Information regarding QLD legalities are available from the QLD Department of Transport Modifications Guide which is based on the Vehicle Standards and Safety Regulation 1999. You can access the guide at:
Please note I am in no way an expert and I hope my initial comments will be subject to friendly ridicule and lively debate.
The basics (there may be more specific points for each item in the modification guide):
- The rim diameter may be varied from the standard size but the overall diameter of the tyre must not vary by more than +15mm or -26mm.
- The rims and tyres must not protrude beyond the bodywork of the vehicle, including flares, when viewed from above with the wheels facing straight ahead.
- For an off-road passenger vehicle fitted with front and rear beam axles, the maximum tyre width must not be more than 1.5 times the vehicle manufacturer’s widest optional tyre.
- The speed rating of all tyres for an off-road passenger vehicle must be a speed of at least – 140km/h
- Load ratings of tyres must be at least equal to those specified by the manufacturer on the tyre placard fitted to vehicles made after 1972.
- The wheel track must not be reduced to less than the standard track specified by the vehicle manufacturer for the particular model of vehicle. Off-road passenger vehicles fitted with front and rear beam axles, may have an increase in track up to 50mm beyond the maximum specified by the vehicle manufacturer for the particular model of vehicle.
I would love to fit a 31 inch tyre like so many have before me, but they are outside the legal increase in Qld to my knowledge. My understanding is 15mm max overall diameter increase and the same or higher load rating. I can only go to 754mm (SR5 - 255/70R15 112S is 739mm). The 31 is beyond the 15mm OD increase and generally seem to be of a lower load rating across the brands.
I know I'm being picky here but I checked with my insurance company and they said "we don't mind what you do to your car, as long as it's legal". Whilst I don't want to wish a car accident upon myself, if I was in that situation with 31s I'm not insured, bad luck for me, for anyone else involved and the police might even decide to throw a few charges in for a vehicle that is not within legal specs. For a few inches of extra rubber I just think the risk far exceeds the benefits.
I called a few tyre shops when looking around for available brands. I was pretty amazed how many said to me, "look I can't recommend you put 31s on your hilux but we do it everyday and we haven't had any problems yet". It all just seems like a massive gamble.
I would love to be corrected if my research is not accurate. I simply can't find anything other than a passenger tyre that would legally fit my SR5.
Any ideas or feedback are welcomed.