Patently,
are they the PS2 N rated tyres ?
I would ask what pressures you run them at, I know that on earlier 911's the porsche recommendations were not neccessarily the best. Also many people seemed to unwittingly run the wrong pressures after putting larger wheels on.
I always found on the 964 that the edges wore more than the centre but not by that much - makes me wonder if you need a higher pressure in them.
Are the inside edges as worn as the outsides ? How are the fronts ?
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are they the PS2 N rated tyres ?
Yes - N1.
I would ask what pressures you run them at, I know that on earlier 911's the porsche recommendations were not neccessarily the best. Also many people seemed to unwittingly run the wrong pressures after putting larger wheels on.
The wheels are the original 18" as supplied with the 996 4S. They are at the Porsche recomended front 2.5 & rear 3 bar pressures - the handling has been fantastic (!) so I saw no need to fiddle.
I always found on the 964 that the edges wore more than the centre but not by that much - makes me wonder if you need a higher pressure in them.
Yes - I did wonder. The difference seems to correspond roughly to the "drop" in the bottom of the groove at the transition between tread patterns, though. Perhaps that would help. 3 bar seems high already, though!Are the inside edges as worn as the outsides ?
Yes.
How are the fronts ?
fine - even and several mm left.
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Legal or not, you'll find that the ride and handling is noticeably better with evenly worn tyres especially if it's 4WD.
Which is sort of my point. At the moment, 3 tyres are pretty even and one is within sight of the other three. If I just replace that one then the situation will be less even. If I replace just the rears then there will be a noticeable difference between front & rear, and if I do all 4 then I'm wasting quite a lot of rubber.
Why spoil a good car and risk a fine and points for the sake of £150 of rubber?
It's handling really well, in fact. And £150 is a bit below the mark. More like £250 per corner - so between £250 and £1,000 depending on how many I go for!
PS. 1.6mm is the 'legal' minimum. On a roadgoing 911 I'd want to keep it above 3mm.
Agreed - as I said originally, I don't have any safety concerns, but if that was not the case then they would be replaced immediately. I don't intend to run them down to 1.6 or even 2mm. As I said originally, mainly they are at 4-5mm at the moment.
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I was going to suggest popping into a tyre place and looking at a brand new tyre, but not many places stock n rated stuff, my ps1 n's were very different in tread pattern to ps1 ordinaries.
Michelin do have a very good technical advice centre, number is hidden somewhere on their web site. I would give them a ring and see what they say.
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How's this for a crazy idea:
Replace your one worn tyre with an absolutely-as-cheap-as-possible (new) one, and run the car like that until the other three have worn down, and then replace all four with your preferred brand+model.
It'll be an interesting experiment in the car's handling (and I suspect that provided you drive sensibly, the difference won't be as dramatic as one might think).
An interesting experiment in driving 'sensibly' for a period of time too, with associated experimental results on fuel economy etc etc.
Interesting all-round, then!
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Yep, that's certainly a crazy idea;
1). I doubt there is such a thing as a "absolutely-as-cheap-as-possible" tyre in the size/spec that Patently needs ...
2). I wouldn't like to "experiment in the car's handling" with one dodgy tyre and 3 half worn ones, especially when the car is worth > £50K.
3). I certainly would never drive a 996 4S "sensibly" and wouldn't give a hoot about the fuel consumption ;-)
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OK, sorry, I forgot it was the 4WD model (all tyres must be the same model etc)
But for what it's worth, mytyres have the Kumho KU31 in 295/30 R18 Y for £136.40
Does this car have a space-saver spare wheel? Or would using that gnash-up the transmission too?!
Of course you wouldn't be interested in the fuel consumption Chad - it was purely from an experimental, interest, point of view.
But by the same token, if one says "hang the expense", one would just go out and blow £1200 on four new tyres, even if three don't need replacing.
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mytyres have the Kumho KU31 in 295/30 R18 Y for £136.40
Sadly, Porsche are fussy. It's not enough that they fit, they need to be Porsche approved by way of a special 'N' rating. So mytyres' Pirellis (295/30 ZR18 94ZR N3) are the cheapest available, but I think I would need the Rossos not the Assymetrico which pushes the price up again.
Does this car have a space-saver spare wheel?
Yes - 50mph max, limited distance only. The fun comes when the space saver is on the car and you try to fit the full size wheel on the passenger's lap!
Of course you wouldn't be interested in the fuel consumption Chad - it was purely from an experimental, interest, point of view.
:-) You don't buy a 911 for the fuel economy...
