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hi, the new Michelin 4S tires are not an exact fit for the rear for the 996 with 18". Do you think the other size would fit and not rub? Maybe 285/35ZR18/XL (101Y) or 275/35ZR18/XL (99Y)

 

 

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Sorry, I don’t understand the question.

I run almost the same tires as Loren noted on my 2003 C4$.  Michelin PS2, N3, 295/30 on the rear, 225/40 on the front.

Porsche specs. 

What’s the problem?

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The problem is that the Michelin PS4S tires are not available in the proper sizes.  And the 4S is a much better tire than the PS2 and is also much cheaper.  The new 4S is arguably the best tire available for street use at the moment.

 

I plan on running 235/40R18 on the front and 285/35R18 on the rear as the OP had suggested on my 02 Targa with 11" rear wheels.  I'm pretty sure it will work, but I haven't actually tried it yet.

 

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Appreciate your take on the tires. 

I can say that I used several sets of tires by other makers, changing all 4 at a time, liking Pirelli P Zero rosso a lot, and Bridgestone Potenza as well.  But when I ran on the Michelin PS2 they were just simply the best.  

I don’t even search for others now.

I’m curious as to the basis of your comment re PS4S.  I haven’t thought about other tires in years.  

Difference might be that my car is all-wheel drive 4$.  

Cheers, 

 

 

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The PS2 is now an old tire and uses the same technologies that it was developed with a long time ago (almost 20 years I think).  It was superseded by the Pilot Super Sport (PSS) and now the Pilot Sport 4S (PS4S).  There are lots of articles discussing the improvements that were made, but the quick summary was that the PSS was better than the PS2 in every dimension.  The PS4S apparently improves on the PSS.

 

I ran through 2 sets of PS2 tires before switching to the PSS.  The PSS has noticeably better traction especially on wet roads.  It rides quieter, lasts longer, and is cheaper.  But sadly the new tires do not come in the proper sizes for the 996.  I'd still rather run non-standard sizes than switch to another tire though.

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As far as dry traction goes, the PS2s were the best of the 3 Michelin tires mentioned here. Sure, the MPSS and the new PS4S are better in the wet, last longer, and are less $. But I only care about dry traction. I do miss the old PS2s.

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Actually Michelin's own testing showed better performance for the MPSS on dry tracks compared to the PS2 according to Motortrend.

https://www.motortrend.com/news/testing-the-michelin-pilot-super-sport/

 

Also 'dry' score the on Tirerack's survey page shows a 9.6 for the 4s compared to a 9.3 for the PS2. 

https://www.tirerack.com/tires/surveyresults/surveydisplay.jsp?type=MP

 

I've logged more than 30K km on both tires including a handful of trackdays on each.  I'd still take the MPSS any day over the PS2 even if I never drove in the wet.  And the 4S is apparently better in every dimension.  Just wish Michelin would support more sizes for 18 inch wheels ?

 

 

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Lots of good information here. 

Thsnks, as I will be looking and shopping around in a few months.  

03 C4$.  Liked and would likely again put on PS2.  220 AA A rating also pretty good. I live in wet coastal climate with all roads in/out twisty and over hills.  

Good Porsche country.  Little or zero snow.  So I can use summer tires all year without changing to all-season M&S.  Especially like PS2 AA traction in wet conditions.  How do other tires noted compare on sidewall ratings?

Spouse drives X5 with Pirelli Scorpions, rated 520 A A.  That’s ok on big suv.  Wear important to her. 

My former 911SC ran great on Potenza’s, as I recall rated 180 AA A, again year round use.  

I’m often on the road in hot country in summer playing music.  Grip in heat and wet conditions my prime consideration.

If we do get very cold, snow conditions and ice, which is rare, but does occur on the mountain occasionally, C4S stays home.

Comments on PS4S treadware, traction, temp ratings will be welcomed and appreciated. 

 

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Thanks for all the feedback. I think its a good discussion going on. To clarify the topic:

 

Porsche has tires specs for the 2002 911 Carrera:  

Front: 225/40 ZR 18

Rear:285/30 ZR 18

 

The 4S are available in the following sizes:

Front: 225/40 ZR 18 (perfect fit)

(rear will fit?) 275/35ZR18

(rear will fit?) 285/35ZR18 => Loren says 295/30ZR x 18 fits so maybe this is the closest fit?

