MidEngineRules

I'm assuming the tire company doesn't pay to be tested. N spec only matters to the tire Porsche chooses to mount as OEM. There are no N spec tires that aren't OEM. Sometimes like in the case of the GT4 there are two tires in which Porsche contracted as OEM (Michelin and Dunlop). Why, who knows? Maybe based on where the car was to be imported? I'm sure tire companies bid on the contract, but once chosen they'll make the tire to Porsche's specification. It's not voodoo and it's not a marketing gimmick. There are real differences in the specs, whether the average driver can tell or not. It's easy for the manufacturer to change the compound based on whatever variables the car maker requires. Did Michelin ever make a N spec PSS? I bought two non-rated sets for 2 different 997s and they both were terrible.

daylorb

You might be right, I really don't know. It just doesn't add-up though. There is no way most would buy an N-spec Conti or Pirelli over a PS4. They are universally dominated in performance by a non-N spec PS4. Maybe the N-spec's are different for different manufacturers? I'd bet there are some marketing $$ changing hands.