PAULUNM

Good info on the N ratings. It's too bad Bridgestone doesn't make the RE11 in turbo or GT2 sizes.

Also, Tirerack's list of GT2 sizes does not include the PS2!

Bryce

I like my Toyo Proxes T1R tires. I will probably buy them again. Much less expensive than Michelins.

adam_

This is nonsense. No doubt the dealer said this, but I'd want to see a rationale for it (other than to sell tires)

Side to side I can see, front to back- no.

A

PS N ratings are over rated, IMHO. Sure, it is a 'short cut' for a P owner to get a tire that works for the car...but there are plenty of other tires that are suitable.

Chuck Jones

The tire shop I use has been around for 20 years. They handle all the tires for Mercedes, Porshe, Aston Martin, Lambo etc. They have all the latest equipment for computerized balancing, alignment, corner balance etc.

I've been going there for year for all the cars, truck, fifth wheel etc....and trust Randy's expertise and judgement. He informs me that the Porsche TT usually runs out of tread on the rears at right around 10K miles...and that you usually get two to one on the fronts over the rears. The right rear passenger tire wears slightly faster than the other....which he writes off to right hand cornering is usually tighter in street driving with AWD or posi traction. It's just the nature of the beast to expect a two to one wear ratio on the TT....part of P car ownership. Im looking for a little less expensive alternative for the TT next time around....I've been running Michelin PS2's....but with a custom 315 rear wheel, the options are somewhat limited to find a good mathing set all the way around. If I had it to do over, I'd probably have bought a different size wheel just to increase my availability options since I don't track and mostly drive street.

Macster

As I believe I mentioned in my post on this subject the dealer's service department told me that if it was unable to source the same N rated Conti tires all 4 tires would be replaced. The two fronts at Porsche's expense -- cause of the CPO warranty -- and the two rears at my expense, cause they wore out (even though due to another dealer's service department doing a very bad job of aligning the car).

Based on what I was told that Porsche appears to when the money is coming from its pocket adhere to not mixing N numbers front to rear even if the tires are otherwise the same.

However, I would add that based on my understanding of the N-rating system the tires are not otherwise the same or they would not have different N-rating numbers. They are different and I guess different enough that Porsche doesn't feel it appropriate to mix them.

Sincerely,

Macster.

Macster

I do not have much experience with my Turbo yet, but I have plenty of experience with my Boxster and the rear to front tire replacement ratio is 2 to 1. A full set of new tires, then 15K or more miles later a new pair of rear tires then another 15K or more miles and when new rear tires required I replace the fronts too. While the fronts could go another 15K or so, they are by this time so hard and noisy I replace them.

If tire wear shows any signs of alignment problems I have car aligned. Generally dealer will extend a discount on alignment when I buy four tires.

And yes the right rear tire wears a bit more than the left. The cause is due to the lack of LSD. Since most turns to the right are sharper the inside wheel experiences a bit more slippage (if turn taken a bit aggressively) and this causes the right rear tire to wear more. How much more depends upon how aggressive the car is driven.

Taking right corners with a lead foot will see the right rear tire worn much more noticably than the left. A more sedate driving style could have the tires exhibiting the same wear.

I'm hoping I can get more than 10K miles out of the rear tires of my Turbo. I think I can, now the car has received a proper alignment. After over 5K miles tire wear is not very much and appears quite even from side to side and across tread faces.

Sincerely,

Macster.

adam_

1. What one dealer said is not necessarily the official Porsche position

2. The N rating system has been published. It is NOT true that a different "N number" means it is a different tire.

Taking what you hear from one SA on one day, and extrapolating that to be an absolute truth is like taking one doctor's comments at a medical check up and saying it represents the total consensus of all medical opinion.

rennlist is a place to argue the "N rating" nonsense... at 6speed it is laughable.

