Would you recommend winter tires over all-seasons? I probably only need to use them for about 3 or 4 months, so I'm thinking that maybe winter tires are best, so that I can get through a little snow if necessary.

 

Yes, the concern about damaging the tires when swapping them on the same wheels was raised by my local Porsche dealer. Sounds like it's doable though, from your experience; maybe the installer would be more careful if I watched them while they do it (I watched the process when I had a flat tire repaired for my C63).

Plus, I'm not keen on the idea of spending all that money on extra wheels and TPMS either, especially since I have to deal with this for three cars.

 

Just had Pirelli winter tires placed on my c4s with oz ultralegerra wheel with TPMS sensors. Wife has PS 2 on her Boxster but doesn't drive it much in winter with temps in Seattle in sub 35 temps. Drives SUV. I drove her Boxster yesterday but only spirited straight line shifting to perk up the car. Thinking I might get Conti all season replacements vs Pilot Supersports (summers on my 911)

 

Damon @ TireRack can explain the issue (and sell you some N rated snows). The rubber on a summer tire basically gets as hard as rock below 38 deg F. Though the winter tread pattern is also a help it's the compound that allows the rubber to remain pliant to 0 deg F and lower. Anyone who thinks that just driving a summer tire will 'warm it up' should get a spot thermometer and check the tires. I'd love to see a 911 with steel wheels; anyone have that set up ?

My snows are on 18" Carrera IV wheels. With a $180 lift you can switch the snows in 30 mins. Cleaning the wheels takes me as long as the mechanical work.

http://www.tirerack.com/accessories/detail.jsp?ID=68

 

+1, but still waiting for the Sotozero's. You'd think with the so called recession Pirelli would make all the Sotozeros they could sell. In the Porsche size 295-30-19 there are none to be had anywhere in the states. My dealer can't get 'em either. Guess you need to buy them in the summer.

 

Tirerack has them, they're just not posted on the website since they're low on supply. (I just bought that exact tire and size from Damon last week after STS told me nobody has them, and Damon told me why the confusion).

Re the suggestion from another poster about buying all seasons: Sure you'll save some bucks but you're giving up performance in one of the most critical aspects of the car or put differently you'll never have the best tire for the given season.

 

I have a brand new set of Mich Lattitude (summer only) tires on my 08 Cayenne GTS. Even on that vehicle w/AWD and broken-in tires (couple thousand miles) there was a SIGNIFICANT difference in grip in the cold, and even more so when the roads were wet. In fact, even during normal driving they were a bit scary for me. I purchased a set of 18" Mich Alpine snows for the winter (I'm in MA) on dedicated rims and it made a world of difference - MUCH more confidence now. I always have a set of dedicated snows mounted on their own rims for this very reason and I make sure my kids' cars have the same for safety. Allot of this really depends on the tire - brand, compound, air pressure, etc. Also, while I don't have any hard evidence, I don't think driving around to warm up your tires makes much difference (especially in 30 degree weather or lower) unless you're drifting around every corner. I don't think the tires warm up that much when it's that cold and when the roads are freezing cold as well. Of course, my GTS doesn't handle as well with the snows, but it's well worth the sacrifice for a few months for the safety. I kinda like the idea of prolonging the life of my very expensive summer tires by not driving them in the winter as well...

 

I ordered my Pirelli sottozeros in sept. the 295 30 19 were the last to arrive on my ultraleggerras. Came in mid of nov from tire rack

 

Here in the Bay Area of Norcal we get sub-40 F and frost and sometimes snow, especially in the Santa Cruz Mountains.

My GTS is running Pilot SS tires, and I take it easy when the temp is in the low 40s, and never use Sport Mode at these temps. I always monitor the temp gauge so not to get caught out.

In my experience with the Pilot SS tires, pushing harder results in a bit of sliding, so I leave margin in case of emergency or avoidance maneuver.

Have fun driving and be safe,

UJ

 

http://www.perkinelmer.com/CMSResour...TireRubber.pdf

I don't know how relevant it is to our specific stock tires, but the lower graph in Figure 1 suggests that maybe tire performance wouldn't be much worse at 30 F compared to 40 F. But I'd still like to see a graph for our specific tire, and which plots grip (eg, braking distance or skidpad g) versus temp.

 

We had a rare dusting of snow last winter. The Porsche had new PS2s so I thought with advantage of the rear engine it might be better than my other car with summer tires. No way. Couldn't even get out of the driveway. Amazing how slick they were!

Just did a track day. First session was 34 deg F. On R compounds. It was like the track was wet. 4 laps to warm the tires then it was just OK. Much better when the sun came out and warmed the track to 50 deg.

 

Based on everything I've read in this forum and elsewhere, I'm convinced that summer tires are hopeless and dangerous in any amount of snow.

On dry roads, the variation of grip with temp is what I'm now trying to pin down. The 40 F temp seems to be the most common benchmark, but I doubt that we can go all out at 42 while having to tremble in fear at 38. There has to be a transition range from excellent to lousy grip, but I don't know what that transition is. I did happen to do some spirited driving this weekend at temps of 41 to 44, and didn't notice any reduction in grip, but I was holding back somewhat. I also did some braking tests at temps around 33 to 35, and didn't notice a big reduction in braking force, though there might have been some.

As far as warming up the tires by driving the car, I might try to run a quick calc to estimate that by relating temp to tire pressure (using PV = nRT), since we can use our TPMs to easily get pressure data.

 

That's exactly what I use to get a feel for how warm (or not) the tires are getting - the temp readouts. I've actually found that during the first several miles of travel in cold temps (mid-low 30s), even on the highway, the pressure actually goes down a couple of degrees which I relate to the tires actually getting a bit colder, not warmer. I think this is due to my car being parked in a heated garage - but it's not all that warm in my garage - mid to low 50's when it's freezing outside. When it's cold and the roads are wet, the pressure goes down even more and faster. It takes quite a lot of miles to even get them back up to cold pressure again - not sure exactly, but I'd say 30-40 or maybe even more. Bottom line, there really is no good substitute for dedicated winter tires, especially in the cold and snow regions. If I lived in a state where it would get below 40 and snow only very occasionally then I probably wouldn't bother but here it New England it's an absolute must in my view.

 

Yes, I have the same situation with the garage, so I expect the tire temp to drop before it increases again. At work, my car stays in a covered but open garage, so that should eliminate the initial drop in tire temp.

Another complication to consider is that tire pressure relates directly to the temp of the air in the tire, not the tire itself, so the temp of the tire should be intermediate to the temps of the air inside and outside the tire.

 

It really depends on where you live and how you drive. I had summer tires on E55 all winter last year in Seattle and it was fine. I didn't drive the day after the big storm (which was only 2" but it was enough to shut down the city). The car handles fine as long as you don't drive a jerk and keep a good distance between yourself and the vehicle in front.

This year, I have installed a set of Bridgestone Potenza 970AS that were just released on my 4S. My reasoning is that I don't drive in the snow any more so I only need the more compliant rubber compound for low temp driving. I don't drive that aggressively in the winter so it works well for me.