Oversized tyres and roadworthiness/insurance

Wizard1, Wizard1, Wizard1!

So sorry to interupt your day and cause you to waste some of your valuable time on what is obviously such a futile question and so unrelated to this forum.

Have you ever tried ringing QLD transport and obtaining useful information?

I thought the idea of this forum was to share knowledge and experience. I was hoping for some such knowledge and experience on this topic. Your reply has let me down on both counts.

Thank you to the people who have read this thread - had nothing useful to contribute and have therefore not contributed.

I will continue to persist with whatever questions I feel appropriate. That is what I've paid my membership for.

Thanks in advance to those with constructive information!

Brad

Wizard1,
You must be a very lucky person or know someone and get the correct answers, unfortunately all to often two people can call and get two different answers. I know because it has happened to me more than once. Maybe a better way of helping someone who has asked for help is to guide them.
Cheers Walter

Wizard,

I gave up trying to get people at Queensland Transport to provide constructive and/or intelligent answers to questions raised. Most often the response was 'You will have to put your question in writing so it can be referred to the minister"

So I took my questions to the minister through my local MP and the responses received actually provided me with the reason I could not get answers previously.

The ministers reply to the local MP left him shaking his head in total bewilderment.

I am left to wonder why we allow these people walk around without someone holding their hand. And they make decisions!!!

Brad. Suggest you contact your insurance coy but I believe that
oversize tyres could prove expensive in the event of an accident.
Not sure that you can apply for recertification for tyres.

Kevin J

Thanks JustT

That is a good link - saved to my desktop.

Will talk to an engineer i think.

cheers Just T,
That is a good link.
Wonder if the RTA in New South as a similar one/.

Its a great link, but I'm not so sure that those figures apply, as they are under the section 'Low profile tyres'. Having said that they don't seem to talk about increasing the tyre size.
A mate who recently puchased a low lux said the rules (in nsw anyway) were dependant on when the car was made. He said that till recent days 50mm was OK and post, 50mm was to big.
Paul

This link was posted on this thread some time ago. I can read the particular post out for you if you like.

Do people usually cop this much crap for asking a fairly straight forward question??

Are there this many people with nothing better to do than chastise people for trying to gather information?

It must be nice to know everything and not have to ask others for advice, thats what this forum is for isn't it?

OK So I'm not some kind of internet nerd or expert on all things 4wd. Thats why I'm here.

Thank you to the guys who have helped me out. It is much appreciated. It was mostly a simple and painless process.

To the others - get a life.

Brad G,

You're right that's what this forum is all about and I would say that the fact of the matter is that of the 277 views so far a vast majority of those people have found it informative.

So don't be discouraged keep posting when you want an issue discussed.

Brad
Don't take things too serious , what might seem like people copping crap for asking a fairly straight forward question is in my case done in jest , so chin up old mate and enjoy .......the flak.
You'll get the hang of it as time wears on, now I didn't know the link had been posted before , sometimes it is a good thing to re-post things because there will be new Members or just visitors to the site that would have missed it , you offered to read it to me , do you want my phone number ,

.

That would be a great bedtime story for the kids hey Doug LMAO

Cheers Kev

Cheers Bushy, exactly what I want to avoid. will do some further research.

Brad

Excellant info - Thanks John. Maybe tyre fitters can issue a mod plate as well - you would think they would be doing this all the time.

Thanks again, Brad.

Brad, interesting isn't it.

A few rant and rave, but not many go out and find the solution, and it only took a few phone calls and a little research on the web. I started with a question like yours on a forum.

Mechanic also suggested some slightly softer pads to increase the braking capacity. After fitting, we could still lock up the front wheels so every one was happy.

The reason I went for N speed rated tyres is that it gave me a larger range of tyres to choose from. And the Q rating was for the petrol model, the diesel's top speed is 20km/hr less. The speed rating is for continuous use too, can't see me sitting on over 130km/hr for any sustained period. :o) The first hill would slow me down to less than that even with foot flat to the floor.

Impresses the tyre fitters no end showing them the blue plate, if they ask, but not many actually query putting the oversize tyres on.

