zer026T

I have a 2005 Carrera with Sport Chrono and noticed the PCM has a "Tire Change" reset option... Don't believe the '05 has TPMS so I know it's not that. The PCM manual explains the reset process but doesn't explain what it's for. I've googled it and searched the forums with no luck.

Edgy01

I ordered TPMS for my 06 and it became standard in 07. Perhaps you have it on your 05--can't be sure unless you see the option code on your list.

Tire change is allowing you to tell the car that you have put snow tires or summer tires on it, and 19s or 18s on it.

cviles

I don't have this function on my '07 and it has sport chrono as well, so consider this a silly wild *** guess: Could it be related to the PSM system? Perhaps the software needs to know when to expect different performance and slippage from winter tires versus summer high-performance tires?

You can always call your local dealer's service department and ask them what it does. Or send an email to PCA or PCNA asking for clarification.

Edgy01

My guess (cviles) is that you just aren't familiar with your car. Since TPMS was standard on 07 USA models you have the ability to tell the TPMS what tires that you have on it.

zer026T

My car doesn't have TPMS so the only other reason the car would need to know this info is if it would need to anticipate different grip/performance from tire to tire. Makes perfect sense to me!

zer026T

I have the options list, TPMS isn't one on it. Also there's no TPMS menu on the cluster options for this car, and I've read it's not available on MY05 in the first place so pretty sure there's no chance this car is equipped. But didn't connect the dots that this triggers the system to expect different performance/grip and assume it needs to relearn how the tire change affects handling.

tgavem

The law, and Dan is correct.
The Act mandated the use of a suitable TPMS technology in all light motor vehicles (under 10,000 pounds), to help alert drivers of severe under-inflation events. This act affects all light motor vehicles sold after September 1, 2007. Phase-in started in October 2005 at 20%, and reached 100% for models produced after September 2007. In the United States, as of 2008

Other factoid, the 959 was the first car with TPMS back in 1986, then there was the Ford / Firestone "deathmobile" and the rest is history.

To clarify, it is called TPC in your Porsche . :-)
Although, at the moment my car has learning disability. Reset it to re-learn as one of the tires were slow to pick up. Now the car has been learning for four weeks even after taking it on longer trips. Time to take it to dealer :-(

cviles

No, I know how my car works. I just replaced all 4 TPMS sensors and used the menu to re-select the tire size and type so the new sensors would sync up. The TPC system predates PTMS and probably worked via the ABS sensors to detect a change in the tire diameter when they get low or go flat. My last M3 had this kind of system back when the law allowed it.