carbi...yre_bible.html
http://www.miata.net/garage/tirecalc.html
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