(rear will fit?) 265/40ZR18

 

Here is a link to the available tire sizes:

https://www.michelin.ca/CA/en/tires/products/pilot-sport-4s.html#Sizes-and-versions

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I spoke of tire width change and what will fit under the fenders without interference.

You want to be careful changing the tire height profile. Changing the tie height profile changes the tires rolling diameter - which can affect ABS , PSM, and GPS. As I recall Porsche recommends no more that a 5% change in overall rolling diameter.

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Posted (edited)

Resurrecting an old thread...

 

I'm moving on from a set of Pirelli P-zeroes that I "inherited" when I bought my 2004 Anniversary Edition (235/40r18 and 295/30r18). I want to get a set of Pilot Sport 4S, but they still don't make the proper rear size. Smokeman909, what did you end up doing?

 

My winter tires are 235/40r18 and 265/40r18. They don't throw any errors ( ABS, PSM, or TPMS). They give up 1" in height, but 1.2" in contact patch width. For winter, that's fine. It's arguably beneficial. But for summer, I'd prefer not to give up the width. I'm considering keeping the front at the recommended 235/40r18 and stepping down to a 285/35r18 for the back on the new summer tires. According to online calculators, that tire gives up .4" in contact patch width, but 1.4" in height. My understanding is that changing the height of the tires, or more specifically changing the proportional height of the front to rear tires, will cause errors to be thrown by ABS, PSM, or TPMS. The 285/35r18 is a 5.1% size change compared to the 295/40r18. Has anyone successfully run this size of tire?

 

Thanks in advance for any input. I'm hoping to take advantage of Discount Tires' 15% discount this weekend and set myself up for summertime!

 

Edited by Kip
poor grammar, incorrect stock tire size listed

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Posted (edited)

Updated after initial posting...

Yep. As predicted, I made a mistake. The stock size for the Carrera is 225/40 r18. I entered it as 225/30. Updating to the proper spec changed the low end of the stock f/r tire diameter ratio range. This bumped one of the original options off the list. I've updated the long, rambling detail below to reflect this. I've also updated the attached .pdf with my data

 

 

So I nerded out last night and did some analysis to answer my own question. Thought I would share it with the group in case anyone else is considering the Pilot Sport 4S for your 996 C2. If you don't want all the background info, jump down to "Results".

 

My situation: I'm shopping for a daily driver/summer tire for my 2004 996 40th Anniversary model. It has the VF Engineering supercharger. It is running 8x18and 10x18 wheels. My goal was to find a good performance tire that performed in the wet and dry, might be able to handle a track day or two, isn't excessively loud, and would last for ~15k miles at a minimum. I liked the Pilot Sport 4S. This tire is made in the proper front tire size (235/40 r18), but not the proper rear size (295/30 r18). Michelin does make a 285/35 r18. I wanted some level of assurance that I could choose a front tire that would work with a 285/35 r18 without causing problems for PSM or ABS. I'm not too concerned about speedometer or odometer inaccuracy that can happen with tire size changes.

 

Base assumption: My understanding is that the speed sensors that "tell" the ECU to throw errors to PSM and ABS are sensitive to changes in tire size. Specifically, changes in tire size differences between the front and rear tire diameters. So if a car has all the same size tires, it has a 1.00 ratio for front to rear tire diameter. With this 1.00 ratio, the ECU interprets everything is fine as long all four wheels are turning at the same speed. If you were to put a smaller tire on the front only or a larger tire on the back only, you would deviate from the 1.00 f/r tire diameter ratio. The speed sensors would see the front tires turning faster than the rears. If this deviates beyond whatever the ECU deems as acceptable, it will throw PSM and ABS errors. Based on this, my decision for a front tire to match the 285/35 r18 needs to be directed by the f/r tire diameter ratio.

