The following is an extract from the QLD Code of Practice Vehicle Modifications, if you click on the following link it will bring up the entire file, you will notice that you can increase the width by up to 50% 225 x 50% = 112.5 + original 225 = 337.5, so a 335 would be legal width, but way too tall.
Vehicle height can only be increased by 25mm, so that means a 50mm diameter increase so using Cooper Tyre figures as shown the standard 225/70R16 was 728mm tall and the 255/70R16 is only 763 tall which is 30.4" but more importantly 35mm taller than standard so YES you could use those tyres, you will need to check your clearances if using stock rims as they may rub on control arms at full lock, but that can be adjusted.
225/70R16 6.00-7.50 W 728 103T 50,000
255/70R16 6.50-8.50 W 763 111T 50,000
http://www.tmr.qld.gov.au/~/media/sa...ations1112.pdf
3.4 Wheels and Tyres
The overall tyre diameter can be increased to allow an increase of 7.5mm in vehicle height
for passenger vehicles and no more than 25mm in vehicle height for four wheel drive
vehicles (typically MC ADR category).
Tyres fitted to off-road passenger and light goods vehicles (MC, NA, NB ADR category) must
not be more than 50% wider than the vehicle manufacturer’s widest optional tyre. Tyres fitted
to passenger vehicles must not be more than 30% wider than the vehicle manufacturer’s
widest optional tyre.