tyre sizes (again)

Submitted: Wednesday, Mar 19, 2008 at 21:33
ThreadID: 55724 Views:3590 Replies:7 FollowUps:4
This Thread has been Archived
Please don't shoot me!!!
I know its been done thousands of times, but I just can't seem to get a definitive answer.

My GU 4 handbook states a tire size on 16 x 8jj rims as LT265/75R16
As a lot of others do, I run BFG 285/75R16's

NSW RTA state "The outside diameter of the wheel and tyre combination must be no more than 15mm over the largest diameter
wheel and tyre combination specified for the vehicle and not more than 15mm below the smallest diameter wheel
and tyre combination specified for the vehicle."

Since my aspect ratio is still 75%:
75% x 265 = 198.75
75% x 285 = 213.75
difference is 15 mm

Also since the NSW RTA states "Wheels up to 26mm wider than the largest optional wheel recommended by the vehicle manufacturer for the
vehicle can be fitted without the need to notify the RTA."

265 to 285 only 20mm. Well within parameters.

Pardon my ignorance or lack of understanding if I'm off track, but does this not mean my tyres comply?
If so, why does everyone keep telling me otherwise???
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Reply By: Kev & Darkie - Wednesday, Mar 19, 2008 at 21:38

Wednesday, Mar 19, 2008 at 21:38
I just went through this with the QLD mob and my tyre rim combination was approved as compliant to the same details as you have just indicated.

Cheers Kev
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AnswerID: 293687

Reply By: Member - Shane D (QLD) - Wednesday, Mar 19, 2008 at 21:39

Wednesday, Mar 19, 2008 at 21:39
Nope,
I think you have misunderstood the wording.
15mm is in reference to overall hieght of the tyre, so if your standard tyre height is say 900mm, you can't go higher than 915 mm
Shane
AnswerID: 293688

Follow Up By: briann532 - Wednesday, Mar 19, 2008 at 21:47

Wednesday, Mar 19, 2008 at 21:47
Wife is currently out spending, so I cant actually measure, but it appears obvious to me then that my tires exceed the 15mm rule thereby making them illegal.

??? Ho hum, insurance issues...........legalities............
Can this be fixed with alcohol???
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FollowupID: 559381

Follow Up By: Member - Shane D (QLD) - Wednesday, Mar 19, 2008 at 22:03

Wednesday, Mar 19, 2008 at 22:03
Nothing can be fixed with alcohol. . . . . . . . slurp. . . . . . . . . .alcohol . . . .MMM found a tasty bourbon in the fridge. . . I'VE GOT TO GO NOW !!!
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FollowupID: 559387

Reply By: Member - Shane D (QLD) - Wednesday, Mar 19, 2008 at 21:52

Wednesday, Mar 19, 2008 at 21:52
Exploreoz has an excellent tyre calculator which also allows you to compare tyre sizes in detail.
Outside diameter of the 265/75 16 is 803.9 mm
Outside diameter of the 285/75 16 is 833.9 mm

30 mm bigger outside diameter of the 285's makes them technically illegal.
Shane
AnswerID: 293693

Follow Up By: Member - Graham H (QLD) - Thursday, Mar 20, 2008 at 19:58

Thursday, Mar 20, 2008 at 19:58
Heres another one that is very good as it allows you to change offset of rims etc

http://www.rims-n-tires.com/rt_specs.jsp
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FollowupID: 559549

Reply By: Member - Phil G (SA) - Wednesday, Mar 19, 2008 at 22:08

Wednesday, Mar 19, 2008 at 22:08
Brian,

This tyre law is ridiculous and was intended for smaller cars and not 4wds. The new ADRs (federal) have eliminated any reference to the 15mm rule, but the States have been very slow in catching on.

So when your tyres are half worn, they should be 100% legal :-)))

I personally would fit the 285's and not give it another thought.
No one has ever been nobbled for fitting 285's to a Patrol or LandCruiser.
Its extremely common and the tyre shops don't usually baulk at doing it.
AnswerID: 293700

Reply By: Member - Longtooth (SA) - Wednesday, Mar 19, 2008 at 22:14

Wednesday, Mar 19, 2008 at 22:14
The March issue of 4x4 Australia state that the rule has changed except in Qld and NSW to not greater than 50mm more than the largest approved by the vehicle manufacturer. This was attributed to the Michelin (B.F Goodrich) rep. I don't have the magazine - saw it at the library - so this is as I recall but not guaranteed totally accurate. Maybe someone with the magazine can confirm this. Don't buy the magazine anymore since I had a letter printed a few years ago which was heavily edited and changed to completely change the content and meaning of the letter. Haven't commented on a magazine content since however wrong it may be.
AnswerID: 293702

Follow Up By: Truckster (Vic) - Thursday, Mar 20, 2008 at 22:20

Thursday, Mar 20, 2008 at 22:20
"The March issue of 4x4 Australia state that the rule has changed except in Qld and NSW to not greater than 50mm more than the largest approved by the vehicle manufacturer"

The rules have been agreed on and accepted - they have not been changed yet. NCOP its known as..
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FollowupID: 559604

Reply By: Member - mel D (NSW) - Thursday, Mar 20, 2008 at 10:30

Thursday, Mar 20, 2008 at 10:30
In 4x4 Australia 290 (March 2008) page 27 they reprint a letter from Jason Mordacz, Michelin and BF Goodrich RV and SUV Category specialist. He wrote "There is a national code which has now come into place (and all states except Qld and NSW have adopted it) which says "The overall diameter of any tyre fitted to an off-road passenger or commercial vehicle must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that model"
AnswerID: 293758

Reply By: Andrew - Tuesday, Mar 25, 2008 at 16:11

Tuesday, Mar 25, 2008 at 16:11
Truckster is right

The code of practice has been adopted in principle but it is not yet law (in Victoria) The info is in VSB 14 which is on the feds website. (used to be Dotars before the change of guvunnmunt)
It also talks about suspension and body lifts etc and is meant to be an agreed standard for modifying vehicles but there are a few "issues" to be sorted out before it will be accepted.

regards

A
AnswerID: 294621

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