Winter Tires Sizes..fall 2011? ...also PSS10 Winter Settings?

Hi All, I have been trying to find winter tires for the past couple months for my '99 C4. For the past few years, I have run the Blizzak LM-22, then the LM-25 once they came out. I use 17 inch wheels with the following sizes: F: 255/40/17 R: 205/50/17 After last year, my rears were worn past the point of being decent snow tires. Of course, I thought that I could just "buy" a new set of rears this winter. Alas, that tire size for the rears are not possible to find! Literally, there is one new Blizzak LM25 at 255/50/17 on ebay, but I cannot find a second (new one) anywhere in the USA. ...tirerack.com, discount tire, multiple other online sites. Even worse, I cannot find ANY tire with those sizes for a complete set! Hankook Icebear W300 has rear size, but not the fonts Vredestein makes both sizes but with different speed ratings. (1 month or more until possible shipments to USA warehouse with matching speed ratings) With the C4, I know that matching diameters is important. To get a close diameter, it looks like a 245/35/17 could work for the rear. However, the tire width reduces to about 9.3" (from 10" on the 255/40/17) The fronts 205/50/17 would be 8.1 (reduced from 8.9" stock - 225/40/18) The rears 245/35/17 would be 9.3 (reduced from 10.4 stock at 265/35/18) Clearly the ratios of width reduction is not even close. Yet, the diameter is a close match. So here are my questions: 1) Would that tire size of 245/35/17 even be an option? ...anyone tried it or considered it? 2) Anyone know of any Blizzak LM-25's in 255/40/17? 3) Anyone know of any available winter tires that can be a complete set with: 205/50/17 255/40/17 4) Has anyone tried "raising" a car with PSS10 for the winter? Is the "max" height as high as stock?...higher? Thanks! Douglas

I think the LM-25 has been discontinued. I believe the LM-60 is the current Blizzak tire.

Yes, the LM-60 is the current model. They no longer have the size: 255/40/17 Thus, the problem! BTW - I spoke to the Vredestien USA National warehouse today. They have not yet received at 255/40/17 tires for this year - there is no stock. They do not have an expected shipping date at this time.

Sorry to say you may be out of luck. I went through this about one month ago. Needed 2 rears and no one had them. Got lucky and found 2 new rears in eBay. Keep looking and something may pop up. My old rears have 6mm but didn't want to use them again even though good for one moe season.

After lots of WW research, I have found a couple tires that are available in the correct sizes. 1) Falken Eurowinter HS439 ...about $150 per tire (F + R) 2) Toyo Snowprox S952 ...about $250-300 per tire 3) Hankook Icebear W300 ...about $150-175 per tire 4) Kumho I*Zen (KW27) Tires ...about $250-325 per tire Note: availability is still tough for these sizes in most cases above, the tire pairs are in stock at different locations, requiring multiple purchases to get a set. Does anyone have experience with these tires? I am trying to get the best snow/ice/slush performance rather than dry. I like early morning drives "rally" drives in the snow here in the mountains - one of the great pleasures of a C4. With the thinner, 17" wheels, dry performance is already decreased significantly. If I need a speed fix, I'll wait for a 50 degree weekend in Denver, swap tires/wheels and head out to the track at High Plains. Any thoughts, comments?

For what its worth, I drive an '02 C4 Cab with 18" wheels and it is my daily driver. This will be my first winter with the car and i just put on 17" turbo twists with Nokian's. I was going to go with Blizzak's on the 18" rims but since its a daily driver, i wanted to go with the best traction i could get, thus the 17" rims with the Nokians. While i have yet to test them in the crappy weather, i am looking forward to it. I have used Nokian's in the past on other cars (minivan, Audi S4 and a Murano) and have never been disspointed. If you want the actual sizes of the tires themselves, let me know and I'll look at them tonight when i get home.

Yes, I am interested in more info about your Nokians (size and model). I use Nokians for my Land Rover and have used them in the past for a couple Audis. They are great winter tires. However, the Nokian WWW site does not show any tires in 255/40/17. I think the older "WR" tire came in that size, but the new WR A3 does not. The new version does come in the 245/35/17. ...I am still wondering if that size is an option. Correct diameter, but much "thinner." Possibly, "thinner is better" for snow, but is that too thin?

Rather than make you wait until i got home this evening, I just called the place i purchased them from and here are the sizes of the nokian tires i am using on my c4 cab, which are obviously much thinner than my regular summer tires and they do have them in 255/40/17. If you want the name of the place i purchased them from, just shoot me a PM. Front: 205/50/17 Rear: 255/40/17

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Max spec height on the PSS10 will take you about .5 inches lower than stock on the C4S.

