N rated Tyres

[dlknight]

Hey All,

I know this has been discussed to great depth before but I was just browsing through the Porsche 944 workshop manual. In section 44 of the chassis manual it states that:

"When replacing summer tires, check for the correct tire specification character. The specification character N 1 or N 0, respectively, helps to distinguish summer tires approved by Porsche from other versions of identical tire type and same tire size. The tires approved by Porsche are also identified in the corresponding TI."

I know you all have your own opinions and many of you run non-Porsche-approved tyres without problems. But I remember seeing some posts which stated that the Porsche tire specification started after 944 production finished and didn't apply.

Amazing what detail is contained in the workshop manuals

Regards

Dave K.

 

[JCB..]

ORIGINAL: dlknight

Hey All,

I know this has been discussed to great depth before but I was just browsing through the Porsche 944 workshop manual. In section 44 of the chassis manual it states that:

"When replacing summer tires, check for the correct tire specification character. The specification character N 1 or N 0, respectively, helps to distinguish summer tires approved by Porsche from other versions of identical tire type and same tire size. The tires approved by Porsche are also identified in the corresponding TI."

I know you all have your own opinions and many of you run non-Porsche-approved tyres without problems. But I remember seeing some posts which stated that the Porsche tire specification started after 944 production finished and didn't apply.

Amazing what detail is contained in the workshop manuals

Regards

Dave K.

The number following the N on todays N rated tyres refers to minor manufacturers revisions of the tyre and has nothing to do with the seasons.

JCB..

 

[sawood12]

The N rated tyres you will be able to get today will not have been homologated on the 944 or 968 specifically so therefore is not applicable. Having said that i'm sure they will do no harm.

 

[dlknight]

ORIGINAL: JCB..

The number following the N on todays N rated tyres refers to minor manufacturers revisions of the tyre and has nothing to do with the seasons.

JCB..

Hi JCB,

It doesn't say that the N rating refers to the seasons ? From how I read it, it is saying the N rating shows that the tyre has been approved by Porsche.

Regards

Dave K.

 

[lali]

Its afunny one this... I have had more than my fair share of tyres on the 944 in the Uk without anyone questioning my selection. however on a recent trip to belgium we had some questions raised when we wanted to have some SSR's fitted.

 

[andygrey]

I recently fitted a set of Conti Sport Contacts, with the N1 designation, to replace the worn out P7000's. Initial thoughts are thus...

1) The comfort is degraded
2) The yaw acceleration is increased (I.E. the yaw response to steering input is less linear, manifesting itself as a rapid increase of yaw on the initial turn-in) A BAD thing.
3) Road noise has increased.
4) Camber sensitivity is reduced
5) Steering weight has reduced, with a corresponding reduction in on-centre detent.
6) Mid-corner power-on/off response is less benign.

It should be noted that the tyres have only done 200 miles, so could not be considered to be bedded in, but for what it's worth... I'll see what I think after at least 500 miles.
Intrestingly enough, the P7000 is actually the same construction and compound as the P6000, but with a diffrent tread pattern and marketed as an aftermarket tyre.

I can only assume that these tyres have been developed for the Boxster, which from my experience is not particually senstive to tyre type.

 

[carlmthompson]

I have Conti Sport N1's on mine.

I used to have a link to a guy in the US who'd compared bigger (i.e something like 235/50's front instead of 225/50, and 265/45 raer instead of 245/45) non N rated Conti's to the N1 rated tyres, and found the N1 rated tyres to be wider. Can't find the site though!

 

[John Sims]

It has been suggested previously that the only reason manufacturers developed N spec tyres were that their original standard offering performed poorly on a Porsche compared to other manufactures standard tyres. But which Porsche were they using as a bench mark?

911's obviously have unusual dynamic qualities compared to normal cars by virtue of the engine being in the wrong place. 944's have excellent dynamic properties and so shouldn't require any special treatment tyre wise. Continental do produce N spec tyres - now up to N3 I believe, Pirrelli have a different letter for Porsche related tyres. All tyres have evolved in the 20 years since the 944 was manufactured so they will be "better" than what ever tyre the car came out of the factory on. If there was a specific 944 tyre I doubt that tyre would still be available any way.

In summary, I don't think it matters on a 944.

 

[Guest]

ORIGINAL: andygrey

I recently fitted a set of Conti Sport Contacts, with the N1 designation, to replace the worn out P7000's. Initial thoughts are thus...

