Tyre Size

Hi all, I am still working out which way to go in regards to mud tyres. I have found Maxxis bighorn do a size which may suit as below this is a tyre chart and this were the resluts by punching in my factory size tyre which is 265/65/17 and the bighorns at 255/65/17, what do you think in regards firstly the tyre its self and also would the size be all ok ?? I know I could just go to a 70 profile but as technically it will be ilegal Im trying to keep it all legal

Results for your selected Wheel/Tyre 1
Rolling Radius 388.15mm
Circumference 2438.82mm
Diameter 776.3mm
Wheel Cover Size Size 007

Results for your selected Wheel/Tyre 2
Rolling Radius 381.65mm
Circumference 2397.98mm
Diameter 763.3mm
Wheel Cover Size Size 007

Differences between Wheel/Tyre 1 & 2
Rolling Radius -6.5mm
Circumference -40.84mm
Diameter -13mm
When your speedo reads 100km/hr you're actually at 98.3 km/hr

Does this look like it could be a winner for me ??

Regards Steve
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Reply By: olcoolone - Sunday, May 29, 2011 at 12:16

Sunday, May 29, 2011 at 12:16
you have answered your own question and seeing you don't want to go to a ILLEGAL size what option have you got.

It was said in your previous post that a little bigger in tyre isn't a bad thing and the chances of getting caught is well close to zero.

Yes go the size you feel comfortable with and stop worrying.
AnswerID: 455766

Reply By: Member - Tony V (NSW) - Sunday, May 29, 2011 at 13:53

Sunday, May 29, 2011 at 13:53

If you are in NSW VSI09 states plus or minus 15mm in rolling diameter so you are fine

The hidden issue with tyre is that any tyre size e.g. 265/70/17 is the carcass size of a highway tyre.
This does not include the tread of an AT or mud tyre.
This variation can be up to 50mm depending on the tyre brand.

While this is no issue for the RTA as you comply with their rules, your speedo may not be reading correctly.So keep that in mind when travelling.

Please note that I have no affiliation with them but the only tyre company that I have seen that details this is Cooper,
Image Could Not Be Found

Cooper Tyre web site

Tyres shouldn't really be this complicated, but good luck the Maxxis are good tyres.

AnswerID: 455775

Follow Up By: blown4by - Sunday, May 29, 2011 at 14:24

Sunday, May 29, 2011 at 14:24
With 4WD (not AWD) tyres you are allowed to go +50mm or -26mm in diameter compared to the manufacturers tyre sizes shown on the tyre placard. See VSB14 Jan2011 Light Vehicle National Code of Practice.
With cars the sizes are +15mm or -26mm in diameter.
FollowupID: 728712

Follow Up By: Kimba10 - Sunday, May 29, 2011 at 14:25

Sunday, May 29, 2011 at 14:25
Hi there Tony, seems to be the only muddy I can get and still stay legal. If I run the BF's they only come in 70 profile which puts the rolling diameter to 28mm above standard so technically will make me ilegal. So I take it the 255 just means Ill be a tad narrower then standard ?? As my speedo at the moment is spot on 100% with GPS, so if I went the higher profile of 70 series then it will put my speedo out by around 3 to 4k approx meaning if my speedo says I'm doing 100 Ill actually be doing around 103/104 but with the bighorns Ill be a tad under whats indicated on speedo which is fine, less chance of getting pinged. Just did a google review on the tyres, seem to have pretty good reviews..........Regards Steve
FollowupID: 728715

Follow Up By: Member - Tony V (NSW) - Sunday, May 29, 2011 at 15:13

Sunday, May 29, 2011 at 15:13

Thanks for that, I agree that VSB14 states plus 50mm or minus 26mm, the National VSB14 is advisory and overruled by state law, as I stated in NSW VSI09 is enforced the same was NSW were to impose VSI50 which was to be different to other states. (Stopped by 4WDer's)

I quote from the VSB pdf "Queries regarding VSB 14 should be directed to your local Registration Authority."

