Winter wheels/tires

[Mijostyn]

Hey Api sorry I'm late. Wrong approach all together. I'm in NH. Most of your driving will be on dry winter roads. Stick with 19" wheels and go with 235s up front and 295s in rear. Only Pirelli makes the right tires for this set up, Sottozero Series 2. They are N rated. The car will handle much better in 95% of the driving you will do. I also have a C4S and it does great with this set up in all conditions except heavy slush when you might as well waterski. The 265s might do marginally better but you are still going to have a really loose *** end. 18 inch wheels are harder to re sell and I think the feel is a little .. soggy for lack of a better term. I have the wheels on now. Since you are in the area you are welcome to come give the car a spin if you like.

This picture was taken at Saddleback Mountain in Maine. This is a Porsche snow plow ;-}

Edited December 8, 2013 by Mijostyn

[racerken]

Hey API,

I've had 18" snow tire set (current set is Michelin PA2) for 8 years now... I'm traveling now so I can't run out to check the exact tire sizes but it was per Porsche recommendation. I drive the 997 C2 everyday in the Michigan snow (and free salt bath) which accumulates up to 4" when the roads are un-plowed. My street is usually the last street plowed so snow tires are a requirement to get to work. I don't drive on ice and usually the roads are closed when that happens. It's not you with the problem it's everyone else who will drive the posted speed limit then hit you when they lose control. Further the un-registered, un-licensed, un-insured motorist, in a white chevy van will keep driving away.

Here is my experience:

as Mijostyn mentioned, 18" are sloppy at high speeds and you will feel the difference the first hard/fast turn as you understeer/oversteer, on the otherhand, it's good driver training because you learn what the car can do at low speeds. With summer tires, if you push the tires to the limit it's usually at high speeds and you most likely will risk damage. It cuts thru snow but remember if the snow is too deep or you make hard turns too fast you'll just plow snow. If too deep you'll sit on the snow.

if you practice your 4 wheel slides in deep snow, the snow will accumulate in the rims that will start thumping at about 50 mph due to wheel imbalance - carry a dirty set of gloves so you can reach in between the rim spokes to clean out the snow.

Use the hand brakes to pull into your driveway, to do this turn off the traction control, turn the wheel with a jerk and pull hard till you align with your driveway. It impresses the neighbors but not the ones with children playing with snow balls as you barrel down the street. Go too fast and you'll swing your rear-end all the way around - too cool. it's like being 16 again!

If I had to do it again, I'd go with 19" rims and N rated tires (I'd go 265 on the rears as Mijostyn stated) to maintain high speed performance for those dry days.

Words of advice: Don't forget to rinse the engine after each heavy road salting - you will get serious corrosion on all exhaust related fasteners from the manifold back. You might want to replace all corroded fasteners before it's too late.

Final word: The Porsche was designed to be driven every day in snow so don't let it sit in the garage.

[api]

Thanks for the input Mijostyn and Racerken. I waited to have the 18" wheels with Michelin PA2 235 front and 265 rear installed and a chance to drive a bit before posting my impressions. (I was leaning Michelin to begin with and Sottozero 295 were nowhere available anyway.) We've had some good storms lately in which I had to drive so I think they got a fair shake.

To recap: The main question was for a 2007 C4S, whether rear 265 is OK even though the owner's manual only allows 295 in rear (see page 332). The short answer was yes because I was able to obtain a document from Porsche NA stating so. I'll be happy to email the document to anyone else who faces the conundrum. (The owner's manual already lists 265 for rear on C2S (see page 330), so that wasn't the question. The question had -I think- further importance for a C4S as the front/back turning ratios might affect the AWD, which was also laid to rest -I think. I've subsequently wondered what the new tires option in the computer does and whether it does some related measuring.)

My impressions after about 400 miles on wet/slush/ice highway and 100 miles state roads on snow/slush in heavy storm: No surprises.

Handling: 18" definitely feels softer in cornering and when doing a quick jig around a pothole. More rally less track feel. But that was the tradeoff I expected and wanted to make for a softer ride on wintery uneven surfaces with minor potholes. Happy.

