20” by 10 with 275/30/20 all around is it possible? Please do help

[RevNev]

Tyre fitament laws are uniform throughout Australia and New Zealand

The SA publication basically states that the wheel/tyres must not foul on or protrude outside the body work with a maximum track of +26mm The tyre diameter must remain within +/- 15mm and the load and speed ratings must meet the manufacture's specifications.

My 295/30 setup doesn't foul on or protrude outside the body work, the track is increased 10mm and the tyre diameter is increased 11 mm with the load and speed ratings matching the tyre placard for the vehicle and fully complies with the requirements as published.

The OP's 295/25 setup we'll pass on it's protrusion (haven't seen it properly or measured it) but the track is increased 28mm if they're ET43 and doesn't comply. The tyre diameter is reduced 18mm and doesn't comply and the load rating on the tyre doesn't meet manufacture specifications and doesn't comply. Unless you're happy to run at least 3 non compliances, I wouldn't be recommending a 259/25 setup on a VF Commodore, it's totally the wrong way to get 295 width rubber under the rear of the car in my opinion!

Technically speaking on a staggered setup, ET44 is the maximum compliant offset for a VF Commodore rear wheel, ET35 on the front.

 

[vc commodore]

The SA publication basically states that the wheel/tyres must not foul on or protrude outside the body work with a maximum track of +26mm The tyre diameter must remain within +/- 15mm and the load and speed ratings must meet the manufacture's specifications.

My 295/30 setup doesn't foul on or protrude outside the body work, the track is increased 10mm and the tyre diameter is increased 11 mm with the load and speed ratings matching the tyre placard for the vehicle and fully complies with the requirements as published.

The OP's 295/25 setup we'll pass on it's protrusion (haven't seen it properly or measured it) but the track is increased 28mm if they're ET43 and doesn't comply. The tyre diameter is reduced 18mm and doesn't comply and the load rating on the tyre doesn't meet manufacture specifications and doesn't comply. Unless you're happy to run at least 3 non compliances, I wouldn't be recommending a 259/25 setup on a VF Commodore, it's totally the wrong way to get 295 width rubber under the rear of the car in my opinion!

Technically speaking on a staggered setup, ET44 is the maximum compliant offset for a VF Commodore rear wheel, ET35 on the front.

Track I'm not 100% sure if it is uniform across Australia......I have a suspicion it is....Fouling/protrusion of suspension components/bodywork are and rolling radius are....

And yes, just having it underload rated would be enough to prevent me fitting them to a customers or my own car

 

[RevNev]

Here's a proper look at a 10.5 and 295/30 at ET52

On the inside, I've got 12mm clearance between the tyre and fender liner at the narrowest point. This bit of wood fits nicely behind the wheel/tyre. With a plumb bob hanging from the outside of the guard in the hub centre line, I've got 10mm at the tyre and 12mm at the wheel with 0.8 degrees camber.

We're pretty well smack in the middle of the two extremities with 10.5 and 295/30 at ET52 but could we go to an 11" wheel or 305/30 tyre?

With an 11" wheel at ET52 and the same 295/30 Bridgestone S007A tyre, we'll lose 5mm tyre clearance on both sides leaving 7mm clearance on the inside and we could reduce that a couple of mm. I'm think an 11" wheel and 295/30 tyre will work best at ET55. 4mm clearance on the fender liner is enough and could probably massage one spot with a heat gun.

305/30 on a 10.5" wheel will work much the same and I think ET55 is the ideal offset for both variants. a 305/30 on an 11" inch wheel unless you're prepared to pump the guards a bit I think could be stretching it although I'd like to physically try it.

If I ordered a 20x11" wheel to run the 295/30, I'd go ET53 and could always machine a couple of mm off the mounting pad if need be.

