Replacement Tyres from OEM Continentals

[Sydneykid]

Mine reads ~104 kph at a 100 kph, that's when the tyres were brand new, so no reduction in diameter due to wear. Obviously a worn out tyre will give a more optimistic speedo reading. But tyre wear is unavoidable so it's the same for them all. A 215/45/17 is 3.6% larger in diameter/circumference than a 215/40/17.

Cheers
Gary

[BenT]

Replacement Tyres from OEM Continentals

Larger diameter and weight may throw out ABS / stability control. Do you really want to risk voiding warranty and /or insurance?


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[Sword_Dude]

So 215/45/17 is actually over 20mm larger in diameter than 215/40/17 so not an option to go up, legally you can only go up to 15mm larger in diameter in Qld.

This pretty much cuts back the tyre options again and Michelin don't seem to be in stock at that size (at least on Tyresales).

Oh well, need to keep an eye out for specials...

[Sydneykid]

Larger diameter and weight may throw out ABS / stability control. Do you really want to risk voiding warranty and /or insurance?

I don't know of any ABS systems that uses tyre weight or diameter in their algorithms. Plus a new tyre with full tread is larger in diameter and weight than a worn out (but still legal) tyre, so that would be an issue. Then there is the issue of space saver spares, a difference in diameter, profile and a huge difference in weight, it would be hard for a dealer to claim warranty breach just because we used the space saver. Of course the ABS handles that OK.

It's worth noting that tyres aren't a warranty item themselves, they are consumables like brake pads.

Cheers
Gary

[Sydneykid]

So 215/45/17 is actually over 20mm larger in diameter than 215/40/17 so not an option to go up, legally you can only go up to 15mm larger in diameter in Qld.
This pretty much cuts back the tyre options again and Michelin don't seem to be in stock at that size (at least on Tyresales).
Oh well, need to keep an eye out for specials...

Seriously ...... new tyre tread depth is commonly 8 mm with a usable 6 mm before tread wear indicators. A 215/45/17 Michelin Pilot Sport is 624 mm in diameter and a 215/40/17 Continental is 605 mm. So a half worn 215/45/17 Michelin Pilot Sport (at 619 mm) would be under 15 mm larger diameter than a new 215/40/17 Continental and would therefore be legal.

Are you really expecting a highway patrol officer to get out his verniers and measure your tyre diameter?


Cheers
Gary

[JustCruisn]

Are you really expecting a highway patrol officer to get out his verniers and measure your tyre diameter?

Probably not. They would only need to look at the tyre markings to see they are wrong and issue a defect notice.
But say you are somehow involved in a serious or fatal accident. Then the forensic team is going check those tyres. The insurance company is always looking for any reason not to pay and an illegal vehicle modification is all they need to walk away.

[Sydneykid]

Probably not. They would only need to look at the tyre markings to see they are wrong and issue a defect notice.
But say you are somehow involved in a serious or fatal accident. Then the forensic team is going check those tyres. The insurance company is always looking for any reason not to pay and an illegal vehicle modification is all they need to walk away.

Shoot, then I better make sure I only use OEM wiper blades, if I have an accident in the rain then they could blame my non genuine wiper blades. Battery, better only have an OEM one of those too, electronics caused the accident. Using non VW washer fluid, dam that’s a biggy. Non OEM brake pads, OMG, there’s one hell of a reason for cancelling my insurance. Same with shock absorbers, must have the VW parts there.

The common theme with the above is that they are all disposables, normal wear and tear items not covered by warranty, just like tyres. So where does it stop? My experience is when it gets unreasonable, modifications carried out drastically outside the OE spec.

If you have any concerns then by all means call your insurance company and ask, mine doesn’t actually care what tyres I use, but substantial mods are noted on the policy.

Cheers
Gary

[Sword_Dude]

Shoot, then I better make sure I only use OEM wiper blades, if I have an accident in the rain then they could blame my non genuine wiper blades. Battery, better only have an OEM one of those too, electronics caused the accident. Using non VW washer fluid, dam that’s a biggy. Non OEM brake pads, OMG, there’s one hell of a reason for cancelling my insurance. Same with shock absorbers, must have the VW parts there.

The common theme with the above is that they are all disposables, normal wear and tear items not covered by warranty, just like tyres. So where does it stop? My experience is when it gets unreasonable, modifications carried out drastically outside the OE spec.