So Kimba, if you are in NSW I would suggest you comply with the rules on the RTA compliance web page

Please note that Victoria banned the Chinese Chery being sold in Victoria which has ADR compliance and is sold everywhere else in Australia.

Drive Feb 2011


FollowupID: 728719

Follow Up By: Kimba10 - Sunday, May 29, 2011 at 16:06

Sunday, May 29, 2011 at 16:06
when I went into the RTA last week (again) I was told 15mm max on any vehicle including 4WD doesnt make a difference wether its a toyota yaris or a landcruiser, even today I rang a tyre place and he informed me (to my suprise) I would be over the legal limit running bf muddies in 70 profile as it increases my rolling diameter by more then 15mm, this was with out me asking or mentioning any thing about it. Yes Tony im in Penrith NSW and it was Penrith RTA I have been into a couple of times to query them. I was also told by other people even a well known tyre dealer I would be legal then when I led him to the RTA page he was suprised, even been a 4wd makes no difference, he was a bit concerned after I pointed it out to him. Blown4by, if you could copy and paste that on here would be appreciated I will print it up and take it to RTA tomorrow and question them about it as he (RTA) was informing me didnt make a difference been 4wd, I think for memory (dont quote me on it) but Im sure he said up to 4.5T are all the same requirements ?? Regards Steve
FollowupID: 728723

Follow Up By: Member - Tony V (NSW) - Sunday, May 29, 2011 at 16:48

Sunday, May 29, 2011 at 16:48

Use the vsb.pdf link in my last post, you will want the section 4.1 regarding tyres, it will be around 4.2.4 about +50mm and -26mm. It does differentiate between car (15mm) with an exemption for 4WD to 50mm. However, as I said the NCOP is advisory and the states rules are law so VSI 09 is the one that counts.

Ther are

You should also check your insurance company, I think they will say, if you don't comply with your state of registration rules, your not insured.

There are heaps of threads on this forum on tyres, heres just one.
Thread 55724
FollowupID: 728730

Follow Up By: Kimba10 - Sunday, May 29, 2011 at 17:47

Sunday, May 29, 2011 at 17:47
Vehicle Standards Bulletin 14 (VSB 14) Vehicle Regulation Related Links
?Certified Road-Friendly Suspensions
?Seatbelts for Kids
?Vehicle Safety
?Vehicle Standards Bulletins
?Road Safety
National Code of Practice for Light Vehicle Construction and Modification (NCOP)

4.2.4 Overall Nominal Diameter
The overall diameter of any tyre fitted to a passenger car or passenger car derivative must not
be more than 15mm larger or 26mm smaller than that of any tyre designated by the vehicle
manufacturer for that model.
The overall diameter of any tyre fitted to:
? 4WD passenger vehicles specifically designed for off-road use (typically MC ADR
category). All wheel drive (AWD) vehicles including those AWD vehicles that may be
certified as MC ADR category, (also commonly known as soft roaders) are not
included in this category;
? 4WD goods vehicles and their 2WD equivalents if the chassis and running gear are
essentially the same as the 4WD version (N ADR category); or
? any medium weight goods vehicle (NA2, NB ADR category).
Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the
vehicle manufacturer for that vehicle.
Note: Increases in tyre diameter are subject to compliance with all other requirements
specified under this clause (Clause 4.2 Non-Standard Tyres and Rims) and may
therefore be limited by other factors such as insufficient clearance.
Speedometer accuracy must be maintained for the selected tyre and rim combination to within
the degree of accuracy specified in ADR 18 where applicable. It is suggested that the degree of
accuracy is in accordance with the most recent version of ADR18.
FollowupID: 728740

Reply By: Member - nick b - Sunday, May 29, 2011 at 16:56

Sunday, May 29, 2011 at 16:56
I have just fitted bighorns 762 tyres they are a lot less noisy on the road than i thought they would be ,very happy with the way they handle . maxxis say they are around 806 high but pumped up off car 790 and a little under that on the car. in SA 50mm higher for 4x4s .

regards nick
Cheers Nick b

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