Zig,

Just came across this thread and wondered if someone would refer to the DRAFT National Code of Practice (NCOP).

I have been a contributor to the working party on LS11 in relation to tyres.

Right at the outset, the NCOP is still a draft code and has not been approved in all states but there is a high likelihood the NCOP will be approved and adopted in all states. The drive is to have the NCOP precisely that, a NATIONALLY adopted code so that all states have the same regs so that no longer will vehicle which is legal in one state is not in another.

For you BradG, the NCOP is planned to be adopted in Qld from Jan 1, 2009 and in it's current form has already been approved for tyre sizes for vehicles designed for off-road use to allow an increase of Overall Diameter by 50mm without the need for certification. The problem with this is that the suspension section specifies that the maximum lift without certification is 50mm which can be made up of a combination of suspension lift, body lift or tyre size increase (a 50mm increase in OD results in a 25mm lift in chassis height). So if you changed your suspension to say an OME kit from ARB, you would not be able to increase your tyre size. OME = 50mm lift and a 50mm tyre = 25mm thus 25mm more than the regulation. As many of us already know and do, a popular replacement is the 285/75R16 which is about 40mm bigger than a Landcruiser's OE tyre.

There is a proposal to change the draft NCOP to allow a 75mm lift made up of a combination of up to 50mm suspension and/or body lift plus an increase of the tyre size by 50mm OD (25mm lift). This is still under consideration. The states' transport authorities are concerned that 75mm is higher than they are currently comfortable with in regards to affects on braking, swerve and tilt (centre of gravity). Members of the tyre and 4x4 vehicle aftermarket manufacturers are in discussions on how to provide testing to alleviate these concerns.

All of the anacdotal comments about what people are currently doing would be moot if your insurer abandoned your claim. however the keys to understanding the current situation for 4x4 owners revolve around the applications of ADRs. ADRs overrule state laws in some cases as so long as a vehicle meets ADRs, the federal law takes precedent. And currently there are some anomilies. But I won't detail them here.

But right now and in short you may fit a replacemnent tyre that is up to 15mm taller (or up to 26mm smaller) than the largest or smallest tyre fitted to the vehicle's make, model and series. The key is SERIES as within a series there may be many different tyres fitted to different series within the model. EG a GU patrol may have a 265/70R16 (779mm), 275/70R16 (792mm), 275/65R17 (792mm) but the DX models can be ordered with a 750R16 (810mm). Therefore, even if your GU ST model had say a 265/70R16, you can fit a LT265/75R16 (806mm) because it is well within the maximum size permissable, ie, 825mm (7.50R16 @ 810mm + 15mm = 825mm). This fact is little understood by most tyre retailers and some inspectors too.

The second consideration is Load Index. Replacement tyres must have a Load Index not less than the OE tyre as indicated on the placard. Therefore if your placard states the tyre should 112 LI, then your replacement tyres must be 112 or greater. NOT LESS. If more than one LI is listed you may refer to the lowest LI on the placard. There is one exception. If the placard lists an Axle Rating as in the case of Hilux and several other 4x4 utes, then you may use a Load Index that equates to the axle rating. In the case of Hilux, the axle rating is 1570kg. 1570kg/2 = 785kg = LI of 99. So even though the tyre may be 104 to 112 depending on model, you can replace the original tyre with a lower LI so long as it exceed the axle rating. This is also often not understood.

The final consideration is Speed Rating. This is simple and straight forward. 4WD vehicles require a minimum speed rating of N (140kph) even when higher speed rating OE tyres are fitted but if fitted with a lower speed rating (some vehicles use L) then the lower speed rated tyre may be used. Simple as that. (for cars it is S or 180kph). However, you may want to consider the maximum speed you are likely to drive at and if higher than 140, you should use tyres of a higher speed. But in that case, you are probably well over the gazetted speeds anywhere in Australia, including the new 130 limit in NT, so you've probably got problems with your insurer and the police if driving that fast...!

These last two factors are controlled by ADRs and all states recognise ADRs where they conflict with he literal interpretation of the regualtions as written.

I hope everyone finds this info useful.

John