legal tyre size in Vic

Submitted: Friday, Sep 13, 2002 at 00:00
ThreadID: 1967 Views:6032 Replies:3 FollowUps:1
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I have been looking at upgrading the BFG A/T 225/75 tyres on my discovery to 245/75's. The problem as I see it is that vicroads state that the maximum increase in wheel/tyre diameter is only 15mm. The 245's are 38mm (1.5") larger than the stock size. Not a big increase and still 30mm smaller than the similar Defender drivetrain.

Does this mean the only option would be to get an engineers certificate? There seem to be an awfull lot of 4wds running around on 31 or 32" rubber.
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Reply By: Member - Willem- Friday, Sep 13, 2002 at 00:00

Friday, Sep 13, 2002 at 00:00
I do not live in Victoria BUT the rule of thumb is that if you do not modify your vehicle do the degree that it is noticable then the chances are that nobody( including the law enforcers) will notice you. Please do not worry too much about the minute details of the law makers as far as vehicle modifications go. I have spent the past 30 years travelling around Australia with what could be deemed as illegal vehicles and have never been faulted including being stopped at Police road blocks in every state. I am not advocating that you should break the law. Just "Don't happy" !!! Cheers, Willem
AnswerID: 6599

Follow Up By: Mark - Friday, Sep 13, 2002 at 00:00

Friday, Sep 13, 2002 at 00:00
Unfortunately its the insurance assessors that you have to worry about these days, if your vehicle is involved in a prang and is found to be outside RTA spec's or modified without notifying them.... good luck with the claim.
FollowupID: 2968

Reply By: Mal58 - Monday, Sep 16, 2002 at 00:00

Monday, Sep 16, 2002 at 00:00
I went through a similar thing recently. My 4X4 comes out of the factory with 265/70/r16. I needed new tyres and wanted to get an AT tyre, so went to quite a few tyre dealers who recommended I change size to the 265/75/r16 as it is a more common tyre size whith much greater choice and is less expensive than the smaller size. The higher profile tyre gives an increase in diameter of 25mm.

I wrote to my insurance company, and they said it was OK, but when you read the fine print in their policy, its has words to effect that you must keep the vehicle in a roadworthy condition. In Victoria, 15mm is all you are allowed for increase of diameter otherwise it is not roadworthy.

I was confused. I also note that the ADR that the Vic Roads standards is based on is under review with the recommendation that it be scrapped. But I could not find anyone who could tell me the status and what the follow on effects would be. As I needed new tyres I had to make a decision, so I bought the more expensive, less choice tyre (ie the same size but in the AT form factor) to remain legal.

Something I checked out on the way though, I I looked through all variants of the model vehicle I have to see what the largest size tyre they fit from standard. This may give pointers to the max size that you can legally fit.

Difficult choice, particulary when 8/10 4X4 fitted with after market tyres have tyres with on the letter of the law are not roadworthy due to size.

Hope this helps with your confusion.

AnswerID: 6650

Reply By: flappan - Monday, Sep 16, 2002 at 00:00

Monday, Sep 16, 2002 at 00:00
Interesting problem this one, that gets discussed time and time again, really without a conclusive result.

I'm fairly sure the facts are that you can't increase your tyre diameter by more then 15mm. The only time you can is with an engineers cert, and for most vehicles that just want happen because, rightly or wrongly, the manufacturer knows best. The Engineer isn't going to override it. The only exemption to that I'm aware of, is some of the Jeeps with whats considered an aftermarket axles, vastly overengineered for normal running. The engineers don't seem to have much problem with agreeing on those. HOWEVER, the one thing I would consider is how modified is the vehicle. If its quite modified with lots of bar work, raised, etc etc, anything illegal according to the RTA IMO is asking for trouble with your Insurance co. If its basically your standard beast, and your insurance co with accept the bigger tyres, and most will, then maybe you take your chances. Remembering one thing though, if its a minor bingle your in, or not your fault, the Insurance co may not look to hard, BUT, if you happen to crash into a Porche dealership, the Insurance co will be looking to get out any way they can.

I made a comment on another thread, about something similar, that it doesn't matter what your insurance co acknowledges on the policy, if it's not legal according to the RTA then insurance wont cover it. Savvas says that incorrect and NRMA will cover it, I still have some reservations about that, from other peoples experiences to the contry, but it may be worth considering and looking at further.

AnswerID: 6660

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