I've got the "bug" and must change my wheels and tires on my 04 Coupe. Finally decided on the C6 Z06 wheels 18x9.5 and 19x11. That decision is over and the tires! After reading numberous threads on what everybody is running, I decided on the PS2 with 265/35/18 and 305/30/19. I called Tirerack to place the order and the gentleman advised me not to mix "N rated" 305's with non "N Rated" 265 or 275. He would not recommend!

Now I have read and seen numberous Vettes running this combination. Has anybody experienced any issue with the different ratings? The only tire in the sizes I'm wanting that don't have a "N Rating" is the Bridgestone Potenza RE050A, and their ratings aren't that great.

I need some feed back on this, can you help?

Mike

 

I am running the exact tires you are talking about - except that I'm running a 275-35x18 in front and a 305-30x19 in the rear. Please enlighten me - what is an "N" rating?

I went to Tire Rack's web site, and the only thing I found was a "N" rating as it pertains to a temporary spare tire.

 

N Rating is Porche spec, meaning the tires are manufactured to a Porche approved spec. The sales person at tirerack says that many times that means made with different compounds. Possibly a difference in sidewall construction. Tirerack says they could not recommend placing a Non N Rated tire (frnt) with a N Rated (rear).

If I want to purchase, they would of course sell me what I want.

 

I've never heard of the "N" rating either and I work in a tire shop! BTW I'm in Clarksville too ...I'd say whatever tire you choose, go Michelin!

 

i believe the same tire can be had in runflat and non-runflat. one set is OEM for porche and one set is OEM for ferrari.

i run the 305/30/19 bridgestone potenza re050a and they are just fine for me.

where's EK when you need a definitave answer???

 

Well, JD, good buddy, I just happened to log on momentarily and noticed your PM in reference to this specific thread: To begin, StrokednTN, you basically answered your own question.

In general, in the tire industry, you will find that many auto manufacturers (especially exotic car makers such as Porsche, Ferrari, Lamborghini, Bugatti, Koenigsegg, etc.) will privately commission a unique tire product and model for a new specific o.e. vehicle application from several of the well known European tire makers. Commonly, Michelin, Pirelli, and, Continental are utilized, for they have long since been chosen as o.e. tire manufacturers for the European automotive market for decades.

The N rating (as it refers to the Porsche tire model) refers only to the fact that this specific model tire by Michelin was solicited and tested with the inclusion of Porsches' new car design and specs for a particular vehicle-model application. In fact, here is a link that briefly describes this issue:

http://www.lsrpca.com/misc_web_stuff...ed%20tires.htm

And, yes, in general, tire distributors do not recommend mixing tires that do not match in several categories: Speed, Tread Pattern (model), and, Load Bearing Capacity. Therefore, they do not recommend mixing unique N-Tested Matching Sets that are slated for a specific vehicle application with other non "N" designated tires.

However, you can purchase the Porsche N-Tested tires that are o.e. for the Porsche, provided the available sizing is appropriate for your specific wheel application and vehicle. The downside to this is the fact that typically, the N-Test designated Porsche tires only come in one specific tire size for the front wheels, and, only one specific tire size for the rear wheels. BUT, all four are the Porsche "N" type. So, if you need a tire size other than the o.e. "N" designated tires, the vendor might not want to sell them to you.

Now, since you have chosen a 9.5 inch wide wheel for the front, the ideal tire width size for this specific wheel width is a 275mm. However, you can go up, or, down (i.e., 265mm) one tire width size. And, for the rear, you have properly selected an 11.0 inch wide wheel. The ideal tire width size for this specific wheel width is a 315mm. However, again, you can go up, or, down (i.e., 305mm) one tire size. BUT, do keep in mind that if you opt for the smaller size widths, you may find yourself with a "narrow" tire. Manufacturers build certain model tires with very shallow, and, rounded shoulder edges which may allow the tire to appear stretched. And, this is why I personally recommend "ideal" tire width sizes for specific wheel widths. Please feel free to PM me for any further questions and I would be more than happy to assist you.

 

damn EK, you rock!

 

Yes, Rands! The traditional "N Rating" does indeed designate a spare tire.

 

EK I'm enlightened by your knowledge of tires. I'm going to local shop today to look the Potenza over. But, I still am VERY INTERESTED in the PS2.

I'll touch base with you as I gather more info.

 

don't worry about running the Porsche "N" spec tires with the non "N" spec tire ... even Michelin says it's ok .... but never mix them on the same end of the car which is not something you need to worry about since there is no non 'N' spec in the size you need

 

Thanks Luke!
Puts my mind at ease! You guys have a lot of information, sometimes information is just TOO MUCH!