 

[Skylarking]

I have never ever seen these labels...Tyre fitament laws are an Australian/New Zealand wide thing.....This is easily to prove by checking out the placard....It says, it complies with AU/NZ design rule "xyz wheel barrow"

I’ve never seen a winning lotto ticket but I know they exist just like that document that references the label exists…

If that’s not enough, read the following doc, section 4

https://www.infrastructure.gov.au/s..._LS_Tyres_Suspension_Steering_Nov_2015_v4.pdf

4 BASIC MODIFICATIONS WITHOUT CERTIFICATION​

The following modifications may be carried out provided they do not affect compliance with ADRs, the in-service provisions of the AVSR and provided they meet the general safety requirements specified below for each modification:​

4.1 REPLACEMENT TYRES ON STANDARD (OR MANUFACTURER’S OPTIONAL) RIMS​

Some tyre sizes have become obsolete and are no longer available. Equivalent replacement tyres with different size designations may be fitted without specific certification under this Section.​

Every passenger car manufactured after 1972 (ADR 24) is fitted with a tyre placard that contains information on original and optional tyres and rims for that vehicle model.​

A motor vehicle under 4.5 tonnes GVM which is required to comply with ADR 24 may be equipped with tyres other than those listed on the tyre placard provided that:​

• the load rating of the tyres is not less than the lowest load rating listed on the tyre placard of the vehicle or equivalent variant of that model vehicle;
• the speed rating of the tyres fitted to a passenger vehicle is at least 180 km/h (S) when the tyre placard requires a higher speed rating than S;
• the speed rating of the tyres fitted to vehicles with special features for off-road use of at least 140 km/h N when the tyre placard requires a higher speed rating than N; and
• for all other vehicles a speed rating of at least 120 km/h.
• In special circumstances, the speed rating may be less than the ratings specified above if the speed rating of the tyre is more than the vehicle’s maximum speed. This will need to be confirmed with the Registration Authority.

Thats the national regulators view and rather clear that lower speed rated tyres can be fitted… and without certification is you read the earlier parts. But state rego authorities always have the final say since nationalised rules aren’t fully nationalised and there is I rony just in that

The above NCOP 11 clearly states certification isn’t needed as does the previous NSW doc when rules around lowered tyre speed rating are followed, the difference is in the allowed speed rating itself. NSW doc is a mess in referencing vehicle top speed, NCOP is not.

Interestingly in S.A it seems that the NCOP view is followed as the following website shows

https://www.sa.gov.au/topics/drivin...-standards-and-modifications/wheels-and-tyres

Tyres​

The overall diameter of a wheel and tyre fitted to a vehicle must not be more than 50mm (4WDs) or 15 mm (other vehicles) larger than the largest tyre size listed on the tyre placard and not more than 15 mm less than the smallest tyre size listed on the placard on all vehicles.​

​

Specifications for overall tyre diameters are listed in the Tyre and Rim Association of Australia - Standards Manual. Note: if tyres are to be fitted with a diameter outside of this requirement then an MR620 Application to Modify a Motor Vehicle (891.8 KB PDF) and a report from a MR426 Chartered Professional Engineer (438.4 KB PDF) is required.​

​

The following requirements must also be met.​

• The tyres fitted must be suitable for the rim. The tyre retailer should have information about matching tyres and rims. Specifications for overall tyre diameters are listed in the Tyre and Rim Association of Australia - Standards Manual.
• The tyres must be free of any apparent defect that could make them unsafe.
• The replacement tyres must have a load capacity not less than the lowest load rating specified on the tyre placard.
• The speed rating of the tyres fitted to vehicles for off-road must be of at least 140 km/h ('N') when the tyre placard requires a higher speed rating than 'N'.
• The speed rating of the tyres fitted to a passenger vehicle must be at least 180 km/h ('S') when the tyre placard requires a higher speed rating than 'S', for all other vehicles a speed rating of at least 120 km/h applies ('L').
• Tyres fitted to an axle of a vehicle must be of the same size and carcass construction
• …

So again, even in S.A as long as tyre diameter increase or decrease is within allowed limits, S rated tyres can be fitted even if higher speed rated tyres are listed on the tyre placard while tyre load ratings can’t ever be downgraded.