I have a set of the Hankooks on our Audi Allroad on 17" wheels. It's an absolute beast in the snow. This tire, coupled with the Audi Quattro system is great. I have no complaints.

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I'm in a very similar situation (I'd like to get 17" winter tires for a 996.2), with similar issues, as there are very few tires available, and probably no one model that is available for both front and rear. So I'm also considering different sizes. I'm not sure I understand the concern about the ratios of width reduction. I would not be concerned about the resutling front/rear ratio. With 205s front and 245s rear, the (r/f) ratio is 1.2. That's less than with the stock tires for the 996.2 on 17s and 18s and the 996.1 on 17s (1.24, 1.27, and 1.24). BUT it is greater than with the 18" winter tires for the 996.2 and the 18" stock (summers) for the 996.1 (1.18). I also probably wouldn't be cocerned with the difference in Vredestein speed ratings, at least if I am thinking about the same Vredesteins as the OP was several years earlier. The fronts are Vs, the rears are Ys. Since Y is faster than V, and there is no other winter tire available in the front or rear sizes faster than V, there is no problem. But what I am concerned about is whether 245 isn't simply too narrow for the car. Anyone have any experience with this? Thanks!

I've been looking into this also, as my current snows are quite old ... I'm actually thinking about using a 235/45-17 on the back. The diameter is about 1% off from the 205/50 on the front, which isn't too bad. A 235 looks to be about as narrow as I can go and still mount comfortably on a 17x9 rim. Load ratings look to be in the ballpark also ... ratings on the OEM N-spec Michelins are 89 front/94 rear for the stock sizes (205/50 front, 255/40 rear). Several manufacturers either meet or exceed these ratings in 205/50 front, 235/45 rear. I'm still trying to decide what brand to go with if I decide to pull the trigger ... I like Blizzaks, but at half tread life they're basically a glorified all-season tire. I'm actually looking at (*gasp*) the General Altimax Arctic ... they're relatively cheap, studdable (although I haven't run studded snows in years), and have surprisingly strong reviews. They're only Q-rated, but I don't expect to exceed 99 mph on my snow tires. That said, I do notice that the Pirellis carry a V rating, and most of the other brands are either T or H.

Only 17's I could find were the vredesteins. Yes they have different speed ratings front and back. I got closed out last year and had to use summer rubber in the winter. Spent a lot of time driving the truck instead of the Porsche. So this year I started early. Took 6 weeks but the final tire arrived yesterday. I got 4 OEM 17 inch rims for $500, $50 for OEM center caps, two front tires off ebay for $375, one rear for $235 and one rear for $277. Total about $1500 with mounting and balancing. Tires by Web just got a shipment so they may have the rears in stock.

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Interesting. I hadn't thought of going that narrow. I can see it has some advantages, but I'm still not sure I would. I just spoke with someone handling technical questions for one of the top tire manufacturers. He told me that the rule "go narrow in winter" died in the tire industry about 10 years ago, and now the rule is go wide. In fact, the manufacturers are tempted to recommend wider tires in winter than in summer. Apparently wider is better for absolutely every condition except one: lots of new snow. (I'd give a lot of weight to that one, though. If there's lots of old snow on the ground, I can often choose to stay home - and if I don't, the only place I can't go is up a steep hill. If I'm driving and a blizzard strikes and I can barely see where I'm going, then the last thing I need is to be without grip.) On the other hand, I recently (within the last year) saw a review comparing the same winter tire on the same car, in 3 different sizes. While there was very little difference in overall scores, they slightly preferred the middle tire (205/16s). And while wider was better for both braking and speed around a circuit in all conditions, smaller was distinctly better than larger for aquaplaning, both straight line and in a curve. It also provided better snow traction with stability control off (and unless 996s are different from my previous car, you can go up steeper hills with stability control off, so it's traction in such conditions that limits where you can go). Anyway, while I'm not sure I'd go wider than stock, I'd be nervous about going narrower. Also, have you checked tire rack's site to see if wheels as wide as 9" are recommended for the 235s you are interested in? And I'd be worried about curbing the wheels. If I go with 245s, I'll definitely invest in some alloygators to protect them.

