jumper5836

True, I think fronts are cutting thought the deep stuff anyways. So the rears are not as important as the fronts.

JBRipps

Hi all,


I have a full set of snows from my '02 C4S. The rims are replica technos, the same wheel on the '04 C4S. I used them for 2 winters, and they are pretty clean. I have Blizzak LM-25's all around. The tires have half the tread left and are unbelievable in the snow. I never once got stuck and the car is so well grounded with the set.

The rears are 10's, and I have the spacers to correct the stock look for the rear.

I think I paid about $1700 all in. I'm willing to sell the entire package for $800.00.

Please email me directly at jbripps@aol.com if you are interested. I live in the NY Tri-State area. Tires are still mounted on the wheels, so shipping would be a bear.

Thanks, and sorry for barging in here.

J

remedy451

I went ahead and ordered the Blizzak LM-60's (225/40/18 & 275/35/18) from Tire Rack. Came to about a grand cheaper than any price quoted locally in Calgary - and the fact that they're being delivered directly to the shop that's going to install them is a bonus!

Thanks everyone for your input into this thread.

Dennis C

I would think that even though you have a larger contact patch, you still have less weight per square inch on a wider tire, which may not necessarily lead to improved performance or traction on slippery surfaces. I'm just speculating - I'm sure that there are tire experts that have looked at all the data and could tell us for sure.

BruceP

I think the value of narrow tires is that they cut through soft stuff to find a firm surface. That's about it. Otherwise, the basic nature of the mechanical grip that sticks a wide tire to warm pavement is the same as the one that sticks it to cold pavement, ie. a bigger contact patch is better. The critical difference with a winter performance tire is that its compound stays sticky in colder temps, and its tread is designed to manage moisture better than a typical summer performance tire can.

The idea that more weight per square inch helps with traction on ice is kind of counterintuitive if you think about it: Consider a skate blade, which uses exactly that principle to generate a lubricating layer of water.

I went with OE widths because I don't drive the car if the snow is more than spoiler-deep, or there's slush piled up between lanes such as after a storm. Then, you'd be right, a narrow tire would be safer. But I prefer to trade off those rare (around here) days in exchange for keeping some of the fun to drive quotient.

I don't think there's a right or wrong choice, just the compromise that suits your conditions.

brad@tirerack.com

On the stock 11" wheels 265 is too narrow and not recommended. The new 275/35 LM-60 is a better idea. If fits better, and looks better.

bentlink

I have a daily driver 996 C4S (live in Kelowna, BC).
Bought new rims/tires for summer, and mounted
225/40R18 DUNLOP WINTER SPORT 3D (front) and
275/35R18 DUNLOP WINTER SPORT M3 (rear) based on Damon's Tirerack recommendation.

They worked wonderfully and look fine on the stock C4S Turbo Twist 2's.

Loved it. Wonderful winter car.

But my rears are worn out... so plan to replace them with the 285/35ZR18 SP Winter Sport M3 (if the aspect ration is OK)...

Damon? Anyone?

brad@tirerack.com

Not recommended. 285/35 is about 26.2" tall vs. the 25" tall front - outside of the 4% they recommend you stay within. You risk doing differential damage doing this. 265/35 or 285/30 with a 225/40 please.

Dennis C

I hear ya.

My knowledge of tribology is more in the realm of artificial joint replacements and other load bearing applications. In those situations, a larger surface area means less weight per square inch, and means the forces are distributed over a larger area. As a result, the two surfaces slide more easily against each other, and there is less wear. The same thing seems logical for a tire - larger area means less weight, meaning easier sliding. Obviously sliding is a bad thing in the case of the tire.

Right or wrong, I agree that the proper tire compound is the most important thing. I can't imagine there is a huge difference in terms of grip between a 265 and a 285 on ice or snow.

