Just don't drive to Victoria as 15mm is the maximum oversize:
Vic standard vsi8 13.3.2 Option 2 says:
"the overall diameter of any replacement rim and tyre must not be: 1 more than 15mm greater than largest diameter tyre specified by the vehicle manufacturer for that model"
http://www.fx-hzcarclub.com/componen...-modifications
245/75 is 19.25mm over standard
245/70 is only 7mm over.
My insurance company was happy for me to fit 245/70 but not 245/75 in Vic.

