Using the search terms wheel offset winter I found some useful info, but nothing that guides me through to the answer to my question. I don't want to tell a sad story later and learn, "you shouldn't done that". Lots of well informed and experienced winter wheelers. Maryland salts their roads so I will not be driving during those times. I have a much better vehicle for that, if needed. I want to continue to enjoy this driving experience when it is cold with appropriate tires (Nov-Mar)

Question. Is this a safe setup for the winter?

I found a set of 4 used wheel/winter-tires with TPMS for my 997.2 4S for sale. Haven't bought them yet.

Front 8x18 ET 45 235/40/18
Rear 11x18 ET 55 295/35/18

Porsche manual for 18" calls for all of the above EXCEPT:

Front ET 57
Rear ET 51

So if I did the math correctly:

Front Each wheel moves 12mm out (Track goes from 1488mm to 1512mm)
Rear Each wheel moves 4mm in (Track goes from 1548mm to 1540mm)

Just eyeballing the front, 12mm is a lot from a clearance standpoint, maybe. However, Porsche does sell 5mm (maybe even larger) spacers. The rears not so much but I didn't look on the inside either.

My gut sez Porsche can't test all of the wheel offsets for winter set ups so the smartest/safest/least-liability thing for them to state is use the same wheel size but slightly different tire profiles.

But finding so many different offsets out there and then to see these begs the questions:

Is this a safe setup for winter?

If you are not using Porsche recommended wheels, then what are you using (wheel dimensions and tires)?

Don't beat me up too bad folks.

 

I bought a set of "Sport Edition Cup 4" rims from TireRack and mounted Michilin Alpins on them. The rims are cheap and I won't care (too much) if they get dinged up in the winter. I also had these rims on my 987. They looks good IMHO, sort of a like a modern take on the Turbo Twist rims from the 996.

As for your wheel math, I recently confused myself on a similar issue, so I won't comment there.

Jason