BruceP

The physics of a tire on the road, where traction is concerned, aren't really about load bearing. They're about mechanical friction. Exhibit A is race cars, which are both lighter than street cars and employ larger contact patches to achieve higher lateral adhesion, adhesion being the key, here. To illustrate, imagine dragging a hand towel across your living room carpet. Now imagine dragging a bath towel across that carpet. Which one is going to take more tugging to make it slide? It's a lame but essentially correct analogy for the way that rubber and asphalt stick to each other. And it's why bigger contact patches mean more traction, regardless of vehicle weight. Braking depends on the same physics.

(With regard to wear, remember that a tire is meant to sacrifice itself to its job. A tire that didn't wear would suck.)

What winter tires do is preserve the mechanical friction that would otherwise be lost to temperature, when summer rubber hardens (I think they call this 'glassing up' in the business).

A tire for deep snow is narrower because it's trading off adhesion for the ability to find a firm surface. It's a compromise I wouldn't make with a tire that was going to spend most of its time on cold, wet pavement at highway speeds.

Dennis C

Thanks for that clarification. I appreciate the analogy. I absolutely understand it for dry applications, and I think you've given me a better understanding of it for wet/snow/cold applications. I guess the thing that made me think differently about it (aside from what I mentioned above) is the fact that many people in my part of the country put extra weight in the trunk or truck bed during the winter to get more weight on the drive wheels during the winter. This tends to make you think that the force per square inch issue is more important, justifying the need for a narrower tire. You see what I mean? Thanks again for the clarification.

In my case, I ended up going with the Porsche recommended winter tire sizes, which are 265s for the rears (not exactly what I would call a narrow tire anyway) vs. the 295s that are on for summer. I'm sure they'll do fine.

htny

Anyone ever try the Toyo Proxes 4?

I just got a note from my old tire guy about this tire being available in low profile, 11 inch specs. (I run their T1R on the 19s, mostly because it was the only tire available that would fit without rubbing at the time). The T1Rs are excellent rain tires in general, as long as you keep your foot out of the power in the cold. I just did a road trip up to montreal and back in 45 degree weather, raining buckets for 750 miles up and down a couple of weeks ago, and even with 14K on the tires they were flawless, however they are approaching replacement in the near future.

So apparently the Proxes 4 is M&S rated (Mud and Snow). While I have an AWD car for the snow, it would be nice to have an all season, cold weather tire that could handle some slush from time to time, just so I can take advantage of clear, cold winter days. Plus I like the idea of just having one set of wheels and tires (since my 17s seem to have disappeared). I run 19X8.5J ET40 up front and 19X11J ET67 out back (and I have some extra spacers in case I need another couple of mm back there). Available in 245/35 R19 and 295/30 R19, RDs are 25.7 and 25.9 respectively. I'm currently running a little short at 315/25/19 out back which at full tread depth is 25.2" RD (same as many 997 fitments)

Price look like 270s for the rears and 170s for the fronts, so very inexpensive for 19s

Any experience/opinions on this Toyo Proxes 4 tire in the cold and any comments on the RD?

pongobaz

Yup, I run 295/35/18 for the rear matched to 235/40/18 front; you need to go to the wider front to keep the front/rear rolling diameters within tolerances so not to confuse the ABS/PSM sensors. Yes, the Snowsport 240 are no longer available at TR (I did find a new old-stock set of rears locally to replace my worn ones), but they've been replaced by the Sotto Zero II in the same sizing. Contact Damon, he'll set you up.

jumper5836

bump because I know this is gona come up again very soon.

Looks like for a C4S the
Pirelli Winter 240 Sotto Zero II
235/40/18 f
295/35/18 r

are the best choice still for winter performance? any new stuff out there to be aware of?

adg44

If anyone is looking for a set of OEM wheels in great condition (only 18k miles on the wheels) and as-new Bridgestone Blizzak LM-25's (only 3k miles), I'm selling mine. I sold my Porsche earlier this month, so I have no need for the wheels. I'm located in Northern VA.

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