1) The comfort is degraded
2) The yaw acceleration is increased (I.E. the yaw response to steering input is less linear, manifesting itself as a rapid increase of yaw on the initial turn-in) A BAD thing.
3) Road noise has increased.
4) Camber sensitivity is reduced
5) Steering weight has reduced, with a corresponding reduction in on-centre detent.
6) Mid-corner power-on/off response is less benign.

I`ve had Contisport for 3years and they are noisy and hard, but they last well, at least one is 25000 + miles of normal road use. Have you got a strut brace because that makes a noticeable difference.

 

[andygrey]

Strut brace eh?
Where can one buy such a thing?

Cheers

 

[944turboS]

Here

http://www.porscheclubgbforum.com/tm.asp?m=206985&mpage=1&key=strut%2Cbrace

 

[sawood12]

Funnily enough I read an old copy of 911 and Porsche world the other day that had an article in it on Dunlops N-rating homoligation process of its new range of sports tyres. The N rated tyre visually looks identical to it's non-N rated counterpart but under the skin the tyres are completely different in their construction. Obviously Dunlop did not list the differences in great detail in the artical but the differences they did site were 5 instead of 3 ply's, shallower tread deapth for optimised out-of-the-box performance (and therefore lower life!!) and Kevlar beads instead of steel. The most important thing was the process that they go through with Porsche to JOINTLY develop the tyres specifically for Porsches. They described a very intensive and comprehensive development programme that involved alot of testing at significant cost to Dunlop so the whole N rating thing is not just a marketting ploy. Having said that the N ratings are not valid for 944's although 968's did have an N rated tyre but I think you'd be hard stretched to find them now.

 

[oliverjamesthomas]

Sorry chaps, just jumping over from the 993 forum to share my views[]

I run two sets of wheels - road with freshly fitted P-Zero Rossos and a recently bought set of the same wheels with Conti's on, that are for track. Previously I had Conti's, which came with the car. A few observations:

The Pirellis are noisy, soft and sensitive to tyre pressure.
The Conti's are quieter and funnily enough, were fitted brand new less than a month ago by a well respected indie in N. Yorks. Guess what - no 'N' rating!!![8|]
Factory suggested pressure for a 993 on 17" is 36 PSI all round. Conti's rise to around 39 PSI warm, whilst the Pirelli's rise to circa 44PSI, give a really nasty vibration and generally screw the handling. I'm now playing with tyre pressures to get to a happy medium.

Basically, there are a couple of questions. If we accept that the 'N' rating is so important, why has said specialist fitted non 'N' spec tyres? Secondly, if it is so critical to have 'N' spec, why are we not given differing sets of tyre pressures for differing makes of tyre? I would suggest the P-Zero Rosso's are bl**dy dangerous at 36PSI cold after normal driving, whereas the Conti's are great! Finally, are we to believe that the manufacturers run tyres down the line, size for size, in batches of non 'N' rated, then 'N' rated for Porsche, 'MB' rated for Mercedes and finally 'whatever rated' for BMW and the likes?

Just some food for thought........

Regards

 

[sawood12]

I think Porsche are fairly unique in specifying their own spec for tyres, I'm not aware are all manufacturers having their own spec apart from Ferrari. To me with tyres being such an important part of the car it seems common sense to work with tyre manufacturers to 'customise' the characteristics of the tyre for your car - especially for something that goes against the norm like the 911. I think it's details like this that has kept Porsche as the sportscar benchmark for the last 30 years against often more powerful and much more expensive alternatives. Ultimately I think its the case that 99.9% of Porsche drivers simply are not good enough drivers or drive often enough in situations that push the tyres to their absolute limits for N rated tyres to make any difference at all to the driver so by that analysis I agree - what's the point in N rated tyres? But the fact remains that they are different to their non-N rated counterparts, they are the result of extensive development which represents a significant financial committment by the tyre manufacturer, they have shown improvements in the hands of proffessional test drivers over extensive tests on a track and ultimately they are practically the same price at the non-N rated tyres so why not fit them if they are homologated for your particular car??

I've lost count of the number of people who blindly use Mobil 1 on the recommendation of Porsche so why the synicism on the use of N rated tyres?