Grip: Grip improved visibly as the tires wore in. Impressive grip more than I at first expected upon limit braking and cornering, with very decent initial grip for hill starting, and predictable gradual letting go at the threshold. I didn't push it anywhere near the point of planing on slush but it felt solidly planted during the occasional overtake requiring crossing the middle slush barrier that forms between two lanes on the highway. Happy.

Balance: On dry cold pavement the car is obviously more tail happy with the 265, though at colder temps I fear the summer 305 might have hardened and let go very suddenly and I didn't push to find out. On wet/snow/ice the 265 is tail happy but progressive as the tail breaks away then less so as the power gets transferred to the front. Again as expected, and again as I wanted it. (Having spent formative years and winters in an old Beetle I am happy with plenty oversteer, but prefer it not be the jack knife variety while I'm tired after a long day of skiing. Also a function of age I sadly admit.)

PS. I agree undercarriage washing can only be good to reduce corrosion. I wonder if most of the damage is already done during driving when the parts are hot and might react and corrode more quickly? Google search for "steel salt corrosion temperature" brings up a bunch of data showing temperature does matter though not so obvious how much it matters. I guess the corrosion question is worthy of its own forum thread.

PPS. I'd also like to give a thumbs up to both Tire Rack as well as My Tire Guys, who made the delivery and installation work among considerable uncertainty and inclement weather.

Happy safe and sensual winter driving to all.

Edited February 24, 2014 by api

[Mijostyn]

Well I finally received and installed the 18" Michelin Alpin PA2s. So far very happy with them this cold weekend in eastern Iowa. There was about 1-2 inches of snow on the ground (with much more around from a storm a week ago) and about 14 degrees F when I drove my car to the tire shop--this was one of the scariest driving experiences I've ever had. Obviously, my car had the summer tires on (19" Michelin Pilot Sports) but it was gliding around even on a straightaway going < 25 mph. I put my hazards on because it was nearly uncontrollable, fortunately only for a mile to the shop. Once they were on, it was like night and day. I had great grip of the road and could turn, start, and stop (and drive straight) with full confidence. Excited to finally have it back, I even took it around some empty side streets where there was still 4-6" inches of snow and developed a good feel for how it handles on these kinds of conditions. Despite AWD/4WD, you can definitely sense the power coming from the rear as I felt a little oversteer that was pretty easily correctable. The TPC/TPMS took a good 10 minutes or so to get adjusted to the new wheels (I had TPMS installed in all 4) but the computer found all four wheels automatically without needing to go to the dealer (but I'm not sure if the tire installer fed the serial numbers into the car before I drove it off). Did change the settings to winter tyres instead of summer in the TPC. Can't explain in words how great it is to have the 997 back in action! OZ had their wheel caps on so I removed then measured them and ordered some black Porsche colored wheel caps from ebay that should arrive this week. Nevertheless, here are the before and after pics as promised!

Hey Seahawkeye, How do you like your OZs?? I really think they are the absolute best value in high performance wheels. That finish is as tough as nails.

Racerken is absolutely right. These fat wheels collect all kinds of crap in the winter. Way more than enough to throw the wheels out of balance. Your teeth will rattle at 80 MPH. After a messy trip I power wash the wheels right in my garage just to blow all the crap away. With a power washer it does not take much water to do this.

[racerken]

PS. I agree undercarriage washing can only be good to reduce corrosion. I wonder if most of the damage is already done during driving when the parts are hot and might react and corrode more quickly? Google search for "steel salt corrosion temperature" brings up a bunch of data showing temperature does matter though not so obvious how much it matters. I guess the corrosion question is worthy of its own forum thread.

All of the exhaust related fasteners should be replaced at a minimum once every two years. The bolts that really corrode fast are the exhaust manifold bolts which in my case are toast so i'm going to wait until my engine overhaul to deal with them. If I had to do it over again, I'd replace the exhaust manifold bolts annually but do remember that if they snap, you're going to have to buy a template or drilling rig to remove without damaging the block. The rest of the fasteners: manifold to catalytic converter, cat to muffler are all pretty simple. I used Porsche fasteners but if replacing often i think anything will do.

