What tyre size is legal

[laocius Lurker Find all posts View Profile Close laocius]

This question might have been asked many times.
But I never find an answer.
Can you legally fit 285/70/r17 to a Prado.
Almost every state in Australia has a 50mm diameter increase limit. NSW also has a 7% increase limit, which means if you got small stock wheels, like jimny, you can only increase the diameter by 48mm.

But I have seen so many people fitting 285/70/r17, which is 54 mm increase from 265/65/r17. If you have a VX/Kakadu that comes with 18 in wheels, the increase would be 56mm.
That is obviously out of the legal range.

My calculation is based on the profiles of the tire. I have seen in other forums referring tire manufacture specifications. For example, Nitto tires has a size chart on which 265/65/r17 has a diameter of 782mm, and 285/70/r17 has a diameter of 832. And the increase is just 50mm.
My question is what's the right way to calculate tire diameters?
Will fitting 285/70/r17 void your insurance? I haven't heard of anyone getting trouble with the police with that big tires.

Even if it's not legal, I'd like to hear people's real life experience.
Has anyone had trouble with his insurance claim because of illegal mods?


I do love 285/70/r17. They just look bloody awesome!.

Thanks

[Boneyone Member Find all posts View Profile Close Boneyone]

By my calculations 285/70R17 is bang on for 7% so you should be good if you are in NSW. Although looking at mine I reckon you would struggle to fit them in.

2010 Prado standard 265/65R17 = 769.5mm or 30.78 inches
My tyres 265/70R17 = 796mm or 31.84 inches
285/70R17 = 824mm or 32.96 inches

Queensland is a whole different kettle of fish though...