bikeman wrote:How did you get on with the engineering to make the larger tyres legal???
Hey bikeman,
Currently going through the process, Are you in Tassie? If so I can give you the details of the Engineer I'm going through.
The largest legal tyre that can be fitted to the MN Triton has an outside diameter of 800mm. No tyre comes in that size, the closest is a 245/75/16 which is 799mm, but isn't a common size and you would be paying an arm and a leg if you can find them. 265/75/16s which are 804mm are very common and much more attractivly priced.
In Tassie we have a Modification form that needs to be filled out and sent to the Department of Transport, I was hoping that they would just approve a 4mm difference without having to go to an engineer. Unfortunately not. They sent out a letter in the mail stating that the larger tyres wouldnt be approved due to the NCOP. They also stated that they would keep the application on file for three months, in which time I could consult an engineer.
Talking to the engineer, he said that most tyres actually measure under their advertised outside diameter. In this case the Cooper S/T's were advertised at 807mm but measured 788mm vertically and 800mm exactly horizontally when fitted to the vehicle. As such the engineer has said he has no problems sigining off on the certification. The paper work is currently going through. Its probably going to cost me about $200 all up.
Coopers generally have a larger OD than other tyre brands, so you would probably find that some 265/75/16's would actually measure well under the 800mm limit.
I asked him about 33's and he said that they would not be approved without going through a proper stability test which would be around the $1000 mark, possibly cheaper if more than one car was done on the same day.
Form can be found here:
http://www.transport.tas.gov.au/standards/vehicle_modificationsCheers,
Buddah