Rad997

New C4S owner with 19" Turbo Wheels. I have a set of Blizzaks from my Maserati 235/40x18 and 265/35x18. I have searched the board and these seem like good candidates to put on 18" wheels in the winter. Looking for feedback on this.

Now if I do get 18" wheels It seems like 8jx18 for the front (not sure about offset) and 10jx18 for rears (not sure about offset).

Are spacers required for the rears, or are they optional for looks? Are there spacers for the front? (I wouldn't expect there to be)

Is TPMS required and where can I obtain them? Any idea on the expected cost?

I assume all 18" 997 wheels would work. Is this correct? Are there OEM 996 wheels that would work? Are there any that I should avoid.

Finally, If my primary objective is not to take it out in the snow and only use it for cold weather driving, do 19" make any sense?

Your feedback is appreciated
Thanks

Edgy01

Welcome aboard. Having purchased a new Porsche you should start getting Porsche's factory magazine,--Christophorus. Every Autumn, they run a story about winter wheels, tires, chains, etc. Look for that in your mail box soon.

The 8-18 and 10-18 rims are the ideal rims for the winter. Not only do they fit, but you cn also easily clear a set of chains if push comes to shove. (I maintain a set for that reason).

For the 4WD cars the rear offsets are routinely different than those for the 2WD. The front offsets are the same for 2WD and 4WD. You will probably need a 17mm spacer. Check with Dave Coochas (herein) for guidance in what he did for his C4S in Boston's winter driving.

All 997 18s should work. Not sure about the 996 stuff.

You should pop for a set of TPMS sensors,--one per wheel. Go to Sunset (Portland, OR) for a set of those which will be close to $100 each. If you don't opt for them, the TPMS system will go off 9 minutes after you're heading down the road, indicating a tire problem. (Of course, if you can live with that, save the money).

If you TRULY will not be taking it out on the snow, you will still need something other than summer performance tires. Since they are only good down to 40ºF then you should go ahead and pop for the winter tires. They don't need to be bonnafide snow tires, but they need to be suitable for the colder temps. The Michelins I run on one or more of my other cars as full-fledged snow tires are made with something like sunflour oil which keeps the tires resilient in the winter temps. I would then consider sticking to 19s.

RH512

The OEM solution is 235/40VR18 and 295/35VR18 winter tires on 8x18" ET57 and 11x18" ET51 Carrera IV wheels with TPMS mounted and balanced, can be had for about $3,800 - MSRP is almost $4,900

As your search showed, there are many variations that can work well.

I just ordered the above for my '09 C4S, so no first hand experience yet.

rcg412

No it is not, that is only for 997.2

For a 997.1, and 997.2, on carrera IV it is 235/40 R 18 91V M+S and 265/40 R 18 97V M+S. from the TSBs.

Carrera GT

I have a C4S too. I read somewhere that Porsche does not "permit" the use of spacers and snow chains (perhaps this is just because the 5mm spacer is a cosmetic device to push the wheel out to "fill" up the wheel arch and would tend to therefore move the chain closer to the body panel.

I read (again ... somewhere ...) that Nokian now makes an N-rated snow tire, which is what I plan to use. I was told by one of the driving instructors in the US that instructed the snow driving course in Europe (Finland?) that Porsche uses the Nokian tire for their snow and ice driving schools.

Rad997

I Found the Porsche reccomendation for 8x18" ET57 and 11x18" ET51 Carrera III. It is here:

http://www.sudsmotors.com/peoria/acc...911TYPE997.pdf

I did not find the doc on Carrera IV. Anyone know where it is?

Also, what is the 91V in the spec above?

rcg412

Rad, on renntech.org it is in 997-2 section. I just bought a set of carrera IV wheels with michelin pilot alpin PA2 winter tires for my 07 carrera 2s with the sizes I listed above.

RH512

I believe the 91 is the load rating which corresponds to 91 = 1356 lbs 615 kg.
The V is the speed rating of 149 mph or 240 km/h.

RonCT

Did you try the TireRack website to see what they have available for wheels in 18"? You might have to trick the system by putting in a C4 instead of the S - For some reason (despite asking them for years to fix this), they won't show 18" wheel options for the S cars thinking that we only want 19s.

One thing to consider on the tire size is I recall that Porsche shows an "undersized" tire for winter because they assume you will have chains. The rear diameter of our 997 rear tires should be about 26.3". If you go with smaller (ie: 265/35) you are going to be too small by about 1" and your speedometer and odometer are going to be off and you also might start to meddle with PSM, ABS, etc.

I've always felt that you should stick with 18" summer tire sizing (235/40 and 265/40) for winter use and not go with the Porsche figures that assume chains (unless you are planning to use chains all winter long and the thickness of the chains is going to get you back to 26.3" diameter).

TireRack shows a Sport Edition 4 wheel in 18x8 and 18x10 and several "new" snow tire options for as little as $1500 complete (mounted and balanced). That's hard to beat and I don't know that you could get a set of Porsche wheels for that. TPMS would add another $400 or so and I'd probably do it. I've only had 2 flats in the last 10 years and both have been on snows with a previous BMW M3 that I drove year-round (would have been nice to get an early warning of pressure loss). Otherwise, you might find a set of take-off 18s here at the forum or elsewhere online.

Coochas

What Ron said....
Call or PM Damon at Tire Rack. He can set you up with a nice 18" set up for winter. You want good tires and not good rims. At the end of last winter, I hit a pothole at about 70 mph and bent about 3 inches of the rim. Why the tire did not blow out I have no idea. Cost to replace the rim,...not much.
I actually run a big spacer in the back (I think 32mm) to make the car look a little less ridiculous as a 265 mm rear tire looks a bit 'doughnutty' on a wide body 997 w/o a spacer.
Yes, I am talking about crappy heavy wheels and spacers,....remember, it's winter and your driving needs to be curtailed anyhow.