I've been driving every day in this Polar Vortex and here in michigan we have had so much snow this season that school outages are going to force our kids to extend into summer. For the driver, it's all 4 wheel slide city! I've not had this much fun since high school but it is getting old. As for the salt, I don't see any other signs of corrosion. Note: Michigan is the largest producer of Salt and it's all over my car.

I'm glad you enjoy 'real' driving. Never allow your Porsche to sit in the garage.

Something to thank about the weather: Notice how quiet the car is when driving on snow? It's peaceful.

Enjoy your winter!

Ken

[racerken]

Hey Seahawkeye, How do you like your OZs?? I really think they are the absolute best value in high performance wheels. That finish is as tough as nails.

Racerken is absolutely right. These fat wheels collect all kinds of crap in the winter. Way more than enough to throw the wheels out of balance. Your teeth will rattle at 80 MPH. After a messy trip I power wash the wheels right in my garage just to blow all the crap away. With a power washer it does not take much water to do this.

You have a garage with working water? Our pipes are frozen!!!

[Mijostyn]

Hey Seahawkeye, How do you like your OZs?? I really think they are the absolute best value in high performance wheels. That finish is as tough as nails.

Racerken is absolutely right. These fat wheels collect all kinds of crap in the winter. Way more than enough to throw the wheels out of balance. Your teeth will rattle at 80 MPH. After a messy trip I power wash the wheels right in my garage just to blow all the crap away. With a power washer it does not take much water to do this.

You have a garage with working water? Our pipes are frozen!!!

Yes, I have a freeze proof faucet in the garage. BUT, after I use the power washer I turn off the faucet and run the washer till it clears. I had one washer that froze to death. Expanding ice cracked its inners. My garage joins my house on two sides and the garage doors and walls are insulated so, it rarely drops below freezing, maybe twice a year. The floor is well pitched so any water runs nicely out under the doors. I also painted the walls with alkyd semi gloss enamel so, I can spray water all over the place with utter abandon if I want to. In the spring I pressure wash the whole garage. Cleans out all the dirt and spider webs.

A complete set of Porsche exhaust manifold cap screws is $21.00. I was using stainless ones but on careful concideration I switched back to Porsche's plain steel ones. Better to change the screws on occasion than risk damaging your heads. They are easy to change and if they are not over tightened they come out easily. Just replace one at a time. Tighten to 17 ftlb. The screws break due to a process called stress corrosion cracking. Rust forming on the surface creates a stress riser. A crack forms along the lines of stress usually at the junction between the head and shaft of the screw. Rust spreads down the crack and the crack expands until finally the head just snaps off. The more stress the faster the crack develops. Thus over tightening these fasteners is the worst thing you can do.

[api]

Well I finally received and installed the 18" Michelin Alpin PA2s. So far very happy with them this cold weekend in eastern Iowa. There was about 1-2 inches of snow on the ground (with much more around from a storm a week ago) and about 14 degrees F when I drove my car to the tire shop--this was one of the scariest driving experiences I've ever had. Obviously, my car had the summer tires on (19" Michelin Pilot Sports) but it was gliding around even on a straightaway going < 25 mph. I put my hazards on because it was nearly uncontrollable, fortunately only for a mile to the shop. Once they were on, it was like night and day. I had great grip of the road and could turn, start, and stop (and drive straight) with full confidence. Excited to finally have it back, I even took it around some empty side streets where there was still 4-6" inches of snow and developed a good feel for how it handles on these kinds of conditions. Despite AWD/4WD, you can definitely sense the power coming from the rear as I felt a little oversteer that was pretty easily correctable. The TPC/TPMS took a good 10 minutes or so to get adjusted to the new wheels (I had TPMS installed in all 4) but the computer found all four wheels automatically without needing to go to the dealer (but I'm not sure if the tire installer fed the serial numbers into the car before I drove it off). Did change the settings to winter tyres instead of summer in the TPC. Can't explain in words how great it is to have the 997 back in action! OZ had their wheel caps on so I removed then measured them and ordered some black Porsche colored wheel caps from ebay that should arrive this week. Nevertheless, here are the before and after pics as promised!