If you have any concerns then by all means call your insurance company and ask, mine doesn’t actually care what tyres I use, but substantial mods are noted on the policy.

Cheers
Gary

Sorry, I think the problem here is what are legally approved modifications and what aren't. Oversized tyres are not approved under the ADR (at least in Qld). Hence it is not an option to go with the 215/45/17s. You are correct though that I can go with any brand I want provided they meet specifications.

[Sydneykid]

Sorry, I think the problem here is what are legally approved modifications and what aren't. Oversized tyres are not approved under the ADR (at least in Qld). Hence it is not an option to go with the 215/45/17s. You are correct though that I can go with any brand I want provided they meet specifications.

Replacing a worn out tyre with a new one isn't a "modification" it's normal maintenance. The first fact is sizes get discontinued all the time by the tyre manufacturers. For example, my M3 from the factory runs Michelin Pilot Sports 235/40/17 fronts but they aren't available any more and no one else sells that size in Australia with the appropriate speed rating. But there is a 235/45/17 Michelin Pilot Sports, so I either run a 40 series tyre with a lower speed rating or a larger diameter tyre with the appropriate speed rating. What you are suggesting is that I would have to park my car and not drive it because the right spec tyres aren't available?

The other issue is that tyre size is not absolute, for example all tyres marked 225 are not 225 mm in width. Since the aspect ratio is a % of the width that number is also not absolute. So taking a 225/40/17 from one company and comparing it to a 225/45/17 from another company may not result in the theoretical change in diameter.

An example, a 225/50/15 Yokohama A050 is 235 mm wide and a 225/45/16 is 227 mm wide. But they are both 225's, aren't they supposed to be the same width? The 225/50/15 is 606 mm in diameter whilst the 225/45/16 is 605 mm in diameter. Plainly their quoted aspect ratios are not exactly accurate. Advan A050 (Semi-Slick)

If I remember correctly the regulation doesn't specify a tyre pressure, so is a 225/45/17 at 10 psi more than 15 mm larger in diameter than a 225/40/17 at 60 psi? The reason why I remember is because a number of automotive engineers were asked to comment on the regulation when it was proposed and it was pointed out that it was next to unenforceable on technical grounds. Plus it varies from State to State which in itself is a breach in the application of the ADR's, which are of course National.

Speaking of ADR's Vehicle Standard (Australian Design Rule 23/02 – Passenger Car Tyres) 2007 the act specifically refers to "nominal section height", "nominal section width" and "nominal aspect ratio". Nominal means "existing in name only" in others words they aren't absolute and can vary. For example the ADR allows a tolerance of 4% in the overall diameter as well as tolerances in width and hence aspect ratio. Unless my maths is way off 4% would mean a 24 mm in the A050's above. So the ADR's in fact allow a larger change in diameter for the same sized tyre than the Qld regulations (ooops).

Bottom line, it's a pretty damn easy defense, if by some miracle an over zealous HWP decided to pick on you because of some "nominal" (ie; inaccurate) numbers written on the side of your tyre. The new tyres comply with the ADR's ie; they are within 4%. The "old" tyre size wasn't available at the time I needed tyres. If necessary, I had the "new" tyres measured and they aren't more than 15 mm larger in diameter, because the ADR's allow 225/40/17 tyres to be 24 mm larger and still be that "nominal" size.


Cheers
Gary

[Guest001]

Replacing a worn out tyre with a new one isn't a "modification" it's normal maintenance. The first fact is sizes get discontinued all the time by the tyre manufacturers. For example, my M3 from the factory runs Michelin Pilot Sports 235/40/17 fronts but they aren't available any more and no one else sells that size in Australia with the appropriate speed rating. But there is a 235/45/17 Michelin Pilot Sports, so I either run a 40 series tyre with a lower speed rating or a larger diameter tyre with the appropriate speed rating. What you are suggesting is that I would have to park my car and not drive it because the right spec tyres aren't available?

The other issue is that tyre size is not absolute, for example all tyres marked 225 are not 225 mm in width. Since the aspect ratio is a % of the width that number is also not absolute. So taking a 225/40/17 from one company and comparing it to a 225/45/17 from another company may not result in the theoretical change in diameter.

