Question about N rated tires...

I follow Porsche's recommendation on N ratings for tires. I can't remember if N ratings can be mixed on different axles. For example, I am looking at Michelin PS-2 (Pilot Sports). The supplier tells me that he can get the fronts as N1 and the rear as N-3.

Is that a problem?

I tried to access the archives at PPBB, but was unsuccessful.



Tony

Tony,

Here's the gospel from Saint Owner's Manual:

"Only tires with the same make and with the same specification code (e.g. "NO", "Nl"...)
can be mounted.

Before mounting new tires, check with your Porsche dealer about the current release status.

Use tires with "ZR" quality standards. There are currently no standards concerning tire
strength at speeds above 150 mph (240 kmjhJ.

Tires should be replaced no less than on one axle at the time.

Only tires of the same make and type must be used. Mixed tires are not permissible.

Initially, new tires do not have their full traction. You should therefore drive at moderate speeds
during the first 60 - 120 miles (100 - 200 kmJ. If new tires are installed only on 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 the new tires are broken in."

BTW, posts about tires, i.e., N-Rated vs. Non N-Rated, are as passionate as discussions about oil brands and oil viscosity, or Porsche's culpability with regards to engine design.

Bill

...so i would hesitate to mix them on one axle. Mixing 2 fronts with 2 different rears is a much longer and more nuanced discussion.

Grant

The change from N0 to N1 to N2 etc just means they changed the compound used and had to reapply for re-certification. Higher number could be they discovered an improvement or it could be they discovered a way to make it cheaper.

Would I mix different numbers as long as the same pattern/N-number was on the axle? Yes as long as the tread design looked similar. My first Boxster had a set of Pirelli tires where the fronts were one pattern and the rears completely another. But they were designed to work together that way.

I would guess so but with the same pattern and a slight compound difference you are probably not so far off from the fronts that it would make a big difference. Not like all-season and UHPsummer mixed.

in most countries that i know of in europe it is illegal to mount different tires on the same axle. there is no law against mounting different tires on front and back. and this is from countries like germany and switzerland where you are not even allowed to use different wheels without approval.

i may sound like a broken record but my boxster had 205s in the front and 255s in the back. how much more difference can there be?

think about the physics; mass, acceleration, momentum, etc. the danger comes from differences left to right which will destabilize the car. you might not get optimal performance from different tires front to back but the car will be no more unbalanced than it is from the factory.

--
MY 2000 S, Ocean Blue, Metropol Blue, Savanah Beige.
Bought June 2000 - Sold May 2010