But by the same token, if one says "hang the expense", one would just go out and blow £1200 on four new tyres, even if three don't need replacing.
Quite!
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What exactly do Porsche do if you fit tyres they haven't approved?
Refuse to service the car?
Stop sending you a Christmas card?
;-)
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What exactly do Porsche do if you fit tyres they haven't approved?
Excommunication, I suspect :)
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>> What exactly do Porsche do if you fit tyres they haven't approved? Excommunication, I suspect :)
Worse. When you walk into the showroom muttering about warranty claims and third party liability for the farmer's hedge that now has a 911-shaped hole in it, they look at the tyres and wet themselves laughing.
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>> >> What exactly do Porsche do if you fit tyres they haven't approved? >> Excommunication, I suspect :) Worse. When you walk into the showroom muttering about warranty claims and third party liability for the farmer's hedge that now has a 911-shaped hole in it, they look at the tyres and wet themselves laughing.
All that money for a v expensive status symbol, and the priests laugh at you? If it's not excommunication, it's at least equivalent to a public dressing-down from the pulpit!
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All that money for a v expensive status symbol, and the priests laugh at you? If it's not excommunication, it's at least equivalent to a public dressing-down from the pulpit!
Laughing is reserved for those who buy it thinking it is just a status symbol, NW.
;-)
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Also, although I dont know of it happening to anyone, there is always the chance of an insurance co saying that you had substandard tyres fitted, Not nice when considering say £20K of repair cost (I know someone who took a 6 month old 993 through a hedge (and a fence, part of a tree, a pond, etc) and it was repaired despite a final bill in excess of £20K)
For the benefit of non-porsche owners (sniff ;-), Porsche specifically approve particular tyres for particular models and issue an approval or N number. The N numbers are sequential for a specific tyre, so the first PZero approved gets N0, the next N1, the next N2, etc. The N numbers restart when the tyre name changes, so you shouldnt assume that a PZero N3 is more recent than a PS2 N1 for example.
Sometimes the N rated tyres look identical to non-N tyres. I had SO2's that looked exactly the same, my PS1 N's were totally different to the standard PS1.
So far as I understand it the N tyres are stiffer and higher temp capable than non-N's.
Not sure what the story is these days but Pirelli used to say put directionals on the front of 2wd models but not on 4wd models (supposed to clear the standing water before the driven wheel hits it)
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Lateral thinking, tunacat. I like it. There are only two snags!
One is that when you're talking about 295/30 tyres with Porsche approval, they're all about the same price! The other is that Porsche instruct that all 4 tyres must be the same make.
Oh - and have you tried driving sensibly in a 911? Not easy :-D
Anyway, the problem is now solved!! Michelin have answered my query:
"UK regulation, regarding tyre tread depth, states that that the central 75% of the tread width, in a continuous band around the circumference of the tyre, must have at least 1.6mm depth. The remaining tread area can have zero depth in the UK, although law in Continental Europe requires visible tread depth.
The tread pattern width considered, is that having the principle tread grooves, not the sipe/fine-cut design, being in contact with the road. The nominal sizing (295mm) is not the dimension used as the reference width.
Once again thank you for your interest in Michelin
Yours sincerely
Michelin Tyre Public Limited Company"
So the tyre is legal because the reference for the 75% range is not the tyre width but the tread width ... and all of that is well over 1.6mm. The fine pattern on the shoulders is irrelevant.
At this point, I would like to record my genuine thanks to Michelin for a quick response to a point that had worried me. Pilot Sports are now the likely replacement, when the time comes.
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So the tyre is legal because the reference for the 75% range is not the tyre width but the tread width ... and all of that is well over 1.6mm. The fine pattern on the shoulders is irrelevant. At this point,
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You have had to find out what the manufacturer says and they confirm what you thought re safety.
Consider what would happen if the BiB stopped you and viewed the tyres as in your original view, i.e. they appear to to illegal sir. Do you now carry the letter with you and would they accept that?
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Do you now carry the letter with you
Oh yes. You bet!
and would they accept that?
I don't care. It's not up to them; it's up to a magistrate. And I believe that a magistrate would take the view that I had been reasonable and diligent; I checked the tyres regularly, developed a concern based on the strictest possible interpretation of the law, checked with an expert, and was told it was ok.
Anyway, the difference between the two possibilities is not a question of degree; one is a genuine misunderstanding of the legal terms.
It's a shame I can't show you all the tyre; if you look at the middle bit, it really doesn't look like a worn out tyre!
