Tyre sizes still a bit confused

[discojools]

About to get some BFG KM2s for D3. Looking at 245/70/17 (776mm diam), 245/75/17 (800mm diam) or even 265/70/17 (804mm diam).
Which ones of those are legal to fit in Vic and will the larger two rub? I believe the stock diameter of the 235/70/17s are 760mm, is that correct?
I thought the rule in Vic was that tyres could not be more than 15mm bigger, but my tyrefitter says it should be 5%.
Any thoughts?

[gghaggis]

No serious rubbing issues with any of those sizes. The 265's may just rub the plastic inner lining of the rear wheel well, but only at max articulation and isn't something to worry about.

Legally I can't advise on Victoria - RMP should be able to give you some idea. In WA they're legal.

Cheers,

Gordon

[rmp]

Tyre fitters really make me angry sometimes because they are almost always wrong. Apologies to the good ones out there (and there are some great shops), but if I had a dollar for every time someone comes up with "but my tyre shop said..." and the tyre shop was wrong then I'd have a Sport TDV8 in my garage. Half of them don't understand offset, this 5% rule get bandied about, and many don't understand that modern radials can now be rotated onto any wheel, tyres get set to max-inflation or placard level with no accounting for load, tyre type etc. It wouldn't be so bad but most of them advertise as being experts in the field.

Rant off.

Anyway. The regulations are not all that hard to comprehend. They are clearly stated in VSI 8 and VSI 26 available from vicroads.vic.gov.au. VSI 8 says:

"The overall diameter of any replacement rim and tyre must not be:

- more than 15mm greater than the largest diameter tyre specified by the vehicle manufacturer for that model or vehicle series"

pretty clear.

Doesn't hurt to print the regs out and show it to them. Worked for me last time I had to argue the proposed offset was illegal.

[discojools]

So the 245/75/17s and the 265/70/17s are both illegall on a D3 in Victoria?

[gghaggis]

Apparently so ...

Robert, when (if ever) is Victoria contemplating mandating the NCOP regs on vehicle modifications? I seem to remember that is was Victoria that pushed for 'nationwide' rulings in the first place. Under NCOP, you'd be allowed 50mm oversize for an off-road capable vehicle, (15mm for a std car).

Cheers,

Gordon

[rmp]

DJ

Multiply out the overall diameter of those tyres against the stock sizes and see if there is more than 15mm difference.

GGH

I know, I know....Victoria hasn't adopted it yet and nobody seems to know what's happening, least of all Vicroads. The fact each state sees fit to have different road regulations is one of the banes of my life and you can see why many people in the industry simply give up and adopt a "she'll be right" attitude or a "if it fits, it's all good" principle.

Why on this green earth we permit 50mm in WA and 15mm in NSW and Vic, not to mention various other differences I do not know. Australia is over-governed in some ways. NCOP is I believe agreed, but agreed is not the same as passed into law.

[ADMIRAL]

Google VSB14. or AAAA VSB14. Some smaller pieces have been rolled out in all states, as have changes to make road rules more uniform. I think the main reason this code has not been introduced nationally( at this point ) , is the different state beauracracies don't want to relinquish any control.

The AAAA and several of the 4WD interest groups are lobbying to have some changes made to the draft code. The principle focus at this stage is to allow a 50mm lift and a tyre change without an engineering sign off. There has been some testing with the Queensland Dept. of Transport, which I think revolved around swerve or ' moose ' testing of std. and 50mm modified 4wd's. The reports coming back, are that the 2 out of 6 std vehicles failed the test. All the modified ( 6 again I believe ) vehicles passed, but some degradation of braking performance was noted. Still within ADR's I think. Not unexpected with larger diameter tyres.
The expectation is that Australia will have uniform vehicle modification regulations when this code is introduced. There is talk some states may take the opportunity to introduce tougher vehicle inspection regulations.
W.A. is a prime candidate.

[discojools]

Yeah I have had a look Vicroads Vehicle standards and VSB14. So, the NCOP VSB14 is not applicable to Victoria. And Vic roads says no bigger than 15mm than the max manufactures size for passenger cars and 4wds. Ridiculous that it should be different for each state. I wonder if there is a larger size than the standard 235/70/17 that Landrover recommend? Every day I see a modded 4wd that must be illegal.
Anyway it looks to me that I am restricted to the 245/70/17 KM2s if I am going to abide the law.
Also, thinking of fitting bead locks. Are they OK on road and legal?

[rmp]

Land Rover recommend only what's on the placard and on their rims. What is legal, what fits, and what they recommend are not necessarily the same.

Internal beadlocks are ok, external are definitely not. I doubt you'd need them anyway and even if you did fit them that would be a modification to the rim which would I think render it illegal, but check that.

Yes, there are thousands of illegal vehicles out there. If you know the regs you can spot defects on pretty much any non-standard vehicle.

[ADMIRAL]

Yeah I have had a look Vicroads Vehicle standards and VSB14. So, the NCOP VSB14 is not applicable to Victoria. And Vic roads says no bigger than 15mm than the max manufactures size for passenger cars and 4wds. Ridiculous that it should be different for each state. I wonder if there is a larger size than the standard 235/70/17 that Landrover recommend? Every day I see a modded 4wd that must be illegal.
Anyway it looks to me that I am restricted to the 245/70/17 KM2s if I am going to abide the law.
Also, thinking of fitting bead locks. Are they OK on road and legal?