Hey Seahawkeye, How do you like your OZs?? I really think they are the absolute best value in high performance wheels. That finish is as tough as nails.

Racerken is absolutely right. These fat wheels collect all kinds of crap in the winter. Way more than enough to throw the wheels out of balance. Your teeth will rattle at 80 MPH. After a messy trip I power wash the wheels right in my garage just to blow all the crap away. With a power washer it does not take much water to do this.

I got BBS SR Anthracite wheels. The fat wheels immediately accumulated snow and ice on the down sides when parked outside. And sure enough the unbalanced shaking started at about 40 mph. My low tech solution was to scoop out some of it with my hand - good to keep old gloves around. No unbalanced wheel feel after that at legal highway speeds anyway. While I have water and power wash hooked in my home garage it's too tight so I can only use it outside when its above freezing which isn't often lately. There's a no touch car wash with undercarriage wash option not far off my route so I go there as soon as I am back from a long salty drive.

Edited February 25, 2014 by api

[seahawkeye]

I'm very happy with the OZ wheels. Have the 265 in the back and still happy 1+ year later but admittedly haven't driven it much this winter because of the massive salt/sand on the roads and my limited access to car washing (see other post about washing in winter). My garage is detached and there's no way I will get running water in -20 to 15 degree F weather outside.

Does anyone have a picture of the exhaust manifold screws/fasteners that are replaced?

What exactly do people 'rinse' after taking the car out in snow/salt? You pop open the engine compartment and spray hot water on it? It seems difficult to spray undercarriage without a lift! I would like to drive my car more often in snowy conditions, just worry about the salt and sand destroying the car

[racerken]

Hi Seahawkeye, Iowa has the best wrestlers on earth because they have to shovel their way just to leave the house. I have same situation with a detached garage.

As for driving it every day? That's what i've been doing since 2004 so don't worry. You'll be the only smiling guy on the road with 4 wheel slider.

Go to this thread to check out my pictures of corrosion:

http://www.renntech.org/forums/topic/44118-weekend-maintenance-35k-miles/#entry237588

I had to do a lot of grinding so if you're lucky you can replace the fasteners before they seize. The 12 exhaust manifold bolts remain seized and I also have 1 seized exhaust chrome tip bolt. Other than that, the car is very resistant to corrosion. As for cleaning, I just go to a powerwash place once a month and just gently rinse down from the engine compartment (you can see the blue oxidation the first time) and full power wash from below. Every summer, I crawl underneath (and wheel well) to wire brush all rusted fasteners and paint. These are mostly the ones that secure the plastic panels to the body, nothing major and it's because I'm OCD.

Mijostyn has the good life. One day after the kids our out of college, I'm getting a heated garage or rather a living room with a lift.

[Mijostyn]

I'm very happy with the OZ wheels. Have the 265 in the back and still happy 1+ year later but admittedly haven't driven it much this winter because of the massive salt/sand on the roads and my limited access to car washing (see other post about washing in winter). My garage is detached and there's no way I will get running water in -20 to 15 degree F weather outside.

Does anyone have a picture of the exhaust manifold screws/fasteners that are replaced?

What exactly do people 'rinse' after taking the car out in snow/salt? You pop open the engine compartment and spray hot water on it? It seems difficult to spray undercarriage without a lift! I would like to drive my car more often in snowy conditions, just worry about the salt and sand destroying the car

Seahawkeye, the other way you might be able to deal with stuff in your wheels is to blow it out with compressed air. A little compressor won't freeze but it won't blow hard for long. Running to a car wash in sub zero temps is a bad idea. Water collects in crevices, freezes, expands and cracks stuff like tail light lenses. Ask me how I know.

My wife has just agreed to let me put a lift in the living room. Way to go Racerken :-)))