Finally, the N system starts at N0... as that tire design is revised, it is incremented to N1, then N2. If it is then redesigned to represent a departure from that base design the new tire is ...back to an N0. SO IS IT PROPER TO MATCH THIS NEW DESIGN TIRE WHICH IS AN N0, with that old design that is also an N0??? Such is the silliness at the heart of 'matching N ratings'

I don't know, but I'd venture to bet that nobody racing these cars runs "only matching N ratings"... indeed, I don't think serious racing tires are N rated.

A

PS feels like I'm arguing motor oils....

Macster

The dealer was speaking from the position of having to honor the CPO warranty thus I believe it was expressing Porsche's official position.

A different N number does mean the tire is different from the previous N number. You admit this later in your post when you say "...the N system starts at N0... as that tire design is revised, it is incremented to N1, then N2."

I do not recall advising matching an older N0 rated tire and a new N0 rated tire, assuming you are correct in that the N number resets or wraps back to zero after N3.

All I said was what the dealer told me that if it was unable to source the same N rated tires for the new rear tires as the existing front tires it would replace the front tires under CPO warranty with the same N rated tires as the new rear tires.

(I do not know what I would have done had I been faced with having to replace both the rear tires and the front tires because of the difference in N numbers between the older front tires and the newer rear tires. I might have opted to leave the fronts alone and see if I could notice any difference. Or I might have bitten the bullet and had the fronts replaced. Don't know.)

Owners who race or use their car on the track can run any tire the sanctioning body or track day organizers allow.

The N rating only applies to tires intended for street use and deals with other factors beside absolute grip and things more of a concern to a car being used on the track.

To repeat: I was only passing on what I was told regarding the mixing of N rated tires.

Apparently Porsche feels strongly enough about this -- against it -- that when it is Porsche's money is at stake -- vis a vis the CPO warranty -- it was going to pay for the new front tires in order their N number matched the new rear tires I was paying for.

If you chose to ignore the N rating when selecting tires, mixing tires, up to you. It is your car and you can do with it as you wish, of course.

Sincerely,

Macster.

roberga

and the reason serious racers do not use N rated is that their cars do not have much in common with street cars including racing on street tires.

I would be a happy guy if I got 10K out of my rear tires

Michael-Dallas

I'm running Nitto up front and Hankooks in the rear.

My car hasn't turned into a pumpkin and I haven't careened to a fiery death yet...

///Michael

Macster

Give it time...

Seriously, if you're happy with performance of your car with you mixing/matching tires, even running non N-rated tires, more power to you.

I'm not anxious to experiment in this area, and as long as I don't have to I'm not gonna.

And I'm not going to advise anyone to go against Porsche's guidelines regarding this cause I'm not about to back up any contrary advice should someone have a bad experience mixing/matching tires.

Sincerely,

Macster.

Michael-Dallas

I've given it plenty of time. I've run mismatched front/rear tires on my E46 M3, E36 M3, Nissan Sentra SE-R, 350z, 300ZX TT (and NA), and even on my fiancee's Murano.

If you can seriously tell a difference in grip/handling on the street, then methinks you should be saving that sort of driving for the track.

Ok, so you would listen to what your local Porsche dealer says about tires, but you would be willing to experiment w/ oil viscosity?

///Michael

roberga

since it is a 4X4 the tire choices mostly likely mean less. Like you said it is not an issue for the road.

mmcmilla

I'm also happy with the Sumitomos. I've bought 2 x front and 4 x rear. Maybe about 90% the performance of a top tire, like PS2, but 1/3 the price and I'm getting about 25% greater wear (e.g., 12,000 or so on rears).

Macster

My consideration about "experimenting" with oil viscosity was triggered by the advice of the senior tech at a local Porsche dealer who told me I should be running 15w-50 in the Turbo.

I elected not to follow his advice and at the next oil change will be switching to Castrol Syntec 5w-40 oil. Currently the Turbo has Castrol Syntec 5w-50. Before this it had Mobil 1 5w-50 oil in it. The Mobil 1 5w-50 oil I have to mail order. The Castrol 5w-50 oil I found on the shelf of an autoparts store and discounted $2/quart.

All these 5w-40 and 5w-50 oils are recognized by Porsche as suitable for use in the car.

Sincerely,

Macster.