 

[andygrey]

Generally, specific versions (I.E. differing compound,construction etc.) are developed for alll new performance and high end cars. I was (in a previous life) a chassis engineer very involved in tyre testing, and in one project whilst working with Michelin, tested over 20 diffrent bespoke variants of the Pilot Sport before choosing the tyre that would be fitted to the car when it left the factory. This is about the norm, most manufacturers multi source tyres (I understand the you have a choice of 4 diffrent makes whan you buy a Ferrari, each one being specifacally developed for the vehicle). Ultimate performance is only one of the criteria that the tyre is rated on when being tested, so comments above about most drivers not being able to see any benefit from an N rated tyre aren't really valid as drivers of all levels will be able to notice diffrences in steering feel, noise, turn-in etc.
Some cars are much more senstive to tyres than others (normanly because the OE tyre has been developed to cure an inherant problem with the chassis). The tyre that you buy at your local QuickFit will be the after market variant, and as such will have been tested on a varitey of vehicles by the manufacturer and developed to represent a tyre that is 'all things to all men'.
Most tyre manufacturers are contracted by the vehicle manufacturer to support tyre supply for a specific vehicle 10 years after the the last car rolls off the line, this may be longer with Porsche, but I would think that it is fairly safe to assume that you will no longer be able to get your hands on a set of 'factory' tyres. Shame really, it would be intresting to give them a go...

 

[Hilux]

Funnily enough I read an old copy of 911 and Porsche world the other day that had an article in it on Dunlops N-rating homoligation process of its new range of sports tyres. The N rated tyre visually looks identical to it's non-N rated counterpart but under the skin the tyres are completely different in their construction. Obviously Dunlop did not list the differences in great detail in the artical but the differences they did site were 5 instead of 3 ply's, shallower tread deapth for optimised out-of-the-box performance (and therefore lower life!!) and Kevlar beads instead of steel. The most important thing was the process that they go through with Porsche to JOINTLY develop the tyres specifically for Porsches. They described a very intensive and comprehensive development programme that involved alot of testing at significant cost to Dunlop so the whole N rating thing is not just a marketting ploy.

The tyre size and type differ on 911`s due to rear weight bias and that they load the inner rear wheel heavily when cornering. I cannot believe this makes any difference to a neutral (relatively) 944

All tyres have evolved in the 20 years since the 944 was manufactured so they will be "better" than what ever tyre the car came out of the factory on. If there was a specific 944 tyre I doubt that tyre would still be available any way.

Agree totally. How do all these 2 ton 300 - 400 bhp Audi and BMW's manage without N3 ratings []

 

[burrow01]

ORIGINAL: Hilux


Agree totally. How do all these 2 ton 300 - 400 bhp Audi and BMW's manage without N3 ratings []

They limit the top speed to 155MPH..[]

Pete

 

[Hilux]

They limit the top speed to 155MPH..[]

Pete

True, but the tyres fitted have to match the theoretical top speed.

N rated is not the speed rating. []

 

[burrow01]

ORIGINAL: Hilux

They limit the top speed to 155MPH..[]

Pete

True, but the tyres fitted have to match the theoretical top speed.

N rated is not the speed rating. []

I agree with that- but it does mean that the manufacturers do not have to test that the tyres are compatible with the vehicles handling characteristics at those speeds, ie the tyres can potentially be more generic

Also these vehicles rely very heavily on traction control systems to limit the amount of power that the tyres are actually handling.

I the end, with regard to N rated tyres, I agree that the situation with N rated tyres is murky. You have to note that the N ratiing is model specific, so tyres N rated for a 996 are not necessarily rated for Boxsters, 993's etc, and this process started after the 944 was discontinued, although you could use the 968 as the reference.

Given that the price difference is minimal, I use N rated tyres on my 993, as I am paying for Porsche engineering standards, and to me this includes the tyres. I used to do this also on my previous 3.2, on the basis similar rear weight distribution etc even though the tyres were not specifically N rated for that model.

If you review all the tyre threads on the forum, lots of people are requesting opinions on the best tyres to use, and get many differing opinions. Porsche do extensive testing, and recommend specific tyres based on this testing. As a non tyre engineer, non test driver, I'm happy to go with their recommendations []

Pete

 

[Fen]

Actually I think a good traction control system (like a good ABS system) puts more not less load on the tyres as it manages the power to keep the tyres at their maximum traction point rather than letting them spin wildly. Of course bad traction control that just cuts power blindly will give the tyres an easier time, but you wouldn't want that on anything fun to drive. Also consider that in everything I've driven with traction control (except nanny Mercedes [:'(]) you can turn it off and therefore the tyres have to be safe in that condition.