My car came with 19 PZero summer tires on 19 Turbo II wheels. My OBC is set for 18 inch tires from the dealer. Is this correct or do I need to change it to 19's?

 

Excuse my ignorance, what is OBC?

 

On board computer. Maybe not the correct term for Porsche but I was trying to abbreviate myself.

 

Are you referring to the TPMS (Tire Pressure Monitoring System)? If so, if your tire pressures are the same then there is no reason to change them.

BTW, the computer is referred to as the PCM.

 

Looking for TPMS setting info .. Had to correct this error.

No it isn't.

The on board computer IS the OBC

The PCM is a different thing in the middle and they are not the same. You can have a car without a PCM and still have a car with an OBC

 

Right - it was OBC on the 996 too.

 

There is a 19 inch setting you can change with the OBC - check your owner's manual.

 

You can change your wheel size between 18" and 19". Press the lever on the left of the steering wheel to get to the settings menu in the dash.

 

I believe that setting in the OBC will adjust the fuel mileage the computer estimates you have remaining. It really doesn't do anything else, I have 20" rims and there is no setting, nor does it matter.

 

Really? Is there a specific section in the settings menu for wheel size?

 

Yes, you can change it on the OBC as mentioned above. Like I said, it won't do anything to affect performance.