ML

Just got my new snow tires installed. They are the Pirelli Ice Scorpion Ice and Snow 255/50 19. I kow that they have been approved by Porsche but the Computer does not allow me to choose them as an option for the TPMS so I am concerned that I may be getting incorrect readings.

Funny that I am experiencing wheel vibratiins when I had no issues with my 275/45 19. Probably due to a bad balancing (which I will get the dealer to fix).

Does anyone have a suggestion/comments on the TPMS issue?

Periokid

I would check the actual pressure vs the tpms pressure to see if is an issue.

BenLee

On the vibration part, my Pirelli Scorpions M&S (not Ice and Snow) 285/45 19 have also had vibration issues for the last 3K miles despite 3 balances, including 1 'road force balance' done at the dealer. I've been told that my Pirelli's have a roundness issue. Haven't decided if I want to take this up with Wheel Works/Pirelli or not. Do I want to live with it or waste more time on this?

ML

I specifically asked for a roadforce balancing and was told that this is what was done. I will put a bit more mileage and will get them to redo it. Will keep you posted.

Thanks.

k2kv

Your TPMS transmits tire pressure only, while the computer setup exists to allow you to input the correct tire size, which it uses to calibrate the speedometer, since each set of wheels/tires has a slightly different diameter. Tire pressure is tire pressure, and is not relevant to tire size. Regardless of how you set up the computer, your tire pressure should remain accurate.

ML

Maybe I was being to geeky (or just getting too old or just stupid) but given the ideal gas law (PV=nRT), if all other factors remain the same and one changes the volume, this could have an impact on the pressure. Not sure how the device actually calculates the pressure in the tires (whether it calculates it based on a set reading and factors in tires (hence volume)) size.

If it is just an internal "gage" then I agree with you. Judging by the way the electronics work in the truck, one can never tell though!

cobalt

I have the same snows on mine and find no vibration issues at all. In fact I was rather surprised to see that the ride quality did not change a bit. Ususally snow tires have a tendancy to wonder. These are as good as the Rosso's.