I agree with RMP on the beadlocks. I think even with the internal locks, you will have more difficulty in achieving good wheel balance. External locks you are almost wasting your time trying to balance the wheel. Have a talk to your favourite tyre dealer. I'll bet he will have an opinion, and it won't be positive. Unless you are going to use under 10 psi on a regular basis, I would question their usefulness.

[ADMIRAL]

VSB14 is a proposed national code. Ultimately all states will fall into line and apply it, even Vic. I suspect the Federal government will look to withhold funding for those slow in the uptake. Seems to be the general method used these days when negotiations fall over between state and federal bodies.

[rmp]

Beadlocks are used to secure a tyre to rim. They are not really required at pressures of more than 15psi provided you are not driving like bat out of hell, and you can go as low as say 8 if you're nice and gentle.

Very large tyres such as those fitted on comp cars must be deflated a long way to air down, often below 15. Funnily enough, these cars tend to be driven with a bit of brisk pace. Hence the popularity of beadlocks.

Even if you do pop a tyre off a rim it's not a big problem to pop it back on again.

[gghaggis]

I ran internal beadlocks for over a year in my D1 - both in comps and as a daily drive. Never had issues with balancing or handling. You never notice that they're there.

However, they are a significant investment (around $250 each), you have to drill a hole in the rim for the additional valve, and they're only really useful at pressures under 14psi, so unless you do that on a regular basis (and drive like you stole it), it's probably not a "must have" accessory.

Cheers,

Gordon

[VladTepes]

DJ
Australia is over-governed in some ways..

Some ways ! How about "in all respects".

On tyres:

This might be useful to people:

Tire size calculator (http://www.miata.net/garage/tirecalc.html)

[discojools]

Just an update to this subject discussed recently.. Found this on the Vicroads website after talking to local Tyrepower man re legally allowed sizes. He said it was 2" or 50mm and it had been changed recently. Here's what it says on Vicroads website:
"OVERALL DIAMETER
Section LS Tyres, Rims, Suspension & Steering
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 an off-road passenger vehicle or a 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.
Speedometer accuracy must be maintained for the selected tyre and rim combination to within the degree of accuracy specified in ADR 18 where applicable."
So it appears that BFG KM2MTs 265/70/17 (804mm diam)or 245/75/17 (800mm diam) are legal now.
Any body fitted these sizes to a D3 and if so any probs?

[gghaggis]

So it appears that BFG KM2MTs 265/70/17 (804mm diam)or 245/75/17 (800mm diam) are legal now.
Any body fitted these sizes to a D3 and if so any probs?

Many of us in the West have fitted the 265/70/17 size to the D3, as our rules on oversize tyres for 4x4's have been more lenient in the past (although it now looks as if Victoria has adopted the NCOP guidelines).

With this size, at max articulation you'll barely/slightly notice a rubbing of the rear tyre on the front of the wheel-well plastic lining. How much varies with the make of tyre (as they're not all exactly the same size). However, it's not significant.

Cheers,

Gordon

[trobbo]

I believe you can fit the 265/70/17 without mods but havent done it yet myself.


edit - gordon just beat me to it - doh!

[LeighW]

Whilst many of the posts here have been about the tyre size/legality/rubbing, etc. no mention has been made about putting a 265 section width on a 7 inch rim.

Check Car Bibles : The Wheel and Tyre Bible Page 3 of 4 (http://www.carbibles.com/tyre_bible_pg4.html) under the title An ideal rim-width calculator and a 265 needs a 7.5 inch wide rim as a minimum. Also all major manufacturers will specify a rim width range for each of their tyre sizes usually found on their web site.

I currently run 245/70x17 tyres and the speedo indicates the vehicle speed almost perfectly (according to the GPS) whereas it was 5-7 km/h optimistic before changing to the 245s.

Just my two bob's worth...

[Owl]

Whilst many of the posts here have been about the tyre size/legality/rubbing, etc. no mention has been made about putting a 265 section width on a 7 inch rim.

Check Car Bibles : The Wheel and Tyre Bible Page 3 of 4 (http://www.carbibles.com/tyre_bible_pg4.html) under the title An ideal rim-width calculator and a 265 needs a 7.5 inch wide rim as a minimum. Also all major manufacturers will specify a rim width range for each of their tyre sizes usually found on their web site.

I currently run 245/70x17 tyres and the speedo indicates the vehicle speed almost perfectly (according to the GPS) whereas it was 5-7 km/h optimistic before changing to the 245s.

Just my two bob's worth...

BFG website says 265/70R16 Mud's are OK on 7.0" to 8.5" rims - makers recomendation rules

[rmp]

Maker recommendation indeed rules and go outside that at your peril.

The minimum rim width is a function of the tyre width and tyre sidewall height. The minimum width for a 235 will vary if it is a 235/40 to a 235/85 for example.

[trobbo]

Having run my 34 x 10.5 simex's on a 7 inch rim at very low pressures (8psi) without beadlocks or popping a bead, my preference is to use a narrow rim for my offroad tyres