On all other points I agree with you except the need for certification if only tyre speed rating is reduced. Comments around AS/NZ standards are just ignoring the facts before you around modifying speed rating. Just accept you may have learnt something (if anything that national and state modification documents are a mess and don’t always clearly agree as fed and nsw docs show)

 

[vc commodore]

I’ve never seen a winning lotto ticket but I know they exist just like that document that references the label exists…

If that’s not enough, read the following doc, section 4

https://www.infrastructure.gov.au/s..._LS_Tyres_Suspension_Steering_Nov_2015_v4.pdf

4 BASIC MODIFICATIONS WITHOUT CERTIFICATION​

The following modifications may be carried out provided they do not affect compliance with ADRs, the in-service provisions of the AVSR and provided they meet the general safety requirements specified below for each modification:​

4.1 REPLACEMENT TYRES ON STANDARD (OR MANUFACTURER’S OPTIONAL) RIMS​

Some tyre sizes have become obsolete and are no longer available. Equivalent replacement tyres with different size designations may be fitted without specific certification under this Section.​

Every passenger car manufactured after 1972 (ADR 24) is fitted with a tyre placard that contains information on original and optional tyres and rims for that vehicle model.​

A motor vehicle under 4.5 tonnes GVM which is required to comply with ADR 24 may be equipped with tyres other than those listed on the tyre placard provided that:​

• the load rating of the tyres is not less than the lowest load rating listed on the tyre placard of the vehicle or equivalent variant of that model vehicle;
• the speed rating of the tyres fitted to a passenger vehicle is at least 180 km/h (S) when the tyre placard requires a higher speed rating than S;
• the speed rating of the tyres fitted to vehicles with special features for off-road use of at least 140 km/h N when the tyre placard requires a higher speed rating than N; and
• for all other vehicles a speed rating of at least 120 km/h.
• In special circumstances, the speed rating may be less than the ratings specified above if the speed rating of the tyre is more than the vehicle’s maximum speed. This will need to be confirmed with the Registration Authority.

Thats the national regulators view and rather clear that lower speed rated tyres can be fitted… and without certification is you read the earlier parts. But state rego authorities always have the final say since nationalised rules aren’t fully nationalised and there is I rony just in that

The above NCOP 11 clearly states certification isn’t needed as does the previous NSW doc when rules around lowered tyre speed rating are followed, the difference is in the allowed speed rating itself. NSW doc is a mess in referencing vehicle top speed, NCOP is not.

Interestingly in S.A it seems that the NCOP view is followed as the following website shows

https://www.sa.gov.au/topics/drivin...-standards-and-modifications/wheels-and-tyres

Tyres​

The overall diameter of a wheel and tyre fitted to a vehicle must not be more than 50mm (4WDs) or 15 mm (other vehicles) larger than the largest tyre size listed on the tyre placard and not more than 15 mm less than the smallest tyre size listed on the placard on all vehicles.​

​

Specifications for overall tyre diameters are listed in the Tyre and Rim Association of Australia - Standards Manual. Note: if tyres are to be fitted with a diameter outside of this requirement then an MR620 Application to Modify a Motor Vehicle (891.8 KB PDF) and a report from a MR426 Chartered Professional Engineer (438.4 KB PDF) is required.​

​

The following requirements must also be met.​

• The tyres fitted must be suitable for the rim. The tyre retailer should have information about matching tyres and rims. Specifications for overall tyre diameters are listed in the Tyre and Rim Association of Australia - Standards Manual.
• The tyres must be free of any apparent defect that could make them unsafe.
• The replacement tyres must have a load capacity not less than the lowest load rating specified on the tyre placard.
• The speed rating of the tyres fitted to vehicles for off-road must be of at least 140 km/h ('N') when the tyre placard requires a higher speed rating than 'N'.
• The speed rating of the tyres fitted to a passenger vehicle must be at least 180 km/h ('S') when the tyre placard requires a higher speed rating than 'S', for all other vehicles a speed rating of at least 120 km/h applies ('L').
• Tyres fitted to an axle of a vehicle must be of the same size and carcass construction
• …

So again, even in S.A as long as tyre diameter increase or decrease is within allowed limits, S rated tyres can be fitted even if higher speed rated tyres are listed on the tyre placard while tyre load ratings can’t ever be downgraded.

