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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996 C4S tire sizes
Leading reported evidence
Run pilot super sport in 235/40r18 and 285/35r18
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I ran Pilot Super Sport in 235/40R18 and 285/35R18 for a year, and it didn't destroy the front differential.
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Suggestion · Original poster
I want to buy MICHELIN PILOT SPORT 4S for all four, however they're not available in 285/30/18 that's recommended by the owners' manual but they are available in 285/35/18.
Leading evidence: 'Run pilot super sport in 235/40r18 and 285/35r18' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Recommend by the owners' manual' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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I run PZero's and love them, even compared to the PSS.
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Performed · outcome unconfirmed · Original poster
I've mostly used Michelin tires with occasional pirellis and bridgestones and have been extremely happy with Michelins.
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The problem is that the 265 rears are too narrow to be used on standard 11" wide rims.
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Suggestion · Original poster
I want to buy MICHELIN PILOT SPORT 4S for all four, however they're not available in 285/30/18 that's recommended by the owners' manual but they are available in 285/35/18.
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Recommend by the owners' manual
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Suggestion · Original poster
I want to buy MICHELIN PILOT SPORT 4S for all four, however they're not available in 285/30/18 that's recommended by the owners' manual but they are available in 285/35/18.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Even the stock 19" 997 tires offer cheaper alternatives for good tires such as conti extreme sport contact or bridgestone s-04 (both run about $1,000 per set).
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Hello,
Before I get cited by the forums Police for asking these questions, YES I've spent hours searching and reading other posts. I have not found the answer.
I want to buy MICHELIN PILOT SPORT 4S for all four, however they're not available in 285/30/18 that's recommended by the owners' manual but they are available in 285/35/18.
Ideally I'd like to have the 225/40/18 in the front and 285/35/18 on stock wheels if it doesn't cause any issues.
Please also share what tire sizes you've successfully run on your 4S stock wheels.
Thank you!
If you want the awd system to work, the front tires must have a diameter greater than the rear.
I ran Pilot Super Sport in 235/40R18 and 285/35R18 for a year, and it didn't destroy the front differential. It did have more understeer, which was fun. But eventually I relented and went back to stock sizes.
There are people who claim 225/45R18 will (or can be made) to fit on the front by modifying the radiator brackets. This would give you 802 revs per mile front, 804 revs per mile back. Which would be perfect.
Good luck!
...not really.
I run PZero's and love them, even compared to the PSS. Other people use the Sumitomo HTR III and like them. Tire Rack even has POTENZA S-02As in those sizes.
The other option is to remove the front differential and drive shaft...and take the AWD system out of the car. Then you can run GT2 sizes if you wanted, or the 285s.
No No No No! I've always wanted a proper 4X4 LOL this one's gonna be a keeper. I've mostly used Michelin tires with occasional pirellis and bridgestones and have been extremely happy with Michelins.
I'll look into the other ones you've listed. Thank you!
I can't offer much help because I have 19s... but I have Pilot Super Sport tires on mine and have been very happy with them. They may be available in a few additional sizes.
When I bought the car it came with 235/35/19 in the front and 295/30/19 in back - which is the standard setup for the 997 C4S.
I recently switched the front to 245/35/19 though. I like this setup better because I can inflate everything properly without throwing the circumferences off too much.
Interesting. Need to crunch up some numbers tonight to map out the possibilities... Sounds like as long as front tires have a diameter greater than the rear we're good.
The Porsche recommended sizes for winter tires are 225/40-18 and 265/35-18. The problem is that the 265 rears are too narrow to be used on standard 11" wide rims. 235/40-18 works for front clearance and 275/35-18 is ok on the 11" rear rims. The diameters are a good match. 285/35-18 is also seems to be a reasonably close diameter match and is a bit wider.
