Legalities of Wider Tyres

[Hawkeye 135i]

I am proposing to change from rft to conventional rubber in 225/40R18 (front) and 255/35R18 rear. My insurer has no problem with continuing my insurance provided that the change in tyre size is legal.

The RTA (NSW) specifies that "if the wheels are listed on your car's tyre placard or in the owner's handbook then the tyres you fit must be those listed on the placard or in the handbook for those wheels."

Our placards specify maximum tyre sizes of 215/40R18 front and 245/35R18 rear. Wheel sizes are not specified on the placard other than by reference to the diameter of the wheel in the specified tyre sizes, that is, 18".

I suspect that the RTA statement is concerned with tyre sizes which are not supported by the appropriate wheel width (in which case 225/255 are OK on the standard wheels) but it is by no means certain that this is the intention from the RTA's statement above. Is this the case or should I be concerned that "the tyres you fit must be those listed on the placard" means that the maximum tyre size to be fitted is 215/245?

[chylld]

your chosen sizes are fine.

the new wheel/tyre combo just has to be within 15mm of the factory rolling diameter, and wheel width not more than 1" wider.

more info here: http://www.rta.nsw.gov.au/registrati...vsi09_rev4.pdf

[Hawkeye 135i]

Thanks for your reply.

The link you provided is where my confusion came from.

Reading the "Tyres" section from the link again, the RTA seems to be concerned with ensuring that tyres are matched to appropriate width wheels given that in the first paragraph the RTA says "the tyre and rim industry sets standards for the correct combinations of wheels and tyres" and "the tyres you fit must
correctly match your car’s wheels."

It makes sense in this context that the RTA's statement that "if the wheels are listed on your car’s tyre placard or in the owners handbook then the tyres you fit must be those
listed on the placard or in the handbook for these wheel" is focused on tyre size to wheel width, not setting the maximum tyre size as that which is on the placard (215/245), provided that the rolling diameter of the wheel and tyre is within 15mm of FRD.

[Hawkeye 135i]

Thanks for your reply.

The link you provided is where my confusion came from.

Reading the "Tyres" section from the link again, the RTA seems to be concerned with ensuring that tyres are matched to appropriate width wheels given that in the first paragraph the RTA says "the tyre and rim industry sets standards for the correct combinations of wheels and tyres" and "the tyres you fit must
correctly match your car’s wheels."

It makes sense in this context that the RTA's statement that "if the wheels are listed on your car’s tyre placard or in the owners handbook then the tyres you fit must be those
listed on the placard or in the handbook for these wheel" is focused on tyre size to wheel width, not setting the maximum tyre size as that which is on the placard (215/245), provided that the rolling diameter of the wheel and tyre is within 15mm of FRD.

[chylld]

Originally Posted by Hawkeye 135i

Reading the "Tyres" section from the link again, the RTA seems to be concerned with ensuring that tyres are matched to appropriate width wheels given that in the first paragraph the RTA says "the tyre and rim industry sets standards for the correct combinations of wheels and tyres" and "the tyres you fit must
correctly match your car’s wheels."

Yep tyres need to fit properly to the wheel, if they are too narrow or wide then they won't seal properly with the rim and you'll have quite dramatic problems

Michelin's website makes it easy to find the min/recommended/max wheel widths for a given tyre - simply pick a tyre (e.g. the Pilot Sport 3) and then the size and the info is all there.

Interesting fact: under heavy braking, the tyre can rotate as much as half a revolution around the rim!

[MickyD]

make sure the load rating is the same or higher.

[Taymaishu]

Originally Posted by MickyD

make sure the load rating is the same or higher.

Speed rating as well.

[MickyD]

as stupid as it sounds (and it is ridiculous), last time I checked, the speed rating doesn't affect the legality. The load rating does though.

[Hawkeye 135i]

Thanks guys.

As far as which tyre, I'm considering the Hankook Ventus if I buy local as they appear to offer decent performance at a good price. If I buy through tirerack, ps2, Conti DW and the Yoko Advans look good for competitive prices to the locally sourced Kooks. All these tyres tick the boxes re speed and load ratings.

Which brings me to another question - for those who have imported tyres, are the tyres stamped as ADR compliant? If not, does this present a problem for roadworthiness and insurance? I've read the ADR and think that it will be OK but would appreciate if someone has something more concrete - I'd hate to put my insurance in jeopardy on a little detail like ADR compliance for the sake of saving a few hundred $ on tyres.

[Taymaishu]

Standard advice on tyres, from what i understand..

Maximum further width is 20mm from original spec. My fronts were 205's, I now have 225s. Any further and I am not able to drive legally.

With wheels, you can't go more than 1" wider than what you originally had.

Cheers

[555]

Originally Posted by Taymaishu

Standard advice on tyres, from what i understand..

Maximum further width is 20mm from original spec. My fronts were 205's, I now have 225s. Any further and I am not able to drive legally.

With wheels, you can't go more than 1" wider than what you originally had.

Cheers

Vicroads states that you can go up to 1" diameter and width increase based on the largest available wheel for the series/model of the car...

E.g: a 118i can fit 19" x 9.5" rims (since the largest available wheel for a 1 series is 18 x 8.5) - it is not based on what the actual car came with...
[whether it fits without guard mods is another issue]

caveats: load rating must be same or greater.

[MrBlonde]

I strongly suggest you guys that are *that* worried about your respective state legislation and insurance concerns .. just don't modify your car at all. Enjoy it stock which is pretty good.

[Choclove23]

...says the guy with the 135i!

Originally Posted by MrBlonde

I strongly suggest you guys that are *that* worried about your respective state legislation and insurance concerns .. just don't modify your car at all. Enjoy it stock which is pretty good.