Premature wear of transmission due to different tire wear?

I've got 6mm of tread left on the fronts and the driver's side rear. The passenger side rear shows 3mm of tread left. The dealer was trying to convince me that Porsche does not recommend any more than 30% difference in wear between the rear tires or it will cause premature wear of the Tiptronic. Is that true? I'd rather verify before replacing a $450 Michelin Power 285/30/18.

Is your car a C4? Did you put the tires on or did you buy the car that way? Been doing alot of left handers?

Quotes source post: 12660082

It's an '02 C2 Cab Tiptronic with 56k miles. I just bought it 2 days ago. I don't have the service records, but the local dealer has been doing service since new, and the oil has been changed every 3k miles among other things. I suspect it was a nice weather, occasional driver. I can't figure out why the odd tire has less tread. Usually it's the other way around (one tire replaced due to flat). Depths were measured at the center of the tread.

This what Porsche say about different tread depths on the same axle; front or rear.

Quotes source post: 12660027

Porsche guidelines call for no more than 30% difference in tread depth between tires on the same "axle". Most often this arises when one tire suffers a puncture and has to be replaced. If the new tire and the used tire on the other side differ in tread depth by 30% or more the used tire should be replaced too. Porsche doesn't give any explanation for this guideline/rule. Could be concern for the Tip (or manual) transmission and excessive wear and tear to the transmission, or possibly to the differential. My WAG is the primary concern is how the ABS or PSM systems will perform. The controller could be "confused" by too large a difference in tire diameter due to uneven wear between the two tires. BTW, if the right rear tire is worn more than the left rear unless the car's alignment is severely off this is a sign of very aggressive driving. Absent LSD the inside rear tire on a turn can spin if the car is accelerated aggressively around a turn. Since most turns in the USA are right hand and these are the sharpest turns the right rear tire wears more than the left rear tire in this case. My SOP is to err on the side of caution so faced with a similar situation I'd replace both rear tires, have the alignment checked and adjusted just in case it was out of spec, and if found not to be bad enough to account for the uneven rear tire wear vow to be less aggressive in going around sharp right hand (and left hand) turns.

Now that I'm tire shopping, I'm trying to figure out what tire I need. The tires are labeled Michelin Pilot Sports, but they don't look like the stock Michelin Pilot Sports. They look like the Michelin Pilot Super Sports. They are labeled "Pilot Sport N3", which looks like the Pilot Sport Porsche spec tire according to Tirerack. Are these really Pilot Super Sports?

Look like worn PS2s to me

I would recommend you buy a cheaper tire, michelin is going to wear out fastest of all and youre not going to tell any difference using a cheaper, sensable brand tire

Quotes source post: 12662985

I hear you! I went ahead and bought a matching rear since the other one is nearly new and the fronts are at 70% wear. That should last me until beginning of next summer when I'll reconsider something else and I'm ready to replace all 4. I was up in the N. Ga. mountains today keeping up with the sport bikes, so these Pilots aren't half bad. And the PSM never complained. I felt like I was glued to the road no matter what line I picked. (Which were much safer lines that track lines since I was on public roads.)