 

Analysis approach: Using Michelin.com, TireSize.com, and TireRack.com, I collected info about tire diameter, width, and sidewall for three stock sizes for a 2004 996: Carrera, 40th Anniversary Edition, Winter. I calculated a f/r tire diameter ratio for each of these stock sizes. I used the max and min from those three data points to determine an acceptable range for the f/r tire diameter ratio. It's assumed that the stock sizes would not throw PSM or ABS errors. From there, I looked at the sizes available for the Pilot Sport 4S that fit an 8" front wheel. I calculated a f/r tire diameter ratio (against the 285/35 r18) for all tires that fit an 8" wheel. I found six five sizes that had a f/r tire diameter ratio within the range defined by the stock sizes. These six five tires represented my potential front tire selections. I then considered the overall diameter of the tire. I didn't want a tire that was taller than any of the stock sizes for fear of rubbing. That took the six five choices down to three two. Finally, I considered width. Width gives some indication of contact patch. Since the 285/35 r18 will be the rear tire regardless of the front tire size chosen, the steering dynamic could be slightly modified with front contact patch: more contact patch = less understeer, less contact patch = more understeer. I find my car to have more understeer than I'd prefer. The rear contact patch of the new tire would be slightly smaller (.4") than what I currently have, so that will potentially dial back some of the understeer. To avoid negating the change created by the rear tire or to potentially decrease understeer further, I wanted a front width that was at least equal to or greater than my current stock front tire . That narrowed it down to two one front tire choice.

 

Results: Based on above, the two front tire size that should fit without rubbing, not throw any errors, and potentially provide a driving dynamic with less understeer are 235/40 r18 and 245/35 r18. The 235/40 is the stock 40th Anniversary front tire. Yes, all this work and I came back to "stock size is the recommended size". At least now, I feel it was less than a guess. Interestingly, the 245/35 would be a fatter tire, having .3" more width than stock. Could it rub on full steering lock? Maybe, but I'd be surprised if the tolerances are that tight. Will the extra .3" of width in front coupled with the decrease of .4" of width in back turn this car into a 911 of old where I'm going to oversteer my way *** backwards into a field somewhere? Maybe, but that's more of a reflection of the car's real weak point: the nut holding the steering wheel.

 

Hope this helps someone. Take it with as many grains of salt as necessary. I hopefully haven't made any ridiculous assumptions or stupid math mistakes somewhere that negates all of this work. Data and details are in the attached file, if you want to see how I came to my conclusion. Be aware that each snapshot from TireSize.com has front/rear tire combinations, not comparisons of one size of front tire to another. Now I'm off to decide whether I want to experiment with the fatter front tire at the risk of having to buy front tires twice.

 

-Brad

 

Tire size comparison.pdf

Edited by Kip
Corrected data point and updated analysis

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That's great timing.  My current Hankook tires are completely worn and I need new tires before I bring my car out of hibernation.  I was planning on buying the MPSS in the same rear size as you suggested above, but I wasn't sure about the front size yet.  Your analysis definitely helps, and I'd also like to reduce oversteer on the car so if there is a chance that the 245/35r18 would fit I might try it.  I'd have to double check that the tires would fit on a 8" wheel though.

 

Has anyone run with these sizes yet?

 

 

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According to Michelin, the 245/35r18 will fit an 8" wheel. That said, it creates a f/r diameter ratio of .95. That's a little bit below the stock range ratio for winter of .97. I  was assuming that since the stock sizes won't throw errors, anything within the range of ratios from the stock sizes would also not throw errors. This one, being outside of the range may throw errors. I wasn't willing to risk it. I bought the 235/40r18.

 

If you go with the 245/35r18, please let us/me know if they fit and throw errors.

 

-Brad

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Thanks Brad.

I think you right in that a 5% difference in sizes is way too much.  Adding a bit more width up front would be nice, but it isn't worth the risk to me.  I'll also go with 235/40. That actually helps solve another minor annoyance I have surrounding the front bumper.  My car is only H&R coilovers and below the stock height which means I occasionally scrape the front bumper on steep driveways.  The coilovers are at their maximum height setting but adding slightly more sidewall on the front wouldn't be a bad thing.

 

I'm probably going to order tires next week ?

 

Kevin

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