I took my car in to get rear tires (i do need new rears ). The dealer told me that I NEED to replace the front tires too bc the new rear tires have an N2 porsche rating and the older front tires have an N1 rating... can this possibly be true? I am and was very sceptical on the phone and made sure I didn't misunderstand him. I don't see how this could even matter. As far as i know you can even mix and match different brands of tire. front vs rear. Does anyone know the official answer to this?

 

Not necessarily true. For example, Michelin currently recommends N0 cup for front, and N2 rear for GT2. Bottom line is I think difference is minor and doesn't warrant getting rid of current tire.
Actually a very confusing issue. Read more about it here: http://www.rennteam.com/forum/thread...ide/page1.html

 

I travel to Korea quite often on business and am quite impressed by everything they make. As such, I took a chance on Hankook tires vs. the original Bridgestones. Frankly, pushing the car quite hard into turns, braking hard before turns, I can not see or hear any difference except the $700 cost vs. $2k. They don't cry on high speed or low speed turns and I can see no lose in braking under any condition - including rain. Frankly, for aggressive street use, my opinion is that Porsche tested tires from their suppliers and nothing more.

 

From Tirerack:

"
Sports cars are often described as vehicles that "stick to the road." Sports car tires make a major contribution to this phenomenon. These tires are very complex products meeting numerous, largely contradictory demands. Finding the proper structure that balances these demands for any given application is the great challenge in tire design.
Porsche designs and manufacturers some of the highest performance vehicles in the world. Because of the integral role that tires play in vehicle performance, Porsche has integrated tire development throughout their process of vehicle development. To be an Original Equipment tire provider on a Porsche vehicle or be approved by Porsche for the replacement market requires the joint product development efforts of the tire engineers working alongside the Porsche vehicle engineers.
The focus in recent radial tire development for Porsche vehicles has primarily included optimum handling on dry surfaces and the safest possible behavior on wet surfaces, even at high speeds. Tires developed by various manufacturers, in concert with Porsche, offer a specific set of wet grip properties which few, if any, other automobile manufacturers demand in equal measure from the tires they use on their vehicles.
Tires may be specified for a particular vehicle or range of vehicles and must successfully pass the tire company's laboratory tests to assure that they would be capable of adequately supporting the Porsche vehicle while allowing it to reach its top speed on the German Autobahn. Additional laboratory, test track and race track tests are conducted to confirm that the prototype tires meet Porsche's noise, hydroplaning and handling requirements. Prototype tires will also be evaluated to assess their high-speed durability, uniformity and serviceability. Upon test completion, the tires will be released for production.
Production tires that have passed all of the tests and received the engineering department's release can be branded with an N-specification. The N-specification brandings include: N-0 (N-zero), N-1, N-2, N-3 or N-4. These markings on a tire's sidewall clearly identify them as approved by Porsche for their vehicles. The N-0 marking is assigned to the first approved version of a tire design. As that design is refined externally or internally, the later significant evolutions will result in a new generation of the tire to be branded with N-1, N-2, N-3, etc., in succession. When a completely new tire design is approved, it receives the N-0 branding and the succession begins again.
It is recommended that only matching tires be used on Porsche vehicles. Since many Porsche vehicles are fitted with differently sized tires on their front and rear axles, this means matching the tire make, tire type and N-specification. If a vehicle was originally delivered with N-specification tires that have been discontinued and are no longer available, it is recommended to change all four tires to a higher numeric N-specification design appropriate for that vehicle. Mixed tire types are not permissible.
It is also important to know that while Porsche N-specification tires have been fine tuned to meet the specific performance needs of Porsche vehicles, the tire manufacturers may also build other tires featuring the same name, size and speed rating as the N-specification tires for non-Porsche applications. These tires may not be branded with the Porsche N-specification because they do not share the same internal construction and/or tread compound ingredients as the N-specification tires. Using tires that are not N-specific is not recommended and mixing them with other N-specification tires is not permissible.
Tires should be replaced no less than in pairs on one axle at a time. Only tires of the same tire make and type must be used. However, in case of tire damage such as cuts, punctures, cracks or sidewall bulges that cause a single tire to be replaced for safety reasons, the remaining matching tire on that axle must not exceed 30 percent wear. If the remaining tire has more than 30 percent wear from new, it should also be replaced. Handling inconsistencies may result if this is not done.
Initially, new tires do not offer their full traction. Drivers should therefore drive at moderate speeds during the first 60-100 miles (100-200 km). If new tires are installed on only one axle, a noticeable change in handling occurs due to the different tread depth of the other tires. This happens especially if only rear tires are replaced. However, this condition disappears as new tires are broken in. Drivers should adjust their driving style accordingly."

 

I read the tire rack thing... still can't help but feel that i am getting ripped off thought. I mean, those guys sell tires, there arern't exactly unbiased. I guess the best question is .. would it damage my car somehow.. i.e. diff or w/e. BC service manager at the dealership is useless .. his explanation of it can basically be summed up in saying "well they have to match, .. that's the point of the N rating."

 

Regardless of what your dealer and Tire Rack say, you are very unlikely to ever notice any differences between N1 and N2 tires.

The recommendation of having the same N number is more likely driven by some lawyer whose concern is product liability, not performance or practicality.

 

Agree

 

There is no way unmatched tires (in the proper size) will cause any damage to your car.

Just order the 2 tires you need from Tire Rack and have a good independent shop mount them. You'll probably end up saving a bunch over what the dealer will charge you.

 

Just so you know there is a footnote on Tirerack's site indicating the last two paragraphs above were from Porsche.

That said, I personally doubt the front and rears need to be the same, but I would make sure the rears match and the fronts match.

 

I'm assuming we are talking about an AWD Turbo here. If so, one aspect that hasn't been discussed is the wear disparity between the front tires and the rear tires. If the tread depth disparity between the front and the rear is more than 50% then all four tires should be replaced. Failure to do this will cause undo wear on the AWD system resulting in premature failure (very expensive) that will not be covered under warranty. Don't ask me how I know this.

I believe the tread depth disparity between tires on the same axle should not exceed 30% as stated in a previous post

 

I don't believe there is a problem with having say a pair of N1's on the front and a pair of N3's on the rear. Where a problem occurs is mixing N numbers on the same axle. The tires most likely will have different tread patterns and/ or slight construction differences resulting in handling problems albeit hardly noticeable in around town and country club driving. Since it is a "sports car", meant for sports car type driving you'd want to minimize potential handling problems.

 

You bring up an excellent point!

I shudder at the thought!

 

Exactly....thats what i would have thought. Tires, fuel, oils, brake pads, all merely expendable items in the course of having fun .

And the OP's request for official advice... its ironic how advice is given but rarely taken, instead, often winds up being sunk by opinion and heresay .

 

Well it's a hard decision to take, and every opinion must be carefully examined and considered!

We all know the dire dire consequences of mismatched tires...

At best, if you don't get the issue properly squared away:



And potentially, if you really let fly with your choices, you really let fly:



Choose carefully!

 

Now THATS funny. Lets just hope we dont see that choice ever taken. Square wheels are a bit tacky on a 997tt....but hey they may be cheaper to replace than the round ones. and wear a bit better too.