I totally understand where you are coming from OP. I, too, have looked into tire options in anticipation of when I have to replace mine. Unfortunately, almost all of the OEM-sized tires are N-rated options that are still made (bridgestone, pirelli, michelin PS2) and are very expensive ($13-1400/set iirc), and not as good as modern options such as the PS4S (they cost more too). Even the stock 19" 997 tires offer cheaper alternatives for good tires such as conti extreme sport contact or bridgestone s-04 (both run about $1,000 per set).
I'm hoping that Michelin starts offering the PS4S in our size, but dont see it being highly likely. I may either go to a 19" wheel or try out a set of the Sumitumo tires for less than half the price. A lot of guys on the turbo forums seem to like them as strath said.
Porsche say to get it as close to even as possible, but definitely not to exceed 3% circumference difference. Many people on the forums have said that having front slightly larger than rear is the preference (vs. the rear being larger than front). I've found this to be true. The rear tires are typically inflated to a higher pressure, and increases their size - so I'm guessing that has a lot to do with it.
I have mines mounted with 235/35 R19 (25,5 Diameter) on the front and 295/30 R19 (26 Diameter) on the back, four corners on Michelin Super Sport.
I think it should be a good setup, since it is the standard setup for the 997 C4S with 19"s, and the AWD system is basically the same (997.1 had the same viscous multiplate clutch).
I also have read several times that the rear diameter should be as close as the front as possible (or even smaller) but I dont know what is the basis for that, taking into consideration the 997 setup is like that.
An alternative could be, to mount on the rear 285/30 R19, which are closer to the front (25,7) and will fit on the 11" wide wheels.
Thank you for your reply. I've decided to go the Sumitomo route until I figure out get new wheels. the PS4S are very well worth the price. They are in my opinion the Best all around premium tires on the market.
My C4S came with 225/40/18's one the front and 295/30/18's on the rear. I have 235/40/18's and 295/30/18 on a set od Kenisis rims and 225/35/19's with 305/30/19's on a set of 997 TT rims, For St Louis, the 19's gave me too harsh a ride with a crap roads.
I have read that a lot of times, but as far as I know, there is not technical justification for that. Where did you get that information?
Actually, the 997.1, which shares the same AWD system than the 996, runs on wheels with bigger diameter on front. Besides, according to Adrian Streather statement in his book "Suprem Porsche", there is no documentation or technical reason for that requirement neither.
Just want to know if I am missing anything.
So, the 997.1 and 996 share the same front limited slip viscus coupling system. It works like a torque converter, in that power is transferred when the input shaft (running from the front of the transmission) is turning faster than the output shaft (leading to the front, open differential). The actual viscus clutch part number is the same between 997.1 and 996
In the 996 this means power is only transferred forward because the rear tires are smaller than the front, and that, coupled with the final drive ratio for the front sets the conditions for the input shaft to turn faster than the output. The 997.1 has a different final drive ratio for the front. So the rear tires can be larger than the front, but the input shaft still spins faster.
What I don't know is if the different front final drive ratio is built into the G97/31 gearbox or if it is in the front open differential on the 997.1.
Thanks Strathconaman,
What you mention, is only valid for the "stationary" split of power between both axles. If you modify the circumference of the wheels, you are modifying the differential speed between both shafts. Even though, that effect is really low (in comparison with the effect of the final drive ratios) on the split of power between the rear and the front. We can be talking of having 4% in the front vs 5% in normal conditions. However, when the rear wheels spin faster because they slip, the 4WD system is going to work the same way.
I will tray to reproduce the part of the book that I mentioned where it is actually addressing exactly that aspect of the 4WD system.
Looking into some summer options and this thread has been a big help.
This site is great for comparing F/R options in relation to % difference for the AWD concern -
https://tiresize.com/calculator/
Not related to the OP, but to the last page of discussion or so.
I am going to be picking up a C4 this weekend that currently is running 225/40R18 in the front and 265/35R18 in the rears.
I plan on getting the right set of wheels and tires put on the car eventually, but will I damage the front differential driving the vehicle 1000 miles home with the .86% larger diameter rear tires?
