A question about Performance Tyres? Ask the Michelin Expert!

[Master_Betty]

It's simply not worth often risking the 4wd system as often the sizing can be slightly different and you never find out until the drivetrain starts making grumbly noises :sad:

You're not suggesting that fitting non-n-rated tyres risks damage to the 4wd system are you?? There is obviously tolerance but you get variation in rolling circumference between front and rear, between different manufacturers of tyres, not to mention a fair difference just from losing 6mm of rubber during the life of the tyre. Those are all realities for all tyres, not just if whether they are N rated rubber compound or not.

Best to stick to the facts.

By the way.. What wasn't factual???

The non-factual bit? I've put it in bold for you - you've made a statement with nothing to back it up, yet included the word 'often'.

You are absolutely correct in the fact that tyres marked with a certain size on the side are not exactly the same size as each other.

But they will all be within tolerance of the 4WD system, unless of course you know of some that are not?

... or know of some confirmed cases of 4wd transmission damage from fitting non-n-rated tyres?

 

[MJA911]

We have the car manufacturer testing and approving tyres. With 4WD here is some advise that N rating offers a little more reassurance on top. Take it or leave it :dont know:

 

[Master_Betty]

We have the car manufacturer testing and approving tyres. With 4WD here is some advise that N rating offers a little more reassurance on top. Take it or leave it :dont know:

It's somebody that is in a position to know better than to make unfounded wild claims, stating that using non-n-rated tyres can damage your 4wd system. It's quite a clear statement. That's how bizarre automotive rumours start, for example, your Insurance will be void if using other tyres etc..

To some of us that is laughable, but we are just enquiring what facts there are to back this up.

Maybe I should just drop a note to Porsche so see if they agree with Michelins claim.

 

[Michelin Tyres]

Ok.. some more information

How many cases of transmission damage have I come across on 4wd cars by using "different" tyres?
Hundreds

How many cases of transmission damage have I come across on 911's?
None

Does that change my advice on "N" rating?
No

My advice is that if you want to run the car as per the way Porsche has approved and tested use "N" rated tyres

If your car is out of warranty, or you aren't a big beleiver in the homologations process, fit what you want

My comments on what the differences are between homologated and replacement market tyres, are based on commercial facts I know about the tyres we produce. And sorry guys but I'm not publishing specification information about the products we produce on a forum. Am I hiding anything? No.

Will your Porsche "blow up" using an non "N" rated tyres?
Probably statistically not

If I was lucky enough to own a 4wd Porsche what would I do?
Fit "N" rated tyres

After all they are YOUR cars. YOU decide.
8)

 

[Michelin Tyres]

Re: Winter tyres

We've just booked to go to Copenhagen for a Christmas/New Year break, going to fly this time, but the old grey matter has been working overtime and I suggested to the boss that if we enjoy it perhaps we could drive over the following year as I have significant birthday and this could also provide a large pile of spending money (thanks Mr Osborne). This train of thought has raised a couple of questions

1) how will a two wheel drive 911 compare to a four wheel drive 911 in winter conditions?
2) what are the road conditions like in Scandinavia in winter? ice, snow or slush around Christmas
3) has anyone used a winter tyre and would they recommend a
particular brand
4) can you fit snow chains to a 911

Mrs MZ and I have had some experience of winter driving but with rather less BHP. The first picture is going up the Col de Turini and the second is on the ice circuit at the top of Alpe D'Huez
:drive:

AUO (1a) by k810ant, on Flickr

img003a by k810ant, on Flickr

Ok.. 2wd vs. 4wd

With both it really comes down to tyres.
If you've no grip (e.g. no winter tyres on snow/ice) it doesn't matter if you have 2 or 4 tyres driving. It's still a low grip situation

A 4wd on the right tyres is always the best option, then a 2wd on the right tyres is better than a 4wd on the wrong ones.

With chains, you might struggle, but their are some thinner composite style chains that are better, but it comes down to fitting them in under the arches really. If you've a smaller wheel/tyre combination, e.g. 17" or 18" compared to a 19" or 20" it's possible.
Other option is look for snow socks..

Winter tyre brands well, apart from our's their are plenty. And do consider if you need a normal "european" winter tyre or a "nordic" type studdable one as they also go down to lower temperatures.

Just be aware that stocks of winter tyres of all brands can be tough to get hold of so you may need to order some

 

[DynoMike]

Re: Winter tyres

We've just booked to go to Copenhagen for a Christmas/New Year break, going to fly this time, but the old grey matter has been working overtime and I suggested to the boss that if we enjoy it perhaps we could drive over the following year as I have significant birthday and this could also provide a large pile of spending money (thanks Mr Osborne). This train of thought has raised a couple of questions

1) how will a two wheel drive 911 compare to a four wheel drive 911 in winter conditions?
2) what are the road conditions like in Scandinavia in winter? ice, snow or slush around Christmas
3) has anyone used a winter tyre and would they recommend a
particular brand
4) can you fit snow chains to a 911

Mrs MZ and I have had some experience of winter driving but with rather less BHP. The first picture is going up the Col de Turini and the second is on the ice circuit at the top of Alpe D'Huez
:drive:

AUO (1a) by k810ant, on Flickr

img003a by k810ant, on Flickr

Very nice S there, doing what they do best. There is nothing like driving a Mini on snow for fun! Enormous grin factor. Thanks for posting the pics. :bye:

 

[mzmini]

Cheers DynoMike not bad for a barn find, fitted with a brand new Gold Seal S lump 5 tea chests of bits and bobs oh and a Heuer Super Autavia a two grand watch all for a grand happy days ,when I went to collect it he had to move Foggy's world championship winning Ducatti lucky man
cheers
MZmini

 

[Master_Betty]

Ok.. some more information

How many cases of transmission damage have I come across on 4wd cars by using "different" tyres?
Hundreds

How many cases of transmission damage have I come across on 911's?
None

Does that change my advice on "N" rating?
No

My advice is that if you want to run the car as per the way Porsche has approved and tested use "N" rated tyres

If your car is out of warranty, or you aren't a big beleiver in the homologations process, fit what you want

My comments on what the differences are between homologated and replacement market tyres, are based on commercial facts I know about the tyres we produce. And sorry guys but I'm not publishing specification information about the products we produce on a forum. Am I hiding anything? No.

Will your Porsche "blow up" using an non "N" rated tyres?
Probably statistically not

If I was lucky enough to own a 4wd Porsche what would I do?
Fit "N" rated tyres

After all they are YOUR cars. YOU decide.
8)

Well there are a few questions there that weren't asked, but staying on point, it seems you've confirmed that there is no evidence to suggest that running non-n-rated tyres damages the 4wd system. That's all I wanted to clarify after your previous post suggested the exact opposite.

I'm not wanting to confuse that with a debate on pros/cons of n-rating. Just that 'opting out' doesn't cause damage to the car. There will be many on here with a technical/engineering understanding who would not have believed it anyway, but many others who will just follow official guidance. So best to be clear on these things.

 

[Master_Betty]

While I'm in here though... A question - linked to me opting away from N in favour of latest tech (super sport, conti 5 etc) - what is the bottleneck to developing/approving N tyres? Is it Porsches priorities focussed on new models, or is capacity of the tyre manufactures to only develop so many new products at once or something else?

 

[Michelin Tyres]

While I'm in here though... A question - linked to me opting away from N in favour of latest tech (super sport, conti 5 etc) - what is the bottleneck to developing/approving N tyres? Is it Porsches priorities focussed on new models, or is capacity of the tyre manufactures to only develop so many new products at once or something else?

It's simply getting through the numerous, and I do mean numerous tests as part of the testing process.

We've been ready and able to get Supersport "N" marked from 2011.. but for various reasons it's never got through all the tests. So the bottleneck doesn't tend to be our production capacity, simply, getting the approval done

On the advice I gave before, I've never intended to scare anyone off.
But as the guy who's on the phone after customers have had the wrong advice or fitted the wrong (and sometimes all brands of product) to 4wd cars, I always err on the side of caution.

Equally I know more than a few owners who've gone to Pilot Super Sport and loved them, and my advice has to follow somewhat what Porsche's is.. simply as we have a long and sucessful partnership that I don't want to jepordise. So it's not towing the "party line" it's simply having clear and consistent advice, so I hope I've cleared that up

 

[Michelin Tyres]

I've recently acquired an early 2001 996 C4. (3.4), it has Porsche Design 19" wheels with 235/35/19s on the front and 295/30/19s on the rear. All N rated. Your advise on normal operating pressures would be really appreciated. The handbook doesn't help due to the non std size.
Many thanks,
Duncan

Duncan

I'd stick with the Pressures for the 17" or 18" tyres
Why?
As the 996 didn't come on any 19" options there is no 996 pressure for that tyres size. Then the fact that the 17" and 18" options have the same pressure recomendation, I'd use that as the appropriate pressures for the 19" tyres

In most instances we set pressures for the Car, and they only vary model by model, in order to carry the load of the vehicle and the appropriate front/rear pressures to give the car the appropriate handling balance.

Therefore I'd stick with what's recommended for your car for 18"

My records show 2.2bar front, 2.5bar rear cold

 

[stirling]

Thanks for coming back to me regarding my query Jamie, that makes sense.
Duncan

 

[Floydsolo]

Tyre lifespan?

Is it safe to use a set of part worn Pilot Sports from 2006? I've been offered a set of rears with 7mm tread but they are from 2006, is this OK? They look good.

 

[DRZ911]

Is it safe to use a set of part worn Pilot Sports from 2006? I've been offered a set of rears with 7mm tread but they are from 2006, is this OK? They look good.

Michelin appear to base all their recommendations relative to the date of manufacture on the side of the tyre.

Their general guidance appears to be that after 5 years from the date of manufacture, the tyres should be regularly inspected for signs of deterioration such as splitting, cracking, tearing, etc.

At 10 years from the date of manufacture, Michelin indicate that the tyres should be scrapped irrespective of the tread remaining.

Think the above guidance is roughly in line with that given by other tyre manufacturers.

Hope this helps.

 

[kas750]

I work on 6 years from date of manufacture and will condemn any tyre with sidewall cracks or in between the tread at any time on or before those dates.