On all other points I agree with you except the need for certification if only tyre speed rating is reduced. Comments around AS/NZ standards are just ignoring the facts before you around modifying speed rating. Just accept you may have learnt something (if anything that national and state modification documents are a mess and don’t always clearly agree as fed and nsw docs show)

According to this document, to fit a lower speed rated tyre specified by the tyre placard, firstly, the correct speed rated tyre must not exist....And secondly, it would have to be approved by the registration authority, which I have already said, because they deem it altering the safety of the vehicle...(Not that I agree with it)

Have you found where a tyre store can get this magic label? Have you found where to source the information relating to the maximum speed of a car, so a point lower speed rated tyre can be fitted and a tyre store can therefore fit this magic label? Or is it, this document now overrides the single point lower speed rated tyre portion you previously suggested and you only have to fit a tyre that has a minimum speed rating of "S" and you don't have to fit this magic label...Or do you still have to fit this magic label when you have fitted the minimum "S" rated tyre?

If all states differ in this area, how do travellers get on, if they have to replace tyres and the correct placarded tyre is unavailable? How would it work with an insurance company, if you replaced tyres with lower rated tyres and you were to have an accident in that state or your own state? Does your insurance company work on the state laws you live in, or do they work by the state laws you had the tyres fitted in?

Why would it have on the placard, a vehicle was designed to confirm to Aus/NZ design rules in this area, if all states want to have their own rules relating to the changing of tyre load and/or speed ratings?

And no I'm not being difficult or unrealistic...This sort of thing can and does happen, so having the relevant answers would be terrific

 

[Skylarking]

To fit a lower speed rated tyre specified by the tyre placard, firstly, the correct speed rated tyre must not exist....And secondly, it would have to be approved by the registration authority, which I have already said, because they deem it altering the safety of the vehicle...(Not that I agree with it)

There is no requirement specified in the S.A. reference in provided that the correct speed rated tyre must not exists or changes need to be certified, neither is such a requirement stated in the NCOP doc

So where do the requirement you mention come from if not from S.A. Rego authority or the National Code Of Practice for vehicle modification?

This hasn't mentioned about the maximum speed of a car you have previously mentioned about...Have you found where that information can be found, so tyre stores can refer to it, if this scenario ever crops up.....Can you find where to get this magic label, that a store must fit, if the speed rating of the tyre is below the placard specified speed rating?

The label recommendation is in the NSW doc I thought I linked to in my earlier post but must have forgotten the link…

https://www.nsw.gov.au/sites/defaul...-Standards-Information-No-9-November-2003.pdf

Other states don’t mention such a label so it may be NSW specific thing. S.A is aligned with NCOP which doesn’t recommend such a label (and in fact allows S rated tyres) while VIC seems to be vague in the one doc I looked at.

As for getting the recommended label, anyone can print one up themselves to the NSW specs or they could call RMS and ask if they supply them (but I’d expect an aahhhh what? cause bureaucracy)

So it's all good and well to put all this stuff up, but the simple basic questions that have been asked, especially based on your previous quotations you have found, are yet to be answered....

I’ve mostly put up references and extract except I missed the RMS link though Google search string would have found it… Where’s the references to the S.A. requirement that reducing speed rating requires engineering which is in stark contrast to NCOP?

What all this does highlight is that if a tyre professional like yourself doesn’t know the NCOP rules and S.A. rules around speed ratings, which isn’t a sledge at you cause bureaucracy is the problem, how will the cop by the road handle such issues… What ever the case, a cop whose frustrated cause he didn’t get any from the missus last night will decides to take it out on you by putting you over the pits cause of your lower speed rated tyres… It’s fooked up but obviously Bob Jane has sussed it out and taken the NSW tyre speed rating approach which requires higher ratings than NCOP (unless their website provides location specific tyre specs for each vehicle?) Don’t know if they put on the sticker but I’d guess not as it’s not mandatory.