Here's a summary of how some size combinations compare: [Edit: The last row can be ignored - there are no winter tires available in size 265/40/17 :-( .] Some notes: 1. The last two columns may provide a clue about whether the tires are too narrow or wide - they show the relationships between the car's weight and the tire's width (in the first of these columns, the total weight with a passenger and some fuel, in the second of these columns, the weight over the rear wheels). I was pretty happy with the winter tires on my previous cars, including one rear-wheel-drive car with a similar power to weight ratio to a 996. So I imagine anything within the same range should be fine. 235s are a bit out of range in the rear, but not much. (I'm also happy with the winter tires on another, 4wd car (not shown) that has about 4.0 kg/mm on the front) - though the power to weight ratio is a lot lower, and most power usually goes to the rear.) 2. (Max) rear diamter: I'd be concerned about rubbing with a taller tire than stock. The 235 rear option is slightly taller, but only slightly, and being narrower should help, so it's probably OK (at least with a car that hasn't been lowered). 3. R/F width: Given that 996.2s are criticized for slow turn in, understeer, lack of throttle adjustability, and inability to break the rear loose in the dry, you would think the lower the ratio of rear to front width, the better. But the 996.1 was not criticized for this, and it had a ratio as low as 1.18. So I'm not sure going lower (as with 235s on the rear) would make sense. (And I'm not sure the ratio is the solution anyway - I haven't searched for the answer yet, but I've nonetheless seen a post saying geometry is.) 4. The F/R diameter ratio column shows the range of stock ratios. However, of the four stock summer & winter size combinations, three have a ratio above 1. If that is the optimum, the one exception (18" winter tires) is already at over a percentage point from optimum, so I'd be nevous about going with a significantly lower ratio than .99. Still, I think these combinations are all close enough. And there is something else interesting in this column. PSM does not allow much oversteer. Zero, apparently. I'd prefer more - as allowed by later 911s, apparently. I believe PSM determines when to kick in by comparing the rotational speeds of the wheels. But if the rear wheels are bigger, relative to stock, than the front wheels, they will rotate more slowly than normal rear wheels would in the same situation. So PSM would allow a bit of oversteer. This makes the 235s look interesting. Of course, even if I understand how this works, it might allow too little oversteer for anyone to notice - no idea. (Anyone have an idea about this???)

I just checked Tire Rack. Not all the 235/45/17s indicate what wheel sizes they work on, but the two I looked at worked on a maximum wheel width of 9", including the Sottozero 3s, which would be my choice in this size. On the other hand, the PA4s, which I'd prefer, are available in 245s ... .

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I'm probably going to pull the trigger on the Generals ... a 9" rim is the maximum recommended width for a 235/45-17.

Did you get the Generals? I'm curious to know how they work out - please keep us posted!

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Actually, I did not. Damon from Tire Rack said that although most tables list a 235/45 as an acceptable fit on a 9" wheel, he thought it would be overly stretched and might expose the bead. So I decided not to proceed. He recommended a 245/45-17 for the rear, but that looks to be a bit taller than I want to use. So I am back to the drawing board.

I'm surprised he didn't recommend the 40s (245/40/17). It's closer to the stock diameters & sidewall heights, as well as to the stock front/rear ratio. Any idea why he recommended 45s?

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Not sure if this helps, but I ran 235/50/17s last winter (fitment from a 2010 Cayman) on my 2000 996 cab, and ran the same size summer tires (the guy I bought the winter snows and rims threw in the summer tires, so I figured I would give them a shot) over the past eight or nine months with no issues. The rear rims are 8.5". I thought the tires would be too tall, but they ended up working out, if only barely by way of height. So, unless I am doing the math wrong, the 245/45 set would seem to fit a 996.

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Nope. 245/45-17 would fit. They're about 3/4" diameter larger than the stock 255/40-17, which probably isn't very much, but I just didn't know if I wanted to add that much height. My rear wheels are 17 x 9, 55 offset. At one point I thought about trying to track down a pair of 8.5" rear wheels from a 986, which I think would've been better suited to the 235/45 that I was planning on using. Then I said the hell with it and went with Plan C, which was the Falken Eurowinter. It's not a great snow tire according to the reviews I've read, but probably suitable to my purposes as I don't drive my 996 in bad winter conditions anyway (I also have a AWD SUV with 4 Blizzaks). On the rear I'll use the Eurowinter HS439 in a 255/40-17. I'll be using a Eurowinter HS449 on the front, in the stock 205/50-17. Hopefully the rear tires will arrive early next week and I'll have them mounted up by next weekend. This weekend's job is to put the Blizzaks on the SUV, which I think I should've done last weekend.

I ended up with Pirelli Sottozero IIIs, stock size in front, 245/40/17 in the rear, and I'm very pleased with them. No complaints on wet or snowy roads (though I've nothing to compare them to). Lots of fun in the dry. More compliant and less noisy than the (7 year old) PS2s that came with the car. I was worried that the rear diameter would be too low when stretched over a 9" wheel, but when I measured the circumfrence, it seemed to slightly larger (under 1 mm) than the front. Though I still think I must have measured wrong ...