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If you are concerned change it ,I would never drive a high performance car with tyres down to wear bars especially a Porshe
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If you are concerned change it
As I said, if I had safey worries then I would. My concern was purely one of legality.
Sadly, I no longer regard motoring law as coterminous with safety.
I would never drive a high performance car with tyres down to wear bars especially a Porshe
Me neither. They will get done before the wear bars. Just not at 5mm, especially at £1200 a pop!
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This is a grey area, I recently had a similar situation with the front tyres on my Mondeo, less than 1.6mm on the shoulders though 4mm+ in the middle, one slightly better than the other, the general concensus amongst all that I asked (strangely I didn't post this on here) was that despite the 75% accross the centre "rule" if any significant area of tread is less than 1.6mm then change 'em.
It is a road and traffic reg that is open to interpretation, therefore you do not want it to be wrongly interpreted by Police Officers attending an RTA, that may not be your fault, thus potentialy invalidating an insurance claim relating to significant damage to a £50k 911.
I changed both on the Mondeo, albeit just under £100 each, though kept the better one in the event that I need to put a tyre on the car to sell/trade it.
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Apologies for bringing this back up again, but I was thinking some more about this ?tyres approved by Porsche? thing:
Is it basically that your insurer won?t insure the car unless it is wearing approved tyres?
(A colleague of mine used to have a 911, and his rears, at least, were some unheard-of brand, but he did have insurance.)
Otherwise, it seems a little bizarre: I assume it?s not that Porsche would be coughing up the repair bills if you put the car backwards through a hedge; rather, it?s that they may balk at repairing any mechanical failure under warranty if they spot the car is wearing non-approved tyres.
And yet one (only) of your rear tyres was replaced due to getting a puncture, so inherently you?ve been running the car since last December with a different tread depth on one side versus the other, and different overall diameter of wheel.
But presumably these must be considered to be acceptable from a ?potential for dangerousness? and ?potential for contributing to mechanical breakdown? point of view?
And seemingly it?s also fine to thrash the car round a circuit on a track day, so long as any breakdown occurs when you?re just driving on the public road?
But drive on public roads with 4 brand new fully-treaded, ?Y? speed-rated Kumhos which are non-approved? Oh no!! Tsk tsk!!
Hey, how?s this for getting one over on Porsche ? put the Kumhos on for the track day, then put the Michelins back on when you leave the circuit?!
Hilarious!!
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Re the replacement after the puncture, there are acceptable limits to the difference in tread between tyres on the car, pulished by Porsche. As the other 3 were still relatively unworn at the time, the new fourth tyre was within limits. An official Porsche Centre confirmed the tyre combination was ok shortly after. If the puncture had happened later, it might have doubled or quadrupled my bill.
As regards the track use, Porsche's warranty stands up even if the failure was on track, provided that it was not a result of abuse. So if you get distracted at 115mph and drop it into 2nd instead of 4th, Porsche will not be sympathetic. From time to time there have been arguments about precisely what constitutes abuse, naturally, but track use per se is not a warranty killer. Of course, do the same thing on the road and there will be the same result.
Porsche make great stock in their marketing that their cars are ready to roll onto the track, and that their technology is informed by race experience. They are not making it up. OK a plain jane Carrera is not going to win at Le Mans, not is it suitable for out and out competition use, but go to a track day and you'll have fun, and you won't be humiliated.
The issue about approved tyres is a result of Porsche's general attitude. They do seem to want their cars to run well and in the manner they were designed to, and that means that high demands can be placed on the equipment. Bear in mind that mine has the lowest form of 911 engine yet can do 174 mph, and I am perfectly entitled to go and do that whenever I feel like it on a suitable German autobahn with tyres at the German legal limit for tread depth. Not many cars are designed with that in mind. Thus, Porsche regularly publish details of what tyres they have tested and approved, even for models that are, by most standards, quite old.
This doesn't mean that other tyres are worse, just that Porsche don't know whether they are good enough.
Frankly, I've no idea what the consequences of using non-Porsche-approved tyres (or any other part). I suspect some comeback in the warranty and insurance areas, but frankly I don't care as the question is never going to arise for me. There is no chance that I would risk blatting down the main straight of Castle Combe with Avon Rise looming ahead, relying on a part that I was (potentially) going to be the first person to test. ;-)
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I see, so really it *is* ultimately more of a personal choice thing - like whether to go down the M1 at an indicated 120mph in a 10 year old 100k mile Mondeo one bought second-hand with no service history and four different unheard-of-branded tyres of possibly-lower-than-they-ought-to-be speed rating... ...It's just a matter of degree.
:-)
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