You could always ring Bob Jane and ask them how they get around the rules as you understand them Or better still ask S.A rego (DIT vehicle standards?) since what you say is inconsistent from the national approach in NCOP VSB11

 

[vc commodore]

There is no requirement specified in the S.A. reference in provided that the correct speed rated tyre must not exists or changes need to be certified, neither is such a requirement stated in the NCOP doc

So where do the requirement you mention come from if not from S.A. Rego authority or the National Code Of Practice for vehicle modification?
The label recommendation is in the NSW doc I thought I linked to in my earlier post but must have forgotten the link…

https://www.nsw.gov.au/sites/defaul...-Standards-Information-No-9-November-2003.pdf

Other states don’t mention such a label so it may be NSW specific thing. S.A is aligned with NCOP which doesn’t recommend such a label (and in fact allows S rated tyres) while VIC seems to be vague in the one doc I looked at.

As for getting the recommended label, anyone can print one up themselves to the NSW specs or they could call RMS and ask if they supply them (but I’d expect an aahhhh what? cause bureaucracy)
I’ve mostly put up references and extract except I missed the RMS link though Google search string would have found it… Where’s the references to the S.A. requirement that reducing speed rating requires engineering which is in stark contrast to NCOP?

What all this does highlight is that if a tyre professional like yourself doesn’t know the NCOP rules and S.A. rules around speed ratings, which isn’t a sledge at you cause bureaucracy is the problem, how will the cop by the road handle such issues… What ever the case, a cop whose frustrated cause he didn’t get any from the missus last night will decides to take it out on you by putting you over the pits cause of your lower speed rated tyres… It’s fooked up but obviously Bob Jane has sussed it out and taken the NSW tyre speed rating approach which requires higher ratings than NCOP (unless their website provides location specific tyre specs for each vehicle?) Don’t know if they put on the sticker but I’d guess not as it’s not mandatory.

You could always ring Bob Jane and ask them how they get around the rules as you understand them Or better still ask S.A rego (DIT vehicle standards?) since what you say is inconsistent from the national approach in NCOP VSB11

You have missed the very first paragraph of point 4.1....

QUOTE... Some tyre sizes have become obsolete and are no longer available. Equivalent replacement tyres with different size designations may be fitted without specific certification under this Section.

This is where they want to apply the rules around fitting the lower speed rated tyres.....And even that, you have put up conflicting information....First it was the next lower speed rated tyre providing it could cope with the cars maximum speed....Now it's a minimum of an "S" rated tyre

Then we go to the insurance claim....Someone has a tyre fitted in NSW that is of a lower speed rating than what my placard says.....Does the insurance company take into account the laws in the state someone has the tyre fitted or the state the car is registered?

Having a Joe off the street is fraught with danger...It is effectively saying you have training in this area, approving a safety modification....Now we all know how that'll end up in the long run

Finally, this document can't be pat of the national code of practice, as it is NSW specific...Unless NSW is the centre point of the national code, which in case means I'll speak with my boss about having this information available for me to consult

 

[Anthony121]

Adding to this long discussion on wheels and tyres..... last week I decided to put my original front cast wheels (I have a set of forged and cast SSV redline wheels) so now I have 245/40/19 all round for a few weeks. The fun started as soon as I placed them on the rear. Lots of fun

 

[Skylarking]

Adding to this long discussion on wheels and tyres..... last week I decided to put my original front cast wheels (I have a set of forged and cast SSV redline wheels) so now I have 245/40/19 all round for a few weeks. The fun started as soon as I placed them on the rear. Lots of fun

Unfortunately, if the car came with staggered wheels from the factory, the tyre placard wouldn’t have listed same size tyres on all corners. In such cases, as mod rules don’t allow going skinnier, placing those skinnier front wheels on the rear makes the vehicle unroadworthy

But it’s definitely more fun (in a boon sort of way) and more cost effective (being noonish) with 245/&0R19’s all around

 

[Anthony121]

Unfortunately, if the car came with staggered wheels from the factory, the tyre placard wouldn’t have listed same size tyres on all corners. In such cases, as mod rules don’t allow going skinnier, placing those skinnier front wheels on the rear makes the vehicle unroadworthy

But it’s definitely more fun (in a boon sort of way) and more cost effective (being noonish) with 245/&0R19’s all around

My argument is that I got two punctures and they were both getting fixed