An example, a 225/50/15 Yokohama A050 is 235 mm wide and a 225/45/16 is 227 mm wide. But they are both 225's, aren't they supposed to be the same width? The 225/50/15 is 606 mm in diameter whilst the 225/45/16 is 605 mm in diameter. Plainly their quoted aspect ratios are not exactly accurate. Advan A050 (Semi-Slick)

If I remember correctly the regulation doesn't specify a tyre pressure, so is a 225/45/17 at 10 psi more than 15 mm larger in diameter than a 225/40/17 at 60 psi? The reason why I remember is because a number of automotive engineers were asked to comment on the regulation when it was proposed and it was pointed out that it was next to unenforceable on technical grounds. Plus it varies from State to State which in itself is a breach in the application of the ADR's, which are of course National.

Speaking of ADR's Vehicle Standard (Australian Design Rule 23/02 – Passenger Car Tyres) 2007 the act specifically refers to "nominal section height", "nominal section width" and "nominal aspect ratio". Nominal means "existing in name only" in others words they aren't absolute and can vary. For example the ADR allows a tolerance of 4% in the overall diameter as well as tolerances in width and hence aspect ratio. Unless my maths is way off 4% would mean a 24 mm in the A050's above. So the ADR's in fact allow a larger change in diameter for the same sized tyre than the Qld regulations (ooops).

Bottom line, it's a pretty damn easy defense, if by some miracle an over zealous HWP decided to pick on you because of some "nominal" (ie; inaccurate) numbers written on the side of your tyre. The new tyres comply with the ADR's ie; they are within 4%. The "old" tyre size wasn't available at the time I needed tyres. If necessary, I had the "new" tyres measured and they aren't more than 15 mm larger in diameter, because the ADR's allow 225/40/17 tyres to be 24 mm larger and still be that "nominal" size.


Cheers
Gary

While your post is impressive, from what I asked the QLD TMR they said that if the diameter exceeds 15mm more than largest allowable tyre on the tyre placard for the model of vehicle it will be illegal So if in your calculations with nominal values etc you still cant get past the 15mm difference above allowable sizes.

[BenT]

Probably safest to just ask your insurance company and your state registration department.


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[Sydneykid]

While your post is impressive, from what I asked the QLD TMR they said that if the diameter exceeds 15mm more than largest allowable tyre on the tyre placard for the model of vehicle it will be illegal So if in your calculations with nominal values etc you still cant get past the 15mm difference above allowable sizes.

Let's makes this really simple, what diameter is a 215/40/17? The nominal diameter is 604 mm, but they can be 628 mm legally (ie; with the ADR 23/02 allowed +4%). A 215/45/47 is nominally 625 mm in diameter. So a 215/45/17 could legally (ie; according to the ADR's) be 3 mm smaller (yes smaller) in diameter than a 215/40/17.

Presented with these facts (and they are truly admissible evidence supported by the ADR's) what Magistrate is going to uphold the ticket? I asked a NSW Magistrate and he laughed that such a case would even be brought before him ie; the Police wouldn't prosecute it because it's a guaranteed loss.

Cheers
Gary

[Guest001]

Let's makes this really simple, what diameter is a 215/40/17? The nominal diameter is 604 mm, but they can be 628 mm legally (ie; with the ADR 23/02 allowed +4%). A 215/45/47 is nominally 625 mm in diameter. So a 215/45/17 could legally (ie; according to the ADR's) be 3 mm smaller (yes smaller) in diameter than a 215/40/17.

Presented with these facts (and they are truly admissible evidence supported by the ADR's) what Magistrate is going to uphold the ticket? I asked a NSW Magistrate and he laughed that such a case would even be brought before him ie; the Police wouldn't prosecute it because it's a guaranteed loss.

Cheers
Gary

Your car your money do what you like I am only quoting what I was told by the people who make the rules

[Sydneykid]

Your car your money do what you like I am only quoting what I was told by the people who make the rules

So you asked a politician (they are the ones who make the rules) about the diameter of tyres? My experience has been that most of them don't know how to change a flat tyre, let alone it's dimensions.

I suspect that what you are quoting is a vanilla answer to a simplistic question. Tyre sizes are not simple and as a result there is no vanilla answer. The question (as I posted above) you should ask is "can I run a 215/45/17 with a diameter of 625 mm if my car comes with 215/40/17 with a diameter of 628 mm?" Do you really think that the answer would be no?

Cheers
Gary

[Guest001]

No asked the TMR who enforce the rules along with the Police You can disort sizes all you like by comparing half worn tyres with new ones .

As I said your car do what you like as Im sure you will anyway.